SERVER-13641 rename TransactionExperiment to OperationContext

168 files changed, 919 insertions, 923 deletions

diff --git a/src/mongo/db/auth/auth_index_d.cpp b/src/mongo/db/auth/auth_index_d.cpp
index 09c289b70c7..2b510698b60 100644
--- a/src/mongo/db/auth/auth_index_d.cpp
+++ b/src/mongo/db/auth/auth_index_d.cpp
@@ -38,7 +38,7 @@
 #include "mongo/db/dbhelpers.h"
 #include "mongo/db/index/index_descriptor.h"
 #include "mongo/db/jsobj.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/util/assert_util.h"
 #include "mongo/util/log.h"
 
@@ -84,7 +84,7 @@ namespace {
 
             // Make sure the old unique index from v2.4 on system.users doesn't exist.
             Client::WriteContext wctx(systemUsers);
-            DurTransaction txn;
+            OperationContextImpl txn;
             Collection* collection = wctx.ctx().db()->getCollection(NamespaceString(systemUsers));
             if (!collection) {
                 return;
@@ -97,7 +97,7 @@ namespace {
         }
     }
 
-    void createSystemIndexes(TransactionExperiment* txn, Collection* collection) {
+    void createSystemIndexes(OperationContext* txn, Collection* collection) {
         invariant( collection );
         const NamespaceString& ns = collection->ns();
         if (ns == AuthorizationManager::usersCollectionNamespace) {
diff --git a/src/mongo/db/auth/auth_index_d.h b/src/mongo/db/auth/auth_index_d.h
index 09547a1f47c..3d3cf711e40 100644
--- a/src/mongo/db/auth/auth_index_d.h
+++ b/src/mongo/db/auth/auth_index_d.h
@@ -33,7 +33,7 @@
 namespace mongo {
 
     class Collection;
-    class TransactionExperiment;
+    class OperationContext;
 
 namespace authindex {
 
@@ -41,7 +41,7 @@ namespace authindex {
      * Creates the appropriate indexes on _new_ system collections supporting authentication and
      * authorization.
      */
-    void createSystemIndexes(TransactionExperiment* txn, Collection* collection);
+    void createSystemIndexes(OperationContext* txn, Collection* collection);
 
     /**
      * Ensures that exactly the appropriate indexes to support authentication and authorization
diff --git a/src/mongo/db/catalog/collection.cpp b/src/mongo/db/catalog/collection.cpp
index 531f59eeccf..245d34fa151 100644
--- a/src/mongo/db/catalog/collection.cpp
+++ b/src/mongo/db/catalog/collection.cpp
@@ -40,7 +40,7 @@
 #include "mongo/db/dbhelpers.h"
 #include "mongo/db/index/index_access_method.h"
 #include "mongo/db/ops/update.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/db/structure/catalog/namespace_details.h"
 #include "mongo/db/structure/catalog/namespace_details_rsv1_metadata.h"
 #include "mongo/db/structure/record_store_v1_capped.h"
@@ -76,7 +76,7 @@ namespace mongo {
 
     // ----
 
-    Collection::Collection( TransactionExperiment* txn,
+    Collection::Collection( OperationContext* txn,
                             const StringData& fullNS,
                             NamespaceDetails* details,
                             Database* database )
@@ -169,7 +169,7 @@ namespace mongo {
         return BSONObj( rec->data() );
     }
 
-    StatusWith<DiskLoc> Collection::insertDocument( TransactionExperiment* txn,
+    StatusWith<DiskLoc> Collection::insertDocument( OperationContext* txn,
                                                     const DocWriter* doc,
                                                     bool enforceQuota ) {
         verify( _indexCatalog.numIndexesTotal() == 0 ); // eventually can implement, just not done
@@ -185,7 +185,7 @@ namespace mongo {
         return StatusWith<DiskLoc>( loc );
     }
 
-    StatusWith<DiskLoc> Collection::insertDocument( TransactionExperiment* txn,
+    StatusWith<DiskLoc> Collection::insertDocument( OperationContext* txn,
                                                     const BSONObj& docToInsert,
                                                     bool enforceQuota ) {
         if ( _indexCatalog.findIdIndex() ) {
@@ -211,7 +211,7 @@ namespace mongo {
         return status;
     }
 
-    StatusWith<DiskLoc> Collection::insertDocument( TransactionExperiment* txn,
+    StatusWith<DiskLoc> Collection::insertDocument( OperationContext* txn,
                                                     const BSONObj& doc,
                                                     MultiIndexBlock& indexBlock ) {
         StatusWith<DiskLoc> loc = _recordStore->insertRecord( txn,
@@ -234,7 +234,7 @@ namespace mongo {
     }
 
 
-    StatusWith<DiskLoc> Collection::_insertDocument( TransactionExperiment* txn,
+    StatusWith<DiskLoc> Collection::_insertDocument( OperationContext* txn,
                                                      const BSONObj& docToInsert,
                                                      bool enforceQuota ) {
 
@@ -271,7 +271,7 @@ namespace mongo {
         return loc;
     }
 
-    Status Collection::aboutToDeleteCapped( TransactionExperiment* txn, const DiskLoc& loc ) {
+    Status Collection::aboutToDeleteCapped( OperationContext* txn, const DiskLoc& loc ) {
 
         BSONObj doc = docFor( loc );
 
@@ -283,7 +283,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    void Collection::deleteDocument( TransactionExperiment* txn,
+    void Collection::deleteDocument( OperationContext* txn,
                                      const DiskLoc& loc,
                                      bool cappedOK,
                                      bool noWarn,
@@ -316,7 +316,7 @@ namespace mongo {
     Counter64 moveCounter;
     ServerStatusMetricField<Counter64> moveCounterDisplay( "record.moves", &moveCounter );
 
-    StatusWith<DiskLoc> Collection::updateDocument( TransactionExperiment* txn,
+    StatusWith<DiskLoc> Collection::updateDocument( OperationContext* txn,
                                                     const DiskLoc& oldLocation,
                                                     const BSONObj& objNew,
                                                     bool enforceQuota,
@@ -431,7 +431,7 @@ namespace mongo {
         return StatusWith<DiskLoc>( oldLocation );
     }
 
-    Status Collection::updateDocumentWithDamages( TransactionExperiment* txn,
+    Status Collection::updateDocumentWithDamages( OperationContext* txn,
                                                   const DiskLoc& loc,
                                                   const char* damangeSource,
                                                   const mutablebson::DamageVector& damages ) {
@@ -466,7 +466,7 @@ namespace mongo {
         return _database->getExtentManager();
     }
 
-    void Collection::increaseStorageSize(TransactionExperiment* txn, int size, bool enforceQuota) {
+    void Collection::increaseStorageSize(OperationContext* txn, int size, bool enforceQuota) {
         _recordStore->increaseStorageSize(txn, size, enforceQuota ? largestFileNumberInQuota() : 0);
     }
 
@@ -513,7 +513,7 @@ namespace mongo {
      * 3) truncate record store
      * 4) re-write indexes
      */
-    Status Collection::truncate(TransactionExperiment* txn) {
+    Status Collection::truncate(OperationContext* txn) {
         massert( 17445, "index build in progress", _indexCatalog.numIndexesInProgress() == 0 );
 
         // 1) store index specs
@@ -548,7 +548,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    void Collection::temp_cappedTruncateAfter(TransactionExperiment* txn,
+    void Collection::temp_cappedTruncateAfter(OperationContext* txn,
                                               DiskLoc end,
                                               bool inclusive) {
         invariant( isCapped() );
@@ -572,7 +572,7 @@ namespace mongo {
         };
     }
 
-    Status Collection::validate( TransactionExperiment* txn,
+    Status Collection::validate( OperationContext* txn,
                                  bool full, bool scanData,
                                  ValidateResults* results, BSONObjBuilder* output ){
 
@@ -614,7 +614,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    Status Collection::touch( TransactionExperiment* txn,
+    Status Collection::touch( OperationContext* txn,
                               bool touchData, bool touchIndexes,
                               BSONObjBuilder* output ) const {
         if ( touchData ) {
@@ -647,21 +647,21 @@ namespace mongo {
         return _details->isUserFlagSet( flag );
     }
 
-    bool Collection::setUserFlag( TransactionExperiment* txn, int flag ) {
+    bool Collection::setUserFlag( OperationContext* txn, int flag ) {
         if ( !_details->setUserFlag( txn, flag ) )
             return false;
         _syncUserFlags(txn);
         return true;
     }
 
-    bool Collection::clearUserFlag( TransactionExperiment* txn, int flag ) {
+    bool Collection::clearUserFlag( OperationContext* txn, int flag ) {
         if ( !_details->clearUserFlag( txn, flag ) )
             return false;
         _syncUserFlags(txn);
         return true;
     }
 
-    void Collection::_syncUserFlags(TransactionExperiment* txn) {
+    void Collection::_syncUserFlags(OperationContext* txn) {
         if ( _ns.coll() == "system.namespaces" )
             return;
         string system_namespaces = _ns.getSisterNS( "system.namespaces" );
@@ -687,7 +687,7 @@ namespace mongo {
 
     }
 
-    void Collection::setMaxCappedDocs( TransactionExperiment* txn, long long max ) {
+    void Collection::setMaxCappedDocs( OperationContext* txn, long long max ) {
         _details->setMaxCappedDocs( txn, max );
     }
 
diff --git a/src/mongo/db/catalog/collection.h b/src/mongo/db/catalog/collection.h
index 32d34ff5f46..8cccf53dc4a 100644
--- a/src/mongo/db/catalog/collection.h
+++ b/src/mongo/db/catalog/collection.h
@@ -51,7 +51,7 @@ namespace mongo {
     class NamespaceDetails;
     class IndexCatalog;
     class MultiIndexBlock;
-    class TransactionExperiment;
+    class OperationContext;
 
     class RecordIterator;
     class FlatIterator;
@@ -102,7 +102,7 @@ namespace mongo {
      */
     class Collection : CappedDocumentDeleteCallback {
     public:
-        Collection( TransactionExperiment* txn,
+        Collection( OperationContext* txn,
                     const StringData& fullNS,
                     NamespaceDetails* details,
                     Database* database );
@@ -154,7 +154,7 @@ namespace mongo {
          */
         int64_t countTableScan( const MatchExpression* expression );
 
-        void deleteDocument( TransactionExperiment* txn,
+        void deleteDocument( OperationContext* txn,
                              const DiskLoc& loc,
                              bool cappedOK = false,
                              bool noWarn = false,
@@ -164,15 +164,15 @@ namespace mongo {
          * this does NOT modify the doc before inserting
          * i.e. will not add an _id field for documents that are missing it
          */
-        StatusWith<DiskLoc> insertDocument( TransactionExperiment* txn,
+        StatusWith<DiskLoc> insertDocument( OperationContext* txn,
                                             const BSONObj& doc,
                                             bool enforceQuota );
 
-        StatusWith<DiskLoc> insertDocument( TransactionExperiment* txn,
+        StatusWith<DiskLoc> insertDocument( OperationContext* txn,
                                             const DocWriter* doc,
                                             bool enforceQuota );
 
-        StatusWith<DiskLoc> insertDocument( TransactionExperiment* txn,
+        StatusWith<DiskLoc> insertDocument( OperationContext* txn,
                                             const BSONObj& doc,
                                             MultiIndexBlock& indexBlock );
 
@@ -182,7 +182,7 @@ namespace mongo {
          * if not, it is moved
          * @return the post update location of the doc (may or may not be the same as oldLocation)
          */
-        StatusWith<DiskLoc> updateDocument( TransactionExperiment* txn,
+        StatusWith<DiskLoc> updateDocument( OperationContext* txn,
                                             const DiskLoc& oldLocation,
                                             const BSONObj& newDoc,
                                             bool enforceQuota,
@@ -191,21 +191,21 @@ namespace mongo {
         /**
          * right now not allowed to modify indexes
          */
-        Status updateDocumentWithDamages( TransactionExperiment* txn,
+        Status updateDocumentWithDamages( OperationContext* txn,
                                           const DiskLoc& loc,
                                           const char* damangeSource,
                                           const mutablebson::DamageVector& damages );
 
         // -----------
 
-        StatusWith<CompactStats> compact(TransactionExperiment* txn, const CompactOptions* options);
+        StatusWith<CompactStats> compact(OperationContext* txn, const CompactOptions* options);
 
         /**
          * removes all documents as fast as possible
          * indexes before and after will be the same
          * as will other characteristics
          */
-        Status truncate(TransactionExperiment* txn);
+        Status truncate(OperationContext* txn);
 
         /**
          * @param full - does more checks
@@ -214,14 +214,14 @@ namespace mongo {
          *         OK will be returned even if corruption is found
          *         deatils will be in result
          */
-        Status validate( TransactionExperiment* txn,
+        Status validate( OperationContext* txn,
                          bool full, bool scanData,
                          ValidateResults* results, BSONObjBuilder* output );
 
         /**
          * forces data into cache
          */
-        Status touch( TransactionExperiment* txn,
+        Status touch( OperationContext* txn,
                       bool touchData, bool touchIndexes,
                       BSONObjBuilder* output ) const;
 
@@ -232,7 +232,7 @@ namespace mongo {
          * @param inclusive - Truncate 'end' as well iff true
          * XXX: this will go away soon, just needed to move for now
          */
-        void temp_cappedTruncateAfter( TransactionExperiment* txn, DiskLoc end, bool inclusive );
+        void temp_cappedTruncateAfter( OperationContext* txn, DiskLoc end, bool inclusive );
 
         // -----------
 
@@ -241,7 +241,7 @@ namespace mongo {
         // this will add a new extent the collection
         // the new extent will be returned
         // it will have been added to the linked list already
-        void increaseStorageSize( TransactionExperiment* txn, int size, bool enforceQuota );
+        void increaseStorageSize( OperationContext* txn, int size, bool enforceQuota );
 
         //
         // Stats
@@ -268,33 +268,33 @@ namespace mongo {
 
         // TODO(erh) - below till next mark are suspect
         bool isUserFlagSet( int flag ) const;
-        bool setUserFlag( TransactionExperiment* txn, int flag );
-        bool clearUserFlag( TransactionExperiment* txn, int flag );
+        bool setUserFlag( OperationContext* txn, int flag );
+        bool clearUserFlag( OperationContext* txn, int flag );
 
-        void setMaxCappedDocs( TransactionExperiment* txn, long long max );
+        void setMaxCappedDocs( OperationContext* txn, long long max );
         // --- end suspect things
 
     private:
 
-        Status aboutToDeleteCapped( TransactionExperiment* txn, const DiskLoc& loc );
+        Status aboutToDeleteCapped( OperationContext* txn, const DiskLoc& loc );
 
         /**
          * same semantics as insertDocument, but doesn't do:
          *  - some user error checks
          *  - adjust padding
          */
-        StatusWith<DiskLoc> _insertDocument( TransactionExperiment* txn,
+        StatusWith<DiskLoc> _insertDocument( OperationContext* txn,
                                              const BSONObj& doc,
                                              bool enforceQuota );
 
-        void _compactExtent(TransactionExperiment* txn,
+        void _compactExtent(OperationContext* txn,
                             const DiskLoc diskloc,
                             int extentNumber,
                             MultiIndexBlock& indexesToInsertTo,
                             const CompactOptions* compactOptions,
                             CompactStats* stats );
 
-        void _syncUserFlags(TransactionExperiment* txn); // TODO: this is bizarre, should go away
+        void _syncUserFlags(OperationContext* txn); // TODO: this is bizarre, should go away
 
 
         // @return 0 for inf., otherwise a number of files
diff --git a/src/mongo/db/catalog/database.cpp b/src/mongo/db/catalog/database.cpp
index 7db74ef24c8..8e1c28b7d82 100644
--- a/src/mongo/db/catalog/database.cpp
+++ b/src/mongo/db/catalog/database.cpp
@@ -51,7 +51,7 @@
 #include "mongo/db/storage/data_file.h"
 #include "mongo/db/storage/extent.h"
 #include "mongo/db/storage/extent_manager.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/db/storage/mmap_v1/mmap_v1_extent_manager.h"
 #include "mongo/db/storage_options.h"
 #include "mongo/db/structure/catalog/namespace_details.h"
@@ -196,7 +196,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    Database::Database(TransactionExperiment* txn, const char *nm, bool& newDb, const string& path )
+    Database::Database(OperationContext* txn, const char *nm, bool& newDb, const string& path )
         : _name(nm), _path(path),
           _namespaceIndex( _path, _name ),
           _extentManager(new MmapV1ExtentManager(_name, _path, storageGlobalParams.directoryperdb)),
@@ -299,7 +299,7 @@ namespace mongo {
     // todo : we stop once a datafile dne.
     //        if one datafile were missing we should keep going for
     //        repair purposes yet we do not.
-    void Database::openAllFiles(TransactionExperiment* txn) {
+    void Database::openAllFiles(OperationContext* txn) {
         verify(this);
         Status s = _extentManager->init(txn);
         if ( !s.isOK() ) {
@@ -307,7 +307,7 @@ namespace mongo {
         }
     }
 
-    void Database::clearTmpCollections(TransactionExperiment* txn) {
+    void Database::clearTmpCollections(OperationContext* txn) {
 
         Lock::assertWriteLocked( _name );
 
@@ -353,7 +353,7 @@ namespace mongo {
 
     void Database::flushFiles( bool sync ) { return _extentManager->flushFiles( sync ); }
 
-    bool Database::setProfilingLevel( TransactionExperiment* txn, int newLevel , string& errmsg ) {
+    bool Database::setProfilingLevel( OperationContext* txn, int newLevel , string& errmsg ) {
         if ( _profile == newLevel )
             return true;
 
@@ -374,7 +374,7 @@ namespace mongo {
         return true;
     }
 
-    Status Database::dropCollection( TransactionExperiment* txn, const StringData& fullns ) {
+    Status Database::dropCollection( OperationContext* txn, const StringData& fullns ) {
         LOG(1) << "dropCollection: " << fullns << endl;
         massertNamespaceNotIndex( fullns, "dropCollection" );
 
@@ -467,11 +467,11 @@ namespace mongo {
     }
 
     Collection* Database::getCollection( const StringData& ns ) {
-        DurTransaction txn; // TODO remove once we require reads to have transactions
+        OperationContextImpl txn; // TODO remove once we require reads to have transactions
         return getCollection(&txn, ns);
     }
 
-    Collection* Database::getCollection( TransactionExperiment* txn, const StringData& ns ) {
+    Collection* Database::getCollection( OperationContext* txn, const StringData& ns ) {
         verify( _name == nsToDatabaseSubstring( ns ) );
 
         scoped_lock lk( _collectionLock );
@@ -504,7 +504,7 @@ namespace mongo {
 
 
 
-    Status Database::renameCollection( TransactionExperiment* txn,
+    Status Database::renameCollection( OperationContext* txn,
                                        const StringData& fromNS,
                                        const StringData& toNS,
                                        bool stayTemp ) {
@@ -574,7 +574,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    Status Database::_renameSingleNamespace( TransactionExperiment* txn,
+    Status Database::_renameSingleNamespace( OperationContext* txn,
                                              const StringData& fromNS,
                                              const StringData& toNS,
                                              bool stayTemp ) {
@@ -660,10 +660,10 @@ namespace mongo {
     }
 
     Collection* Database::getOrCreateCollection( const StringData& ns ) {
-        DurTransaction txn; // TODO remove once we require reads to have transactions
+        OperationContextImpl txn; // TODO remove once we require reads to have transactions
         return getOrCreateCollection(&txn, ns);
     }
-    Collection* Database::getOrCreateCollection(TransactionExperiment* txn, const StringData& ns) {
+    Collection* Database::getOrCreateCollection(OperationContext* txn, const StringData& ns) {
         Collection* c = getCollection( txn, ns );
         if ( !c ) {
             c = createCollection( txn, ns );
@@ -681,7 +681,7 @@ namespace mongo {
         }
     }
 
-    Collection* Database::createCollection( TransactionExperiment* txn,
+    Collection* Database::createCollection( OperationContext* txn,
                                             const StringData& ns,
                                             const CollectionOptions& options,
                                             bool allocateDefaultSpace,
@@ -777,7 +777,7 @@ namespace mongo {
     }
 
 
-    void Database::_addNamespaceToCatalog( TransactionExperiment* txn,
+    void Database::_addNamespaceToCatalog( OperationContext* txn,
                                            const StringData& ns,
                                            const BSONObj* options ) {
         LOG(1) << "Database::_addNamespaceToCatalog ns: " << ns << endl;
@@ -799,7 +799,7 @@ namespace mongo {
         uassertStatusOK( loc.getStatus() );
     }
 
-    Status Database::_dropNS( TransactionExperiment* txn, const StringData& ns ) {
+    Status Database::_dropNS( OperationContext* txn, const StringData& ns ) {
 
         NamespaceDetails* d = _namespaceIndex.details( ns );
         if ( !d )
@@ -833,7 +833,7 @@ namespace mongo {
             *minor = 0;
             return;
         }
-        DurTransaction txn; // TODO get rid of this once reads need transactions
+        OperationContextImpl txn; // TODO get rid of this once reads need transactions
         const DataFile* df = _extentManager->getFile( &txn, 0 );
         *major = df->getHeader()->version;
         *minor = df->getHeader()->versionMinor;
diff --git a/src/mongo/db/catalog/database.h b/src/mongo/db/catalog/database.h
index 4e0b61903a2..206d28db060 100644
--- a/src/mongo/db/catalog/database.h
+++ b/src/mongo/db/catalog/database.h
@@ -43,7 +43,7 @@ namespace mongo {
     class IndexCatalog;
     class MmapV1ExtentManager;
     class NamespaceDetails;
-    class TransactionExperiment;
+    class OperationContext;
 
     struct CollectionOptions {
         CollectionOptions() {
@@ -98,7 +98,7 @@ namespace mongo {
     class Database {
     public:
         // you probably need to be in dbHolderMutex when constructing this
-        Database(TransactionExperiment* txn,
+        Database(OperationContext* txn,
                  const char *nm,
                  /*out*/ bool& newDb,
                  const string& path = storageGlobalParams.dbpath);
@@ -111,7 +111,7 @@ namespace mongo {
         const string& name() const { return _name; }
         const string& path() const { return _path; }
 
-        void clearTmpCollections(TransactionExperiment* txn);
+        void clearTmpCollections(OperationContext* txn);
 
         /**
          * tries to make sure that this hasn't been deleted
@@ -132,7 +132,7 @@ namespace mongo {
         /**
          * @return true if success.  false if bad level or error creating profile ns
          */
-        bool setProfilingLevel( TransactionExperiment* txn, int newLevel , string& errmsg );
+        bool setProfilingLevel( OperationContext* txn, int newLevel , string& errmsg );
 
         void flushFiles( bool sync );
 
@@ -156,9 +156,9 @@ namespace mongo {
         MmapV1ExtentManager* getExtentManager() { return _extentManager.get(); }
         const MmapV1ExtentManager* getExtentManager() const { return _extentManager.get(); }
 
-        Status dropCollection( TransactionExperiment* txn, const StringData& fullns );
+        Status dropCollection( OperationContext* txn, const StringData& fullns );
 
-        Collection* createCollection( TransactionExperiment* txn,
+        Collection* createCollection( OperationContext* txn,
                                       const StringData& ns,
                                       const CollectionOptions& options = CollectionOptions(),
                                       bool allocateSpace = true,
@@ -173,16 +173,16 @@ namespace mongo {
 
         Collection* getCollection( const NamespaceString& ns ) { return getCollection( ns.ns() ); }
 
-        Collection* getCollection( TransactionExperiment* txn, const StringData& ns );
+        Collection* getCollection( OperationContext* txn, const StringData& ns );
 
-        Collection* getCollection( TransactionExperiment* txn, const NamespaceString& ns ) {
+        Collection* getCollection( OperationContext* txn, const NamespaceString& ns ) {
             return getCollection( txn, ns.ns() );
         }
 
         Collection* getOrCreateCollection( const StringData& ns );
-        Collection* getOrCreateCollection( TransactionExperiment* txn, const StringData& ns );
+        Collection* getOrCreateCollection( OperationContext* txn, const StringData& ns );
 
-        Status renameCollection( TransactionExperiment* txn,
+        Status renameCollection( OperationContext* txn,
                                  const StringData& fromNS,
                                  const StringData& toNS,
                                  bool stayTemp );
@@ -205,7 +205,7 @@ namespace mongo {
 
         ~Database(); // closes files and other cleanup see below.
 
-        void _addNamespaceToCatalog( TransactionExperiment* txn,
+        void _addNamespaceToCatalog( OperationContext* txn,
                                      const StringData& ns,
                                      const BSONObj* options );
 
@@ -216,7 +216,7 @@ namespace mongo {
          * removes from NamespaceIndex
          * NOT RIGHT NOW, removes cache entry in Database TODO?
          */
-        Status _dropNS( TransactionExperiment* txn, const StringData& ns );
+        Status _dropNS( OperationContext* txn, const StringData& ns );
 
         /**
          * @throws DatabaseDifferCaseCode if the name is a duplicate based on
@@ -224,9 +224,9 @@ namespace mongo {
          */
         void checkDuplicateUncasedNames(bool inholderlockalready) const;
 
-        void openAllFiles(TransactionExperiment* txn);
+        void openAllFiles(OperationContext* txn);
 
-        Status _renameSingleNamespace( TransactionExperiment* txn,
+        Status _renameSingleNamespace( OperationContext* txn,
                                        const StringData& fromNS,
                                        const StringData& toNS,
                                        bool stayTemp );
diff --git a/src/mongo/db/catalog/database_holder.cpp b/src/mongo/db/catalog/database_holder.cpp
index bb057697455..a944ce18631 100644
--- a/src/mongo/db/catalog/database_holder.cpp
+++ b/src/mongo/db/catalog/database_holder.cpp
@@ -36,12 +36,12 @@
 #include "mongo/db/clientcursor.h"
 #include "mongo/db/catalog/database_holder.h"
 #include "mongo/db/d_concurrency.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 
 namespace mongo {
 
     Database* DatabaseHolder::getOrCreate( const string& ns, const string& path, bool& justCreated ) {
-        DurTransaction txn; // TODO get rid of this once reads require transactions
+        OperationContextImpl txn; // TODO get rid of this once reads require transactions
         string dbname = _todb( ns );
         {
             SimpleMutex::scoped_lock lk(_m);
diff --git a/src/mongo/db/catalog/index_catalog.cpp b/src/mongo/db/catalog/index_catalog.cpp
index 5dcef027e66..9453f0351a6 100644
--- a/src/mongo/db/catalog/index_catalog.cpp
+++ b/src/mongo/db/catalog/index_catalog.cpp
@@ -61,7 +61,7 @@
 #include "mongo/db/storage/data_file.h"
 #include "mongo/db/storage/extent_manager.h"
 #include "mongo/db/storage/mmap_v1/mmap_v1_extent_manager.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/db/structure/catalog/namespace_details.h"
 #include "mongo/db/structure/catalog/namespace_details_rsv1_metadata.h"
 #include "mongo/db/structure/record_store_v1_simple.h"
@@ -92,7 +92,7 @@ namespace mongo {
         _magic = 123456;
     }
 
-    Status IndexCatalog::init(TransactionExperiment* txn) {
+    Status IndexCatalog::init(OperationContext* txn) {
 
         NamespaceDetails::IndexIterator ii = _details->ii(true);
         while ( ii.more() ) {
@@ -125,7 +125,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    IndexCatalogEntry* IndexCatalog::_setupInMemoryStructures(TransactionExperiment* txn,
+    IndexCatalogEntry* IndexCatalog::_setupInMemoryStructures(OperationContext* txn,
                                                               IndexDescriptor* descriptor) {
         auto_ptr<IndexDescriptor> descriptorCleanup( descriptor );
 
@@ -242,7 +242,7 @@ namespace mongo {
 
     // ---------------------------
 
-    Status IndexCatalog::_upgradeDatabaseMinorVersionIfNeeded( TransactionExperiment* txn,
+    Status IndexCatalog::_upgradeDatabaseMinorVersionIfNeeded( OperationContext* txn,
                                                                const string& newPluginName ) {
 
         // first check if requested index requires pdfile minor version to be bumped
@@ -307,7 +307,7 @@ namespace mongo {
         return StatusWith<BSONObj>( fixed );
     }
 
-    Status IndexCatalog::createIndex( TransactionExperiment* txn,
+    Status IndexCatalog::createIndex( OperationContext* txn,
                                       BSONObj spec,
                                       bool mayInterrupt,
                                       ShutdownBehavior shutdownBehavior ) {
@@ -398,7 +398,7 @@ namespace mongo {
         }
     }
 
-    IndexCatalog::IndexBuildBlock::IndexBuildBlock(TransactionExperiment* txn,
+    IndexCatalog::IndexBuildBlock::IndexBuildBlock(OperationContext* txn,
                                                    Collection* collection,
                                                    const BSONObj& spec )
         : _collection( collection ),
@@ -715,7 +715,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    Status IndexCatalog::ensureHaveIdIndex(TransactionExperiment* txn) {
+    Status IndexCatalog::ensureHaveIdIndex(OperationContext* txn) {
         if ( haveIdIndex() )
             return Status::OK();
 
@@ -735,7 +735,7 @@ namespace mongo {
         return s;
     }
 
-    Status IndexCatalog::dropAllIndexes(TransactionExperiment* txn,
+    Status IndexCatalog::dropAllIndexes(OperationContext* txn,
                                         bool includingIdIndex) {
 
         Lock::assertWriteLocked( _collection->_database->name() );
@@ -819,7 +819,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    Status IndexCatalog::dropIndex(TransactionExperiment* txn,
+    Status IndexCatalog::dropIndex(OperationContext* txn,
                                    IndexDescriptor* desc ) {
 
         Lock::assertWriteLocked( _collection->_database->name() );
@@ -834,7 +834,7 @@ namespace mongo {
         return _dropIndex(txn, entry);
     }
 
-    Status IndexCatalog::_dropIndex(TransactionExperiment* txn,
+    Status IndexCatalog::_dropIndex(OperationContext* txn,
                                     IndexCatalogEntry* entry ) {
         /**
          * IndexState in order
@@ -901,7 +901,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    void IndexCatalog::_deleteIndexFromDisk( TransactionExperiment* txn,
+    void IndexCatalog::_deleteIndexFromDisk( OperationContext* txn,
                                              const string& indexName,
                                              const string& indexNamespace,
                                              int idxNo ) {
@@ -927,7 +927,7 @@ namespace mongo {
         wassert( n == 1 );
     }
 
-    int IndexCatalog::_removeFromSystemIndexes(TransactionExperiment* txn,
+    int IndexCatalog::_removeFromSystemIndexes(OperationContext* txn,
                                                const StringData& indexName) {
         BSONObjBuilder b;
         b.append( "ns", _collection->ns() );
@@ -942,7 +942,7 @@ namespace mongo {
                                                 true ) );
     }
 
-    vector<BSONObj> IndexCatalog::getAndClearUnfinishedIndexes(TransactionExperiment* txn) {
+    vector<BSONObj> IndexCatalog::getAndClearUnfinishedIndexes(OperationContext* txn) {
         vector<BSONObj> toReturn = _unfinishedIndexes;
         _unfinishedIndexes.clear();
         for ( size_t i = 0; i < toReturn.size(); i++ ) {
@@ -963,7 +963,7 @@ namespace mongo {
         return toReturn;
     }
 
-    void IndexCatalog::updateTTLSetting( TransactionExperiment* txn,
+    void IndexCatalog::updateTTLSetting( OperationContext* txn,
                                          const IndexDescriptor* idx,
                                          long long newExpireSeconds ) {
         IndexDetails* indexDetails = _getIndexDetails( idx );
@@ -1177,7 +1177,7 @@ namespace mongo {
 
     // ---------------------------
 
-    Status IndexCatalog::_indexRecord(TransactionExperiment* txn,
+    Status IndexCatalog::_indexRecord(OperationContext* txn,
                                       IndexCatalogEntry* index,
                                       const BSONObj& obj,
                                       const DiskLoc &loc ) {
@@ -1194,7 +1194,7 @@ namespace mongo {
         return index->accessMethod()->insert(txn, obj, loc, options, &inserted);
     }
 
-    Status IndexCatalog::_unindexRecord(TransactionExperiment* txn,
+    Status IndexCatalog::_unindexRecord(OperationContext* txn,
                                         IndexCatalogEntry* index,
                                         const BSONObj& obj,
                                         const DiskLoc &loc,
@@ -1215,7 +1215,7 @@ namespace mongo {
     }
 
 
-    void IndexCatalog::indexRecord(TransactionExperiment* txn,
+    void IndexCatalog::indexRecord(OperationContext* txn,
                                    const BSONObj& obj,
                                    const DiskLoc &loc ) {
 
@@ -1256,7 +1256,7 @@ namespace mongo {
 
     }
 
-    void IndexCatalog::unindexRecord(TransactionExperiment* txn,
+    void IndexCatalog::unindexRecord(OperationContext* txn,
                                      const BSONObj& obj,
                                      const DiskLoc& loc,
                                      bool noWarn) {
diff --git a/src/mongo/db/catalog/index_catalog.h b/src/mongo/db/catalog/index_catalog.h
index a0c802f3b40..7cfb607ca06 100644
--- a/src/mongo/db/catalog/index_catalog.h
+++ b/src/mongo/db/catalog/index_catalog.h
@@ -35,7 +35,7 @@
 #include "mongo/db/catalog/index_catalog_entry.h"
 #include "mongo/db/diskloc.h"
 #include "mongo/db/jsobj.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/platform/unordered_map.h"
 
 namespace mongo {
@@ -58,7 +58,7 @@ namespace mongo {
         ~IndexCatalog();
 
         // must be called before used
-        Status init(TransactionExperiment* txn);
+        Status init(OperationContext* txn);
 
         bool ok() const;
 
@@ -136,31 +136,31 @@ namespace mongo {
 
         // ---- index set modifiers ------
 
-        Status ensureHaveIdIndex(TransactionExperiment* txn);
+        Status ensureHaveIdIndex(OperationContext* txn);
 
         enum ShutdownBehavior {
             SHUTDOWN_CLEANUP, // fully clean up this build
             SHUTDOWN_LEAVE_DIRTY // leave as if kill -9 happened, so have to deal with on restart
         };
 
-        Status createIndex( TransactionExperiment* txn,
+        Status createIndex( OperationContext* txn,
                             BSONObj spec,
                             bool mayInterrupt,
                             ShutdownBehavior shutdownBehavior = SHUTDOWN_CLEANUP );
 
         StatusWith<BSONObj> prepareSpecForCreate( const BSONObj& original ) const;
 
-        Status dropAllIndexes(TransactionExperiment* txn,
+        Status dropAllIndexes(OperationContext* txn,
                               bool includingIdIndex );
 
-        Status dropIndex(TransactionExperiment* txn,
+        Status dropIndex(OperationContext* txn,
                          IndexDescriptor* desc );
 
         /**
          * will drop all incompleted indexes and return specs
          * after this, the indexes can be rebuilt
          */
-        vector<BSONObj> getAndClearUnfinishedIndexes(TransactionExperiment* txn);
+        vector<BSONObj> getAndClearUnfinishedIndexes(OperationContext* txn);
 
 
         struct IndexKillCriteria {
@@ -182,7 +182,7 @@ namespace mongo {
          * The specified index must already contain an expireAfterSeconds field, and the value in
          * that field and newExpireSecs must both be numeric.
          */
-        void updateTTLSetting( TransactionExperiment* txn,
+        void updateTTLSetting( OperationContext* txn,
                                const IndexDescriptor* idx,
                                long long newExpireSeconds );
 
@@ -202,7 +202,7 @@ namespace mongo {
          */
         class IndexBuildBlock {
         public:
-            IndexBuildBlock(TransactionExperiment* txn,
+            IndexBuildBlock(OperationContext* txn,
                             Collection* collection,
                             const BSONObj& spec );
 
@@ -239,15 +239,15 @@ namespace mongo {
             IndexCatalogEntry* _entry;
             bool _inProgress;
 
-            TransactionExperiment* _txn;
+            OperationContext* _txn;
         };
 
         // ----- data modifiers ------
 
         // this throws for now
-        void indexRecord(TransactionExperiment* txn, const BSONObj& obj, const DiskLoc &loc);
+        void indexRecord(OperationContext* txn, const BSONObj& obj, const DiskLoc &loc);
 
-        void unindexRecord(TransactionExperiment* txn,
+        void unindexRecord(OperationContext* txn,
                            const BSONObj& obj,
                            const DiskLoc& loc,
                            bool noWarn);
@@ -264,7 +264,7 @@ namespace mongo {
             return _getAccessMethodName( keyPattern );
         }
 
-        Status _upgradeDatabaseMinorVersionIfNeeded( TransactionExperiment* txn,
+        Status _upgradeDatabaseMinorVersionIfNeeded( OperationContext* txn,
                                                      const string& newPluginName );
 
         // public static helpers
@@ -278,7 +278,7 @@ namespace mongo {
         IndexAccessMethod* _createAccessMethod( const IndexDescriptor* desc,
                                                 IndexCatalogEntry* entry );
 
-        int _removeFromSystemIndexes(TransactionExperiment* txn,
+        int _removeFromSystemIndexes(OperationContext* txn,
                                      const StringData& indexName );
 
         bool _shouldOverridePlugin( const BSONObj& keyPattern ) const;
@@ -299,12 +299,12 @@ namespace mongo {
         // meaning we shouldn't modify catalog
         Status _checkUnfinished() const;
 
-        Status _indexRecord(TransactionExperiment* txn,
+        Status _indexRecord(OperationContext* txn,
                             IndexCatalogEntry* index,
                             const BSONObj& obj,
                             const DiskLoc &loc );
 
-        Status _unindexRecord(TransactionExperiment* txn,
+        Status _unindexRecord(OperationContext* txn,
                               IndexCatalogEntry* index,
                               const BSONObj& obj,
                               const DiskLoc &loc,
@@ -313,18 +313,18 @@ namespace mongo {
         /**
          * this does no sanity checks
          */
-        Status _dropIndex(TransactionExperiment* txn,
+        Status _dropIndex(OperationContext* txn,
                           IndexCatalogEntry* entry );
 
         // just does disk hanges
         // doesn't change memory state, etc...
-        void _deleteIndexFromDisk( TransactionExperiment* txn,
+        void _deleteIndexFromDisk( OperationContext* txn,
                                    const string& indexName,
                                    const string& indexNamespace,
                                    int idxNo );
 
         // descriptor ownership passes to _setupInMemoryStructures
-        IndexCatalogEntry* _setupInMemoryStructures(TransactionExperiment* txn,
+        IndexCatalogEntry* _setupInMemoryStructures(OperationContext* txn,
                                                     IndexDescriptor* descriptor );
 
         static BSONObj _fixIndexSpec( const BSONObj& spec );
diff --git a/src/mongo/db/catalog/index_catalog_entry.cpp b/src/mongo/db/catalog/index_catalog_entry.cpp
index e0c8c0eb746..ed84e9414fe 100644
--- a/src/mongo/db/catalog/index_catalog_entry.cpp
+++ b/src/mongo/db/catalog/index_catalog_entry.cpp
@@ -32,7 +32,7 @@
 
 #include "mongo/db/index/index_access_method.h"
 #include "mongo/db/index/index_descriptor.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/db/structure/catalog/namespace_details.h"
 #include "mongo/db/structure/head_manager.h"
 
@@ -47,7 +47,7 @@ namespace mongo {
             return _catalogEntry->head();
         }
 
-        void setHead(TransactionExperiment* txn, const DiskLoc& newHead) {
+        void setHead(OperationContext* txn, const DiskLoc& newHead) {
             _catalogEntry->setHead(txn, newHead);
         }
 
@@ -109,7 +109,7 @@ namespace mongo {
         verify( isReady() == newIsReady );
     }
 
-    void IndexCatalogEntry::setHead( TransactionExperiment* txn, DiskLoc newHead ) {
+    void IndexCatalogEntry::setHead( OperationContext* txn, DiskLoc newHead ) {
         NamespaceDetails* nsd = _collection->detailsWritable();
         int idxNo = _indexNo();
         IndexDetails& id = nsd->idx( idxNo );
@@ -117,7 +117,7 @@ namespace mongo {
         _head = newHead;
     }
 
-    void IndexCatalogEntry::setMultikey( TransactionExperiment* txn ) {
+    void IndexCatalogEntry::setMultikey( OperationContext* txn ) {
         if ( isMultikey() )
             return;
         NamespaceDetails* nsd = _collection->detailsWritable();
diff --git a/src/mongo/db/catalog/index_catalog_entry.h b/src/mongo/db/catalog/index_catalog_entry.h
index 6c8bf38d919..e5b835405be 100644
--- a/src/mongo/db/catalog/index_catalog_entry.h
+++ b/src/mongo/db/catalog/index_catalog_entry.h
@@ -43,7 +43,7 @@ namespace mongo {
     class IndexAccessMethod;
     class IndexDescriptor;
     class RecordStore;
-    class TransactionExperiment;
+    class OperationContext;
 
     class IndexCatalogEntry {
         MONGO_DISALLOW_COPYING( IndexCatalogEntry );
@@ -73,7 +73,7 @@ namespace mongo {
 
         const DiskLoc& head() const;
 
-        void setHead( TransactionExperiment* txn, DiskLoc newHead );
+        void setHead( OperationContext* txn, DiskLoc newHead );
 
         void setIsReady( bool newIsReady );
 
@@ -83,7 +83,7 @@ namespace mongo {
 
         bool isMultikey() const;
 
-        void setMultikey( TransactionExperiment* txn );
+        void setMultikey( OperationContext* txn );
 
         // if this ready is ready for queries
         bool isReady() const;
diff --git a/src/mongo/db/catalog/index_create.cpp b/src/mongo/db/catalog/index_create.cpp
index a33fe7ff9d8..b62d9d1f849 100644
--- a/src/mongo/db/catalog/index_create.cpp
+++ b/src/mongo/db/catalog/index_create.cpp
@@ -44,7 +44,7 @@
 #include "mongo/db/repl/is_master.h"
 #include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/rs.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/db/structure/catalog/index_details.h"
 #include "mongo/db/structure/catalog/namespace_details.h"
 #include "mongo/util/processinfo.h"
@@ -55,7 +55,7 @@ namespace mongo {
     /**
      * Add the provided (obj, dl) pair to the provided index.
      */
-    static void addKeysToIndex(TransactionExperiment* txn,
+    static void addKeysToIndex(OperationContext* txn,
                                Collection* collection,
                                const IndexDescriptor* descriptor,
                                IndexAccessMethod* accessMethod,
@@ -76,7 +76,7 @@ namespace mongo {
         uassertStatusOK( ret );
     }
 
-    unsigned long long addExistingToIndex( TransactionExperiment* txn,
+    unsigned long long addExistingToIndex( OperationContext* txn,
                                            Collection* collection,
                                            const IndexDescriptor* descriptor,
                                            IndexAccessMethod* accessMethod,
@@ -185,7 +185,7 @@ namespace mongo {
     // ---------------------------
 
     // throws DBException
-    void buildAnIndex( TransactionExperiment* txn,
+    void buildAnIndex( OperationContext* txn,
                        Collection* collection,
                        IndexCatalogEntry* btreeState,
                        bool mayInterrupt ) {
@@ -296,7 +296,7 @@ namespace mongo {
 
     // ----------------------------
 
-    MultiIndexBlock::MultiIndexBlock(TransactionExperiment* txn, Collection* collection)
+    MultiIndexBlock::MultiIndexBlock(OperationContext* txn, Collection* collection)
         : _collection(collection), _txn(txn) {
     }
 
diff --git a/src/mongo/db/catalog/index_create.h b/src/mongo/db/catalog/index_create.h
index bc2681465d8..0bfd413c935 100644
--- a/src/mongo/db/catalog/index_create.h
+++ b/src/mongo/db/catalog/index_create.h
@@ -43,12 +43,12 @@ namespace mongo {
     class BSONObj;
     class Collection;
     class IndexCatalogEntry;
-    class TransactionExperiment;
+    class OperationContext;
 
     // Build an index in the foreground
     // If background is false, uses fast index builder
     // If background is true, uses background index builder; blocks until done.
-    void buildAnIndex( TransactionExperiment* txn,
+    void buildAnIndex( OperationContext* txn,
                        Collection* collection,
                        IndexCatalogEntry* btreeState,
                        bool mayInterrupt );
@@ -56,7 +56,7 @@ namespace mongo {
     class MultiIndexBlock {
         MONGO_DISALLOW_COPYING( MultiIndexBlock );
     public:
-        MultiIndexBlock(TransactionExperiment* txn,
+        MultiIndexBlock(OperationContext* txn,
                         Collection* collection );
         ~MultiIndexBlock();
 
@@ -86,7 +86,7 @@ namespace mongo {
         std::vector<IndexState> _states;
 
         // Not owned here, must outlive 'this'
-        TransactionExperiment* _txn;
+        OperationContext* _txn;
     };
 
 } // namespace mongo
diff --git a/src/mongo/db/client.cpp b/src/mongo/db/client.cpp
index b55666dc070..5d1a1494901 100644
--- a/src/mongo/db/client.cpp
+++ b/src/mongo/db/client.cpp
@@ -383,7 +383,7 @@ namespace mongo {
             actions.addAction(ActionType::internal);
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
-        virtual bool run(TransactionExperiment* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             Client& c = cc();
             c.gotHandshake( cmdObj );
             return 1;
diff --git a/src/mongo/db/clientcursor.cpp b/src/mongo/db/clientcursor.cpp
index 7495146e4db..65e79b52c5b 100644
--- a/src/mongo/db/clientcursor.cpp
+++ b/src/mongo/db/clientcursor.cpp
@@ -257,7 +257,7 @@ namespace mongo {
             actions.addAction(ActionType::cursorInfo);
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result,
+        bool run(OperationContext* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result,
                  bool fromRepl ) {
             _appendCursorStats( result );
             return true;
diff --git a/src/mongo/db/cloner.cpp b/src/mongo/db/cloner.cpp
index 2bdc738a52b..03b2efa4d4c 100644
--- a/src/mongo/db/cloner.cpp
+++ b/src/mongo/db/cloner.cpp
@@ -52,7 +52,7 @@
 #include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/oplogreader.h"
 #include "mongo/db/pdfile.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/db/storage_options.h"
 
 namespace mongo {
@@ -96,7 +96,7 @@ namespace mongo {
     Cloner::Cloner() { }
 
     struct Cloner::Fun {
-        Fun( TransactionExperiment* txn, Client::Context& ctx )
+        Fun( OperationContext* txn, Client::Context& ctx )
             :lastLog(0),
              txn(txn),
              context(ctx)
@@ -176,7 +176,7 @@ namespace mongo {
         }
 
         time_t lastLog;
-        TransactionExperiment* txn;
+        OperationContext* txn;
         Client::Context& context;
 
         int64_t numSeen;
@@ -193,7 +193,7 @@ namespace mongo {
     /* copy the specified collection
        isindex - if true, this is system.indexes collection, in which we do some transformation when copying.
     */
-    void Cloner::copy(TransactionExperiment* txn,
+    void Cloner::copy(OperationContext* txn,
                       Client::Context& ctx,
                       const char *from_collection,
                       const char *to_collection,
@@ -277,7 +277,7 @@ namespace mongo {
         return true;
     }
 
-    bool Cloner::copyCollectionFromRemote(TransactionExperiment* txn,
+    bool Cloner::copyCollectionFromRemote(OperationContext* txn,
                                           const string& host,
                                           const string& ns,
                                           string& errmsg) {
@@ -291,7 +291,7 @@ namespace mongo {
         return cloner.copyCollection(txn, ns, BSONObj(), errmsg, true, false, true, false);
     }
 
-    bool Cloner::copyCollection(TransactionExperiment* txn,
+    bool Cloner::copyCollection(OperationContext* txn,
                                 const string& ns,
                                 const BSONObj& query,
                                 string& errmsg,
@@ -334,7 +334,7 @@ namespace mongo {
 
     extern bool inDBRepair;
 
-    bool Cloner::go(TransactionExperiment* txn,
+    bool Cloner::go(OperationContext* txn,
                     Client::Context& context,
                     const string& masterHost,
                     const CloneOptions& opts,
@@ -513,7 +513,7 @@ namespace mongo {
         return true;
     }
 
-    bool Cloner::cloneFrom(TransactionExperiment* txn,
+    bool Cloner::cloneFrom(OperationContext* txn,
                            Client::Context& context,
                            const string& masterHost,
                            const CloneOptions& options,
@@ -558,7 +558,7 @@ namespace mongo {
             return Status::OK();
         }
         CmdClone() : Command("clone") { }
-        virtual bool run(TransactionExperiment* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             string from = cmdObj.getStringField("clone");
             if ( from.empty() )
                 return false;
@@ -629,7 +629,7 @@ namespace mongo {
                  "is placed at the same db.collection (namespace) as the source.\n"
                  ;
         }
-        virtual bool run(TransactionExperiment* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             string fromhost = cmdObj.getStringField("from");
             if ( fromhost.empty() ) {
                 errmsg = "missing 'from' parameter";
@@ -696,7 +696,7 @@ namespace mongo {
             help << "get a nonce for subsequent copy db request from secure server\n";
             help << "usage: {copydbgetnonce: 1, fromhost: <hostname>}";
         }
-        virtual bool run(TransactionExperiment* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             string fromhost = cmdObj.getStringField("fromhost");
             if ( fromhost.empty() ) {
                 /* copy from self */
@@ -780,7 +780,7 @@ namespace mongo {
             help << "usage: {copydb: 1, fromhost: <connection string>, fromdb: <db>, todb: <db>"
                  << "[, slaveOk: <bool>, username: <username>, nonce: <nonce>, key: <key>]}";
         }
-        virtual bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             string fromhost = cmdObj.getStringField("fromhost");
             bool fromSelf = fromhost.empty();
             if ( fromSelf ) {
diff --git a/src/mongo/db/cloner.h b/src/mongo/db/cloner.h
index 1cd9e06989f..4c1abbf6c42 100644
--- a/src/mongo/db/cloner.h
+++ b/src/mongo/db/cloner.h
@@ -40,7 +40,7 @@ namespace mongo {
     class DBClientBase;
     class DBClientCursor;
     class Query;
-    class TransactionExperiment;
+    class OperationContext;
 
     class Cloner: boost::noncopyable {
     public:
@@ -55,14 +55,14 @@ namespace mongo {
         void setConnection( DBClientBase *c ) { _conn.reset( c ); }
 
         /** copy the entire database */
-        bool go(TransactionExperiment* txn,
+        bool go(OperationContext* txn,
                 Client::Context& ctx,
                 const string& masterHost,
                 const CloneOptions& opts,
                 set<string>* clonedColls,
                 string& errmsg, int *errCode = 0);
 
-        bool copyCollection(TransactionExperiment* txn,
+        bool copyCollection(OperationContext* txn,
                             const string& ns,
                             const BSONObj& query,
                             string& errmsg,
@@ -85,7 +85,7 @@ namespace mongo {
          *                      Currently this will only be set if there is an error in the initial
          *                      system.namespaces query.
          */
-        static bool cloneFrom(TransactionExperiment* txn,
+        static bool cloneFrom(OperationContext* txn,
                               Client::Context& context,
                               const string& masterHost,
                               const CloneOptions& options,
@@ -96,11 +96,11 @@ namespace mongo {
         /**
          * Copy a collection (and indexes) from a remote host
          */
-        static bool copyCollectionFromRemote(TransactionExperiment* txn,
+        static bool copyCollectionFromRemote(OperationContext* txn,
                                              const string& host, const string& ns, string& errmsg);
 
     private:
-        void copy(TransactionExperiment* txn,
+        void copy(OperationContext* txn,
                   Client::Context& ctx,
                   const char *from_ns,
                   const char *to_ns,
diff --git a/src/mongo/db/commands.cpp b/src/mongo/db/commands.cpp
index af626452997..6d2dc6a1433 100644
--- a/src/mongo/db/commands.cpp
+++ b/src/mongo/db/commands.cpp
@@ -336,7 +336,7 @@ namespace mongo {
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
 
-        virtual bool run(TransactionExperiment* txn, const string&, mongo::BSONObj&, int, std::string&, mongo::BSONObjBuilder& result, bool) {
+        virtual bool run(OperationContext* txn, const string&, mongo::BSONObj&, int, std::string&, mongo::BSONObjBuilder& result, bool) {
             shardConnectionPool.flush();
             pool.flush();
             return true;
@@ -359,7 +359,7 @@ namespace mongo {
             actions.addAction(ActionType::connPoolStats);
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
-        virtual bool run(TransactionExperiment* txn, const string&, mongo::BSONObj&, int, std::string&, mongo::BSONObjBuilder& result, bool) {
+        virtual bool run(OperationContext* txn, const string&, mongo::BSONObj&, int, std::string&, mongo::BSONObjBuilder& result, bool) {
             pool.appendInfo( result );
             result.append( "numDBClientConnection" , DBClientConnection::getNumConnections() );
             result.append( "numAScopedConnection" , AScopedConnection::getNumConnections() );
diff --git a/src/mongo/db/commands.h b/src/mongo/db/commands.h
index c9c5920126d..6a8363f7ba4 100644
--- a/src/mongo/db/commands.h
+++ b/src/mongo/db/commands.h
@@ -33,7 +33,7 @@ namespace mongo {
     class Client;
     class Database;
     class Timer;
-    class TransactionExperiment;
+    class OperationContext;
 
 namespace mutablebson {
     class Document;
@@ -72,7 +72,7 @@ namespace mutablebson {
 
            return value is true if succeeded.  if false, set errmsg text.
         */
-        virtual bool run(TransactionExperiment* txn,
+        virtual bool run(OperationContext* txn,
                          const string& db,
                          BSONObj& cmdObj,
                          int options,
@@ -198,7 +198,7 @@ namespace mutablebson {
                                          int queryOptions = 0);
         static Command * findCommand( const string& name );
         // For mongod and webserver.
-        static void execCommand(TransactionExperiment* txn,
+        static void execCommand(OperationContext* txn,
                                 Command* c,
                                 Client& client,
                                 int queryOptions,
@@ -207,7 +207,7 @@ namespace mutablebson {
                                 BSONObjBuilder& result,
                                 bool fromRepl );
         // For mongos
-        static void execCommandClientBasic(TransactionExperiment* txn,
+        static void execCommandClientBasic(OperationContext* txn,
                                            Command* c,
                                            ClientBasic& client,
                                            int queryOptions,
@@ -251,7 +251,7 @@ namespace mutablebson {
                                           bool fromRepl);
     };
 
-    bool _runCommands(TransactionExperiment* txn,
+    bool _runCommands(OperationContext* txn,
                       const char* ns,
                       BSONObj& jsobj,
                       BufBuilder& b,
diff --git a/src/mongo/db/commands/apply_ops.cpp b/src/mongo/db/commands/apply_ops.cpp
index 285c83c7186..82e0b4d5c4d 100644
--- a/src/mongo/db/commands/apply_ops.cpp
+++ b/src/mongo/db/commands/apply_ops.cpp
@@ -41,7 +41,7 @@
 #include "mongo/db/instance.h"
 #include "mongo/db/matcher/matcher.h"
 #include "mongo/db/repl/oplog.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 
 namespace mongo {
     class ApplyOpsCmd : public Command {
@@ -59,7 +59,7 @@ namespace mongo {
             // applyOps can do pretty much anything, so require all privileges.
             RoleGraph::generateUniversalPrivileges(out);
         }
-        virtual bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
 
             if ( cmdObj.firstElement().type() != Array ) {
                 errmsg = "ops has to be an array";
diff --git a/src/mongo/db/commands/auth_schema_upgrade_d.cpp b/src/mongo/db/commands/auth_schema_upgrade_d.cpp
index bd27c4a68b1..90384c524fa 100644
--- a/src/mongo/db/commands/auth_schema_upgrade_d.cpp
+++ b/src/mongo/db/commands/auth_schema_upgrade_d.cpp
@@ -113,7 +113,7 @@ namespace {
 
     class CmdAuthSchemaUpgradeD : public CmdAuthSchemaUpgrade {
         virtual bool run(
-                TransactionExperiment* txn,
+                OperationContext* txn,
                 const string& dbname,
                 BSONObj& cmdObj,
                 int options,
diff --git a/src/mongo/db/commands/authentication_commands.cpp b/src/mongo/db/commands/authentication_commands.cpp
index 249fc0d93e4..8cd8b7afb2f 100644
--- a/src/mongo/db/commands/authentication_commands.cpp
+++ b/src/mongo/db/commands/authentication_commands.cpp
@@ -99,7 +99,7 @@ namespace mongo {
         virtual void addRequiredPrivileges(const std::string& dbname,
                                            const BSONObj& cmdObj,
                                            std::vector<Privilege>* out) {} // No auth required
-        bool run(TransactionExperiment* txn, const string&, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        bool run(OperationContext* txn, const string&, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             nonce64 n = getNextNonce();
             stringstream ss;
             ss << hex << n;
@@ -133,7 +133,7 @@ namespace mongo {
         }
     }
 
-    bool CmdAuthenticate::run(TransactionExperiment* txn, const string& dbname,
+    bool CmdAuthenticate::run(OperationContext* txn, const string& dbname,
                               BSONObj& cmdObj,
                               int,
                               string& errmsg,
@@ -351,7 +351,7 @@ namespace mongo {
         void help(stringstream& h) const { h << "de-authenticate"; }
         virtual bool isWriteCommandForConfigServer() const { return false; }
         CmdLogout() : Command("logout") {}
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
diff --git a/src/mongo/db/commands/authentication_commands.h b/src/mongo/db/commands/authentication_commands.h
index 4c6a2420695..0b4b0a3242a 100644
--- a/src/mongo/db/commands/authentication_commands.h
+++ b/src/mongo/db/commands/authentication_commands.h
@@ -51,7 +51,7 @@ namespace mongo {
         virtual void redactForLogging(mutablebson::Document* cmdObj);
 
         CmdAuthenticate() : Command("authenticate") {}
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
diff --git a/src/mongo/db/commands/cleanup_orphaned_cmd.cpp b/src/mongo/db/commands/cleanup_orphaned_cmd.cpp
index fa9330d358e..dac324345bd 100644
--- a/src/mongo/db/commands/cleanup_orphaned_cmd.cpp
+++ b/src/mongo/db/commands/cleanup_orphaned_cmd.cpp
@@ -61,7 +61,7 @@ namespace mongo {
      *
      * If the collection is not sharded, returns CleanupResult_Done.
      */
-    CleanupResult cleanupOrphanedData( TransactionExperiment* txn,
+    CleanupResult cleanupOrphanedData( OperationContext* txn,
                                        const NamespaceString& ns,
                                        const BSONObj& startingFromKeyConst,
                                        bool secondaryThrottle,
@@ -179,7 +179,7 @@ namespace mongo {
         // Output
         static BSONField<BSONObj> stoppedAtKeyField;
 
-        bool run( TransactionExperiment* txn,
+        bool run( OperationContext* txn,
                   string const &db,
                   BSONObj &cmdObj,
                   int,
diff --git a/src/mongo/db/commands/collection_to_capped.cpp b/src/mongo/db/commands/collection_to_capped.cpp
index 844ec2eec8e..756569d806e 100644
--- a/src/mongo/db/commands/collection_to_capped.cpp
+++ b/src/mongo/db/commands/collection_to_capped.cpp
@@ -36,11 +36,11 @@
 #include "mongo/db/query/internal_plans.h"
 #include "mongo/db/query/new_find.h"
 #include "mongo/db/repl/oplog.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 
 namespace mongo {
 
-    Status cloneCollectionAsCapped( TransactionExperiment* txn,
+    Status cloneCollectionAsCapped( OperationContext* txn,
                                     Database* db,
                                     const string& shortFrom,
                                     const string& shortTo,
@@ -142,7 +142,7 @@ namespace mongo {
                                              NamespaceString(dbname, collection)),
                                      targetActions));
         }
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
             string from = jsobj.getStringField( "cloneCollectionAsCapped" );
             string to = jsobj.getStringField( "toCollection" );
             double size = jsobj.getField( "size" ).number();
@@ -196,7 +196,7 @@ namespace mongo {
             return std::vector<BSONObj>();
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
             // calls renamecollection which does a global lock, so we must too:
             //
             Lock::GlobalWrite globalWriteLock;
diff --git a/src/mongo/db/commands/compact.cpp b/src/mongo/db/commands/compact.cpp
index ec301bac843..14af4c56d03 100644
--- a/src/mongo/db/commands/compact.cpp
+++ b/src/mongo/db/commands/compact.cpp
@@ -43,7 +43,7 @@
 #include "mongo/db/jsobj.h"
 #include "mongo/db/kill_current_op.h"
 #include "mongo/db/catalog/collection.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 
 namespace mongo {
 
@@ -83,7 +83,7 @@ namespace mongo {
             return IndexBuilder::killMatchingIndexBuilds(db->getCollection(ns), criteria);
         }
 
-        virtual bool run(TransactionExperiment* txn, const string& db, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& db, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             string coll = cmdObj.firstElement().valuestr();
             if( coll.empty() || db.empty() ) {
                 errmsg = "no collection name specified";
diff --git a/src/mongo/db/commands/connection_status.cpp b/src/mongo/db/commands/connection_status.cpp
index 1f9e9b7685e..35da228269f 100644
--- a/src/mongo/db/commands/connection_status.cpp
+++ b/src/mongo/db/commands/connection_status.cpp
@@ -46,7 +46,7 @@ namespace mongo {
             h << "Returns connection-specific information such as logged-in users";
         }
 
-        bool run(TransactionExperiment* txn, const string&, BSONObj& cmdObj, int, string& errmsg,
+        bool run(OperationContext* txn, const string&, BSONObj& cmdObj, int, string& errmsg,
                  BSONObjBuilder& result, bool fromRepl) {
             AuthorizationSession* authSession =
                     ClientBasic::getCurrent()->getAuthorizationSession();
diff --git a/src/mongo/db/commands/create_indexes.cpp b/src/mongo/db/commands/create_indexes.cpp
index 76a3c731637..978f0268863 100644
--- a/src/mongo/db/commands/create_indexes.cpp
+++ b/src/mongo/db/commands/create_indexes.cpp
@@ -35,7 +35,7 @@
 #include "mongo/db/commands.h"
 #include "mongo/db/ops/insert.h"
 #include "mongo/db/repl/oplog.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/s/d_logic.h"
 #include "mongo/s/shard_key_pattern.h"
 
@@ -70,7 +70,7 @@ namespace mongo {
             return b.obj();
         }
 
-        virtual bool run(TransactionExperiment* txn,  const string& dbname, BSONObj& cmdObj, int options,
+        virtual bool run(OperationContext* txn,  const string& dbname, BSONObj& cmdObj, int options,
                           string& errmsg, BSONObjBuilder& result,
                           bool fromRepl = false ) {
 
diff --git a/src/mongo/db/commands/dbhash.cpp b/src/mongo/db/commands/dbhash.cpp
index 802a99cba5f..183813f196b 100644
--- a/src/mongo/db/commands/dbhash.cpp
+++ b/src/mongo/db/commands/dbhash.cpp
@@ -125,7 +125,7 @@ namespace mongo {
         return hash;
     }
 
-    bool DBHashCmd::run(TransactionExperiment* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
+    bool DBHashCmd::run(OperationContext* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
         Timer timer;
 
         set<string> desiredCollections;
diff --git a/src/mongo/db/commands/dbhash.h b/src/mongo/db/commands/dbhash.h
index cb0cbdefa1c..688ccada6a5 100644
--- a/src/mongo/db/commands/dbhash.h
+++ b/src/mongo/db/commands/dbhash.h
@@ -46,7 +46,7 @@ namespace mongo {
                                            const BSONObj& cmdObj,
                                            std::vector<Privilege>* out);
 
-        virtual bool run(TransactionExperiment* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool);
+        virtual bool run(OperationContext* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool);
 
         void wipeCacheForCollection( const StringData& ns );
 
diff --git a/src/mongo/db/commands/distinct.cpp b/src/mongo/db/commands/distinct.cpp
index 5b6888154d6..bc05c80195a 100644
--- a/src/mongo/db/commands/distinct.cpp
+++ b/src/mongo/db/commands/distinct.cpp
@@ -68,7 +68,7 @@ namespace mongo {
             help << "{ distinct : 'collection name' , key : 'a.b' , query : {} }";
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result,
+        bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result,
                  bool fromRepl ) {
 
             Timer t;
diff --git a/src/mongo/db/commands/drop_indexes.cpp b/src/mongo/db/commands/drop_indexes.cpp
index ac9deff5ded..332da8c6e3e 100644
--- a/src/mongo/db/commands/drop_indexes.cpp
+++ b/src/mongo/db/commands/drop_indexes.cpp
@@ -39,7 +39,7 @@
 #include "mongo/db/catalog/index_key_validate.h"
 #include "mongo/db/pdfile.h"
 #include "mongo/db/repl/oplog.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 
 namespace mongo {
 
@@ -92,14 +92,14 @@ namespace mongo {
         }
 
         CmdDropIndexes() : Command("dropIndexes", false, "deleteIndexes") { }
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& anObjBuilder, bool fromRepl) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& anObjBuilder, bool fromRepl) {
             Lock::DBWrite dbXLock(dbname);
             bool ok = wrappedRun(txn, dbname, jsobj, errmsg, anObjBuilder);
             if (ok && !fromRepl)
                 logOp(txn, "c",(dbname + ".$cmd").c_str(), jsobj);
             return ok;
         }
-        bool wrappedRun(TransactionExperiment* txn,
+        bool wrappedRun(OperationContext* txn,
                         const string& dbname,
                         BSONObj& jsobj,
                         string& errmsg,
@@ -212,7 +212,7 @@ namespace mongo {
             return IndexBuilder::killMatchingIndexBuilds(db->getCollection(ns), criteria);
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname , BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool /*fromRepl*/) {
+        bool run(OperationContext* txn, const string& dbname , BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool /*fromRepl*/) {
             static DBDirectClient db;
 
             BSONElement e = jsobj.firstElement();
diff --git a/src/mongo/db/commands/fail_point_cmd.cpp b/src/mongo/db/commands/fail_point_cmd.cpp
index bcb46cc4332..aa3c79c5bcb 100644
--- a/src/mongo/db/commands/fail_point_cmd.cpp
+++ b/src/mongo/db/commands/fail_point_cmd.cpp
@@ -81,7 +81,7 @@ namespace mongo {
             h << "modifies the settings of a fail point";
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                 BSONObj& cmdObj,
                 int,
                 string& errmsg,
diff --git a/src/mongo/db/commands/find_and_modify.cpp b/src/mongo/db/commands/find_and_modify.cpp
index 47043005667..44ca0e36609 100644
--- a/src/mongo/db/commands/find_and_modify.cpp
+++ b/src/mongo/db/commands/find_and_modify.cpp
@@ -41,7 +41,7 @@
 #include "mongo/db/ops/update.h"
 #include "mongo/db/ops/update_lifecycle_impl.h"
 #include "mongo/db/query/get_runner.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 
 namespace mongo {
 
@@ -65,7 +65,7 @@ namespace mongo {
             find_and_modify::addPrivilegesRequiredForFindAndModify(this, dbname, cmdObj, out);
         }
         /* this will eventually replace run,  once sort is handled */
-        bool runNoDirectClient( TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
+        bool runNoDirectClient( OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
             verify( cmdObj["sort"].eoo() );
 
             const string ns = dbname + '.' + cmdObj.firstElement().valuestr();
@@ -122,7 +122,7 @@ namespace mongo {
             result.append( "value" , p.transform( doc ) );
         }
 
-        static bool runNoDirectClient(TransactionExperiment* txn,
+        static bool runNoDirectClient(OperationContext* txn,
                                       const string& ns, 
                                       const BSONObj& queryOriginal,
                                       const BSONObj& fields,
@@ -297,7 +297,7 @@ namespace mongo {
             return true;
         }
         
-        virtual bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int x, string& errmsg, BSONObjBuilder& result, bool y) {
+        virtual bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int x, string& errmsg, BSONObjBuilder& result, bool y) {
             DBDirectClient db(txn);
 
             if (cmdObj["sort"].eoo()) {
diff --git a/src/mongo/db/commands/fsync.cpp b/src/mongo/db/commands/fsync.cpp
index 8837c91c05c..428dfd2cf66 100644
--- a/src/mongo/db/commands/fsync.cpp
+++ b/src/mongo/db/commands/fsync.cpp
@@ -92,7 +92,7 @@ namespace mongo {
             actions.addAction(ActionType::fsync);
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
-        virtual bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
 
             if (Lock::isLocked()) {
                 errmsg = "fsync: Cannot execute fsync command from contexts that hold a data lock";
diff --git a/src/mongo/db/commands/geonear.cpp b/src/mongo/db/commands/geonear.cpp
index 9a6582fede5..5976d8a4e3d 100644
--- a/src/mongo/db/commands/geonear.cpp
+++ b/src/mongo/db/commands/geonear.cpp
@@ -68,7 +68,7 @@ namespace mongo {
             out->push_back(Privilege(parseResourcePattern(dbname, cmdObj), actions));
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             const string ns = dbname + "." + cmdObj.firstElement().valuestr();
 
             if (!cmdObj["start"].eoo()) {
diff --git a/src/mongo/db/commands/get_last_error.cpp b/src/mongo/db/commands/get_last_error.cpp
index dde7a40e84f..31005f5e1fb 100644
--- a/src/mongo/db/commands/get_last_error.cpp
+++ b/src/mongo/db/commands/get_last_error.cpp
@@ -57,7 +57,7 @@ namespace mongo {
             help << "reset error state (used with getpreverror)";
         }
         CmdResetError() : Command("resetError", false, "reseterror") {}
-        bool run(TransactionExperiment* txn, const string& db, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        bool run(OperationContext* txn, const string& db, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             LastError *le = lastError.get();
             verify( le );
             le->reset();
@@ -91,7 +91,7 @@ namespace mongo {
                  << "  { wtimeout:m} - timeout for w in m milliseconds";
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                   BSONObj& cmdObj,
                   int,
                   string& errmsg,
@@ -262,7 +262,7 @@ namespace mongo {
                                            const BSONObj& cmdObj,
                                            std::vector<Privilege>* out) {} // No auth required
         CmdGetPrevError() : Command("getPrevError", false, "getpreverror") {}
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             LastError *le = lastError.disableForCommand();
             le->appendSelf( result );
             if ( le->valid )
diff --git a/src/mongo/db/commands/group.cpp b/src/mongo/db/commands/group.cpp
index 8a1608f7e71..6e80bbef1f6 100644
--- a/src/mongo/db/commands/group.cpp
+++ b/src/mongo/db/commands/group.cpp
@@ -202,7 +202,7 @@ namespace mongo {
             return true;
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
 
             if ( !globalScriptEngine ) {
                 errmsg = "server-side JavaScript execution is disabled";
diff --git a/src/mongo/db/commands/hashcmd.cpp b/src/mongo/db/commands/hashcmd.cpp
index cff86b33e42..8af317bf0ef 100644
--- a/src/mongo/db/commands/hashcmd.cpp
+++ b/src/mongo/db/commands/hashcmd.cpp
@@ -72,7 +72,7 @@ namespace mongo {
          *>  "out" : NumberLong(6271151123721111923),
          *>  "ok" : 1 }
          **/
-        bool run(TransactionExperiment* txn, const string& db,
+        bool run(OperationContext* txn, const string& db,
                   BSONObj& cmdObj,
                   int options, string& errmsg,
                   BSONObjBuilder& result,
diff --git a/src/mongo/db/commands/index_filter_commands.cpp b/src/mongo/db/commands/index_filter_commands.cpp
index b4d9d6c93e4..60346f782c4 100644
--- a/src/mongo/db/commands/index_filter_commands.cpp
+++ b/src/mongo/db/commands/index_filter_commands.cpp
@@ -120,7 +120,7 @@ namespace mongo {
         : Command(name),
           helpText(helpText) { }
 
-    bool IndexFilterCommand::run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int options,
+    bool IndexFilterCommand::run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int options,
                            string& errmsg, BSONObjBuilder& result, bool fromRepl) {
         string ns = parseNs(dbname, cmdObj);
 
diff --git a/src/mongo/db/commands/index_filter_commands.h b/src/mongo/db/commands/index_filter_commands.h
index ac372668769..a08ddd816db 100644
--- a/src/mongo/db/commands/index_filter_commands.h
+++ b/src/mongo/db/commands/index_filter_commands.h
@@ -63,7 +63,7 @@ namespace mongo {
          * implement plan cache command functionality.
          */
 
-        bool run(TransactionExperiment* txn, const std::string& dbname, BSONObj& cmdObj, int options,
+        bool run(OperationContext* txn, const std::string& dbname, BSONObj& cmdObj, int options,
                  std::string& errmsg, BSONObjBuilder& result, bool fromRepl);
 
         virtual bool isWriteCommandForConfigServer() const;
diff --git a/src/mongo/db/commands/index_stats.cpp b/src/mongo/db/commands/index_stats.cpp
index 1b0c69e42b2..b8eba5fdce7 100644
--- a/src/mongo/db/commands/index_stats.cpp
+++ b/src/mongo/db/commands/index_stats.cpp
@@ -492,7 +492,7 @@ namespace mongo {
             out->push_back(Privilege(parseResourcePattern(dbname, cmdObj), actions));
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg,
+        bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg,
                  BSONObjBuilder& result, bool fromRepl) {
 
             NamespaceString nss( dbname, cmdObj.firstElement().valuestrsafe() );
diff --git a/src/mongo/db/commands/isself.cpp b/src/mongo/db/commands/isself.cpp
index 8f5fc57210d..df6a9dbb26b 100644
--- a/src/mongo/db/commands/isself.cpp
+++ b/src/mongo/db/commands/isself.cpp
@@ -184,7 +184,7 @@ namespace mongo {
         virtual void addRequiredPrivileges(const std::string& dbname,
                                            const BSONObj& cmdObj,
                                            std::vector<Privilege>* out) {} // No auth required
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
             init();
             result.append( "id" , _id );
             return true;
diff --git a/src/mongo/db/commands/merge_chunks_cmd.cpp b/src/mongo/db/commands/merge_chunks_cmd.cpp
index d7c39a6ecd5..8e9d9f38b28 100644
--- a/src/mongo/db/commands/merge_chunks_cmd.cpp
+++ b/src/mongo/db/commands/merge_chunks_cmd.cpp
@@ -80,7 +80,7 @@ namespace mongo {
         static BSONField<string> shardNameField;
         static BSONField<string> configField;
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                   BSONObj& cmdObj,
                   int,
                   string& errmsg,
diff --git a/src/mongo/db/commands/mr.cpp b/src/mongo/db/commands/mr.cpp
index 543cae19cf0..5ecd9dd52e9 100644
--- a/src/mongo/db/commands/mr.cpp
+++ b/src/mongo/db/commands/mr.cpp
@@ -47,7 +47,7 @@
 #include "mongo/db/repl/is_master.h"
 #include "mongo/db/repl/oplog.h"
 #include "mongo/db/range_preserver.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/db/storage_options.h"
 #include "mongo/scripting/engine.h"
 #include "mongo/s/collection_metadata.h"
@@ -664,7 +664,7 @@ namespace mongo {
             _txn->commitIfNeeded();
         }
 
-        State::State(TransactionExperiment* txn, const Config& c) :
+        State::State(OperationContext* txn, const Config& c) :
                 _config(c),
                 _useIncremental(true),
                 _txn(txn),
@@ -1208,7 +1208,7 @@ namespace mongo {
                 addPrivilegesRequiredForMapReduce(this, dbname, cmdObj, out);
             }
 
-            bool run(TransactionExperiment* txn, const string& dbname , BSONObj& cmd, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+            bool run(OperationContext* txn, const string& dbname , BSONObj& cmd, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
                 Timer t;
                 Client& client = cc();
                 CurOp * op = client.curop();
@@ -1446,7 +1446,7 @@ namespace mongo {
                 actions.addAction(ActionType::internal);
                 out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
             }
-            bool run(TransactionExperiment* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
+            bool run(OperationContext* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
                 ShardedConnectionInfo::addHook();
                 // legacy name
                 string shardedOutputCollection = cmdObj["shardedOutputCollection"].valuestrsafe();
diff --git a/src/mongo/db/commands/mr.h b/src/mongo/db/commands/mr.h
index 88d114fb5b9..9eddac77efc 100644
--- a/src/mongo/db/commands/mr.h
+++ b/src/mongo/db/commands/mr.h
@@ -42,7 +42,7 @@
 
 namespace mongo {
 
-    class TransactionExperiment;
+    class OperationContext;
 
     namespace mr {
 
@@ -239,7 +239,7 @@ namespace mongo {
             /**
              * txn must outlive this State.
              */
-            State( TransactionExperiment* txn, const Config& c );
+            State( OperationContext* txn, const Config& c );
             ~State();
 
             void init();
@@ -343,7 +343,7 @@ namespace mongo {
              */
             int _add(InMemory* im , const BSONObj& a);
 
-            TransactionExperiment* _txn;
+            OperationContext* _txn;
             scoped_ptr<Scope> _scope;
             bool _onDisk; // if the end result of this map reduce is disk or not
 
diff --git a/src/mongo/db/commands/oplog_note.cpp b/src/mongo/db/commands/oplog_note.cpp
index bd5a67fc098..e4d8924408e 100644
--- a/src/mongo/db/commands/oplog_note.cpp
+++ b/src/mongo/db/commands/oplog_note.cpp
@@ -56,7 +56,7 @@ namespace mongo {
             }
             return Status::OK();
         }
-        virtual bool run(TransactionExperiment* txn, const string& dbname,
+        virtual bool run(OperationContext* txn, const string& dbname,
                          BSONObj& cmdObj,
                          int,
                          string& errmsg,
diff --git a/src/mongo/db/commands/parallel_collection_scan.cpp b/src/mongo/db/commands/parallel_collection_scan.cpp
index 58a530184b5..fa0939fc1f1 100644
--- a/src/mongo/db/commands/parallel_collection_scan.cpp
+++ b/src/mongo/db/commands/parallel_collection_scan.cpp
@@ -159,7 +159,7 @@ namespace mongo {
             return Status(ErrorCodes::Unauthorized, "Unauthorized");
         }
 
-        virtual bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int options,
+        virtual bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int options,
                           string& errmsg, BSONObjBuilder& result,
                           bool fromRepl = false ) {
 
diff --git a/src/mongo/db/commands/parameters.cpp b/src/mongo/db/commands/parameters.cpp
index af9ad7c822f..981e04c26a5 100644
--- a/src/mongo/db/commands/parameters.cpp
+++ b/src/mongo/db/commands/parameters.cpp
@@ -72,7 +72,7 @@ namespace mongo {
             appendParameterNames( help );
             help << "{ getParameter:'*' } to get everything\n";
         }
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
             bool all = *cmdObj.firstElement().valuestrsafe() == '*';
 
             int before = result.len();
@@ -126,7 +126,7 @@ namespace mongo {
             help << "{ setParameter:1, <param>:<value> }\n";
             appendParameterNames( help );
         }
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
             int s = 0;
             bool found = false;
 
diff --git a/src/mongo/db/commands/pipeline_command.cpp b/src/mongo/db/commands/pipeline_command.cpp
index 34652d66daf..6967dbe51a6 100644
--- a/src/mongo/db/commands/pipeline_command.cpp
+++ b/src/mongo/db/commands/pipeline_command.cpp
@@ -273,7 +273,7 @@ namespace {
             Pipeline::addRequiredPrivileges(this, dbname, cmdObj, out);
         }
 
-        virtual bool run(TransactionExperiment* txn, const string &db, BSONObj &cmdObj, int options, string &errmsg,
+        virtual bool run(OperationContext* txn, const string &db, BSONObj &cmdObj, int options, string &errmsg,
                          BSONObjBuilder &result, bool fromRepl) {
 
             string ns = parseNs(db, cmdObj);
diff --git a/src/mongo/db/commands/plan_cache_commands.cpp b/src/mongo/db/commands/plan_cache_commands.cpp
index a58dcb78851..f7e97c68072 100644
--- a/src/mongo/db/commands/plan_cache_commands.cpp
+++ b/src/mongo/db/commands/plan_cache_commands.cpp
@@ -114,7 +114,7 @@ namespace mongo {
           helpText(helpText),
           actionType(actionType) { }
 
-    bool PlanCacheCommand::run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int options,
+    bool PlanCacheCommand::run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int options,
                                string& errmsg, BSONObjBuilder& result, bool fromRepl) {
         string ns = parseNs(dbname, cmdObj);
 
diff --git a/src/mongo/db/commands/plan_cache_commands.h b/src/mongo/db/commands/plan_cache_commands.h
index 1c1de2da9f5..8e7eb9667a4 100644
--- a/src/mongo/db/commands/plan_cache_commands.h
+++ b/src/mongo/db/commands/plan_cache_commands.h
@@ -58,7 +58,7 @@ namespace mongo {
          * implement plan cache command functionality.
          */
 
-        bool run(TransactionExperiment* txn, const std::string& dbname, BSONObj& cmdObj, int options,
+        bool run(OperationContext* txn, const std::string& dbname, BSONObj& cmdObj, int options,
                  std::string& errmsg, BSONObjBuilder& result, bool fromRepl);
 
         virtual bool isWriteCommandForConfigServer() const;
diff --git a/src/mongo/db/commands/rename_collection.cpp b/src/mongo/db/commands/rename_collection.cpp
index 196d28ae735..9f173c03d72 100644
--- a/src/mongo/db/commands/rename_collection.cpp
+++ b/src/mongo/db/commands/rename_collection.cpp
@@ -40,7 +40,7 @@
 #include "mongo/db/namespace_string.h"
 #include "mongo/db/ops/insert.h"
 #include "mongo/db/repl/oplog.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 
 namespace mongo {
 
@@ -91,14 +91,14 @@ namespace mongo {
             IndexBuilder::restoreIndexes( indexesInProg );
         }
 
-        virtual bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             Lock::GlobalWrite globalWriteLock;
             bool ok = wrappedRun(txn, dbname, cmdObj, errmsg, result, fromRepl);
             if (ok && !fromRepl)
                 logOp(txn, "c",(dbname + ".$cmd").c_str(), cmdObj);
             return ok;
         }
-        virtual bool wrappedRun(TransactionExperiment* txn,
+        virtual bool wrappedRun(OperationContext* txn,
                                 const string& dbname,
                                 BSONObj& cmdObj,
                                 string& errmsg,
diff --git a/src/mongo/db/commands/server_status.cpp b/src/mongo/db/commands/server_status.cpp
index 8a6923c8772..e5d9a791589 100644
--- a/src/mongo/db/commands/server_status.cpp
+++ b/src/mongo/db/commands/server_status.cpp
@@ -71,7 +71,7 @@ namespace mongo {
             actions.addAction(ActionType::serverStatus);
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             
             _runCalled = true;
 
diff --git a/src/mongo/db/commands/shutdown.h b/src/mongo/db/commands/shutdown.h
index 7120da6fbad..3fdf347a50a 100644
--- a/src/mongo/db/commands/shutdown.h
+++ b/src/mongo/db/commands/shutdown.h
@@ -49,7 +49,7 @@ namespace mongo {
         virtual bool isWriteCommandForConfigServer() const { return false; }
         virtual void help( stringstream& help ) const;
         CmdShutdown() : Command("shutdown") {}
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
diff --git a/src/mongo/db/commands/storage_details.cpp b/src/mongo/db/commands/storage_details.cpp
index 1121a3e22dd..9649cdcdfcf 100644
--- a/src/mongo/db/commands/storage_details.cpp
+++ b/src/mongo/db/commands/storage_details.cpp
@@ -323,7 +323,7 @@ namespace {
         /**
          * Entry point, parses command parameters and invokes runInternal.
          */
-        bool run(TransactionExperiment* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg,
+        bool run(OperationContext* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg,
                  BSONObjBuilder& result, bool fromRepl);
 
     };
@@ -756,7 +756,7 @@ namespace {
 
     static const char* USE_ANALYZE_STR = "use {analyze: 'diskStorage' | 'pagesInRAM'}";
 
-    bool StorageDetailsCmd::run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg,
+    bool StorageDetailsCmd::run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg,
                                 BSONObjBuilder& result, bool fromRepl) {
 
         // { analyze: subcommand }
diff --git a/src/mongo/db/commands/test_commands.cpp b/src/mongo/db/commands/test_commands.cpp
index 3abd64cd40d..a257aa1d335 100644
--- a/src/mongo/db/commands/test_commands.cpp
+++ b/src/mongo/db/commands/test_commands.cpp
@@ -37,7 +37,7 @@
 #include "mongo/db/query/internal_plans.h"
 #include "mongo/db/catalog/collection.h"
 #include "mongo/db/repl/oplog.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 
 namespace mongo {
 
@@ -55,7 +55,7 @@ namespace mongo {
         virtual void help( stringstream &help ) const {
             help << "internal. for testing only.";
         }
-        virtual bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
+        virtual bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
             string coll = cmdObj[ "godinsert" ].valuestrsafe();
             log() << "test only command godinsert invoked coll:" << coll << endl;
             uassert( 13049, "godinsert must specify a collection", !coll.empty() );
@@ -93,7 +93,7 @@ namespace mongo {
                                            const BSONObj& cmdObj,
                                            std::vector<Privilege>* out) {}
         CmdSleep() : Command("sleep") { }
-        bool run(TransactionExperiment* txn, const string& ns, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        bool run(OperationContext* txn, const string& ns, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             log() << "test only command sleep invoked" << endl;
             long long millis = 10 * 1000;
 
@@ -133,7 +133,7 @@ namespace mongo {
         virtual void addRequiredPrivileges(const std::string& dbname,
                                            const BSONObj& cmdObj,
                                            std::vector<Privilege>* out) {}
-        virtual bool run(TransactionExperiment* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
+        virtual bool run(OperationContext* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
             string coll = cmdObj[ "captrunc" ].valuestrsafe();
             uassert( 13416, "captrunc must specify a collection", !coll.empty() );
             NamespaceString nss( dbname, coll );
@@ -180,7 +180,7 @@ namespace mongo {
             return IndexBuilder::killMatchingIndexBuilds(db->getCollection(ns), criteria);
         }
 
-        virtual bool run(TransactionExperiment* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             string coll = cmdObj[ "emptycapped" ].valuestrsafe();
             uassert( 13428, "emptycapped must specify a collection", !coll.empty() );
             NamespaceString nss( dbname, coll );
diff --git a/src/mongo/db/commands/touch.cpp b/src/mongo/db/commands/touch.cpp
index 4039d386ef4..e44a84b6bae 100644
--- a/src/mongo/db/commands/touch.cpp
+++ b/src/mongo/db/commands/touch.cpp
@@ -50,7 +50,7 @@
 #include "mongo/db/pdfile.h"
 #include "mongo/db/storage/extent.h"
 #include "mongo/db/storage/extent_manager.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/util/timer.h"
 #include "mongo/util/touch_pages.h"
 
@@ -77,7 +77,7 @@ namespace mongo {
         }
         TouchCmd() : Command("touch") { }
 
-        virtual bool run(TransactionExperiment* txn,
+        virtual bool run(OperationContext* txn,
                          const string& dbname,
                          BSONObj& cmdObj,
                          int,
diff --git a/src/mongo/db/commands/user_management_commands.cpp b/src/mongo/db/commands/user_management_commands.cpp
index b6e6cc65545..4d9aa3b943e 100644
--- a/src/mongo/db/commands/user_management_commands.cpp
+++ b/src/mongo/db/commands/user_management_commands.cpp
@@ -341,7 +341,7 @@ namespace mongo {
             return checkAuthorizedToGrantRoles(authzSession, args.roles);
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -527,7 +527,7 @@ namespace mongo {
             return Status::OK();
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -651,7 +651,7 @@ namespace mongo {
             return Status::OK();
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -737,7 +737,7 @@ namespace mongo {
             return Status::OK();
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -819,7 +819,7 @@ namespace mongo {
             return checkAuthorizedToGrantRoles(authzSession, roles);
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -917,7 +917,7 @@ namespace mongo {
             return checkAuthorizedToRevokeRoles(authzSession, roles);
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -1033,7 +1033,7 @@ namespace mongo {
             return Status::OK();
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -1175,7 +1175,7 @@ namespace mongo {
             return checkAuthorizedToGrantPrivileges(authzSession, args.privileges);
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -1321,7 +1321,7 @@ namespace mongo {
             return checkAuthorizedToGrantPrivileges(authzSession, args.privileges);
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -1442,7 +1442,7 @@ namespace mongo {
             return checkAuthorizedToGrantPrivileges(authzSession, privileges);
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -1578,7 +1578,7 @@ namespace mongo {
             return checkAuthorizedToRevokePrivileges(authzSession, privileges);
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -1715,7 +1715,7 @@ namespace mongo {
             return checkAuthorizedToGrantRoles(authzSession, roles);
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -1834,7 +1834,7 @@ namespace mongo {
             return checkAuthorizedToRevokeRoles(authzSession, roles);
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -1953,7 +1953,7 @@ namespace mongo {
             return Status::OK();
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -2121,7 +2121,7 @@ namespace mongo {
             return Status::OK();
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -2276,7 +2276,7 @@ namespace mongo {
             return Status::OK();
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -2356,7 +2356,7 @@ namespace mongo {
             return Status::OK();
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
@@ -2400,7 +2400,7 @@ namespace mongo {
             return Status::OK();
         }
 
-        bool run(TransactionExperiment* txn,
+        bool run(OperationContext* txn,
                  const string& dbname,
                  BSONObj& cmdObj,
                  int options,
@@ -2809,7 +2809,7 @@ namespace mongo {
             return Status::OK();
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname,
+        bool run(OperationContext* txn, const string& dbname,
                  BSONObj& cmdObj,
                  int options,
                  string& errmsg,
diff --git a/src/mongo/db/commands/validate.cpp b/src/mongo/db/commands/validate.cpp
index 56f5382548c..28d06c9ae05 100644
--- a/src/mongo/db/commands/validate.cpp
+++ b/src/mongo/db/commands/validate.cpp
@@ -33,7 +33,7 @@
 #include "mongo/db/pdfile.h"
 #include "mongo/db/query/internal_plans.h"
 #include "mongo/db/query/runner.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/db/catalog/collection.h"
 
 namespace mongo {
@@ -59,7 +59,7 @@ namespace mongo {
         }
         //{ validate: "collectionnamewithoutthedbpart" [, scandata: <bool>] [, full: <bool> } */
 
-        bool run(TransactionExperiment* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+        bool run(OperationContext* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
             string ns = dbname + "." + cmdObj.firstElement().valuestrsafe();
 
             NamespaceString ns_string(ns);
diff --git a/src/mongo/db/commands/write_commands/batch_executor.cpp b/src/mongo/db/commands/write_commands/batch_executor.cpp
index d7295a5458f..dd86b3eb476 100644
--- a/src/mongo/db/commands/write_commands/batch_executor.cpp
+++ b/src/mongo/db/commands/write_commands/batch_executor.cpp
@@ -49,7 +49,7 @@
 #include "mongo/db/repl/rs.h"
 #include "mongo/db/server_parameters.h"
 #include "mongo/db/stats/counters.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/db/write_concern.h"
 #include "mongo/s/collection_metadata.h"
 #include "mongo/s/d_logic.h"
@@ -89,7 +89,7 @@ namespace mongo {
 
     using mongoutils::str::stream;
 
-    WriteBatchExecutor::WriteBatchExecutor( TransactionExperiment* txn,
+    WriteBatchExecutor::WriteBatchExecutor( OperationContext* txn,
                                             const BSONObj& wc,
                                             Client* client,
                                             OpCounters* opCounters,
@@ -579,7 +579,7 @@ namespace mongo {
         }
     }
 
-    static void finishCurrentOp( TransactionExperiment* txn,
+    static void finishCurrentOp( OperationContext* txn,
                                  Client* client,
                                  CurOp* currentOp,
                                  WriteErrorDetail* opError ) {
@@ -618,21 +618,21 @@ namespace mongo {
     // - error
     //
 
-    static void singleInsert( TransactionExperiment* txn,
+    static void singleInsert( OperationContext* txn,
                               const BSONObj& docToInsert,
                               Collection* collection,
                               WriteOpResult* result );
 
-    static void singleCreateIndex( TransactionExperiment* txn,
+    static void singleCreateIndex( OperationContext* txn,
                                    const BSONObj& indexDesc,
                                    Collection* collection,
                                    WriteOpResult* result );
 
-    static void multiUpdate( TransactionExperiment* txn,
+    static void multiUpdate( OperationContext* txn,
                              const BatchItemRef& updateItem,
                              WriteOpResult* result );
 
-    static void multiRemove( TransactionExperiment* txn,
+    static void multiRemove( OperationContext* txn,
                              const BatchItemRef& removeItem,
                              WriteOpResult* result );
 
@@ -653,7 +653,7 @@ namespace mongo {
         /**
          * Constructs a new instance, for performing inserts described in "aRequest".
          */
-        explicit ExecInsertsState(TransactionExperiment* txn,
+        explicit ExecInsertsState(OperationContext* txn,
                                   const BatchedCommandRequest* aRequest);
 
         /**
@@ -687,7 +687,7 @@ namespace mongo {
          */
         Collection* getCollection() { return _collection; }
 
-        TransactionExperiment* txn;
+        OperationContext* txn;
 
         // Request object describing the inserts.
         const BatchedCommandRequest* request;
@@ -887,7 +887,7 @@ namespace mongo {
     // IN-DB-LOCK CORE OPERATIONS
     //
 
-    WriteBatchExecutor::ExecInsertsState::ExecInsertsState(TransactionExperiment* txn,
+    WriteBatchExecutor::ExecInsertsState::ExecInsertsState(OperationContext* txn,
                                                            const BatchedCommandRequest* aRequest) :
         txn(txn),
         request(aRequest),
@@ -1015,7 +1015,7 @@ namespace mongo {
      *
      * Might fault or error, otherwise populates the result.
      */
-    static void singleInsert( TransactionExperiment* txn,
+    static void singleInsert( OperationContext* txn,
                               const BSONObj& docToInsert,
                               Collection* collection,
                               WriteOpResult* result ) {
@@ -1042,7 +1042,7 @@ namespace mongo {
      *
      * Might fault or error, otherwise populates the result.
      */
-    static void singleCreateIndex( TransactionExperiment* txn,
+    static void singleCreateIndex( OperationContext* txn,
                                    const BSONObj& indexDesc,
                                    Collection* collection,
                                    WriteOpResult* result ) {
@@ -1065,7 +1065,7 @@ namespace mongo {
         }
     }
 
-    static void multiUpdate( TransactionExperiment* txn,
+    static void multiUpdate( OperationContext* txn,
                              const BatchItemRef& updateItem,
                              WriteOpResult* result ) {
 
@@ -1126,7 +1126,7 @@ namespace mongo {
      *
      * Might fault or error, otherwise populates the result.
      */
-    static void multiRemove( TransactionExperiment* txn,
+    static void multiRemove( OperationContext* txn,
                              const BatchItemRef& removeItem,
                              WriteOpResult* result ) {
 
diff --git a/src/mongo/db/commands/write_commands/batch_executor.h b/src/mongo/db/commands/write_commands/batch_executor.h
index 6406474e396..fcb55f2b6b6 100644
--- a/src/mongo/db/commands/write_commands/batch_executor.h
+++ b/src/mongo/db/commands/write_commands/batch_executor.h
@@ -43,7 +43,7 @@ namespace mongo {
     class BSONObjBuilder;
     class CurOp;
     class OpCounters;
-    class TransactionExperiment;
+    class OperationContext;
     struct LastError;
 
     struct WriteOpStats;
@@ -59,7 +59,7 @@ namespace mongo {
         // State object used by private execInserts.  TODO: Do not expose this type.
         class ExecInsertsState;
 
-        WriteBatchExecutor( TransactionExperiment* txn,
+        WriteBatchExecutor( OperationContext* txn,
                             const BSONObj& defaultWriteConcern,
                             Client* client,
                             OpCounters* opCounters,
@@ -134,7 +134,7 @@ namespace mongo {
                             const WriteErrorDetail* error,
                             CurOp* currentOp );
 
-        TransactionExperiment* _txn;
+        OperationContext* _txn;
 
         // Default write concern, if one isn't provide in the batches.
         const BSONObj _defaultWriteConcern;
diff --git a/src/mongo/db/commands/write_commands/write_commands.cpp b/src/mongo/db/commands/write_commands/write_commands.cpp
index dcdd527f19f..c9b77e1b831 100644
--- a/src/mongo/db/commands/write_commands/write_commands.cpp
+++ b/src/mongo/db/commands/write_commands/write_commands.cpp
@@ -102,7 +102,7 @@ namespace mongo {
     // Write commands are counted towards their corresponding opcounters, not command opcounters.
     bool WriteCmd::shouldAffectCommandCounter() const { return false; }
 
-    bool WriteCmd::run(TransactionExperiment* txn,
+    bool WriteCmd::run(OperationContext* txn,
                        const string& dbName,
                        BSONObj& cmdObj,
                        int options,
diff --git a/src/mongo/db/commands/write_commands/write_commands.h b/src/mongo/db/commands/write_commands/write_commands.h
index 9a8d96b5ac2..42cbc3e7b87 100644
--- a/src/mongo/db/commands/write_commands/write_commands.h
+++ b/src/mongo/db/commands/write_commands/write_commands.h
@@ -73,7 +73,7 @@ namespace mongo {
 
         // Write command entry point.
         virtual bool run(
-                 TransactionExperiment* txn,
+                 OperationContext* txn,
                  const string& dbname,
                  BSONObj& cmdObj,
                  int options,
diff --git a/src/mongo/db/db.cpp b/src/mongo/db/db.cpp
index 8914bb981d0..3e5aee43993 100644
--- a/src/mongo/db/db.cpp
+++ b/src/mongo/db/db.cpp
@@ -75,7 +75,7 @@
 #include "mongo/db/stats/snapshots.h"
 #include "mongo/db/storage/data_file.h"
 #include "mongo/db/storage/extent_manager.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/db/storage/mmap_v1/mmap_v1_extent_manager.h"
 #include "mongo/db/storage_options.h"
 #include "mongo/db/ttl.h"
@@ -188,7 +188,7 @@ namespace mongo {
         }
 
         virtual void process( Message& m , AbstractMessagingPort* port , LastError * le) {
-            DurTransaction txn;
+            OperationContextImpl txn;
             while ( true ) {
                 if ( inShutdown() ) {
                     log() << "got request after shutdown()" << endl;
@@ -282,7 +282,7 @@ namespace mongo {
         if (serverGlobalParams.isHttpInterfaceEnabled)
             boost::thread web( boost::bind(&webServerThread,
                                            new RestAdminAccess(), // takes ownership
-                                           DurTransaction::factory) ); // XXX SERVER-13931
+                                           OperationContextImpl::factory) ); // XXX SERVER-13931
 
 #if(TESTEXHAUST)
         boost::thread thr(testExhaust);
@@ -292,7 +292,7 @@ namespace mongo {
 
 
     void doDBUpgrade( const string& dbName, DataFileHeader* h ) {
-        DurTransaction txn;
+        OperationContextImpl txn;
         DBDirectClient db(&txn);
 
         if ( h->version == 4 && h->versionMinor == 4 ) {
@@ -359,7 +359,7 @@ namespace mongo {
         LOG(1) << "enter repairDatabases (to check pdfile version #)" << endl;
 
         Lock::GlobalWrite lk;
-        DurTransaction txn;
+        OperationContextImpl txn;
         vector< string > dbNames;
         getDatabaseNames( dbNames );
         for ( vector< string >::iterator i = dbNames.begin(); i != dbNames.end(); ++i ) {
diff --git a/src/mongo/db/dbcommands.cpp b/src/mongo/db/dbcommands.cpp
index bf31ff9d1e7..a6c5444614a 100644
--- a/src/mongo/db/dbcommands.cpp
+++ b/src/mongo/db/dbcommands.cpp
@@ -94,7 +94,7 @@ namespace mongo {
              << "N to wait N seconds for other members to catch up.";
     }
 
-    bool CmdShutdown::run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+    bool CmdShutdown::run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
         bool force = cmdObj.hasField("force") && cmdObj["force"].trueValue();
 
         if (!force &&
@@ -191,7 +191,7 @@ namespace mongo {
 
         CmdDropDatabase() : Command("dropDatabase") {}
 
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             // disallow dropping the config database
             if (serverGlobalParams.configsvr && (dbname == "config")) {
                 errmsg = "Cannot drop 'config' database if mongod started with --configsvr";
@@ -275,7 +275,7 @@ namespace mongo {
             return allKilledIndexes;
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        bool run(OperationContext* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             BSONElement e = cmdObj.firstElement();
             if ( e.numberInt() != 1 ) {
                 errmsg = "bad option";
@@ -351,7 +351,7 @@ namespace mongo {
 
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             // Needs to be locked exclusively, because creates the system.profile collection
             // in the local database.
             //
@@ -401,7 +401,7 @@ namespace mongo {
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
+        bool run(OperationContext* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
             // This doesn't look like it requires exclusive DB lock, because it uses its own diag
             // locking, but originally the lock was set to be WRITE, so preserving the behaviour.
             //
@@ -448,7 +448,7 @@ namespace mongo {
             return IndexBuilder::killMatchingIndexBuilds(db->getCollection(nsToDrop), criteria);
         }
 
-        virtual bool run(TransactionExperiment* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             const string nsToDrop = dbname + '.' + cmdObj.firstElement().valuestr();
             if (!serverGlobalParams.quiet) {
                 MONGO_TLOG(0) << "CMD: drop " << nsToDrop << endl;
@@ -512,7 +512,7 @@ namespace mongo {
             out->push_back(Privilege(parseResourcePattern(dbname, cmdObj), actions));
         }
 
-        virtual bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
+        virtual bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
             long long skip = 0;
             if ( cmdObj["skip"].isNumber() ) {
                 skip = cmdObj["skip"].numberLong();
@@ -595,7 +595,7 @@ namespace mongo {
 
             return Status(ErrorCodes::Unauthorized, "unauthorized");
         }
-        virtual bool run(TransactionExperiment* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+        virtual bool run(OperationContext* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
             BSONObjIterator it(cmdObj);
 
             // Extract ns from first cmdObj element.
@@ -653,7 +653,7 @@ namespace mongo {
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
         CmdListDatabases() : Command("listDatabases" , true ) {}
-        bool run(TransactionExperiment* txn, const string& dbname , BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool /*fromRepl*/) {
+        bool run(OperationContext* txn, const string& dbname , BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool /*fromRepl*/) {
             vector< string > dbNames;
             getDatabaseNames( dbNames );
             vector< BSONObj > dbInfos;
@@ -735,7 +735,7 @@ namespace mongo {
 
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname , BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool /*fromRepl*/) {
+        bool run(OperationContext* txn, const string& dbname , BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool /*fromRepl*/) {
             Lock::GlobalWrite globalWriteLock;
             Client::Context ctx(dbname);
 
@@ -784,7 +784,7 @@ namespace mongo {
             out->push_back(Privilege(parseResourcePattern(dbname, cmdObj), ActionType::find));
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
             const std::string ns = parseNs(dbname, jsobj);
 
             md5digest d;
@@ -913,7 +913,7 @@ namespace mongo {
             out->push_back(Privilege(parseResourcePattern(dbname, cmdObj), actions));
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
             Timer timer;
 
             string ns = jsobj.firstElement().String();
@@ -1070,7 +1070,7 @@ namespace mongo {
             out->push_back(Privilege(parseResourcePattern(dbname, cmdObj), actions));
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
             const string ns = dbname + "." + jsobj.firstElement().valuestr();
             Client::ReadContext cx( ns );
 
@@ -1144,7 +1144,7 @@ namespace mongo {
             out->push_back(Privilege(parseResourcePattern(dbname, cmdObj), actions));
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
             const string ns = dbname + "." + jsobj.firstElement().valuestr();
 
             Lock::DBWrite dbXLock(dbname);
@@ -1266,7 +1266,7 @@ namespace mongo {
             out->push_back(Privilege(ResourcePattern::forDatabaseName(dbname), actions));
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& jsobj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
             int scale = 1;
             if ( jsobj["scale"].isNumber() ) {
                 scale = jsobj["scale"].numberInt();
@@ -1379,7 +1379,7 @@ namespace mongo {
         virtual void addRequiredPrivileges(const std::string& dbname,
                                            const BSONObj& cmdObj,
                                            std::vector<Privilege>* out) {} // No auth required
-        virtual bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
+        virtual bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
             BSONObj info = cc().curop()->info();
             result << "you" << info[ "client" ];
             return true;
@@ -1387,7 +1387,7 @@ namespace mongo {
     } cmdWhatsMyUri;
 
 
-    bool _execCommand(TransactionExperiment* txn,
+    bool _execCommand(OperationContext* txn,
                       Command *c,
                       const string& dbname,
                       BSONObj& cmdObj,
@@ -1477,7 +1477,7 @@ namespace mongo {
      - context
      then calls run()
     */
-    void Command::execCommand(TransactionExperiment* txn,
+    void Command::execCommand(OperationContext* txn,
                               Command * c ,
                               Client& client,
                               int queryOptions,
@@ -1603,7 +1603,7 @@ namespace mongo {
 
        returns true if ran a cmd
     */
-    bool _runCommands(TransactionExperiment* txn,
+    bool _runCommands(OperationContext* txn,
                       const char* ns,
                       BSONObj& _cmdobj,
                       BufBuilder& b,
diff --git a/src/mongo/db/dbcommands_admin.cpp b/src/mongo/db/dbcommands_admin.cpp
index 5856d0eace7..736e932d4d3 100644
--- a/src/mongo/db/dbcommands_admin.cpp
+++ b/src/mongo/db/dbcommands_admin.cpp
@@ -82,7 +82,7 @@ namespace mongo {
         virtual void addRequiredPrivileges(const std::string& dbname,
                                            const BSONObj& cmdObj,
                                            std::vector<Privilege>* out) {}
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
             boost::filesystem::path p = dur::getJournalDir();
             p /= "journalLatencyTest";
         
diff --git a/src/mongo/db/dbcommands_generic.cpp b/src/mongo/db/dbcommands_generic.cpp
index 2ce435d136d..097e659e86d 100644
--- a/src/mongo/db/dbcommands_generic.cpp
+++ b/src/mongo/db/dbcommands_generic.cpp
@@ -101,7 +101,7 @@ namespace mongo {
         virtual void help( stringstream &help ) const {
             help << "internal command facilitating running in certain cloud computing environments";
         }
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& obj, int options, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& obj, int options, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
             if( !obj.hasElement("servers") ) { 
                 vector<string> ips;
                 obj["servers"].Obj().Vals(ips);
@@ -133,7 +133,7 @@ namespace mongo {
             help << "{ buildinfo:1 }";
         }
 
-        bool run(TransactionExperiment* txn, const std::string& dbname,
+        bool run(OperationContext* txn, const std::string& dbname,
                  BSONObj& jsobj,
                  int, // options
                  std::string& errmsg,
@@ -156,7 +156,7 @@ namespace mongo {
         virtual void addRequiredPrivileges(const std::string& dbname,
                                            const BSONObj& cmdObj,
                                            std::vector<Privilege>* out) {} // No auth required
-        virtual bool run(TransactionExperiment* txn, const string& badns, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
+        virtual bool run(OperationContext* txn, const string& badns, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
             // IMPORTANT: Don't put anything in here that might lock db - including authentication
             return true;
         }
@@ -171,7 +171,7 @@ namespace mongo {
         virtual void addRequiredPrivileges(const std::string& dbname,
                                            const BSONObj& cmdObj,
                                            std::vector<Privilege>* out) {} // No auth required
-        virtual bool run(TransactionExperiment* txn, const string& ns, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& ns, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             if ( globalScriptEngine ) {
                 BSONObjBuilder bb( result.subobjStart( "js" ) );
                 result.append( "utf8" , globalScriptEngine->utf8Ok() );
@@ -206,7 +206,7 @@ namespace mongo {
             actions.addAction(ActionType::hostInfo);
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             ProcessInfo p;
             BSONObjBuilder bSys, bOs;
 
@@ -243,7 +243,7 @@ namespace mongo {
             actions.addAction(ActionType::logRotate);
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
-        virtual bool run(TransactionExperiment* txn, const string& ns, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& ns, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             bool didRotate = rotateLogs();
             if (didRotate)
                 logProcessDetailsForLogRotate();
@@ -262,7 +262,7 @@ namespace mongo {
         virtual void addRequiredPrivileges(const std::string& dbname,
                                            const BSONObj& cmdObj,
                                            std::vector<Privilege>* out) {} // No auth required
-        virtual bool run(TransactionExperiment* txn, const string& ns, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& ns, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             BSONObjBuilder b( result.subobjStart( "commands" ) );
             for ( map<string,Command*>::iterator i=_commands->begin(); i!=_commands->end(); ++i ) {
                 Command * c = i->second;
@@ -339,7 +339,7 @@ namespace mongo {
                                            const BSONObj& cmdObj,
                                            std::vector<Privilege>* out) {} // No auth required
         CmdForceError() : Command("forceerror") {}
-        bool run(TransactionExperiment* txn, const string& dbnamne, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        bool run(OperationContext* txn, const string& dbnamne, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             uassert( 10038 , "forced error", false);
             return true;
         }
@@ -353,7 +353,7 @@ namespace mongo {
         virtual void addRequiredPrivileges(const std::string& dbname,
                                            const BSONObj& cmdObj,
                                            std::vector<Privilege>* out) {} // No auth required
-        virtual bool run(TransactionExperiment* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
+        virtual bool run(OperationContext* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
             result << "options" << QueryOption_AllSupported;
             return true;
         }
@@ -377,7 +377,7 @@ namespace mongo {
             help << "{ getLog : '*' }  OR { getLog : 'global' }";
         }
 
-        virtual bool run(TransactionExperiment* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
+        virtual bool run(OperationContext* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
             string p = cmdObj.firstElement().String();
             if ( p == "*" ) {
                 vector<string> names;
@@ -424,7 +424,7 @@ namespace mongo {
             actions.addAction(ActionType::getCmdLineOpts);
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
-        virtual bool run(TransactionExperiment* txn, const string&, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string&, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             result.append("argv", serverGlobalParams.argvArray);
             result.append("parsed", serverGlobalParams.parsedOpts);
             return true;
diff --git a/src/mongo/db/dbeval.cpp b/src/mongo/db/dbeval.cpp
index 4c33a0a7506..79207366e77 100644
--- a/src/mongo/db/dbeval.cpp
+++ b/src/mongo/db/dbeval.cpp
@@ -139,7 +139,7 @@ namespace mongo {
             RoleGraph::generateUniversalPrivileges(out);
         }
         CmdEval() : Command("eval", false, "$eval") { }
-        bool run(TransactionExperiment* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        bool run(OperationContext* txn, const string& dbname , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             if ( cmdObj["nolock"].trueValue() ) {
                 return dbEval(dbname, cmdObj, result, errmsg);
             }
diff --git a/src/mongo/db/dbhelpers.cpp b/src/mongo/db/dbhelpers.cpp
index 72d60dffbcd..063a2fd7bb0 100644
--- a/src/mongo/db/dbhelpers.cpp
+++ b/src/mongo/db/dbhelpers.cpp
@@ -51,7 +51,7 @@
 #include "mongo/db/query/query_planner.h"
 #include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/write_concern.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/db/storage_options.h"
 #include "mongo/db/catalog/collection.h"
 #include "mongo/s/d_logic.h"
@@ -60,7 +60,7 @@ namespace mongo {
 
     const BSONObj reverseNaturalObj = BSON( "$natural" << -1 );
 
-    void Helpers::ensureIndex(TransactionExperiment* txn,
+    void Helpers::ensureIndex(OperationContext* txn,
                               Collection* collection,
                               BSONObj keyPattern,
                               bool unique,
@@ -221,7 +221,7 @@ namespace mongo {
         return Runner::RUNNER_ADVANCED == state;
     }
 
-    void Helpers::upsert( TransactionExperiment* txn,
+    void Helpers::upsert( OperationContext* txn,
                           const string& ns,
                           const BSONObj& o,
                           bool fromMigrate ) {
@@ -246,7 +246,7 @@ namespace mongo {
         update(txn, context.db(), request, &debug);
     }
 
-    void Helpers::putSingleton(TransactionExperiment* txn, const char *ns, BSONObj obj) {
+    void Helpers::putSingleton(OperationContext* txn, const char *ns, BSONObj obj) {
         OpDebug debug;
         Client::Context context(ns);
 
@@ -264,7 +264,7 @@ namespace mongo {
         context.getClient()->curop()->done();
     }
 
-    void Helpers::putSingletonGod(TransactionExperiment* txn, const char *ns, BSONObj obj, bool logTheOp) {
+    void Helpers::putSingletonGod(OperationContext* txn, const char *ns, BSONObj obj, bool logTheOp) {
         OpDebug debug;
         Client::Context context(ns);
 
@@ -318,7 +318,7 @@ namespace mongo {
         return true;
     }
 
-    long long Helpers::removeRange( TransactionExperiment* txn,
+    long long Helpers::removeRange( OperationContext* txn,
                                     const KeyRange& range,
                                     bool maxInclusive,
                                     bool secondaryThrottle,
@@ -555,7 +555,7 @@ namespace mongo {
     }
 
 
-    void Helpers::emptyCollection(TransactionExperiment* txn, const char *ns) {
+    void Helpers::emptyCollection(OperationContext* txn, const char *ns) {
         Client::Context context(ns);
         deleteObjects(txn, context.db(), ns, BSONObj(), false);
     }
diff --git a/src/mongo/db/dbhelpers.h b/src/mongo/db/dbhelpers.h
index c10c6f24a21..76ef3271c91 100644
--- a/src/mongo/db/dbhelpers.h
+++ b/src/mongo/db/dbhelpers.h
@@ -42,7 +42,7 @@ namespace mongo {
 
     class Collection;
     class Cursor;
-    class TransactionExperiment;
+    class OperationContext;
 
     /**
      * db helpers are helper functions and classes that let us easily manipulate the local
@@ -64,7 +64,7 @@ namespace mongo {
 
            Note: does nothing if collection does not yet exist.
         */
-        static void ensureIndex(TransactionExperiment* txn,
+        static void ensureIndex(OperationContext* txn,
                                 Collection* collection,
                                 BSONObj keyPattern,
                                 bool unique,
@@ -113,8 +113,8 @@ namespace mongo {
             @return true if object exists.
         */
         static bool getSingleton(const char *ns, BSONObj& result);
-        static void putSingleton(TransactionExperiment* txn, const char *ns, BSONObj obj);
-        static void putSingletonGod(TransactionExperiment* txn, const char *ns, BSONObj obj, bool logTheOp);
+        static void putSingleton(OperationContext* txn, const char *ns, BSONObj obj);
+        static void putSingletonGod(OperationContext* txn, const char *ns, BSONObj obj, bool logTheOp);
         static bool getFirst(const char *ns, BSONObj& result) { return getSingleton(ns, result); }
         static bool getLast(const char *ns, BSONObj& result); // get last object int he collection; e.g. {$natural : -1}
 
@@ -123,7 +123,7 @@ namespace mongo {
          * you do not have to have Context set
          * o has to have an _id field or will assert
          */
-        static void upsert( TransactionExperiment* txn,
+        static void upsert( OperationContext* txn,
                             const string& ns,
                             const BSONObj& o,
                             bool fromMigrate = false );
@@ -162,7 +162,7 @@ namespace mongo {
          * Does oplog the individual document deletions.
          * // TODO: Refactor this mechanism, it is growing too large
          */
-        static long long removeRange( TransactionExperiment* txn,
+        static long long removeRange( OperationContext* txn,
                                       const KeyRange& range,
                                       bool maxInclusive = false,
                                       bool secondaryThrottle = false,
@@ -201,7 +201,7 @@ namespace mongo {
          * You do not need to set the database before calling.
          * Does not oplog the operation.
          */
-        static void emptyCollection(TransactionExperiment* txn, const char *ns);
+        static void emptyCollection(OperationContext* txn, const char *ns);
 
         /**
          * for saving deleted bson objects to a flat file
diff --git a/src/mongo/db/dbwebserver.cpp b/src/mongo/db/dbwebserver.cpp
index c5ce87bb068..233e965b27b 100644
--- a/src/mongo/db/dbwebserver.cpp
+++ b/src/mongo/db/dbwebserver.cpp
@@ -50,7 +50,7 @@
 #include "mongo/db/db.h"
 #include "mongo/db/instance.h"
 #include "mongo/db/stats/snapshots.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/util/admin_access.h"
 #include "mongo/util/md5.hpp"
 #include "mongo/util/mongoutils/html.h"
@@ -77,7 +77,7 @@ namespace mongo {
         DbWebServer(const string& ip,
                     int port,
                     const AdminAccess* webUsers,
-                    TransactionExperiment::Factory transactionFactory)
+                    OperationContext::Factory transactionFactory)
                 : MiniWebServer("admin web console", ip, port),
                   _webUsers(webUsers),
                   _transactionFactory(transactionFactory) {
@@ -87,7 +87,7 @@ namespace mongo {
 
     private:
         const AdminAccess* _webUsers; // not owned here
-        const TransactionExperiment::Factory _transactionFactory;
+        const OperationContext::Factory _transactionFactory;
 
         void doUnlockedStuff(stringstream& ss) {
             /* this is in the header already ss << "port:      " << port << '\n'; */
@@ -188,7 +188,7 @@ namespace mongo {
             const SockAddr &from
         ) {
 
-            boost::scoped_ptr<TransactionExperiment> txn(_transactionFactory()); // XXX SERVER-13931
+            boost::scoped_ptr<OperationContext> txn(_transactionFactory()); // XXX SERVER-13931
 
             if ( url.size() > 1 ) {
 
@@ -421,7 +421,7 @@ namespace mongo {
     public:
         FavIconHandler() : DbWebHandler( "favicon.ico" , 0 , false ) {}
 
-        virtual void handle( TransactionExperiment* txn,
+        virtual void handle( OperationContext* txn,
                              const char *rq, const std::string& url, BSONObj params,
                              string& responseMsg, int& responseCode,
                              vector<string>& headers,  const SockAddr &from ) {
@@ -436,7 +436,7 @@ namespace mongo {
     public:
         StatusHandler() : DbWebHandler( "_status" , 1 , false ) {}
 
-        virtual void handle( TransactionExperiment* txn,
+        virtual void handle( OperationContext* txn,
                              const char *rq, const std::string& url, BSONObj params,
                              string& responseMsg, int& responseCode,
                              vector<string>& headers,  const SockAddr &from ) {
@@ -488,7 +488,7 @@ namespace mongo {
     public:
         CommandListHandler() : DbWebHandler( "_commands" , 1 , true ) {}
 
-        virtual void handle( TransactionExperiment* txn,
+        virtual void handle( OperationContext* txn,
                              const char *rq, const std::string& url, BSONObj params,
                              string& responseMsg, int& responseCode,
                              vector<string>& headers,  const SockAddr &from ) {
@@ -541,7 +541,7 @@ namespace mongo {
             return _cmd(cmd) != 0;
         }
 
-        virtual void handle( TransactionExperiment* txn,
+        virtual void handle( OperationContext* txn,
                              const char *rq, const std::string& url, BSONObj params,
                              string& responseMsg, int& responseCode,
                              vector<string>& headers,  const SockAddr &from ) {
@@ -577,7 +577,7 @@ namespace mongo {
     // --- external ----
 
     void webServerThread(const AdminAccess* adminAccess,
-                         TransactionExperiment::Factory transactionFactory) {
+                         OperationContext::Factory transactionFactory) {
         boost::scoped_ptr<const AdminAccess> adminAccessPtr(adminAccess); // adminAccess is owned here
         Client::initThread("websvr");
         const int p = serverGlobalParams.port + 1000;
diff --git a/src/mongo/db/dbwebserver.h b/src/mongo/db/dbwebserver.h
index 445f3f2ef33..42e686b3315 100644
--- a/src/mongo/db/dbwebserver.h
+++ b/src/mongo/db/dbwebserver.h
@@ -34,7 +34,7 @@
 
 #include "mongo/util/admin_access.h"
 #include "mongo/util/net/sock.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 
 namespace mongo {
 
@@ -55,7 +55,7 @@ namespace mongo {
 
         virtual bool requiresREST( const string& url ) const { return _requiresREST; }
 
-        virtual void handle( TransactionExperiment* txn,
+        virtual void handle( OperationContext* txn,
                              const char *rq, // the full request
                              const std::string& url,
                              BSONObj params,
@@ -96,7 +96,7 @@ namespace mongo {
         static vector<WebStatusPlugin*> * _plugins;
 
     };
-    void webServerThread( const AdminAccess* admins, TransactionExperiment::Factory transactionFactory );
+    void webServerThread( const AdminAccess* admins, OperationContext::Factory transactionFactory );
     string prettyHostName();
 
 };
diff --git a/src/mongo/db/driverHelpers.cpp b/src/mongo/db/driverHelpers.cpp
index 135eb2256f5..f98fa46cbb3 100644
--- a/src/mongo/db/driverHelpers.cpp
+++ b/src/mongo/db/driverHelpers.cpp
@@ -66,7 +66,7 @@ namespace mongo {
         virtual void addRequiredPrivileges(const std::string& dbname,
                                            const BSONObj& cmdObj,
                                            std::vector<Privilege>* out) {} // No auth required
-        virtual bool run(TransactionExperiment* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             if ( cmdObj.firstElement().type() != jstOID ) {
                 errmsg = "not oid";
                 return false;
diff --git a/src/mongo/db/exec/stagedebug_cmd.cpp b/src/mongo/db/exec/stagedebug_cmd.cpp
index bae67717c07..5446d2b5c2d 100644
--- a/src/mongo/db/exec/stagedebug_cmd.cpp
+++ b/src/mongo/db/exec/stagedebug_cmd.cpp
@@ -102,7 +102,7 @@ namespace mongo {
             out->push_back(Privilege(parseResourcePattern(dbname, cmdObj), actions));
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result,
+        bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result,
                  bool fromRepl) {
             BSONElement argElt = cmdObj["stageDebug"];
             if (argElt.eoo() || !argElt.isABSONObj()) { return false; }
diff --git a/src/mongo/db/fts/fts_command.cpp b/src/mongo/db/fts/fts_command.cpp
index 853afd04f5d..c95a6c52bb1 100644
--- a/src/mongo/db/fts/fts_command.cpp
+++ b/src/mongo/db/fts/fts_command.cpp
@@ -57,7 +57,7 @@ namespace mongo {
         }
 
 
-        bool FTSCommand::run(TransactionExperiment* txn, const string& dbname,
+        bool FTSCommand::run(OperationContext* txn, const string& dbname,
                              BSONObj& cmdObj,
                              int options,
                              string& errmsg,
diff --git a/src/mongo/db/fts/fts_command.h b/src/mongo/db/fts/fts_command.h
index e5cc881feb4..4dc84bfb6e8 100644
--- a/src/mongo/db/fts/fts_command.h
+++ b/src/mongo/db/fts/fts_command.h
@@ -56,7 +56,7 @@ namespace mongo {
                                        std::vector<Privilege>* out);
 
 
-            bool run(TransactionExperiment* txn, const string& dbname,
+            bool run(OperationContext* txn, const string& dbname,
                      BSONObj& cmdObj,
                      int options,
                      string& errmsg,
diff --git a/src/mongo/db/geo/haystack.cpp b/src/mongo/db/geo/haystack.cpp
index aa05540eeba..13eb964376d 100644
--- a/src/mongo/db/geo/haystack.cpp
+++ b/src/mongo/db/geo/haystack.cpp
@@ -68,7 +68,7 @@ namespace mongo {
             out->push_back(Privilege(parseResourcePattern(dbname, cmdObj), actions));
         }
 
-        bool run(TransactionExperiment* txn, const string& dbname, BSONObj& cmdObj, int,
+        bool run(OperationContext* txn, const string& dbname, BSONObj& cmdObj, int,
                  string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             const string ns = dbname + "." + cmdObj.firstElement().valuestr();
             Client::ReadContext ctx(ns);
diff --git a/src/mongo/db/index/btree_based_access_method.cpp b/src/mongo/db/index/btree_based_access_method.cpp
index 982a9c70097..6d16f375dc0 100644
--- a/src/mongo/db/index/btree_based_access_method.cpp
+++ b/src/mongo/db/index/btree_based_access_method.cpp
@@ -44,7 +44,7 @@
 #include "mongo/db/repl/is_master.h"
 #include "mongo/db/repl/rs.h"
 #include "mongo/db/server_parameters.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/db/structure/btree/btree_interface.h"
 #include "mongo/db/structure/btree/bucket_deletion_notification.h"
 #include "mongo/util/progress_meter.h"
@@ -79,7 +79,7 @@ namespace mongo {
     }
 
     // Find the keys for obj, put them in the tree pointing to loc
-    Status BtreeBasedAccessMethod::insert(TransactionExperiment* txn,
+    Status BtreeBasedAccessMethod::insert(OperationContext* txn,
                                           const BSONObj& obj,
                                           const DiskLoc& loc,
                                           const InsertDeleteOptions& options,
@@ -138,7 +138,7 @@ namespace mongo {
         return ret;
     }
 
-    bool BtreeBasedAccessMethod::removeOneKey(TransactionExperiment* txn,
+    bool BtreeBasedAccessMethod::removeOneKey(OperationContext* txn,
                                               const BSONObj& key,
                                               const DiskLoc& loc) {
         bool ret = false;
@@ -165,7 +165,7 @@ namespace mongo {
     }
 
     // Remove the provided doc from the index.
-    Status BtreeBasedAccessMethod::remove(TransactionExperiment* txn,
+    Status BtreeBasedAccessMethod::remove(OperationContext* txn,
                                           const BSONObj &obj,
                                           const DiskLoc& loc,
                                           const InsertDeleteOptions &options,
@@ -210,7 +210,7 @@ namespace mongo {
         }
     }
 
-    Status BtreeBasedAccessMethod::initializeAsEmpty(TransactionExperiment* txn) {
+    Status BtreeBasedAccessMethod::initializeAsEmpty(OperationContext* txn) {
         return _newInterface->initAsEmpty(txn);
     }
 
@@ -227,7 +227,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    Status BtreeBasedAccessMethod::touch( TransactionExperiment* txn ) const {
+    Status BtreeBasedAccessMethod::touch( OperationContext* txn ) const {
         return _btreeState->recordStore()->touch( txn, NULL );
     }
 
@@ -296,7 +296,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    Status BtreeBasedAccessMethod::update(TransactionExperiment* txn,
+    Status BtreeBasedAccessMethod::update(OperationContext* txn,
                                           const UpdateTicket& ticket,
                                           int64_t* numUpdated) {
         if (!ticket._isValid) {
@@ -323,7 +323,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    IndexAccessMethod* BtreeBasedAccessMethod::initiateBulk(TransactionExperiment* txn) {
+    IndexAccessMethod* BtreeBasedAccessMethod::initiateBulk(OperationContext* txn) {
         // If there's already data in the index, don't do anything.
         if (!_newInterface->isEmpty()) {
             return NULL;
diff --git a/src/mongo/db/index/btree_based_access_method.h b/src/mongo/db/index/btree_based_access_method.h
index 294c2ece470..cee96988710 100644
--- a/src/mongo/db/index/btree_based_access_method.h
+++ b/src/mongo/db/index/btree_based_access_method.h
@@ -60,13 +60,13 @@ namespace mongo {
 
         virtual ~BtreeBasedAccessMethod() { }
 
-        virtual Status insert(TransactionExperiment* txn,
+        virtual Status insert(OperationContext* txn,
                               const BSONObj& obj,
                               const DiskLoc& loc,
                               const InsertDeleteOptions& options,
                               int64_t* numInserted);
 
-        virtual Status remove(TransactionExperiment* txn,
+        virtual Status remove(OperationContext* txn,
                               const BSONObj& obj,
                               const DiskLoc& loc,
                               const InsertDeleteOptions& options,
@@ -78,15 +78,15 @@ namespace mongo {
                                       const InsertDeleteOptions& options,
                                       UpdateTicket* ticket);
 
-        virtual Status update(TransactionExperiment* txn,
+        virtual Status update(OperationContext* txn,
                               const UpdateTicket& ticket,
                               int64_t* numUpdated);
 
         virtual Status newCursor(IndexCursor **out) const;
 
-        virtual Status initializeAsEmpty(TransactionExperiment* txn);
+        virtual Status initializeAsEmpty(OperationContext* txn);
 
-        virtual IndexAccessMethod* initiateBulk(TransactionExperiment* txn) ;
+        virtual IndexAccessMethod* initiateBulk(OperationContext* txn) ;
 
         virtual Status commitBulk( IndexAccessMethod* bulk,
                                    bool mayInterrupt,
@@ -94,7 +94,7 @@ namespace mongo {
 
         virtual Status touch(const BSONObj& obj);
 
-        virtual Status touch(TransactionExperiment* txn) const;
+        virtual Status touch(OperationContext* txn) const;
 
         virtual Status validate(int64_t* numKeys);
 
@@ -121,7 +121,7 @@ namespace mongo {
         }
 
     private:
-        bool removeOneKey(TransactionExperiment* txn,
+        bool removeOneKey(OperationContext* txn,
                           const BSONObj& key,
                           const DiskLoc& loc);
 
diff --git a/src/mongo/db/index/btree_based_bulk_access_method.cpp b/src/mongo/db/index/btree_based_bulk_access_method.cpp
index 5b77a26a360..09af9df2ee1 100644
--- a/src/mongo/db/index/btree_based_bulk_access_method.cpp
+++ b/src/mongo/db/index/btree_based_bulk_access_method.cpp
@@ -31,7 +31,7 @@
 #include "mongo/db/kill_current_op.h"
 #include "mongo/db/pdfile_private.h"  // This is for inDBRepair.
 #include "mongo/db/repl/rs.h"         // This is for ignoreUniqueIndex.
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/util/progress_meter.h"
 
 namespace mongo {
@@ -90,7 +90,7 @@ namespace mongo {
         return NULL;
     }
 
-    BtreeBasedBulkAccessMethod::BtreeBasedBulkAccessMethod(TransactionExperiment* txn,
+    BtreeBasedBulkAccessMethod::BtreeBasedBulkAccessMethod(OperationContext* txn,
                                                            BtreeBasedAccessMethod* real,
                                                            BtreeInterface* interface,
                                                            const IndexDescriptor* descriptor,
@@ -108,7 +108,7 @@ namespace mongo {
         _sorter->hintNumObjects(numRecords);
     }
 
-    Status BtreeBasedBulkAccessMethod::insert(TransactionExperiment* txn,
+    Status BtreeBasedBulkAccessMethod::insert(OperationContext* txn,
                                               const BSONObj& obj,
                                               const DiskLoc& loc,
                                               const InsertDeleteOptions& options,
diff --git a/src/mongo/db/index/btree_based_bulk_access_method.h b/src/mongo/db/index/btree_based_bulk_access_method.h
index cc27f46a71d..cedf1eedf80 100644
--- a/src/mongo/db/index/btree_based_bulk_access_method.h
+++ b/src/mongo/db/index/btree_based_bulk_access_method.h
@@ -47,7 +47,7 @@ namespace mongo {
          * Does not take ownership of any pointers.
          * All pointers must outlive 'this'.
          */
-        BtreeBasedBulkAccessMethod(TransactionExperiment* txn,
+        BtreeBasedBulkAccessMethod(OperationContext* txn,
                                    BtreeBasedAccessMethod* real,
                                    BtreeInterface* interface,
                                    const IndexDescriptor* descriptor,
@@ -55,7 +55,7 @@ namespace mongo {
 
         ~BtreeBasedBulkAccessMethod() {}
 
-        virtual Status insert(TransactionExperiment* txn,
+        virtual Status insert(OperationContext* txn,
                               const BSONObj& obj,
                               const DiskLoc& loc,
                               const InsertDeleteOptions& options,
@@ -81,7 +81,7 @@ namespace mongo {
             return _notAllowed();
         }
 
-        virtual Status touch(TransactionExperiment* txn) const {
+        virtual Status touch(OperationContext* txn) const {
             return _notAllowed();
         }
 
@@ -89,7 +89,7 @@ namespace mongo {
             return _notAllowed();
         }
 
-        virtual Status remove(TransactionExperiment* txn,
+        virtual Status remove(OperationContext* txn,
                               const BSONObj& obj,
                               const DiskLoc& loc,
                               const InsertDeleteOptions& options,
@@ -105,7 +105,7 @@ namespace mongo {
             return _notAllowed();
         }
 
-        virtual Status update(TransactionExperiment* txn,
+        virtual Status update(OperationContext* txn,
                               const UpdateTicket& ticket,
                               int64_t* numUpdated) {
             return _notAllowed();
@@ -115,11 +115,11 @@ namespace mongo {
             return _notAllowed();
         }
 
-        virtual Status initializeAsEmpty(TransactionExperiment* txn) {
+        virtual Status initializeAsEmpty(OperationContext* txn) {
             return _notAllowed();
         }
 
-        virtual IndexAccessMethod* initiateBulk(TransactionExperiment* txn) {
+        virtual IndexAccessMethod* initiateBulk(OperationContext* txn) {
             return NULL;
         }
 
@@ -149,7 +149,7 @@ namespace mongo {
         // Does any document have >1 key?
         bool _isMultiKey;
 
-        TransactionExperiment* _txn;
+        OperationContext* _txn;
     };
 
 }  // namespace mongo
diff --git a/src/mongo/db/index/index_access_method.h b/src/mongo/db/index/index_access_method.h
index e4666ea99d1..6268ad0cb90 100644
--- a/src/mongo/db/index/index_access_method.h
+++ b/src/mongo/db/index/index_access_method.h
@@ -32,7 +32,7 @@
 #include "mongo/db/index/index_cursor.h"
 #include "mongo/db/index/index_descriptor.h"
 #include "mongo/db/jsobj.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 
 namespace mongo {
 
@@ -65,7 +65,7 @@ namespace mongo {
          * 
          * The behavior of the insertion can be specified through 'options'.  
          */
-        virtual Status insert(TransactionExperiment* txn,
+        virtual Status insert(OperationContext* txn,
                               const BSONObj& obj,
                               const DiskLoc& loc,
                               const InsertDeleteOptions& options,
@@ -75,7 +75,7 @@ namespace mongo {
          * Analogous to above, but remove the records instead of inserting them.  If not NULL,
          * numDeleted will be set to the number of keys removed from the index for the document.
          */
-        virtual Status remove(TransactionExperiment* txn,
+        virtual Status remove(OperationContext* txn,
                               const BSONObj& obj,
                               const DiskLoc& loc,
                               const InsertDeleteOptions& options,
@@ -105,7 +105,7 @@ namespace mongo {
          * called.  If the index was changed, we may return an error, as our ticket may have been
          * invalidated.
          */
-        virtual Status update(TransactionExperiment* txn,
+        virtual Status update(OperationContext* txn,
                               const UpdateTicket& ticket,
                               int64_t* numUpdated) = 0;
 
@@ -123,7 +123,7 @@ namespace mongo {
          * only called once for the lifetime of the index
          * if called multiple times, is an error
          */
-        virtual Status initializeAsEmpty(TransactionExperiment* txn) = 0;
+        virtual Status initializeAsEmpty(OperationContext* txn) = 0;
 
         /**
          * Try to page-in the pages that contain the keys generated from 'obj'.
@@ -136,7 +136,7 @@ namespace mongo {
         /**
          * this pages in the entire index
          */
-        virtual Status touch( TransactionExperiment* txn ) const = 0;
+        virtual Status touch( OperationContext* txn ) const = 0;
 
         /**
          * Walk the entire index, checking the internal structure for consistency.
@@ -163,12 +163,12 @@ namespace mongo {
          *
          * Caller owns the returned IndexAccessMethod.
          *
-         * The provided TransactionExperiment must outlive the IndexAccessMethod returned.
+         * The provided OperationContext must outlive the IndexAccessMethod returned.
          *
          * For now (1/8/14) you can only do bulk when the index is empty
          * it will fail if you try other times.
          */
-        virtual IndexAccessMethod* initiateBulk(TransactionExperiment* txn) = 0;
+        virtual IndexAccessMethod* initiateBulk(OperationContext* txn) = 0;
 
         /**
          * Call this when you are ready to finish your bulk work.
diff --git a/src/mongo/db/index_builder.cpp b/src/mongo/db/index_builder.cpp
index 2bea4ef36ed..0def5596b82 100644
--- a/src/mongo/db/index_builder.cpp
+++ b/src/mongo/db/index_builder.cpp
@@ -34,7 +34,7 @@
 #include "mongo/db/catalog/database_holder.h"
 #include "mongo/db/d_concurrency.h"
 #include "mongo/db/repl/rs.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/util/mongoutils/str.h"
 
 namespace mongo {
@@ -63,7 +63,7 @@ namespace mongo {
         cc().curop()->reset(HostAndPort(), dbInsert);
         NamespaceString ns(_index["ns"].String());
         Client::WriteContext ctx(ns.getSystemIndexesCollection());
-        DurTransaction txn;
+        OperationContextImpl txn;
 
         Database* db = dbHolder().get(ns.db().toString(), storageGlobalParams.dbpath);
 
@@ -75,7 +75,7 @@ namespace mongo {
         cc().shutdown();
     }
 
-    Status IndexBuilder::build(TransactionExperiment* txn, Database* db) const {
+    Status IndexBuilder::build(OperationContext* txn, Database* db) const {
         const string ns = _index["ns"].String();
 
         Collection* c = db->getCollection( ns );
diff --git a/src/mongo/db/index_builder.h b/src/mongo/db/index_builder.h
index 82b7b6bfd98..e825794a4c3 100644
--- a/src/mongo/db/index_builder.h
+++ b/src/mongo/db/index_builder.h
@@ -41,7 +41,7 @@
 namespace mongo {
 
     class Collection;
-    class TransactionExperiment;
+    class OperationContext;
 
     class IndexBuilder : public BackgroundJob {
     public:
@@ -55,7 +55,7 @@ namespace mongo {
          */
         virtual std::string name() const;
 
-        Status build(TransactionExperiment* txn, Database* db) const;
+        Status build(OperationContext* txn, Database* db) const;
 
         /**
          * Kill all in-progress indexes matching criteria, if non-empty:
diff --git a/src/mongo/db/index_rebuilder.cpp b/src/mongo/db/index_rebuilder.cpp
index fddb9f59ccb..da1dc347cec 100644
--- a/src/mongo/db/index_rebuilder.cpp
+++ b/src/mongo/db/index_rebuilder.cpp
@@ -36,7 +36,7 @@
 #include "mongo/db/instance.h"
 #include "mongo/db/pdfile.h"
 #include "mongo/db/repl/rs.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/util/scopeguard.h"
 
 namespace mongo {
@@ -90,7 +90,7 @@ namespace mongo {
             // This write lock is held throughout the index building process
             // for this namespace.
             Client::WriteContext ctx(ns);
-            DurTransaction txn;  // XXX???
+            OperationContextImpl txn;  // XXX???
 
             Collection* collection = ctx.ctx().db()->getCollection( ns );
             if ( collection == NULL )
diff --git a/src/mongo/db/instance.cpp b/src/mongo/db/instance.cpp
index ab711aab742..aff142187c6 100644
--- a/src/mongo/db/instance.cpp
+++ b/src/mongo/db/instance.cpp
@@ -55,7 +55,7 @@
 #include "mongo/db/storage/mmap_v1/dur_commitjob.h"
 #include "mongo/db/storage/mmap_v1/dur_journal.h"
 #include "mongo/db/storage/mmap_v1/dur_recover.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/db/global_optime.h"
 #include "mongo/db/instance.h"
 #include "mongo/db/introspect.h"
@@ -96,11 +96,11 @@ namespace mongo {
     inline void opread(Message& m) { if( _diaglog.getLevel() & 2 ) _diaglog.readop((char *) m.singleData(), m.header()->len); }
     inline void opwrite(Message& m) { if( _diaglog.getLevel() & 1 ) _diaglog.writeop((char *) m.singleData(), m.header()->len); }
 
-    void receivedKillCursors(TransactionExperiment* txn, Message& m);
-    void receivedUpdate(TransactionExperiment* txn, Message& m, CurOp& op);
-    void receivedDelete(TransactionExperiment* txn, Message& m, CurOp& op);
-    void receivedInsert(TransactionExperiment* txn, Message& m, CurOp& op);
-    bool receivedGetMore(TransactionExperiment* txn, DbResponse& dbresponse, Message& m, CurOp& curop );
+    void receivedKillCursors(OperationContext* txn, Message& m);
+    void receivedUpdate(OperationContext* txn, Message& m, CurOp& op);
+    void receivedDelete(OperationContext* txn, Message& m, CurOp& op);
+    void receivedInsert(OperationContext* txn, Message& m, CurOp& op);
+    bool receivedGetMore(OperationContext* txn, DbResponse& dbresponse, Message& m, CurOp& curop );
 
     int nloggedsome = 0;
 #define LOGWITHRATELIMIT if( ++nloggedsome < 1000 || nloggedsome % 100 == 0 )
@@ -232,7 +232,7 @@ namespace mongo {
         replyToQuery(0, m, dbresponse, obj);
     }
 
-    static bool receivedQuery(TransactionExperiment* txn, Client& c, DbResponse& dbresponse, Message& m ) {
+    static bool receivedQuery(OperationContext* txn, Client& c, DbResponse& dbresponse, Message& m ) {
         bool ok = true;
         MSGID responseTo = m.header()->id;
 
@@ -329,7 +329,7 @@ namespace mongo {
     }
 
     // Returns false when request includes 'end'
-    void assembleResponse( TransactionExperiment* txn,
+    void assembleResponse( OperationContext* txn,
                            Message& m,
                            DbResponse& dbresponse,
                            const HostAndPort& remote ) {
@@ -514,7 +514,7 @@ namespace mongo {
         debug.reset();
     } /* assembleResponse() */
 
-    void receivedKillCursors(TransactionExperiment* txn, Message& m) {
+    void receivedKillCursors(OperationContext* txn, Message& m) {
         int *x = (int *) m.singleData()->_data;
         x++; // reserved
         int n = *x++;
@@ -563,7 +563,7 @@ namespace mongo {
         delete database; // closes files
     }
 
-    void receivedUpdate(TransactionExperiment* txn, Message& m, CurOp& op) {
+    void receivedUpdate(OperationContext* txn, Message& m, CurOp& op) {
         DbMessage d(m);
         NamespaceString ns(d.getns());
         uassertStatusOK( userAllowedWriteNS( ns ) );
@@ -618,7 +618,7 @@ namespace mongo {
         lastError.getSafe()->recordUpdate( res.existing , res.numMatched , res.upserted );
     }
 
-    void receivedDelete(TransactionExperiment* txn, Message& m, CurOp& op) {
+    void receivedDelete(OperationContext* txn, Message& m, CurOp& op) {
         DbMessage d(m);
         NamespaceString ns(d.getns());
         uassertStatusOK( userAllowedWriteNS( ns ) );
@@ -658,7 +658,7 @@ namespace mongo {
 
     QueryResult* emptyMoreResult(long long);
 
-    bool receivedGetMore(TransactionExperiment* txn, DbResponse& dbresponse, Message& m, CurOp& curop ) {
+    bool receivedGetMore(OperationContext* txn, DbResponse& dbresponse, Message& m, CurOp& curop ) {
         bool ok = true;
 
         DbMessage d(m);
@@ -781,7 +781,7 @@ namespace mongo {
         return ok;
     }
 
-    void checkAndInsert(TransactionExperiment* txn,
+    void checkAndInsert(OperationContext* txn,
                         Client::Context& ctx,
                         const char *ns,
                         /*modifies*/BSONObj& js) {
@@ -830,7 +830,7 @@ namespace mongo {
         logOp(txn, "i", ns, js);
     }
 
-    NOINLINE_DECL void insertMulti(TransactionExperiment* txn,
+    NOINLINE_DECL void insertMulti(OperationContext* txn,
                                    Client::Context& ctx,
                                    bool keepGoing,
                                    const char *ns,
@@ -854,7 +854,7 @@ namespace mongo {
         op.debug().ninserted = i;
     }
 
-    void receivedInsert(TransactionExperiment* txn, Message& m, CurOp& op) {
+    void receivedInsert(OperationContext* txn, Message& m, CurOp& op) {
         DbMessage d(m);
         const char *ns = d.getns();
         op.debug().ns = ns;
@@ -942,11 +942,11 @@ namespace mongo {
     }
 
     DBDirectClient::DBDirectClient() 
-        : _txnOwned(new DurTransaction),
+        : _txnOwned(new OperationContextImpl),
           _txn(_txnOwned.get())
     {}
 
-    DBDirectClient::DBDirectClient(TransactionExperiment* txn) 
+    DBDirectClient::DBDirectClient(OperationContext* txn) 
         : _txn(txn)
     {}
 
diff --git a/src/mongo/db/instance.h b/src/mongo/db/instance.h
index 50a988917ad..1e475f9e89d 100644
--- a/src/mongo/db/instance.h
+++ b/src/mongo/db/instance.h
@@ -35,7 +35,7 @@
 #include "mongo/db/client.h"
 #include "mongo/db/curop-inl.h"
 #include "mongo/db/dbmessage.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/db/storage_options.h"
 
 namespace mongo {
@@ -68,7 +68,7 @@ namespace mongo {
 
     extern DiagLog _diaglog;
 
-    void assembleResponse( TransactionExperiment* txn,
+    void assembleResponse( OperationContext* txn,
                            Message& m,
                            DbResponse& dbresponse,
                            const HostAndPort &client );
@@ -87,7 +87,7 @@ namespace mongo {
     class DBDirectClient : public DBClientBase {
     public:
         DBDirectClient(); // DEPRECATED
-        DBDirectClient(TransactionExperiment* txn); // txn must outlive this object
+        DBDirectClient(OperationContext* txn); // txn must outlive this object
 
         using DBClientBase::query;
 
@@ -133,8 +133,8 @@ namespace mongo {
 
     private:
         static HostAndPort _clientHost;
-        boost::scoped_ptr<TransactionExperiment> _txnOwned;
-        TransactionExperiment* _txn; // Points either to _txnOwned or a passed-in transaction.
+        boost::scoped_ptr<OperationContext> _txnOwned;
+        OperationContext* _txn; // Points either to _txnOwned or a passed-in transaction.
     };
 
     extern int lockFile;
diff --git a/src/mongo/db/introspect.cpp b/src/mongo/db/introspect.cpp
index 77f7835d39e..79894bf88c7 100644
--- a/src/mongo/db/introspect.cpp
+++ b/src/mongo/db/introspect.cpp
@@ -79,7 +79,7 @@ namespace {
     }
 } // namespace
 
-    static void _profile(TransactionExperiment* txn,
+    static void _profile(OperationContext* txn,
                          const Client& c,
                          Database* db,
                          CurOp& currentOp,
@@ -129,7 +129,7 @@ namespace {
         }
     }
 
-    void profile(TransactionExperiment* txn, const Client& c, int op, CurOp& currentOp) {
+    void profile(OperationContext* txn, const Client& c, int op, CurOp& currentOp) {
         // initialize with 1kb to start, to avoid realloc later
         // doing this outside the dblock to improve performance
         BufBuilder profileBufBuilder(1024);
@@ -155,7 +155,7 @@ namespace {
         }
     }
 
-    Collection* getOrCreateProfileCollection(TransactionExperiment* txn,
+    Collection* getOrCreateProfileCollection(OperationContext* txn,
                                              Database *db,
                                              bool force,
                                              string* errmsg ) {
diff --git a/src/mongo/db/introspect.h b/src/mongo/db/introspect.h
index f45d9796b34..07af4ba6653 100644
--- a/src/mongo/db/introspect.h
+++ b/src/mongo/db/introspect.h
@@ -40,13 +40,13 @@ namespace mongo {
 
     class Collection;
     class Database;
-    class TransactionExperiment;
+    class OperationContext;
 
     /* --- profiling --------------------------------------------
        do when database->profile is set
     */
 
-    void profile(TransactionExperiment* txn, const Client& c, int op, CurOp& currentOp);
+    void profile(OperationContext* txn, const Client& c, int op, CurOp& currentOp);
 
     /**
      * Get (or create) the profile collection
@@ -55,7 +55,7 @@ namespace mongo {
      * @param   force   Always create the collection if it does not exist
      * @return  Collection for the newly created collection, or NULL on error
     **/
-    Collection* getOrCreateProfileCollection(TransactionExperiment* txn,
+    Collection* getOrCreateProfileCollection(OperationContext* txn,
                                              Database *db,
                                              bool force = false,
                                              std::string* errmsg = NULL);
diff --git a/src/mongo/db/storage/transaction.h b/src/mongo/db/operation_context.h
index e76e1ab49ca..ac155fe0240 100644
--- a/src/mongo/db/storage/transaction.h
+++ b/src/mongo/db/operation_context.h
@@ -39,20 +39,19 @@ namespace mongo {
     class ProgressMeter;
 
     /**
-     * This name and this class are both a work in progress.
+     * This class encompasses the state required by an operation.
      *
-     * TODO(hk): move up a level, rename to OperationContext (or OpCtx if you're into the whole
-     * brevity thing)
+     * TODO(HK): clarify what this means.  There's one OperationContext for one user operation...
+     *           but is this true for getmore?  Also what about things like fsyncunlock / internal
+     *           users / etc.?
      */
-    class TransactionExperiment  {
-        MONGO_DISALLOW_COPYING(TransactionExperiment);
+    class OperationContext  {
+        MONGO_DISALLOW_COPYING(OperationContext);
     public:
-        virtual ~TransactionExperiment() { }
+        virtual ~OperationContext() { }
 
         /**
          * Interface for durability.  Caller DOES NOT own pointer.
-         *
-         * XXX: what's a better name for this
          */
         virtual RecoveryUnit* recoveryUnit() const = 0;
 
@@ -113,7 +112,7 @@ namespace mongo {
                                           int secondsBetween = 3) = 0;
 
         /**
-         * Returns a TransactionExperiment. Caller takes ownership.
+         * Returns a OperationContext. Caller takes ownership.
          *
          * This interface is used for functions that need to create transactions (aka OpCtx), but
          * don't know which implementation they should create. It allows the calling code to make
@@ -121,16 +120,16 @@ namespace mongo {
          *
          * TODO come up with a better Factory API once we split this class up (SERVER-13931).
          */
-        typedef TransactionExperiment* (*Factory)();
+        typedef OperationContext* (*Factory)();
 
         /**
-         * A TransactionExperiment::Factory that always returns NULL. For things that shouldn't be
+         * A OperationContext::Factory that always returns NULL. For things that shouldn't be
          * touching their txns such as mongos or some unittests.
          */
-        static TransactionExperiment* factoryNULL() { return NULL; }
+        static OperationContext* factoryNULL() { return NULL; }
 
     protected:
-        TransactionExperiment() {}
+        OperationContext() { }
     };
 
 }  // namespace mongo
diff --git a/src/mongo/db/storage/mmap_v1/dur_transaction.cpp b/src/mongo/db/operation_context_impl.cpp
index 8dbf008d5d3..055ab5d6ef0 100644
--- a/src/mongo/db/storage/mmap_v1/dur_transaction.cpp
+++ b/src/mongo/db/operation_context_impl.cpp
@@ -26,7 +26,7 @@
  *    it in the license file.
  */
 
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 
 #include "mongo/db/client.h"
 #include "mongo/db/curop.h"
@@ -35,26 +35,26 @@
 
 namespace mongo {
 
-    DurTransaction::DurTransaction() {
+    OperationContextImpl::OperationContextImpl() {
         _recovery.reset(new DurRecoveryUnit());
     }
 
-    RecoveryUnit* DurTransaction::recoveryUnit() const {
+    RecoveryUnit* OperationContextImpl::recoveryUnit() const {
         return _recovery.get();
     }
 
-    ProgressMeter* DurTransaction::setMessage(const char* msg,
+    ProgressMeter* OperationContextImpl::setMessage(const char* msg,
                                               const std::string& name,
                                               unsigned long long progressMeterTotal,
                                               int secondsBetween) {
         return &cc().curop()->setMessage( msg, name, progressMeterTotal, secondsBetween );
     }
 
-    void DurTransaction::checkForInterrupt(bool heedMutex) const {
+    void OperationContextImpl::checkForInterrupt(bool heedMutex) const {
         killCurrentOp.checkForInterrupt(heedMutex);
     }
 
-    Status DurTransaction::checkForInterruptNoAssert() const {
+    Status OperationContextImpl::checkForInterruptNoAssert() const {
         const char* killed = killCurrentOp.checkForInterruptNoAssert();
         if ( !killed || !killed[0] )
             return Status::OK();
@@ -62,8 +62,8 @@ namespace mongo {
         return Status( ErrorCodes::Interrupted, killed );
     }
 
-    TransactionExperiment* DurTransaction::factory() {
-        return new DurTransaction();
+    OperationContext* OperationContextImpl::factory() {
+        return new OperationContextImpl();
     }
 
 }  // namespace mongo
diff --git a/src/mongo/db/storage/mmap_v1/dur_transaction.h b/src/mongo/db/operation_context_impl.h
index a0dc1029e6a..6f7b5a7ff2d 100644
--- a/src/mongo/db/storage/mmap_v1/dur_transaction.h
+++ b/src/mongo/db/operation_context_impl.h
@@ -29,20 +29,17 @@
 #include <boost/scoped_ptr.hpp>
 #include <string>
 
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 
 #pragma once
 
 namespace mongo {
 
-    /**
-     * TODO(hk): Move to db/ and rename to OperationContextMongoDImpl or something better?
-     */
-    class DurTransaction : public TransactionExperiment  {
+    class OperationContextImpl : public OperationContext  {
     public:
-        DurTransaction();
+        OperationContextImpl();
 
-        virtual ~DurTransaction() { }
+        virtual ~OperationContextImpl() { }
 
         virtual RecoveryUnit* recoveryUnit() const;
 
@@ -56,9 +53,9 @@ namespace mongo {
         virtual Status checkForInterruptNoAssert() const;
 
         /**
-         * Returns a DurTransaction. Caller takes ownership.
+         * Returns an OperationContext. Caller takes ownership.
          */
-        static TransactionExperiment* factory();
+        static OperationContext* factory();
 
     private:
         boost::scoped_ptr<RecoveryUnit> _recovery;
diff --git a/src/mongo/db/ops/delete.cpp b/src/mongo/db/ops/delete.cpp
index 1e28a895855..c78ca1692f1 100644
--- a/src/mongo/db/ops/delete.cpp
+++ b/src/mongo/db/ops/delete.cpp
@@ -38,7 +38,7 @@ namespace mongo {
        justOne: stop after 1 match
        god:     allow access to system namespaces, and don't yield
     */
-    long long deleteObjects(TransactionExperiment* txn,
+    long long deleteObjects(OperationContext* txn,
                             Database* db,
                             const StringData& ns,
                             BSONObj pattern,
diff --git a/src/mongo/db/ops/delete.h b/src/mongo/db/ops/delete.h
index 28327c42c06..f0536b63dd2 100644
--- a/src/mongo/db/ops/delete.h
+++ b/src/mongo/db/ops/delete.h
@@ -36,10 +36,10 @@
 namespace mongo {
 
     class Database;
-    class TransactionExperiment;
+    class OperationContext;
 
     // If justOne is true, deletedId is set to the id of the deleted object.
-    long long deleteObjects(TransactionExperiment* txn,
+    long long deleteObjects(OperationContext* txn,
                             Database* db,
                             const StringData& ns,
                             BSONObj pattern,
diff --git a/src/mongo/db/ops/delete_executor.cpp b/src/mongo/db/ops/delete_executor.cpp
index 7c16d203756..9c14c772bdc 100644
--- a/src/mongo/db/ops/delete_executor.cpp
+++ b/src/mongo/db/ops/delete_executor.cpp
@@ -79,7 +79,7 @@ namespace mongo {
         return status;
     }
 
-    long long DeleteExecutor::execute(TransactionExperiment* txn, Database* db) {
+    long long DeleteExecutor::execute(OperationContext* txn, Database* db) {
         uassertStatusOK(prepare());
         uassert(17417,
                 mongoutils::str::stream() <<
diff --git a/src/mongo/db/ops/delete_executor.h b/src/mongo/db/ops/delete_executor.h
index ee072d957ad..475df92a105 100644
--- a/src/mongo/db/ops/delete_executor.h
+++ b/src/mongo/db/ops/delete_executor.h
@@ -39,7 +39,7 @@ namespace mongo {
     class CanonicalQuery;
     class Database;
     class DeleteRequest;
-    class TransactionExperiment;
+    class OperationContext;
 
     /**
      * Implementation of the processing of a delete operation in a mongod.
@@ -92,7 +92,7 @@ namespace mongo {
          *
          * Returns the number of documents deleted.
          */
-        long long execute(TransactionExperiment* txn, Database* db);
+        long long execute(OperationContext* txn, Database* db);
 
     private:
         /// Unowned pointer to the request object that this executor will process.
diff --git a/src/mongo/db/ops/update.cpp b/src/mongo/db/ops/update.cpp
index 6559c2203a0..07e292f6320 100644
--- a/src/mongo/db/ops/update.cpp
+++ b/src/mongo/db/ops/update.cpp
@@ -49,7 +49,7 @@
 #include "mongo/db/query/query_planner_common.h"
 #include "mongo/db/repl/is_master.h"
 #include "mongo/db/repl/oplog.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/db/catalog/collection.h"
 #include "mongo/platform/unordered_set.h"
 
@@ -416,7 +416,7 @@ namespace mongo {
         }
     } // namespace
 
-    UpdateResult update(TransactionExperiment* txn,
+    UpdateResult update(OperationContext* txn,
                         Database* db,
                         const UpdateRequest& request,
                         OpDebug* opDebug) {
@@ -426,7 +426,7 @@ namespace mongo {
     }
 
     UpdateResult update(
-            TransactionExperiment* txn,
+            OperationContext* txn,
             Database* db,
             const UpdateRequest& request,
             OpDebug* opDebug,
diff --git a/src/mongo/db/ops/update.h b/src/mongo/db/ops/update.h
index cdb76718f3e..f950fbaf08c 100644
--- a/src/mongo/db/ops/update.h
+++ b/src/mongo/db/ops/update.h
@@ -38,7 +38,7 @@
 namespace mongo {
 
     class CanonicalQuery;
-    class TransactionExperiment;
+    class OperationContext;
     class UpdateDriver;
 
     /**
@@ -46,7 +46,7 @@ namespace mongo {
      *
      * Caller must hold the appropriate database locks.
      */
-    UpdateResult update(TransactionExperiment* txn, 
+    UpdateResult update(OperationContext* txn, 
                         Database* db, 
                         const UpdateRequest& request, 
                         OpDebug* opDebug);
@@ -59,7 +59,7 @@ namespace mongo {
      *
      * TODO: Move this into a private method of UpdateExecutor.
      */
-    UpdateResult update(TransactionExperiment* txn,
+    UpdateResult update(OperationContext* txn,
                         Database* db,
                         const UpdateRequest& request,
                         OpDebug* opDebug,
diff --git a/src/mongo/db/ops/update_executor.cpp b/src/mongo/db/ops/update_executor.cpp
index 109a11ebed9..fd2f11701a7 100644
--- a/src/mongo/db/ops/update_executor.cpp
+++ b/src/mongo/db/ops/update_executor.cpp
@@ -62,7 +62,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    UpdateResult UpdateExecutor::execute(TransactionExperiment* txn, Database* db) {
+    UpdateResult UpdateExecutor::execute(OperationContext* txn, Database* db) {
         uassertStatusOK(prepare());
         return update(txn,
                       db,
diff --git a/src/mongo/db/ops/update_executor.h b/src/mongo/db/ops/update_executor.h
index ef2ca7ba503..881c0cc0d36 100644
--- a/src/mongo/db/ops/update_executor.h
+++ b/src/mongo/db/ops/update_executor.h
@@ -39,7 +39,7 @@ namespace mongo {
 
     class CanonicalQuery;
     class OpDebug;
-    class TransactionExperiment;
+    class OperationContext;
     class UpdateRequest;
 
     /**
@@ -91,7 +91,7 @@ namespace mongo {
          * Execute an update.  Requires the caller to hold the database lock on the
          * appropriate resources for the request.
          */
-        UpdateResult execute(TransactionExperiment* txn, Database* db);
+        UpdateResult execute(OperationContext* txn, Database* db);
 
     private:
         /**
diff --git a/src/mongo/db/pdfile.cpp b/src/mongo/db/pdfile.cpp
index 903a78cd12d..3b9170b5c56 100644
--- a/src/mongo/db/pdfile.cpp
+++ b/src/mongo/db/pdfile.cpp
@@ -78,7 +78,7 @@ _ disallow system* manipulations from the database.
 #include "mongo/util/processinfo.h"
 #include "mongo/db/stats/timer_stats.h"
 #include "mongo/db/stats/counters.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 
 namespace mongo {
 
@@ -97,7 +97,7 @@ namespace mongo {
      * @param createDefaultIndexes - if false, defers id (and other) index creation.
      * @return true if successful
     */
-    Status userCreateNS( TransactionExperiment* txn,
+    Status userCreateNS( OperationContext* txn,
                          Database* db,
                          const StringData& ns,
                          BSONObj options,
@@ -141,7 +141,7 @@ namespace mongo {
 
     void dropAllDatabasesExceptLocal() {
         Lock::GlobalWrite lk;
-        DurTransaction txn;
+        OperationContextImpl txn;
 
         vector<string> n;
         getDatabaseNames(n);
@@ -155,7 +155,7 @@ namespace mongo {
         }
     }
 
-    void dropDatabase(TransactionExperiment* txn, Database* db ) {
+    void dropDatabase(OperationContext* txn, Database* db ) {
         invariant( db );
 
         string name = db->name(); // just to have safe
diff --git a/src/mongo/db/pdfile.h b/src/mongo/db/pdfile.h
index 8216e56b08b..92848f13afc 100644
--- a/src/mongo/db/pdfile.h
+++ b/src/mongo/db/pdfile.h
@@ -45,11 +45,11 @@
 namespace mongo {
 
     class Database;
-    class TransactionExperiment;
+    class OperationContext;
 
-    void dropDatabase(TransactionExperiment* txn, Database* db);
+    void dropDatabase(OperationContext* txn, Database* db);
 
-    Status userCreateNS( TransactionExperiment* txn,
+    Status userCreateNS( OperationContext* txn,
                          Database* db,
                          const StringData& ns,
                          BSONObj options,
diff --git a/src/mongo/db/query/new_find.cpp b/src/mongo/db/query/new_find.cpp
index 9236cb92333..51ce8036664 100644
--- a/src/mongo/db/query/new_find.cpp
+++ b/src/mongo/db/query/new_find.cpp
@@ -109,7 +109,7 @@ namespace {
 namespace mongo {
 
     // TODO: Move this and the other command stuff in newRunQuery outta here and up a level.
-    static bool runCommands(TransactionExperiment* txn,
+    static bool runCommands(OperationContext* txn,
                             const char *ns,
                             BSONObj& jsobj,
                             CurOp& curop,
@@ -398,7 +398,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    std::string newRunQuery(TransactionExperiment* txn,
+    std::string newRunQuery(OperationContext* txn,
                             Message& m,
                             QueryMessage& q,
                             CurOp& curop,
diff --git a/src/mongo/db/query/new_find.h b/src/mongo/db/query/new_find.h
index 149bcce9b0a..263bf77065d 100644
--- a/src/mongo/db/query/new_find.h
+++ b/src/mongo/db/query/new_find.h
@@ -39,7 +39,7 @@
 
 namespace mongo {
 
-    class TransactionExperiment;
+    class OperationContext;
 
     /**
      * Called from the getMore entry point in ops/query.cpp.
@@ -50,7 +50,7 @@ namespace mongo {
     /**
      * Run the query 'q' and place the result in 'result'.
      */
-    std::string newRunQuery(TransactionExperiment* txn,
+    std::string newRunQuery(OperationContext* txn,
                             Message& m,
                             QueryMessage& q,
                             CurOp& curop,
diff --git a/src/mongo/db/range_deleter.cpp b/src/mongo/db/range_deleter.cpp
index 229f7e82060..9ae7fdd2674 100644
--- a/src/mongo/db/range_deleter.cpp
+++ b/src/mongo/db/range_deleter.cpp
@@ -74,7 +74,7 @@ namespace mongo {
         RangeDeleteEntry():
                 secondaryThrottle(true),
                 notifyDone(NULL),
-                transactionFactory(TransactionExperiment::factoryNULL) { // XXX SERVER-13931
+                transactionFactory(OperationContext::factoryNULL) { // XXX SERVER-13931
         }
 
         std::string ns;
@@ -100,7 +100,7 @@ namespace mongo {
         // Important invariant: Can only be set and used by one thread.
         Notification* notifyDone;
 
-        TransactionExperiment::Factory transactionFactory;
+        OperationContext::Factory transactionFactory;
 
         // For debugging only
         BSONObj toBSON() const {
@@ -196,7 +196,7 @@ namespace mongo {
         }
     }
 
-    bool RangeDeleter::queueDelete(TransactionExperiment::Factory transactionFactory,
+    bool RangeDeleter::queueDelete(OperationContext::Factory transactionFactory,
                                    const std::string& ns,
                                    const BSONObj& min,
                                    const BSONObj& max,
@@ -252,7 +252,7 @@ namespace mongo {
         return true;
     }
 
-    bool RangeDeleter::deleteNow(TransactionExperiment* txn,
+    bool RangeDeleter::deleteNow(OperationContext* txn,
                                  const std::string& ns,
                                  const BSONObj& min,
                                  const BSONObj& max,
@@ -475,7 +475,7 @@ namespace mongo {
             }
 
             {
-                boost::scoped_ptr<TransactionExperiment> txn(nextTask->transactionFactory()); // XXX SERVER-13931
+                boost::scoped_ptr<OperationContext> txn(nextTask->transactionFactory()); // XXX SERVER-13931
                 if (!_env->deleteRange(txn.get(),
                                        nextTask->ns,
                                        nextTask->min,
diff --git a/src/mongo/db/range_deleter.h b/src/mongo/db/range_deleter.h
index 653fb0105b0..9c47659bf0d 100644
--- a/src/mongo/db/range_deleter.h
+++ b/src/mongo/db/range_deleter.h
@@ -37,7 +37,7 @@
 #include "mongo/base/string_data.h"
 #include "mongo/db/clientcursor.h"
 #include "mongo/db/jsobj.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/util/concurrency/mutex.h"
 #include "mongo/util/concurrency/synchronization.h"
 
@@ -45,7 +45,7 @@ namespace mongo {
 
     struct RangeDeleterEnv;
     class RangeDeleterStats;
-    class TransactionExperiment;
+    class OperationContext;
 
     /**
      * Class for deleting documents for a given namespace and range.  It contains a queue of
@@ -131,7 +131,7 @@ namespace mongo {
          * Returns true if the task is queued and false If the given range is blacklisted,
          * is already queued, or stopWorkers() was called.
          */
-        bool queueDelete(TransactionExperiment::Factory transactionFactory,
+        bool queueDelete(OperationContext::Factory transactionFactory,
                          const std::string& ns,
                          const BSONObj& min,
                          const BSONObj& max,
@@ -147,7 +147,7 @@ namespace mongo {
          * Returns true if the deletion was performed. False if the range is blacklisted,
          * was already queued, or stopWorkers() was called.
          */
-        bool deleteNow(TransactionExperiment* txn,
+        bool deleteNow(OperationContext* txn,
                        const std::string& ns,
                        const BSONObj& min,
                        const BSONObj& max,
@@ -288,7 +288,7 @@ namespace mongo {
          * Must be a synchronous call. Docs should be deleted after call ends.
          * Must not throw Exceptions.
          */
-        virtual bool deleteRange(TransactionExperiment* txn,
+        virtual bool deleteRange(OperationContext* txn,
                                  const StringData& ns,
                                  const BSONObj& inclusiveLower,
                                  const BSONObj& exclusiveUpper,
diff --git a/src/mongo/db/range_deleter_db_env.cpp b/src/mongo/db/range_deleter_db_env.cpp
index 71a0ca86796..44dd93e0c06 100644
--- a/src/mongo/db/range_deleter_db_env.cpp
+++ b/src/mongo/db/range_deleter_db_env.cpp
@@ -54,7 +54,7 @@ namespace mongo {
      * 5. Delete range.
      * 6. Wait until the majority of the secondaries catch up.
      */
-    bool RangeDeleterDBEnv::deleteRange(TransactionExperiment* txn,
+    bool RangeDeleterDBEnv::deleteRange(OperationContext* txn,
                                         const StringData& ns,
                                         const BSONObj& inclusiveLower,
                                         const BSONObj& exclusiveUpper,
diff --git a/src/mongo/db/range_deleter_db_env.h b/src/mongo/db/range_deleter_db_env.h
index 01089fc9d3d..9708fa49495 100644
--- a/src/mongo/db/range_deleter_db_env.h
+++ b/src/mongo/db/range_deleter_db_env.h
@@ -51,7 +51,7 @@ namespace mongo {
          *
          * Does not throw Exceptions.
          */
-        virtual bool deleteRange(TransactionExperiment* txn,
+        virtual bool deleteRange(OperationContext* txn,
                                  const StringData& ns,
                                  const BSONObj& inclusiveLower,
                                  const BSONObj& exclusiveUpper,
diff --git a/src/mongo/db/range_deleter_mock_env.cpp b/src/mongo/db/range_deleter_mock_env.cpp
index 22ecff1bea4..2b40a3e7bc6 100644
--- a/src/mongo/db/range_deleter_mock_env.cpp
+++ b/src/mongo/db/range_deleter_mock_env.cpp
@@ -100,7 +100,7 @@ namespace mongo {
         return _deleteList.back();
     }
 
-    bool RangeDeleterMockEnv::deleteRange(TransactionExperiment* txn,
+    bool RangeDeleterMockEnv::deleteRange(OperationContext* txn,
                                           const StringData& ns,
                                           const BSONObj& min,
                                           const BSONObj& max,
diff --git a/src/mongo/db/range_deleter_mock_env.h b/src/mongo/db/range_deleter_mock_env.h
index 4ba3e686d9d..2bffc7a418b 100644
--- a/src/mongo/db/range_deleter_mock_env.h
+++ b/src/mongo/db/range_deleter_mock_env.h
@@ -126,7 +126,7 @@ namespace mongo {
          * but simply keeps a record of it. Can also be paused by pauseDeletes and
          * resumed with resumeDeletes.
          */
-        bool deleteRange(TransactionExperiment* txn,
+        bool deleteRange(OperationContext* txn,
                          const StringData& ns,
                          const BSONObj& min,
                          const BSONObj& max,
diff --git a/src/mongo/db/range_deleter_stat_test.cpp b/src/mongo/db/range_deleter_stat_test.cpp
index 695da1d8a26..19d85b8a7f1 100644
--- a/src/mongo/db/range_deleter_stat_test.cpp
+++ b/src/mongo/db/range_deleter_stat_test.cpp
@@ -48,9 +48,9 @@ namespace {
     using mongo::RangeDeleter;
     using mongo::RangeDeleterMockEnv;
     using mongo::RangeDeleterStats;
-    using mongo::TransactionExperiment;
+    using mongo::OperationContext;
 
-    TransactionExperiment* const noTxn = NULL; // MockEnv doesn't need txn XXX SERVER-13931
+    OperationContext* const noTxn = NULL; // MockEnv doesn't need txn XXX SERVER-13931
 
     TEST(NoDeletes, InitialState) {
         RangeDeleterMockEnv* env = new RangeDeleterMockEnv();
@@ -88,7 +88,7 @@ namespace {
 
         string errMsg;
         Notification notifyDone;
-        ASSERT_TRUE(deleter.queueDelete(TransactionExperiment::factoryNULL,
+        ASSERT_TRUE(deleter.queueDelete(OperationContext::factoryNULL,
                                         ns,
                                         BSON("x" << 0),
                                         BSON("x" << 10),
@@ -131,7 +131,7 @@ namespace {
 
         Notification deleteDone;
         string errMsg;
-        ASSERT_TRUE(deleter.queueDelete(TransactionExperiment::factoryNULL, // XXX SERVER-13931
+        ASSERT_TRUE(deleter.queueDelete(OperationContext::factoryNULL, // XXX SERVER-13931
                                         ns,
                                         BSON("x" << 0),
                                         BSON("x" << 10),
@@ -175,7 +175,7 @@ namespace {
 
         string errMsg;
         Notification notifyDone;
-        ASSERT_TRUE(deleter.queueDelete(TransactionExperiment::factoryNULL, // XXX SERVER-13931
+        ASSERT_TRUE(deleter.queueDelete(OperationContext::factoryNULL, // XXX SERVER-13931
                                         ns,
                                         BSON("x" << 0),
                                         BSON("x" << 10),
diff --git a/src/mongo/db/range_deleter_test.cpp b/src/mongo/db/range_deleter_test.cpp
index 1bc2ac0beae..5ae950a606b 100644
--- a/src/mongo/db/range_deleter_test.cpp
+++ b/src/mongo/db/range_deleter_test.cpp
@@ -49,9 +49,9 @@ namespace {
     using mongo::RangeDeleter;
     using mongo::RangeDeleterMockEnv;
     using mongo::RangeDeleterStats;
-    using mongo::TransactionExperiment;
+    using mongo::OperationContext;
 
-    TransactionExperiment* const noTxn = NULL; // MockEnv doesn't need txn XXX SERVER-13931
+    OperationContext* const noTxn = NULL; // MockEnv doesn't need txn XXX SERVER-13931
 
     // Capped sleep interval is 640 mSec, Nyquist frequency is 1280 mSec => round up to 2 sec.
     const int MAX_IMMEDIATE_DELETE_WAIT_SECS = 2;
@@ -65,7 +65,7 @@ namespace {
         deleter.stopWorkers();
 
         string errMsg;
-        ASSERT_FALSE(deleter.queueDelete(TransactionExperiment::factoryNULL, // XXX SERVER-13931
+        ASSERT_FALSE(deleter.queueDelete(OperationContext::factoryNULL, // XXX SERVER-13931
                                          "test.user",
                                          BSON("x" << 120),
                                          BSON("x" << 200),
@@ -88,7 +88,7 @@ namespace {
         env->addCursorId(ns, 345);
 
         Notification notifyDone;
-        ASSERT_TRUE(deleter.queueDelete(TransactionExperiment::factoryNULL, // XXX SERVER-13931
+        ASSERT_TRUE(deleter.queueDelete(OperationContext::factoryNULL, // XXX SERVER-13931
                                         ns, BSON("x" << 0), BSON("x" << 10), BSON("x" << 1),
                                         true, &notifyDone, NULL /* errMsg not needed */));
 
@@ -127,7 +127,7 @@ namespace {
         env->addCursorId(ns, 345);
 
         Notification notifyDone;
-        ASSERT_TRUE(deleter.queueDelete(TransactionExperiment::factoryNULL, // XXX SERVER-13931
+        ASSERT_TRUE(deleter.queueDelete(OperationContext::factoryNULL, // XXX SERVER-13931
                                         ns, BSON("x" << 0), BSON("x" << 10),  BSON("x" << 1),
                                         true, &notifyDone, NULL /* errMsg not needed */));
 
@@ -246,7 +246,7 @@ namespace {
         env->pauseDeletes();
 
         Notification notifyDone1;
-        ASSERT_TRUE(deleter.queueDelete(TransactionExperiment::factoryNULL, // XXX SERVER-13931
+        ASSERT_TRUE(deleter.queueDelete(OperationContext::factoryNULL, // XXX SERVER-13931
                                         ns,
                                         BSON("x" << 10),
                                         BSON("x" << 20),
@@ -265,7 +265,7 @@ namespace {
         ASSERT_EQUALS(1, inProgressCount);
 
         Notification notifyDone2;
-        ASSERT_TRUE(deleter.queueDelete(TransactionExperiment::factoryNULL, // XXX SERVER-13931
+        ASSERT_TRUE(deleter.queueDelete(OperationContext::factoryNULL, // XXX SERVER-13931
                                         blockedNS,
                                         BSON("x" << 20),
                                         BSON("x" << 30),
@@ -275,7 +275,7 @@ namespace {
                                         NULL /* don't care errMsg */));
 
         Notification notifyDone3;
-        ASSERT_TRUE(deleter.queueDelete(TransactionExperiment::factoryNULL, // XXX SERVER-13931
+        ASSERT_TRUE(deleter.queueDelete(OperationContext::factoryNULL, // XXX SERVER-13931
                                         ns,
                                         BSON("x" << 30),
                                         BSON("x" << 40),
@@ -363,7 +363,7 @@ namespace {
         ASSERT_TRUE(errMsg.empty());
 
         errMsg.clear();
-        ASSERT_FALSE(deleter.queueDelete(TransactionExperiment::factoryNULL, // XXX SERVER-13931
+        ASSERT_FALSE(deleter.queueDelete(OperationContext::factoryNULL, // XXX SERVER-13931
                                          ns, BSON("x" << 120), BSON("x" << 140),  BSON("x" << 1),
                                          false, NULL /* notifier not needed */, &errMsg));
         ASSERT_FALSE(errMsg.empty());
@@ -412,7 +412,7 @@ namespace {
         env->addCursorId(ns, 58);
 
         Notification notifyDone;
-        deleter.queueDelete(TransactionExperiment::factoryNULL, // XXX SERVER-13931
+        deleter.queueDelete(OperationContext::factoryNULL, // XXX SERVER-13931
                             ns, BSON("x" << 0), BSON("x" << 10), BSON("x" << 1),
                             false, &notifyDone, NULL /* errMsg not needed */);
 
diff --git a/src/mongo/db/repair_database.cpp b/src/mongo/db/repair_database.cpp
index 9151e81300a..aa69da2b021 100644
--- a/src/mongo/db/repair_database.cpp
+++ b/src/mongo/db/repair_database.cpp
@@ -225,7 +225,7 @@ namespace mongo {
 
     class RepairFileDeleter {
     public:
-        RepairFileDeleter( TransactionExperiment* txn,
+        RepairFileDeleter( OperationContext* txn,
                            const string& dbName,
                            const string& pathString,
                            const Path& path )
@@ -264,14 +264,14 @@ namespace mongo {
         }
 
     private:
-        TransactionExperiment* _txn;
+        OperationContext* _txn;
         string _dbName;
         string _pathString;
         Path _path;
         bool _success;
     };
 
-    Status repairDatabase( TransactionExperiment* txn,
+    Status repairDatabase( OperationContext* txn,
                            string dbName,
                            bool preserveClonedFilesOnFailure,
                            bool backupOriginalFiles ) {
diff --git a/src/mongo/db/repair_database.h b/src/mongo/db/repair_database.h
index 16f5ae1d747..eb4f0f9b4e7 100644
--- a/src/mongo/db/repair_database.h
+++ b/src/mongo/db/repair_database.h
@@ -36,7 +36,7 @@
 #include "mongo/platform/cstdint.h"
 
 namespace mongo {
-    class TransactionExperiment;
+    class OperationContext;
 
     // TODO: move
     intmax_t dbSize( const std::string& database );
@@ -45,7 +45,7 @@ namespace mongo {
     void _deleteDataFiles(const std::string& database);
 
     // must have a global lock
-    Status repairDatabase( TransactionExperiment* txn,
+    Status repairDatabase( OperationContext* txn,
                            std::string db,
                            bool preserveClonedFilesOnFailure = false,
                            bool backupOriginalFiles = false );
diff --git a/src/mongo/db/repl/consensus.cpp b/src/mongo/db/repl/consensus.cpp
index 90c1197aaa9..86bcc17f9df 100644
--- a/src/mongo/db/repl/consensus.cpp
+++ b/src/mongo/db/repl/consensus.cpp
@@ -101,7 +101,7 @@ namespace mongo {
             return false;
         }
 
-        virtual bool run(TransactionExperiment* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             if( !check(errmsg, result) )
                 return false;
 
@@ -149,7 +149,7 @@ namespace mongo {
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
     private:
-        virtual bool run(TransactionExperiment* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             if( !check(errmsg, result) )
                 return false;
             theReplSet->elect.electCmdReceived(cmdObj, &result);
diff --git a/src/mongo/db/repl/heartbeat.cpp b/src/mongo/db/repl/heartbeat.cpp
index 7956dc40877..f6b627a70f9 100644
--- a/src/mongo/db/repl/heartbeat.cpp
+++ b/src/mongo/db/repl/heartbeat.cpp
@@ -68,7 +68,7 @@ namespace mongo {
             actions.addAction(ActionType::internal);
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
-        virtual bool run(TransactionExperiment* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             if( replSetBlind ) {
                 if (theReplSet) {
                     errmsg = str::stream() << theReplSet->selfFullName() << " is blind";
diff --git a/src/mongo/db/repl/master_slave.cpp b/src/mongo/db/repl/master_slave.cpp
index a08ad3ccf97..4326a1d146c 100644
--- a/src/mongo/db/repl/master_slave.cpp
+++ b/src/mongo/db/repl/master_slave.cpp
@@ -53,7 +53,7 @@
 #include "mongo/db/repl/repl_settings.h"  // replSettings
 #include "mongo/db/repl/rs.h" // replLocalAuth()
 #include "mongo/db/server_parameters.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/db/storage_options.h"
 #include "mongo/util/exit.h"
 
@@ -162,7 +162,7 @@ namespace mongo {
         string myname = getHostName();
         {
             Client::WriteContext ctx("local");
-            DurTransaction txn;
+            OperationContextImpl txn;
             // local.me is an identifier for a server for getLastError w:2+
             if (!Helpers::getSingleton("local.me", _me) ||
                 !_me.hasField("host") ||
@@ -196,7 +196,7 @@ namespace mongo {
         {
             OpDebug debug;
             Client::Context ctx("local.sources");
-            DurTransaction txn;
+            OperationContextImpl txn;
 
             const NamespaceString requestNs("local.sources");
             UpdateRequest request(requestNs);
@@ -304,7 +304,7 @@ namespace mongo {
         uassert(17066, "Internal error reading from local.sources", Runner::RUNNER_EOF == state);
     }
 
-    bool ReplSource::throttledForceResyncDead( TransactionExperiment* txn, const char *requester ) {
+    bool ReplSource::throttledForceResyncDead( OperationContext* txn, const char *requester ) {
         if ( time( 0 ) - lastForcedResync > 600 ) {
             forceResyncDead( txn, requester );
             lastForcedResync = time( 0 );
@@ -313,7 +313,7 @@ namespace mongo {
         return false;
     }
 
-    void ReplSource::forceResyncDead( TransactionExperiment* txn, const char *requester ) {
+    void ReplSource::forceResyncDead( OperationContext* txn, const char *requester ) {
         if ( !replAllDead )
             return;
         SourceVector sources;
@@ -325,7 +325,7 @@ namespace mongo {
         replAllDead = 0;
     }
 
-    void ReplSource::forceResync( TransactionExperiment* txn, const char *requester ) {
+    void ReplSource::forceResync( OperationContext* txn, const char *requester ) {
         BSONObj info;
         {
             dbtemprelease t;
@@ -355,14 +355,14 @@ namespace mongo {
         save();
     }
 
-    void ReplSource::resyncDrop( TransactionExperiment* txn, const string& db ) {
+    void ReplSource::resyncDrop( OperationContext* txn, const string& db ) {
         log() << "resync: dropping database " << db;
         Client::Context ctx(db);
         dropDatabase(txn, ctx.db());
     }
 
     /* grab initial copy of a database from the master */
-    void ReplSource::resync(TransactionExperiment* txn, const std::string& dbName) {
+    void ReplSource::resync(OperationContext* txn, const std::string& dbName) {
         const std::string db(dbName);   // need local copy of the name, we're dropping the original
         resyncDrop( txn, db );
         Client::Context ctx( db );
@@ -420,7 +420,7 @@ namespace mongo {
         }
     }
 
-    bool ReplSource::handleDuplicateDbName( TransactionExperiment* txn,
+    bool ReplSource::handleDuplicateDbName( OperationContext* txn,
                                             const BSONObj &op,
                                             const char* ns,
                                             const char* db ) {
@@ -504,7 +504,7 @@ namespace mongo {
         return true;
     }
 
-    void ReplSource::applyOperation(TransactionExperiment* txn, Database* db, const BSONObj& op) {
+    void ReplSource::applyOperation(OperationContext* txn, Database* db, const BSONObj& op) {
         try {
             bool failedUpdate = applyOperation_inlock( txn, db, op );
             if (failedUpdate) {
@@ -598,7 +598,7 @@ namespace mongo {
         }
 
         scoped_ptr<Lock::GlobalWrite> lk( alreadyLocked ? 0 : new Lock::GlobalWrite() );
-        DurTransaction txn; // XXX?
+        OperationContextImpl txn; // XXX?
 
         if ( replAllDead ) {
             // hmmm why is this check here and not at top of this function? does it get set between top and here?
@@ -1090,7 +1090,7 @@ namespace mongo {
             int s = 0;
             {
                 Lock::GlobalWrite lk;
-                DurTransaction txn;
+                OperationContextImpl txn;
                 if ( replAllDead ) {
                     // throttledForceResyncDead can throw
                     if ( !replSettings.autoresync || !ReplSource::throttledForceResyncDead( &txn, "auto" ) ) {
diff --git a/src/mongo/db/repl/master_slave.h b/src/mongo/db/repl/master_slave.h
index 41c1e04e146..dbcd0953fb5 100644
--- a/src/mongo/db/repl/master_slave.h
+++ b/src/mongo/db/repl/master_slave.h
@@ -42,7 +42,7 @@
 namespace mongo {
 
     class Database;
-    class TransactionExperiment;
+    class OperationContext;
 
     // Main entry point for master/slave at startup time.
     void startMasterSlave();
@@ -77,7 +77,7 @@ namespace mongo {
     class ReplSource {
         shared_ptr<threadpool::ThreadPool> tp;
 
-        void resync(TransactionExperiment* txn, const std::string& dbName);
+        void resync(OperationContext* txn, const std::string& dbName);
 
         /** @param alreadyLocked caller already put us in write lock if true */
         void sync_pullOpLog_applyOperation(BSONObj& op, bool alreadyLocked);
@@ -100,7 +100,7 @@ namespace mongo {
 
         ReplSource();
 
-        void resyncDrop( TransactionExperiment* txn, const string& db );
+        void resyncDrop( OperationContext* txn, const string& db );
         // call without the db mutex
         void syncToTailOfRemoteLog();
         string ns() const { return string( "local.oplog.$" ) + sourceName(); }
@@ -112,7 +112,7 @@ namespace mongo {
          * master.
          * @return true iff an op with the specified ns may be applied.
          */
-        bool handleDuplicateDbName( TransactionExperiment* txn,
+        bool handleDuplicateDbName( OperationContext* txn,
                                     const BSONObj &op,
                                     const char* ns,
                                     const char* db );
@@ -123,7 +123,7 @@ namespace mongo {
     public:
         OplogReader oplogReader;
 
-        void applyOperation(TransactionExperiment* txn, Database* db, const BSONObj& op);
+        void applyOperation(OperationContext* txn, Database* db, const BSONObj& op);
         string hostName;    // ip addr or hostname plus optionally, ":<port>"
         string _sourceName;  // a logical source name.
         string sourceName() const { return _sourceName.empty() ? "main" : _sourceName; }
@@ -160,9 +160,9 @@ namespace mongo {
             return wait > 0 ? wait : 0;
         }
 
-        static bool throttledForceResyncDead( TransactionExperiment* txn, const char *requester );
-        static void forceResyncDead( TransactionExperiment* txn, const char *requester );
-        void forceResync( TransactionExperiment* txn, const char *requester );
+        static bool throttledForceResyncDead( OperationContext* txn, const char *requester );
+        static void forceResyncDead( OperationContext* txn, const char *requester );
+        void forceResync( OperationContext* txn, const char *requester );
     };
 
     /**
diff --git a/src/mongo/db/repl/oplog.cpp b/src/mongo/db/repl/oplog.cpp
index 61cb23f914b..41c4ac7aacf 100644
--- a/src/mongo/db/repl/oplog.cpp
+++ b/src/mongo/db/repl/oplog.cpp
@@ -55,7 +55,7 @@
 #include "mongo/db/repl/rs.h"
 #include "mongo/db/repl/write_concern.h"
 #include "mongo/db/stats/counters.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/db/storage_options.h"
 #include "mongo/db/catalog/collection.h"
 #include "mongo/s/d_logic.h"
@@ -97,7 +97,7 @@ namespace mongo {
                  result.isOK() );
     }
 
-    static void _logOpUninitialized(TransactionExperiment* txn,
+    static void _logOpUninitialized(OperationContext* txn,
                                     const char *opstr,
                                     const char *ns,
                                     const char *logNS,
@@ -113,7 +113,7 @@ namespace mongo {
         */
     void _logOpObjRS(const BSONObj& op) {
         Lock::DBWrite lk("local");
-        DurTransaction txn;
+        OperationContextImpl txn;
 
         const OpTime ts = op["ts"]._opTime();
         long long h = op["h"].numberLong();
@@ -222,7 +222,7 @@ namespace mongo {
     // on every logop call.
     static BufBuilder logopbufbuilder(8*1024);
     static const int OPLOG_VERSION = 2;
-    static void _logOpRS(TransactionExperiment* txn,
+    static void _logOpRS(OperationContext* txn,
                          const char *opstr,
                          const char *ns,
                          const char *logNS,
@@ -312,7 +312,7 @@ namespace mongo {
 
     }
 
-    static void _logOpOld(TransactionExperiment* txn,
+    static void _logOpOld(OperationContext* txn,
                           const char *opstr,
                           const char *ns,
                           const char *logNS,
@@ -373,7 +373,7 @@ namespace mongo {
         context.getClient()->setLastOp( ts );
     }
 
-    static void (*_logOp)(TransactionExperiment* txn,
+    static void (*_logOp)(OperationContext* txn,
                           const char *opstr,
                           const char *ns,
                           const char *logNS,
@@ -392,14 +392,14 @@ namespace mongo {
     void oldRepl() { _logOp = _logOpOld; }
 
     void logKeepalive() {
-        DurTransaction txn;
+        OperationContextImpl txn;
         _logOp(&txn, "n", "", 0, BSONObj(), 0, 0, false);
     }
     void logOpComment(const BSONObj& obj) {
-        DurTransaction txn;
+        OperationContextImpl txn;
         _logOp(&txn, "n", "", 0, obj, 0, 0, false);
     }
-    void logOpInitiate(TransactionExperiment* txn, const BSONObj& obj) {
+    void logOpInitiate(OperationContext* txn, const BSONObj& obj) {
         _logOpRS(txn, "n", "", 0, obj, 0, 0, false);
     }
 
@@ -410,7 +410,7 @@ namespace mongo {
           d delete / remove
           u update
     */
-    void logOp(TransactionExperiment* txn,
+    void logOp(OperationContext* txn,
                const char* opstr,
                const char* ns,
                const BSONObj& obj,
@@ -441,7 +441,7 @@ namespace mongo {
             ns = rsoplog;
 
         Client::Context ctx(ns);
-        DurTransaction txn;
+        OperationContextImpl txn;
         Collection* collection = ctx.db()->getCollection( &txn, ns );
 
         if ( collection ) {
@@ -512,7 +512,7 @@ namespace mongo {
     /** @param fromRepl false if from ApplyOpsCmd
         @return true if was and update should have happened and the document DNE.  see replset initial sync code.
      */
-    bool applyOperation_inlock(TransactionExperiment* txn,
+    bool applyOperation_inlock(OperationContext* txn,
                                Database* db,
                                const BSONObj& op,
                                bool fromRepl,
diff --git a/src/mongo/db/repl/oplog.h b/src/mongo/db/repl/oplog.h
index f64828bef0d..68714dea96d 100644
--- a/src/mongo/db/repl/oplog.h
+++ b/src/mongo/db/repl/oplog.h
@@ -32,7 +32,7 @@ namespace mongo {
 
     class BSONObj;
     class Database;
-    class TransactionExperiment;
+    class OperationContext;
     class OpTime;
 
     // These functions redefine the function for logOp(),
@@ -68,7 +68,7 @@ namespace mongo {
 
        See _logOp() in oplog.cpp for more details.
     */
-    void logOp( TransactionExperiment* txn,
+    void logOp( OperationContext* txn,
                 const char *opstr,
                 const char *ns,
                 const BSONObj& obj,
@@ -96,7 +96,7 @@ namespace mongo {
      * @param convertUpdateToUpsert convert some updates to upserts for idempotency reasons
      * Returns if the op was an update that could not be applied (true on failure)
      */
-    bool applyOperation_inlock(TransactionExperiment* txn,
+    bool applyOperation_inlock(OperationContext* txn,
                                Database* db,
                                const BSONObj& op,
                                bool fromRepl = true,
diff --git a/src/mongo/db/repl/repl_settings.cpp b/src/mongo/db/repl/repl_settings.cpp
index 623b76ce557..474631dd5e8 100644
--- a/src/mongo/db/repl/repl_settings.cpp
+++ b/src/mongo/db/repl/repl_settings.cpp
@@ -188,7 +188,7 @@ namespace mongo {
                                            const BSONObj& cmdObj,
                                            std::vector<Privilege>* out) {} // No auth required
         CmdIsMaster() : Command("isMaster", true, "ismaster") { }
-        virtual bool run(TransactionExperiment* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool /*fromRepl*/) {
+        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool /*fromRepl*/) {
             /* currently request to arbiter is (somewhat arbitrarily) an ismaster request that is not
                authenticated.
             */
diff --git a/src/mongo/db/repl/replset_commands.cpp b/src/mongo/db/repl/replset_commands.cpp
index e67b24395f4..1ac6e0daec3 100644
--- a/src/mongo/db/repl/replset_commands.cpp
+++ b/src/mongo/db/repl/replset_commands.cpp
@@ -65,7 +65,7 @@ namespace mongo {
                                            const BSONObj& cmdObj,
                                            std::vector<Privilege>* out) {}
         CmdReplSetTest() : ReplSetCommand("replSetTest") { }
-        virtual bool run(TransactionExperiment* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             log() << "replSet replSetTest command received: " << cmdObj.toString() << rsLog;
 
             if( cmdObj.hasElement("forceInitialSyncFailure") ) {
@@ -120,7 +120,7 @@ namespace mongo {
             actions.addAction(ActionType::internal);
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
-        virtual bool run(TransactionExperiment* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             if( !check(errmsg, result) )
                 return false;
             result.append("rbid",rbid);
@@ -155,7 +155,7 @@ namespace mongo {
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
         CmdReplSetGetStatus() : ReplSetCommand("replSetGetStatus", true) { }
-        virtual bool run(TransactionExperiment* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             if ( cmdObj["forShell"].trueValue() )
                 lastError.disableForCommand();
 
@@ -182,7 +182,7 @@ namespace mongo {
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
         CmdReplSetReconfig() : ReplSetCommand("replSetReconfig"), mutex("rsreconfig") { }
-        virtual bool run(TransactionExperiment* txn, const string& a, BSONObj& b, int e, string& errmsg, BSONObjBuilder& c, bool d) {
+        virtual bool run(OperationContext* txn, const string& a, BSONObj& b, int e, string& errmsg, BSONObjBuilder& c, bool d) {
             try {
                 rwlock_try_write lk(mutex);
                 return _run(a,b,e,errmsg,c,d);
@@ -277,7 +277,7 @@ namespace mongo {
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
         CmdReplSetFreeze() : ReplSetCommand("replSetFreeze") { }
-        virtual bool run(TransactionExperiment* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             if( !check(errmsg, result) )
                 return false;
             int secs = (int) cmdObj.firstElement().numberInt();
@@ -307,7 +307,7 @@ namespace mongo {
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
         CmdReplSetStepDown() : ReplSetCommand("replSetStepDown") { }
-        virtual bool run(TransactionExperiment* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             if( !check(errmsg, result) )
                 return false;
             if( !theReplSet->box.getState().primary() ) {
@@ -362,7 +362,7 @@ namespace mongo {
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
         CmdReplSetMaintenance() : ReplSetCommand("replSetMaintenance") { }
-        virtual bool run(TransactionExperiment* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             if( !check(errmsg, result) )
                 return false;
 
@@ -394,7 +394,7 @@ namespace mongo {
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
         CmdReplSetSyncFrom() : ReplSetCommand("replSetSyncFrom") { }
-        virtual bool run(TransactionExperiment* txn, const string&, 
+        virtual bool run(OperationContext* txn, const string&, 
                          BSONObj& cmdObj, 
                          int, 
                          string& errmsg, 
@@ -422,7 +422,7 @@ namespace mongo {
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
         CmdReplSetUpdatePosition() : ReplSetCommand("replSetUpdatePosition") { }
-        virtual bool run(TransactionExperiment* txn, const string& , BSONObj& cmdObj, int, string& errmsg,
+        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg,
                          BSONObjBuilder& result, bool fromRepl) {
             if (!check(errmsg, result))
                 return false;
diff --git a/src/mongo/db/repl/replset_web_handler.cpp b/src/mongo/db/repl/replset_web_handler.cpp
index 5cd7b14ae48..0f4c9b96bca 100644
--- a/src/mongo/db/repl/replset_web_handler.cpp
+++ b/src/mongo/db/repl/replset_web_handler.cpp
@@ -53,7 +53,7 @@ namespace {
             return startsWith( url , "/_replSet" );
         }
 
-        virtual void handle( TransactionExperiment* txn,
+        virtual void handle( OperationContext* txn,
                              const char *rq, const std::string& url, BSONObj params,
                              string& responseMsg, int& responseCode,
                              vector<string>& headers,  const SockAddr &from ) {
diff --git a/src/mongo/db/repl/resync.cpp b/src/mongo/db/repl/resync.cpp
index dd412358b7d..c9c608d6f80 100644
--- a/src/mongo/db/repl/resync.cpp
+++ b/src/mongo/db/repl/resync.cpp
@@ -30,7 +30,7 @@
 #include "mongo/db/repl/master_slave.h"  // replSettings
 #include "mongo/db/repl/repl_settings.h"  // replSettings
 #include "mongo/db/repl/rs.h" // replLocalAuth()
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 
 namespace mongo {
 
@@ -57,7 +57,7 @@ namespace mongo {
         }
 
         CmdResync() : Command("resync") { }
-        virtual bool run(TransactionExperiment* txn,
+        virtual bool run(OperationContext* txn,
                          const string& dbname,
                          BSONObj& cmdObj,
                          int,
diff --git a/src/mongo/db/repl/rs.cpp b/src/mongo/db/repl/rs.cpp
index e25bf26bd90..4b52a60f68a 100644
--- a/src/mongo/db/repl/rs.cpp
+++ b/src/mongo/db/repl/rs.cpp
@@ -43,7 +43,7 @@
 #include "mongo/db/repl/repl_start.h"
 #include "mongo/db/repl/rs.h"
 #include "mongo/db/server_parameters.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/platform/bits.h"
 #include "mongo/s/d_logic.h"
 #include "mongo/util/exit.h"
@@ -120,7 +120,7 @@ namespace {
     void dropAllTempCollections() {
         vector<string> dbNames;
         getDatabaseNames(dbNames);
-        DurTransaction txn;
+        OperationContextImpl txn;
         for (vector<string>::const_iterator it = dbNames.begin(); it != dbNames.end(); ++it) {
             // The local db is special because it isn't replicated. It is cleared at startup even on
             // replica set members.
@@ -939,13 +939,13 @@ namespace {
 
     void ReplSetImpl::clearInitialSyncFlag() {
         Lock::DBWrite lk( "local" );
-        DurTransaction txn; // XXX?
+        OperationContextImpl txn; // XXX?
         Helpers::putSingleton(&txn, "local.replset.minvalid", BSON( "$unset" << _initialSyncFlag ));
     }
 
     void ReplSetImpl::setInitialSyncFlag() {
         Lock::DBWrite lk( "local" );
-        DurTransaction txn; // XXX?
+        OperationContextImpl txn; // XXX?
         Helpers::putSingleton(&txn, "local.replset.minvalid", BSON( "$set" << _initialSyncFlag ));
     }
 
@@ -964,7 +964,7 @@ namespace {
         subobj.appendTimestamp("ts", obj["ts"].date());
         subobj.done();
         Lock::DBWrite lk( "local" );
-        DurTransaction txn; // XXX?
+        OperationContextImpl txn; // XXX?
         Helpers::putSingleton(&txn, "local.replset.minvalid", builder.obj());
     }
 
diff --git a/src/mongo/db/repl/rs_config.cpp b/src/mongo/db/repl/rs_config.cpp
index 75186b24d52..889e79466dd 100644
--- a/src/mongo/db/repl/rs_config.cpp
+++ b/src/mongo/db/repl/rs_config.cpp
@@ -39,7 +39,7 @@
 #include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/repl_settings.h"  // replSettings
 #include "mongo/db/repl/rs.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/util/net/hostandport.h"
 #include "mongo/util/text.h"
 
@@ -51,7 +51,7 @@ namespace mongo {
     const int ReplSetConfig::DEFAULT_HB_TIMEOUT = 10;
 
     static AtomicUInt _warnedAboutVotes = 0;
-    void logOpInitiate(TransactionExperiment* txn, const bo&);
+    void logOpInitiate(OperationContext* txn, const bo&);
 
     void assertOnlyHas(BSONObj o, const set<string>& fields) {
         BSONObj::iterator i(o);
@@ -82,7 +82,7 @@ namespace mongo {
               << newConfigBSON << rsLog;
         {
             Client::WriteContext cx( rsConfigNs );
-            DurTransaction txn;
+            OperationContextImpl txn;
 
             //theReplSet->lastOpTimeWritten = ??;
             //rather than above, do a logOp()? probably
diff --git a/src/mongo/db/repl/rs_initialsync.cpp b/src/mongo/db/repl/rs_initialsync.cpp
index 506e9a8d9a6..25626d83491 100644
--- a/src/mongo/db/repl/rs_initialsync.cpp
+++ b/src/mongo/db/repl/rs_initialsync.cpp
@@ -42,7 +42,7 @@
 #include "mongo/bson/optime.h"
 #include "mongo/db/repl/repl_settings.h"  // replSettings
 #include "mongo/db/repl/initial_sync.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/db/structure/catalog/namespace_details.h"
 #include "mongo/util/mongoutils/str.h"
 
@@ -98,7 +98,7 @@ namespace mongo {
                 sethbmsg( str::stream() << "initial sync cloning indexes for : " << db , 0);
 
             Client::WriteContext ctx(db);
-            DurTransaction txn;
+            OperationContextImpl txn;
 
             string err;
             int errCode;
@@ -129,7 +129,7 @@ namespace mongo {
 
     static void emptyOplog() {
         Client::WriteContext ctx(rsoplog);
-        DurTransaction txn;
+        OperationContextImpl txn;
         Collection* collection = ctx.ctx().db()->getCollection(rsoplog);
 
         // temp
diff --git a/src/mongo/db/repl/rs_initiate.cpp b/src/mongo/db/repl/rs_initiate.cpp
index 82e5c9d4934..b007c1fc8bf 100644
--- a/src/mongo/db/repl/rs_initiate.cpp
+++ b/src/mongo/db/repl/rs_initiate.cpp
@@ -178,7 +178,7 @@ namespace mongo {
             actions.addAction(ActionType::replSetConfigure);
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
-        virtual bool run(TransactionExperiment* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             log() << "replSet replSetInitiate admin command received from client" << rsLog;
 
             if( !replSet ) {
diff --git a/src/mongo/db/repl/rs_rollback.cpp b/src/mongo/db/repl/rs_rollback.cpp
index 93c9e2306fb..0fa386adb00 100644
--- a/src/mongo/db/repl/rs_rollback.cpp
+++ b/src/mongo/db/repl/rs_rollback.cpp
@@ -41,7 +41,7 @@
 #include "mongo/db/query/internal_plans.h"
 #include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/rs.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/db/structure/catalog/namespace_details.h"
 
 /* Scenarios
@@ -337,7 +337,7 @@ namespace mongo {
 
     void ReplSetImpl::syncFixUp(HowToFixUp& h, OplogReader& r) {
         DBClientConnection *them = r.conn();
-        DurTransaction txn;
+        OperationContextImpl txn;
 
         // fetch all first so we needn't handle interruption in a fancy way
 
diff --git a/src/mongo/db/repl/rs_sync.cpp b/src/mongo/db/repl/rs_sync.cpp
index d9867296388..09f0deb86a7 100644
--- a/src/mongo/db/repl/rs_sync.cpp
+++ b/src/mongo/db/repl/rs_sync.cpp
@@ -51,7 +51,7 @@
 #include "mongo/db/repl/sync_tail.h"
 #include "mongo/db/server_parameters.h"
 #include "mongo/db/stats/timer_stats.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/db/storage_options.h"
 #include "mongo/util/fail_point_service.h"
 
@@ -230,7 +230,7 @@ namespace mongo {
         changeState(MemberState::RS_RECOVERING);
 
         Client::Context ctx("local");
-        DurTransaction txn;
+        OperationContextImpl txn;
         ctx.db()->dropCollection(&txn, "local.oplog.rs");
         {
             boost::unique_lock<boost::mutex> lock(theReplSet->initialSyncMutex);
diff --git a/src/mongo/db/repl/sync.cpp b/src/mongo/db/repl/sync.cpp
index 9a4b5ad8073..814ea19997c 100644
--- a/src/mongo/db/repl/sync.cpp
+++ b/src/mongo/db/repl/sync.cpp
@@ -37,7 +37,7 @@
 #include "mongo/db/structure/catalog/namespace_details.h"
 #include "mongo/db/pdfile.h"
 #include "mongo/db/repl/oplogreader.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/db/catalog/collection.h"
 #include "mongo/util/assert_util.h"
 #include "mongo/util/log.h"
@@ -110,7 +110,7 @@ namespace mongo {
         // should already have write lock
         const char *ns = o.getStringField("ns");
         Client::Context ctx(ns);
-        DurTransaction txn;
+        OperationContextImpl txn;
 
         // we don't have the object yet, which is possible on initial sync.  get it.
         log() << "replication info adding missing object" << endl; // rare enough we can log
diff --git a/src/mongo/db/repl/sync_source_feedback.cpp b/src/mongo/db/repl/sync_source_feedback.cpp
index 58daadb7bf2..03c243683b4 100644
--- a/src/mongo/db/repl/sync_source_feedback.cpp
+++ b/src/mongo/db/repl/sync_source_feedback.cpp
@@ -37,7 +37,7 @@
 #include "mongo/db/dbhelpers.h"
 #include "mongo/db/repl/bgsync.h"
 #include "mongo/db/repl/rs.h"  // theReplSet
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 
 namespace mongo {
 
@@ -66,7 +66,7 @@ namespace mongo {
         string myname = getHostName();
         {
             Client::WriteContext ctx("local");
-            DurTransaction txn;
+            OperationContextImpl txn;
             // local.me is an identifier for a server for getLastError w:2+
             if (!Helpers::getSingleton("local.me", _me) ||
                 !_me.hasField("host") ||
diff --git a/src/mongo/db/repl/sync_tail.cpp b/src/mongo/db/repl/sync_tail.cpp
index 91eb4b291db..6071905e8f1 100644
--- a/src/mongo/db/repl/sync_tail.cpp
+++ b/src/mongo/db/repl/sync_tail.cpp
@@ -40,7 +40,7 @@
 #include "mongo/db/repl/bgsync.h"
 #include "mongo/db/repl/oplog.h"
 #include "mongo/db/stats/timer_stats.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/util/fail_point_service.h"
 
 namespace mongo {
@@ -106,7 +106,7 @@ namespace replset {
         }
 
         Client::Context ctx(ns, storageGlobalParams.dbpath);
-        DurTransaction txn;
+        OperationContextImpl txn;
         ctx.getClient()->curop()->reset();
         // For non-initial-sync, we convert updates to upserts
         // to suppress errors when replaying oplog entries.
diff --git a/src/mongo/db/restapi.cpp b/src/mongo/db/restapi.cpp
index bb2243272ea..4ddf39ff3e2 100644
--- a/src/mongo/db/restapi.cpp
+++ b/src/mongo/db/restapi.cpp
@@ -66,7 +66,7 @@ namespace mongo {
                 url.find_last_of( '/' ) > 0;
         }
 
-        virtual void handle( TransactionExperiment* txn,
+        virtual void handle( OperationContext* txn,
                              const char *rq, const std::string& url, BSONObj params,
                              string& responseMsg, int& responseCode,
                              vector<string>& headers,  const SockAddr &from ) {
diff --git a/src/mongo/db/stats/top.cpp b/src/mongo/db/stats/top.cpp
index d1855f842e6..2ec710ae57d 100644
--- a/src/mongo/db/stats/top.cpp
+++ b/src/mongo/db/stats/top.cpp
@@ -188,7 +188,7 @@ namespace mongo {
             actions.addAction(ActionType::top);
             out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
         }
-        virtual bool run(TransactionExperiment* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
+        virtual bool run(OperationContext* txn, const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
             {
                 BSONObjBuilder b( result.subobjStart( "totals" ) );
                 b.append( "note" , "all times in microseconds" );
diff --git a/src/mongo/db/storage/data_file.cpp b/src/mongo/db/storage/data_file.cpp
index adeaf34b129..b6466fd5b71 100644
--- a/src/mongo/db/storage/data_file.cpp
+++ b/src/mongo/db/storage/data_file.cpp
@@ -37,7 +37,7 @@
 #include "mongo/db/d_concurrency.h"
 #include "mongo/db/storage/mmap_v1/dur.h"
 #include "mongo/db/lockstate.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/util/file_allocator.h"
 
 namespace mongo {
@@ -88,7 +88,7 @@ namespace mongo {
     }
 
     /** @return true if found and opened. if uninitialized (prealloc only) does not open. */
-    Status DataFile::openExisting( TransactionExperiment* txn, const char *filename ) {
+    Status DataFile::openExisting( OperationContext* txn, const char *filename ) {
         verify( _mb == 0 );
         if( !boost::filesystem::exists(filename) )
             return Status( ErrorCodes::InvalidPath, "DataFile::openExisting - file does not exist" );
@@ -118,7 +118,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    void DataFile::open( TransactionExperiment* txn,
+    void DataFile::open( OperationContext* txn,
                          const char *filename,
                          int minSize,
                          bool preallocateOnly ) {
@@ -160,7 +160,7 @@ namespace mongo {
         mmf.flush( sync );
     }
 
-    DiskLoc DataFile::allocExtentArea( TransactionExperiment* txn, int size ) {
+    DiskLoc DataFile::allocExtentArea( OperationContext* txn, int size ) {
 
         massert( 10357, "shutdown in progress", !inShutdown() );
         massert( 10359, "header==0 on new extent: 32 bit mmap space exceeded?", header() ); // null if file open failed
@@ -178,7 +178,7 @@ namespace mongo {
 
     // -------------------------------------------------------------------------------
 
-    void DataFileHeader::init(TransactionExperiment* txn, int fileno, int filelength, const char* filename) {
+    void DataFileHeader::init(OperationContext* txn, int fileno, int filelength, const char* filename) {
         if ( uninitialized() ) {
             DEV log() << "datafileheader::init initializing " << filename << " n:" << fileno << endl;
             if( !(filelength > 32768 ) ) {
@@ -217,7 +217,7 @@ namespace mongo {
         }
     }
 
-    void DataFileHeader::checkUpgrade(TransactionExperiment* txn) {
+    void DataFileHeader::checkUpgrade(OperationContext* txn) {
         if ( freeListStart == minDiskLoc ) {
             // we are upgrading from 2.4 to 2.6
             invariant( freeListEnd == minDiskLoc ); // both start and end should be (0,0) or real
diff --git a/src/mongo/db/storage/data_file.h b/src/mongo/db/storage/data_file.h
index d96d20dffd7..f83e9f8f08f 100644
--- a/src/mongo/db/storage/data_file.h
+++ b/src/mongo/db/storage/data_file.h
@@ -37,7 +37,7 @@
 namespace mongo {
 
     class ExtentManager;
-    class TransactionExperiment;
+    class OperationContext;
 
     /*  a datafile - i.e. the "dbname.<#>" files :
 
@@ -77,9 +77,9 @@ namespace mongo {
 
         bool uninitialized() const { return version == 0; }
 
-        void init(TransactionExperiment* txn, int fileno, int filelength, const char* filename);
+        void init(OperationContext* txn, int fileno, int filelength, const char* filename);
 
-        void checkUpgrade(TransactionExperiment* txn);
+        void checkUpgrade(OperationContext* txn);
 
         bool isEmpty() const {
             return uninitialized() || ( unusedLength == fileLength - HeaderSize - 16 );
@@ -95,15 +95,15 @@ namespace mongo {
         DataFile(int fn) : _mb(0), fileNo(fn) { }
 
         /** @return true if found and opened. if uninitialized (prealloc only) does not open. */
-        Status openExisting( TransactionExperiment* txn, const char *filename );
+        Status openExisting( OperationContext* txn, const char *filename );
 
         /** creates if DNE */
-        void open(TransactionExperiment* txn,
+        void open(OperationContext* txn,
                   const char *filename,
                   int requestedDataSize = 0,
                   bool preallocateOnly = false);
 
-        DiskLoc allocExtentArea( TransactionExperiment* txn, int size );
+        DiskLoc allocExtentArea( OperationContext* txn, int size );
 
         DataFileHeader* getHeader() { return header(); }
         const DataFileHeader* getHeader() const { return header(); }
diff --git a/src/mongo/db/storage/extent_manager.h b/src/mongo/db/storage/extent_manager.h
index 7ebb7b199c4..671f4271698 100644
--- a/src/mongo/db/storage/extent_manager.h
+++ b/src/mongo/db/storage/extent_manager.h
@@ -41,7 +41,7 @@ namespace mongo {
 
     class DataFile;
     class Record;
-    class TransactionExperiment;
+    class OperationContext;
 
     struct Extent;
 
@@ -68,7 +68,7 @@ namespace mongo {
         /**
          * opens all current files
          */
-        virtual Status init(TransactionExperiment* txn) = 0;
+        virtual Status init(OperationContext* txn) = 0;
 
         virtual size_t numFiles() const = 0;
         virtual long long fileSize() const = 0;
@@ -76,7 +76,7 @@ namespace mongo {
         virtual void flushFiles( bool sync ) = 0;
 
         // must call Extent::reuse on the returned extent
-        virtual DiskLoc allocateExtent( TransactionExperiment* txn,
+        virtual DiskLoc allocateExtent( OperationContext* txn,
                                         bool capped,
                                         int size,
                                         int quotaMax ) = 0;
@@ -84,14 +84,14 @@ namespace mongo {
         /**
          * firstExt has to be == lastExt or a chain
          */
-        virtual void freeExtents( TransactionExperiment* txn,
+        virtual void freeExtents( OperationContext* txn,
                                   DiskLoc firstExt, DiskLoc lastExt ) = 0;
 
         /**
          * frees a single extent
          * ignores all fields in the Extent except: magic, myLoc, length
          */
-        virtual void freeExtent( TransactionExperiment* txn, DiskLoc extent ) = 0;
+        virtual void freeExtent( OperationContext* txn, DiskLoc extent ) = 0;
 
         virtual void freeListStats( int* numExtents, int64_t* totalFreeSize ) const = 0;
 
diff --git a/src/mongo/db/storage/mmap_v1/mmap_v1_extent_manager.cpp b/src/mongo/db/storage/mmap_v1/mmap_v1_extent_manager.cpp
index 84bfae056e7..85ad027b39b 100644
--- a/src/mongo/db/storage/mmap_v1/mmap_v1_extent_manager.cpp
+++ b/src/mongo/db/storage/mmap_v1/mmap_v1_extent_manager.cpp
@@ -40,7 +40,7 @@
 #include "mongo/db/storage/extent.h"
 #include "mongo/db/storage/extent_manager.h"
 #include "mongo/db/storage/record.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 
 namespace mongo {
 
@@ -74,7 +74,7 @@ namespace mongo {
     }
 
 
-    Status MmapV1ExtentManager::init(TransactionExperiment* txn) {
+    Status MmapV1ExtentManager::init(OperationContext* txn) {
         verify( _files.size() == 0 );
 
         for ( int n = 0; n < DiskLoc::MaxFiles; n++ ) {
@@ -113,7 +113,7 @@ namespace mongo {
 
 
     // todo: this is called a lot. streamline the common case
-    DataFile* MmapV1ExtentManager::getFile( TransactionExperiment* txn,
+    DataFile* MmapV1ExtentManager::getFile( OperationContext* txn,
                                       int n,
                                       int sizeNeeded ,
                                       bool preallocateOnly) {
@@ -174,7 +174,7 @@ namespace mongo {
         return preallocateOnly ? 0 : p;
     }
 
-    DataFile* MmapV1ExtentManager::_addAFile( TransactionExperiment* txn,
+    DataFile* MmapV1ExtentManager::_addAFile( OperationContext* txn,
                                         int sizeNeeded,
                                         bool preallocateNextFile ) {
         DEV Lock::assertWriteLocked( _dbname );
@@ -243,7 +243,7 @@ namespace mongo {
         return DataFile::maxSize() - DataFileHeader::HeaderSize - 16;
     }
 
-    DiskLoc MmapV1ExtentManager::_createExtentInFile( TransactionExperiment* txn,
+    DiskLoc MmapV1ExtentManager::_createExtentInFile( OperationContext* txn,
                                                 int fileNo,
                                                 DataFile* f,
                                                 int size,
@@ -276,7 +276,7 @@ namespace mongo {
     }
 
 
-    DiskLoc MmapV1ExtentManager::_createExtent( TransactionExperiment* txn,
+    DiskLoc MmapV1ExtentManager::_createExtent( OperationContext* txn,
                                           int size,
                                           int maxFileNoForQuota ) {
         size = quantizeExtentSize( size );
@@ -315,7 +315,7 @@ namespace mongo {
         msgasserted(14810, "couldn't allocate space for a new extent" );
     }
 
-    DiskLoc MmapV1ExtentManager::_allocFromFreeList( TransactionExperiment* txn,
+    DiskLoc MmapV1ExtentManager::_allocFromFreeList( OperationContext* txn,
                                                int approxSize,
                                                bool capped ) {
         // setup extent constraints
@@ -400,7 +400,7 @@ namespace mongo {
         return best->myLoc;
     }
 
-    DiskLoc MmapV1ExtentManager::allocateExtent( TransactionExperiment* txn,
+    DiskLoc MmapV1ExtentManager::allocateExtent( OperationContext* txn,
                                            bool capped,
                                            int size,
                                            int quotaMax ) {
@@ -423,7 +423,7 @@ namespace mongo {
         return eloc;
     }
 
-    void MmapV1ExtentManager::freeExtent(TransactionExperiment* txn, DiskLoc firstExt ) {
+    void MmapV1ExtentManager::freeExtent(OperationContext* txn, DiskLoc firstExt ) {
         Extent* e = getExtent( firstExt );
         txn->writing( &e->xnext )->Null();
         txn->writing( &e->xprev )->Null();
@@ -445,7 +445,7 @@ namespace mongo {
 
     }
 
-    void MmapV1ExtentManager::freeExtents(TransactionExperiment* txn, DiskLoc firstExt, DiskLoc lastExt) {
+    void MmapV1ExtentManager::freeExtents(OperationContext* txn, DiskLoc firstExt, DiskLoc lastExt) {
 
         if ( firstExt.isNull() && lastExt.isNull() )
             return;
@@ -488,13 +488,13 @@ namespace mongo {
         return file->header()->freeListEnd;
     }
 
-    void MmapV1ExtentManager::_setFreeListStart( TransactionExperiment* txn, DiskLoc loc ) {
+    void MmapV1ExtentManager::_setFreeListStart( OperationContext* txn, DiskLoc loc ) {
         invariant( !_files.empty() );
         DataFile* file = _files[0];
         *txn->writing( &file->header()->freeListStart ) = loc;
     }
 
-    void MmapV1ExtentManager::_setFreeListEnd( TransactionExperiment* txn, DiskLoc loc ) {
+    void MmapV1ExtentManager::_setFreeListEnd( OperationContext* txn, DiskLoc loc ) {
         invariant( !_files.empty() );
         DataFile* file = _files[0];
         *txn->writing( &file->header()->freeListEnd ) = loc;
diff --git a/src/mongo/db/storage/mmap_v1/mmap_v1_extent_manager.h b/src/mongo/db/storage/mmap_v1/mmap_v1_extent_manager.h
index c045a075df4..47a35d3eb91 100644
--- a/src/mongo/db/storage/mmap_v1/mmap_v1_extent_manager.h
+++ b/src/mongo/db/storage/mmap_v1/mmap_v1_extent_manager.h
@@ -44,7 +44,7 @@ namespace mongo {
 
     class DataFile;
     class Record;
-    class TransactionExperiment;
+    class OperationContext;
 
     struct Extent;
 
@@ -83,13 +83,13 @@ namespace mongo {
         /**
          * opens all current files
          */
-        Status init(TransactionExperiment* txn);
+        Status init(OperationContext* txn);
 
         size_t numFiles() const;
         long long fileSize() const;
 
         // TODO: make private
-        DataFile* getFile( TransactionExperiment* txn,
+        DataFile* getFile( OperationContext* txn,
                            int n,
                            int sizeNeeded = 0,
                            bool preallocateOnly = false );
@@ -97,7 +97,7 @@ namespace mongo {
         void flushFiles( bool sync );
 
         // must call Extent::reuse on the returned extent
-        DiskLoc allocateExtent( TransactionExperiment* txn,
+        DiskLoc allocateExtent( OperationContext* txn,
                                 bool capped,
                                 int size,
                                 int quotaMax );
@@ -105,13 +105,13 @@ namespace mongo {
         /**
          * firstExt has to be == lastExt or a chain
          */
-        void freeExtents( TransactionExperiment* txn, DiskLoc firstExt, DiskLoc lastExt );
+        void freeExtents( OperationContext* txn, DiskLoc firstExt, DiskLoc lastExt );
 
         /**
          * frees a single extent
          * ignores all fields in the Extent except: magic, myLoc, length
          */
-        void freeExtent( TransactionExperiment* txn, DiskLoc extent );
+        void freeExtent( OperationContext* txn, DiskLoc extent );
 
         void printFreeList() const;
 
@@ -153,23 +153,23 @@ namespace mongo {
         /**
          * will return NULL if nothing suitable in free list
          */
-        DiskLoc _allocFromFreeList( TransactionExperiment* txn, int approxSize, bool capped );
+        DiskLoc _allocFromFreeList( OperationContext* txn, int approxSize, bool capped );
 
         /* allocate a new Extent, does not check free list
          * @param maxFileNoForQuota - 0 for unlimited
         */
-        DiskLoc _createExtent( TransactionExperiment* txn, int approxSize, int maxFileNoForQuota );
+        DiskLoc _createExtent( OperationContext* txn, int approxSize, int maxFileNoForQuota );
 
-        DataFile* _addAFile( TransactionExperiment* txn, int sizeNeeded, bool preallocateNextFile );
+        DataFile* _addAFile( OperationContext* txn, int sizeNeeded, bool preallocateNextFile );
 
         DiskLoc _getFreeListStart() const;
         DiskLoc _getFreeListEnd() const;
-        void _setFreeListStart( TransactionExperiment* txn, DiskLoc loc );
-        void _setFreeListEnd( TransactionExperiment* txn, DiskLoc loc );
+        void _setFreeListStart( OperationContext* txn, DiskLoc loc );
+        void _setFreeListEnd( OperationContext* txn, DiskLoc loc );
 
         const DataFile* _getOpenFile( int n ) const;
 
-        DiskLoc _createExtentInFile( TransactionExperiment* txn,
+        DiskLoc _createExtentInFile( OperationContext* txn,
                                      int fileNo,
                                      DataFile* f,
                                      int size,
diff --git a/src/mongo/db/structure/btree/btree_interface.cpp b/src/mongo/db/structure/btree/btree_interface.cpp
index c6601c31330..0511029a40b 100644
--- a/src/mongo/db/structure/btree/btree_interface.cpp
+++ b/src/mongo/db/structure/btree/btree_interface.cpp
@@ -28,7 +28,7 @@
 
 #include "mongo/db/structure/btree/btree_interface.h"
 
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/db/structure/btree/btree_logic.h"
 
 
@@ -37,7 +37,7 @@ namespace mongo {
     template <class OnDiskFormat>
     class BtreeBuilderInterfaceImpl : public BtreeBuilderInterface {
     public:
-        BtreeBuilderInterfaceImpl(TransactionExperiment* trans,
+        BtreeBuilderInterfaceImpl(OperationContext* trans,
                                   typename BtreeLogic<OnDiskFormat>::Builder* builder)
             : _builder(builder), _trans(trans) { }
 
@@ -55,7 +55,7 @@ namespace mongo {
         typename BtreeLogic<OnDiskFormat>::Builder* _builder;
 
         // Not owned here.
-        TransactionExperiment* _trans;
+        OperationContext* _trans;
     };
 
     template <class OnDiskFormat>
@@ -76,14 +76,14 @@ namespace mongo {
 
         virtual ~BtreeInterfaceImpl() { }
 
-        virtual BtreeBuilderInterface* getBulkBuilder(TransactionExperiment* txn,
+        virtual BtreeBuilderInterface* getBulkBuilder(OperationContext* txn,
                                                       bool dupsAllowed) {
 
             return new BtreeBuilderInterfaceImpl<OnDiskFormat>(
                 txn, _btree->newBuilder(txn, dupsAllowed));
         }
 
-        virtual Status insert(TransactionExperiment* txn,
+        virtual Status insert(OperationContext* txn,
                               const BSONObj& key,
                               const DiskLoc& loc,
                               bool dupsAllowed) {
@@ -91,7 +91,7 @@ namespace mongo {
             return _btree->insert(txn, key, loc, dupsAllowed);
         }
 
-        virtual bool unindex(TransactionExperiment* txn,
+        virtual bool unindex(OperationContext* txn,
                              const BSONObj& key,
                              const DiskLoc& loc) {
 
@@ -185,7 +185,7 @@ namespace mongo {
             _btree->restorePosition(saved.key, saved.loc, direction, bucketInOut, keyOffsetInOut);
         }
 
-        virtual Status initAsEmpty(TransactionExperiment* txn) {
+        virtual Status initAsEmpty(OperationContext* txn) {
             return _btree->initAsEmpty(txn);
         }
 
diff --git a/src/mongo/db/structure/btree/btree_interface.h b/src/mongo/db/structure/btree/btree_interface.h
index 7391420a875..35884a809e8 100644
--- a/src/mongo/db/structure/btree/btree_interface.h
+++ b/src/mongo/db/structure/btree/btree_interface.h
@@ -29,7 +29,7 @@
 #include "mongo/bson/ordering.h"
 #include "mongo/db/diskloc.h"
 #include "mongo/db/jsobj.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/db/structure/head_manager.h"
 #include "mongo/db/structure/record_store.h"
 
@@ -100,15 +100,15 @@ namespace mongo {
          * Caller owns returned pointer.
          * 'this' must outlive the returned pointer.
          */
-        virtual BtreeBuilderInterface* getBulkBuilder(TransactionExperiment* txn,
+        virtual BtreeBuilderInterface* getBulkBuilder(OperationContext* txn,
                                                       bool dupsAllowed) = 0;
 
-        virtual Status insert(TransactionExperiment* txn,
+        virtual Status insert(OperationContext* txn,
                               const BSONObj& key,
                               const DiskLoc& loc,
                               bool dupsAllowed) = 0;
 
-        virtual bool unindex(TransactionExperiment* txn,
+        virtual bool unindex(OperationContext* txn,
                              const BSONObj& key,
                              const DiskLoc& loc) = 0;
 
@@ -181,7 +181,7 @@ namespace mongo {
         // Index creation
         //
 
-        virtual Status initAsEmpty(TransactionExperiment* txn) = 0;
+        virtual Status initAsEmpty(OperationContext* txn) = 0;
     };
 
 }  // namespace mongo
diff --git a/src/mongo/db/structure/btree/btree_logic.cpp b/src/mongo/db/structure/btree/btree_logic.cpp
index 6c75249df6e..ceb1e770db3 100644
--- a/src/mongo/db/structure/btree/btree_logic.cpp
+++ b/src/mongo/db/structure/btree/btree_logic.cpp
@@ -29,7 +29,7 @@
 #include "mongo/db/diskloc.h"
 #include "mongo/db/jsobj.h"
 #include "mongo/db/storage/record.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/db/structure/btree/btree_logic.h"
 #include "mongo/db/structure/btree/key.h"
 #include "mongo/db/structure/record_store.h"
@@ -43,13 +43,13 @@ namespace mongo {
 
     template <class BtreeLayout>
     typename BtreeLogic<BtreeLayout>::Builder*
-    BtreeLogic<BtreeLayout>::newBuilder(TransactionExperiment* trans, bool dupsAllowed) {
+    BtreeLogic<BtreeLayout>::newBuilder(OperationContext* trans, bool dupsAllowed) {
         return new Builder(this, trans, dupsAllowed);
     }
 
     template <class BtreeLayout>
     BtreeLogic<BtreeLayout>::Builder::Builder(BtreeLogic* logic,
-                                              TransactionExperiment* trans,
+                                              OperationContext* trans,
                                               bool dupsAllowed)
         : _logic(logic),
           _dupsAllowed(dupsAllowed),
@@ -241,7 +241,7 @@ namespace mongo {
 
     template <class BtreeLayout>
     typename BtreeLogic<BtreeLayout>::BucketType*
-    BtreeLogic<BtreeLayout>::btreemod(TransactionExperiment* trans, BucketType* bucket) {
+    BtreeLogic<BtreeLayout>::btreemod(OperationContext* trans, BucketType* bucket) {
         trans->writingPtr(bucket, BtreeLayout::BucketSize);
         return bucket;
     }
@@ -426,7 +426,7 @@ namespace mongo {
      * Returns false if a split is required.
      */
     template <class BtreeLayout>
-    bool BtreeLogic<BtreeLayout>::basicInsert(TransactionExperiment* trans,
+    bool BtreeLogic<BtreeLayout>::basicInsert(OperationContext* trans,
                                               BucketType* bucket,
                                               const DiskLoc bucketLoc,
                                               int& keypos,
@@ -510,7 +510,7 @@ namespace mongo {
      * it.
      */
     template <class BtreeLayout>
-    void BtreeLogic<BtreeLayout>::_pack(TransactionExperiment* trans,
+    void BtreeLogic<BtreeLayout>::_pack(OperationContext* trans,
                                         BucketType* bucket,
                                         const DiskLoc thisLoc,
                                         int &refPos) {
@@ -1256,7 +1256,7 @@ namespace mongo {
     }
 
     template <class BtreeLayout>
-    void BtreeLogic<BtreeLayout>::delBucket(TransactionExperiment* trans,
+    void BtreeLogic<BtreeLayout>::delBucket(OperationContext* trans,
                                             BucketType* bucket,
                                             const DiskLoc bucketLoc) {
         invariant(bucketLoc != getRootLoc());
@@ -1270,7 +1270,7 @@ namespace mongo {
     }
 
     template <class BtreeLayout>
-    void BtreeLogic<BtreeLayout>::deallocBucket(TransactionExperiment* txn,
+    void BtreeLogic<BtreeLayout>::deallocBucket(OperationContext* txn,
                                                 BucketType* bucket,
                                                 const DiskLoc bucketLoc) {
         bucket->n = BtreeLayout::INVALID_N_SENTINEL;
@@ -1336,7 +1336,7 @@ namespace mongo {
      * May delete the bucket 'bucket' rendering 'bucketLoc' invalid.
      */
     template <class BtreeLayout>
-    void BtreeLogic<BtreeLayout>::delKeyAtPos(TransactionExperiment* trans,
+    void BtreeLogic<BtreeLayout>::delKeyAtPos(OperationContext* trans,
                                               BucketType* bucket,
                                               const DiskLoc bucketLoc,
                                               int p) {
@@ -1396,7 +1396,7 @@ namespace mongo {
      * legacy btree.
      */
     template <class BtreeLayout>
-    void BtreeLogic<BtreeLayout>::deleteInternalKey(TransactionExperiment* trans,
+    void BtreeLogic<BtreeLayout>::deleteInternalKey(OperationContext* trans,
                                                     BucketType* bucket,
                                                     const DiskLoc bucketLoc,
                                                     int keypos) {
@@ -1429,7 +1429,7 @@ namespace mongo {
     }
 
     template <class BtreeLayout>
-    void BtreeLogic<BtreeLayout>::replaceWithNextChild(TransactionExperiment* trans,
+    void BtreeLogic<BtreeLayout>::replaceWithNextChild(OperationContext* trans,
                                                        BucketType* bucket,
                                                        const DiskLoc bucketLoc) {
 
@@ -1539,7 +1539,7 @@ namespace mongo {
     }
 
     template <class BtreeLayout>
-    void BtreeLogic<BtreeLayout>::doMergeChildren(TransactionExperiment* trans,
+    void BtreeLogic<BtreeLayout>::doMergeChildren(OperationContext* trans,
                                                   BucketType* bucket,
                                                   const DiskLoc bucketLoc,
                                                   int leftIndex) {
@@ -1609,7 +1609,7 @@ namespace mongo {
     }
 
     template <class BtreeLayout>
-    bool BtreeLogic<BtreeLayout>::tryBalanceChildren(TransactionExperiment* trans,
+    bool BtreeLogic<BtreeLayout>::tryBalanceChildren(OperationContext* trans,
                                                      BucketType* bucket,
                                                      const DiskLoc bucketLoc,
                                                      int leftIndex) {
@@ -1625,7 +1625,7 @@ namespace mongo {
     }
 
     template <class BtreeLayout>
-    void BtreeLogic<BtreeLayout>::doBalanceLeftToRight(TransactionExperiment* trans,
+    void BtreeLogic<BtreeLayout>::doBalanceLeftToRight(OperationContext* trans,
                                                        BucketType* bucket,
                                                        const DiskLoc bucketLoc,
                                                        int leftIndex,
@@ -1666,7 +1666,7 @@ namespace mongo {
     }
 
     template <class BtreeLayout>
-    void BtreeLogic<BtreeLayout>::doBalanceRightToLeft(TransactionExperiment* trans,
+    void BtreeLogic<BtreeLayout>::doBalanceRightToLeft(OperationContext* trans,
                                                        BucketType* bucket,
                                                        const DiskLoc bucketLoc,
                                                        int leftIndex,
@@ -1710,7 +1710,7 @@ namespace mongo {
     }
 
     template <class BtreeLayout>
-    void BtreeLogic<BtreeLayout>::doBalanceChildren(TransactionExperiment* trans,
+    void BtreeLogic<BtreeLayout>::doBalanceChildren(OperationContext* trans,
                                                     BucketType* bucket,
                                                     const DiskLoc bucketLoc,
                                                     int leftIndex) {
@@ -1739,7 +1739,7 @@ namespace mongo {
     }
 
     template <class BtreeLayout>
-    bool BtreeLogic<BtreeLayout>::mayBalanceWithNeighbors(TransactionExperiment* trans,
+    bool BtreeLogic<BtreeLayout>::mayBalanceWithNeighbors(OperationContext* trans,
                                                           BucketType* bucket,
                                                           const DiskLoc bucketLoc) {
         if (bucket->parent.isNull()) {
@@ -1783,7 +1783,7 @@ namespace mongo {
     }
 
     template <class BtreeLayout>
-    bool BtreeLogic<BtreeLayout>::unindex(TransactionExperiment* trans,
+    bool BtreeLogic<BtreeLayout>::unindex(OperationContext* trans,
                                           const BSONObj& key,
                                           const DiskLoc& recordLoc) {
         int pos;
@@ -1804,7 +1804,7 @@ namespace mongo {
     }
 
     template <class BtreeLayout>
-    inline void BtreeLogic<BtreeLayout>::fix(TransactionExperiment* trans,
+    inline void BtreeLogic<BtreeLayout>::fix(OperationContext* trans,
                                              const DiskLoc bucketLoc,
                                              const DiskLoc child) {
         if (!child.isNull()) {
@@ -1817,7 +1817,7 @@ namespace mongo {
      * Maybe get rid of parent ptrs?
      */
     template <class BtreeLayout>
-    void BtreeLogic<BtreeLayout>::fixParentPtrs(TransactionExperiment* trans,
+    void BtreeLogic<BtreeLayout>::fixParentPtrs(OperationContext* trans,
                                                 BucketType* bucket,
                                                 const DiskLoc bucketLoc,
                                                 int firstIndex,
@@ -1835,7 +1835,7 @@ namespace mongo {
     }
 
     template <class BtreeLayout>
-    void BtreeLogic<BtreeLayout>::setInternalKey(TransactionExperiment* trans,
+    void BtreeLogic<BtreeLayout>::setInternalKey(OperationContext* trans,
                                                  BucketType* bucket,
                                                  const DiskLoc bucketLoc,
                                                  int keypos,
@@ -1869,7 +1869,7 @@ namespace mongo {
      * intent code in basicInsert().
      */
     template <class BtreeLayout>
-    void BtreeLogic<BtreeLayout>::insertHere(TransactionExperiment* trans,
+    void BtreeLogic<BtreeLayout>::insertHere(OperationContext* trans,
                                              const DiskLoc bucketLoc,
                                              int pos,
                                              const KeyDataType& key,
@@ -1915,7 +1915,7 @@ namespace mongo {
     }
 
     template <class BtreeLayout>
-    void BtreeLogic<BtreeLayout>::split(TransactionExperiment* trans,
+    void BtreeLogic<BtreeLayout>::split(OperationContext* trans,
                                         BucketType* bucket,
                                         const DiskLoc bucketLoc,
                                         int keypos,
@@ -1995,7 +1995,7 @@ namespace mongo {
     };
 
     template <class BtreeLayout>
-    Status BtreeLogic<BtreeLayout>::initAsEmpty(TransactionExperiment* trans) {
+    Status BtreeLogic<BtreeLayout>::initAsEmpty(OperationContext* trans) {
         if (!_headManager->getHead().isNull()) {
             return Status(ErrorCodes::InternalError, "index already initialized");
         }
@@ -2005,7 +2005,7 @@ namespace mongo {
     }
 
     template <class BtreeLayout>
-    DiskLoc BtreeLogic<BtreeLayout>::addBucket(TransactionExperiment* trans) {
+    DiskLoc BtreeLogic<BtreeLayout>::addBucket(OperationContext* trans) {
         DummyDocWriter docWriter(BtreeLayout::BucketSize);
         StatusWith<DiskLoc> loc = _recordStore->insertRecord(trans, &docWriter, 0);
         // XXX: remove this(?) or turn into massert or sanely bubble it back up.
@@ -2200,7 +2200,7 @@ namespace mongo {
     }
 
     template <class BtreeLayout>
-    Status BtreeLogic<BtreeLayout>::insert(TransactionExperiment* trans,
+    Status BtreeLogic<BtreeLayout>::insert(OperationContext* trans,
                                            const BSONObj& rawKey,
                                            const DiskLoc& value,
                                            bool dupsAllowed) {
@@ -2227,7 +2227,7 @@ namespace mongo {
     }
 
     template <class BtreeLayout>
-    Status BtreeLogic<BtreeLayout>::_insert(TransactionExperiment* trans,
+    Status BtreeLogic<BtreeLayout>::_insert(OperationContext* trans,
                                             BucketType* bucket,
                                             const DiskLoc bucketLoc,
                                             const KeyDataType& key,
diff --git a/src/mongo/db/structure/btree/btree_logic.h b/src/mongo/db/structure/btree/btree_logic.h
index c2398d86044..de36c8aa11c 100644
--- a/src/mongo/db/structure/btree/btree_logic.h
+++ b/src/mongo/db/structure/btree/btree_logic.h
@@ -32,7 +32,7 @@
 #include "mongo/db/diskloc.h"
 #include "mongo/db/jsobj.h"
 #include "mongo/db/storage/record.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/db/structure/btree/btree_ondisk.h"
 #include "mongo/db/structure/btree/key.h"
 #include "mongo/db/structure/btree/bucket_deletion_notification.h"
@@ -101,7 +101,7 @@ namespace mongo {
         private:
             friend class BtreeLogic;
 
-            Builder(BtreeLogic* logic, TransactionExperiment* trans, bool dupsAllowed);
+            Builder(BtreeLogic* logic, OperationContext* trans, bool dupsAllowed);
 
             // Direct ports of functionality
             void newBucket();
@@ -124,18 +124,18 @@ namespace mongo {
             auto_ptr<KeyDataOwnedType> _keyLast;
 
             // Not owned.
-            TransactionExperiment* _trans;
+            OperationContext* _trans;
         };
 
         /**
          * Caller owns the returned pointer.
          * 'this' must outlive the returned pointer.
          */
-        Builder* newBuilder(TransactionExperiment* trans, bool dupsAllowed);
+        Builder* newBuilder(OperationContext* trans, bool dupsAllowed);
 
         Status dupKeyCheck(const BSONObj& key, const DiskLoc& loc) const;
 
-        Status insert(TransactionExperiment* trans,
+        Status insert(OperationContext* trans,
                       const BSONObj& rawKey,
                       const DiskLoc& value,
                       bool dupsAllowed);
@@ -158,7 +158,7 @@ namespace mongo {
 
         bool exists(const KeyDataType& key) const;
 
-        bool unindex(TransactionExperiment* trans,
+        bool unindex(OperationContext* trans,
                      const BSONObj& key,
                      const DiskLoc& recordLoc);
 
@@ -213,7 +213,7 @@ namespace mongo {
         /**
          * Returns OK if the index was uninitialized before, error status otherwise.
          */
-        Status initAsEmpty(TransactionExperiment* trans);
+        Status initAsEmpty(OperationContext* trans);
 
     private:
         friend class BtreeLogic::Builder;
@@ -286,7 +286,7 @@ namespace mongo {
 
         static void setNotPacked(BucketType* bucket);
 
-        static BucketType* btreemod(TransactionExperiment* trans, BucketType* bucket);
+        static BucketType* btreemod(OperationContext* trans, BucketType* bucket);
 
         static int splitPos(BucketType* bucket, int keypos);
 
@@ -312,7 +312,7 @@ namespace mongo {
         // information).
         //
 
-        bool basicInsert(TransactionExperiment* trans,
+        bool basicInsert(OperationContext* trans,
                          BucketType* bucket,
                          const DiskLoc bucketLoc,
                          int& keypos,
@@ -321,7 +321,7 @@ namespace mongo {
 
         void dropFront(BucketType* bucket, int nDrop, int& refpos);
 
-        void _pack(TransactionExperiment* trans, BucketType* bucket, const DiskLoc thisLoc, int &refPos);
+        void _pack(OperationContext* trans, BucketType* bucket, const DiskLoc thisLoc, int &refPos);
 
         void customLocate(DiskLoc* locInOut,
                           int* keyOfsInOut,
@@ -383,7 +383,7 @@ namespace mongo {
                                bool dumpBuckets,
                                unsigned depth);
 
-        DiskLoc addBucket(TransactionExperiment* trans);
+        DiskLoc addBucket(OperationContext* trans);
 
         bool canMergeChildren(BucketType* bucket,
                               const DiskLoc bucketLoc,
@@ -398,7 +398,7 @@ namespace mongo {
 
         void truncateTo(BucketType* bucket, int N, int &refPos);
 
-        void split(TransactionExperiment* trans,
+        void split(OperationContext* trans,
                    BucketType* bucket,
                    const DiskLoc bucketLoc,
                    int keypos,
@@ -407,7 +407,7 @@ namespace mongo {
                    const DiskLoc lchild,
                    const DiskLoc rchild);
 
-        Status _insert(TransactionExperiment* trans,
+        Status _insert(OperationContext* trans,
                        BucketType* bucket,
                        const DiskLoc bucketLoc,
                        const KeyDataType& key,
@@ -417,7 +417,7 @@ namespace mongo {
                        const DiskLoc rightChild);
 
         // TODO take a BucketType*?
-        void insertHere(TransactionExperiment* trans,
+        void insertHere(OperationContext* trans,
                         const DiskLoc bucketLoc,
                         int pos,
                         const KeyDataType& key,
@@ -427,7 +427,7 @@ namespace mongo {
 
         string dupKeyError(const KeyDataType& key) const;
 
-        void setInternalKey(TransactionExperiment* trans,
+        void setInternalKey(OperationContext* trans,
                             BucketType* bucket,
                             const DiskLoc bucketLoc,
                             int keypos,
@@ -436,22 +436,22 @@ namespace mongo {
                             const DiskLoc lchild,
                             const DiskLoc rchild);
 
-        void fix(TransactionExperiment* trans, const DiskLoc bucketLoc, const DiskLoc child);
+        void fix(OperationContext* trans, const DiskLoc bucketLoc, const DiskLoc child);
 
-        void fixParentPtrs(TransactionExperiment* trans,
+        void fixParentPtrs(OperationContext* trans,
                            BucketType* bucket,
                            const DiskLoc bucketLoc,
                            int firstIndex = 0,
                            int lastIndex = -1);
 
-        bool mayBalanceWithNeighbors(TransactionExperiment* trans, BucketType* bucket, const DiskLoc bucketLoc);
+        bool mayBalanceWithNeighbors(OperationContext* trans, BucketType* bucket, const DiskLoc bucketLoc);
 
-        void doBalanceChildren(TransactionExperiment* trans,
+        void doBalanceChildren(OperationContext* trans,
                                BucketType* bucket,
                                const DiskLoc bucketLoc,
                                int leftIndex);
 
-        void doBalanceLeftToRight(TransactionExperiment* trans,
+        void doBalanceLeftToRight(OperationContext* trans,
                                   BucketType* bucket,
                                   const DiskLoc thisLoc,
                                   int leftIndex,
@@ -461,7 +461,7 @@ namespace mongo {
                                   BucketType* r,
                                   const DiskLoc rchild);
 
-        void doBalanceRightToLeft(TransactionExperiment* trans,
+        void doBalanceRightToLeft(OperationContext* trans,
                                   BucketType* bucket,
                                   const DiskLoc bucketLoc,
                                   int leftIndex,
@@ -471,37 +471,37 @@ namespace mongo {
                                   BucketType* r,
                                   const DiskLoc rchild);
 
-        bool tryBalanceChildren(TransactionExperiment* trans,
+        bool tryBalanceChildren(OperationContext* trans,
                                 BucketType* bucket,
                                 const DiskLoc bucketLoc,
                                 int leftIndex);
 
         int indexInParent(BucketType* bucket, const DiskLoc bucketLoc) const;
 
-        void doMergeChildren(TransactionExperiment* trans,
+        void doMergeChildren(OperationContext* trans,
                              BucketType* bucket,
                              const DiskLoc bucketLoc,
                              int leftIndex);
 
-        void replaceWithNextChild(TransactionExperiment* trans,
+        void replaceWithNextChild(OperationContext* trans,
                                   BucketType* bucket,
                                   const DiskLoc bucketLoc);
 
-        void deleteInternalKey(TransactionExperiment* trans,
+        void deleteInternalKey(OperationContext* trans,
                                BucketType* bucket,
                                const DiskLoc bucketLoc,
                                int keypos);
 
-        void delKeyAtPos(TransactionExperiment* trans,
+        void delKeyAtPos(OperationContext* trans,
                          BucketType* bucket,
                          const DiskLoc bucketLoc,
                          int p);
 
-        void delBucket(TransactionExperiment* trans,
+        void delBucket(OperationContext* trans,
                        BucketType* bucket,
                        const DiskLoc bucketLoc);
 
-        void deallocBucket(TransactionExperiment* trans,
+        void deallocBucket(OperationContext* trans,
                            BucketType* bucket,
                            const DiskLoc bucketLoc);
 
diff --git a/src/mongo/db/structure/capped_callback.h b/src/mongo/db/structure/capped_callback.h
index 0b86bd81709..59c23f9dab9 100644
--- a/src/mongo/db/structure/capped_callback.h
+++ b/src/mongo/db/structure/capped_callback.h
@@ -34,7 +34,7 @@
 
 namespace mongo {
 
-    class TransactionExperiment;
+    class OperationContext;
 
     /**
      * When a capped collection has to delete a document, it needs a way to tell the caller
@@ -48,7 +48,7 @@ namespace mongo {
         /**
          * This will be called right before loc is deleted when wrapping.
          */
-        virtual Status aboutToDeleteCapped( TransactionExperiment* txn, const DiskLoc& loc ) = 0;
+        virtual Status aboutToDeleteCapped( OperationContext* txn, const DiskLoc& loc ) = 0;
     };
 
 }
diff --git a/src/mongo/db/structure/catalog/hashtab.h b/src/mongo/db/structure/catalog/hashtab.h
index 12195cde70b..66ecb5af9dc 100644
--- a/src/mongo/db/structure/catalog/hashtab.h
+++ b/src/mongo/db/structure/catalog/hashtab.h
@@ -25,7 +25,7 @@
 #include "mongo/pch.h"
 #include <map>
 #include "mongo/db/storage/mmap_v1/dur.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 
 namespace mongo {
 
@@ -122,7 +122,7 @@ namespace mongo {
             return 0;
         }
 
-        void kill(TransactionExperiment* txn, const Key& k) {
+        void kill(OperationContext* txn, const Key& k) {
             bool found;
             int i = _find(k, found);
             if ( i >= 0 && found ) {
@@ -134,7 +134,7 @@ namespace mongo {
         }
 
         /** returns false if too full */
-        bool put(TransactionExperiment* txn, const Key& k, const Type& value) {
+        bool put(OperationContext* txn, const Key& k, const Type& value) {
             bool found;
             int i = _find(k, found);
             if ( i < 0 )
diff --git a/src/mongo/db/structure/catalog/namespace_details.cpp b/src/mongo/db/structure/catalog/namespace_details.cpp
index 70e1b8eb763..8eb6132890e 100644
--- a/src/mongo/db/structure/catalog/namespace_details.cpp
+++ b/src/mongo/db/structure/catalog/namespace_details.cpp
@@ -43,7 +43,7 @@
 #include "mongo/db/ops/delete.h"
 #include "mongo/db/ops/update.h"
 #include "mongo/db/structure/catalog/hashtab.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/scripting/engine.h"
 #include "mongo/util/startup_test.h"
 
@@ -84,7 +84,7 @@ namespace mongo {
         memset(_reserved, 0, sizeof(_reserved));
     }
 
-    NamespaceDetails::Extra* NamespaceDetails::allocExtra( TransactionExperiment* txn,
+    NamespaceDetails::Extra* NamespaceDetails::allocExtra( OperationContext* txn,
                                                            const StringData& ns,
                                                            NamespaceIndex& ni,
                                                            int nindexessofar) {
@@ -119,7 +119,7 @@ namespace mongo {
         return e;
     }
 
-    bool NamespaceDetails::setIndexIsMultikey(TransactionExperiment* txn, int i, bool multikey) {
+    bool NamespaceDetails::setIndexIsMultikey(OperationContext* txn, int i, bool multikey) {
         massert(16577, "index number greater than NIndexesMax", i < NIndexesMax );
 
         unsigned long long mask = 1ULL << i;
@@ -146,7 +146,7 @@ namespace mongo {
         return true;
     }
 
-    IndexDetails& NamespaceDetails::getNextIndexDetails(TransactionExperiment* txn,
+    IndexDetails& NamespaceDetails::getNextIndexDetails(OperationContext* txn,
                                                         Collection* collection) {
         IndexDetails *id;
         try {
@@ -220,7 +220,7 @@ namespace mongo {
     }
 
     // must be called when renaming a NS to fix up extra
-    void NamespaceDetails::copyingFrom( TransactionExperiment* txn,
+    void NamespaceDetails::copyingFrom( OperationContext* txn,
                                         const char* thisns,
                                         NamespaceIndex& ni,
                                         NamespaceDetails* src) {
@@ -242,20 +242,20 @@ namespace mongo {
         }
     }
 
-    NamespaceDetails* NamespaceDetails::writingWithoutExtra( TransactionExperiment* txn ) {
+    NamespaceDetails* NamespaceDetails::writingWithoutExtra( OperationContext* txn ) {
         return txn->writing( this );
     }
 
 
     // XXX - this method should go away
-    NamespaceDetails *NamespaceDetails::writingWithExtra( TransactionExperiment* txn ) {
+    NamespaceDetails *NamespaceDetails::writingWithExtra( OperationContext* txn ) {
         for( Extra *e = extra(); e; e = e->next( this ) ) {
             txn->writing( e );
         }
         return writingWithoutExtra( txn );
     }
 
-    void NamespaceDetails::setMaxCappedDocs( TransactionExperiment* txn, long long max ) {
+    void NamespaceDetails::setMaxCappedDocs( OperationContext* txn, long long max ) {
         massert( 16499,
                  "max in a capped collection has to be < 2^31 or -1",
                  validMaxCappedDocs( &max ) );
@@ -285,13 +285,13 @@ namespace mongo {
 
     /* ------------------------------------------------------------------------- */
 
-    void NamespaceDetails::setLastExtentSize( TransactionExperiment* txn, int newMax ) {
+    void NamespaceDetails::setLastExtentSize( OperationContext* txn, int newMax ) {
         if ( _lastExtentSize == newMax )
             return;
         txn->writingInt(_lastExtentSize) = newMax;
     }
 
-    void NamespaceDetails::incrementStats( TransactionExperiment* txn,
+    void NamespaceDetails::incrementStats( OperationContext* txn,
                                            long long dataSizeIncrement,
                                            long long numRecordsIncrement ) {
 
@@ -301,7 +301,7 @@ namespace mongo {
         s->nrecords += numRecordsIncrement;
     }
 
-    void NamespaceDetails::setStats( TransactionExperiment* txn,
+    void NamespaceDetails::setStats( OperationContext* txn,
                                      long long dataSize,
                                      long long numRecords ) {
         Stats* s = txn->writing( &_stats );
@@ -309,40 +309,40 @@ namespace mongo {
         s->nrecords = numRecords;
     }
 
-    void NamespaceDetails::setFirstExtent( TransactionExperiment* txn,
+    void NamespaceDetails::setFirstExtent( OperationContext* txn,
                                            const DiskLoc& loc ) {
         *txn->writing( &_firstExtent ) = loc;
     }
 
-    void NamespaceDetails::setLastExtent( TransactionExperiment* txn,
+    void NamespaceDetails::setLastExtent( OperationContext* txn,
                                           const DiskLoc& loc ) {
         *txn->writing( &_lastExtent ) = loc;
     }
 
-    void NamespaceDetails::setCapExtent( TransactionExperiment* txn,
+    void NamespaceDetails::setCapExtent( OperationContext* txn,
                                          const DiskLoc& loc ) {
         *txn->writing( &_capExtent ) = loc;
     }
 
-    void NamespaceDetails::setCapFirstNewRecord( TransactionExperiment* txn,
+    void NamespaceDetails::setCapFirstNewRecord( OperationContext* txn,
                                                  const DiskLoc& loc ) {
         *txn->writing( &_capFirstNewRecord ) = loc;
     }
 
-    void NamespaceDetails::setFirstExtentInvalid( TransactionExperiment* txn ) {
+    void NamespaceDetails::setFirstExtentInvalid( OperationContext* txn ) {
         *txn->writing( &_firstExtent ) = DiskLoc().setInvalid();
     }
 
-    void NamespaceDetails::setLastExtentInvalid( TransactionExperiment* txn ) {
+    void NamespaceDetails::setLastExtentInvalid( OperationContext* txn ) {
         *txn->writing( &_lastExtent ) = DiskLoc().setInvalid();
     }
 
-    void NamespaceDetails::setDeletedListEntry( TransactionExperiment* txn,
+    void NamespaceDetails::setDeletedListEntry( OperationContext* txn,
                                                 int bucket, const DiskLoc& loc ) {
         *txn->writing( &_deletedList[bucket] ) = loc;
     }
 
-    bool NamespaceDetails::setUserFlag( TransactionExperiment* txn, int flags ) {
+    bool NamespaceDetails::setUserFlag( OperationContext* txn, int flags ) {
         if ( ( _userFlags & flags ) == flags )
             return false;
         
@@ -350,7 +350,7 @@ namespace mongo {
         return true;
     }
 
-    bool NamespaceDetails::clearUserFlag( TransactionExperiment* txn, int flags ) {
+    bool NamespaceDetails::clearUserFlag( OperationContext* txn, int flags ) {
         if ( ( _userFlags & flags ) == 0 )
             return false;
 
@@ -358,7 +358,7 @@ namespace mongo {
         return true;
     }
 
-    bool NamespaceDetails::replaceUserFlags( TransactionExperiment* txn, int flags ) {
+    bool NamespaceDetails::replaceUserFlags( OperationContext* txn, int flags ) {
         if ( flags == _userFlags )
             return false;
 
@@ -366,7 +366,7 @@ namespace mongo {
         return true;
     }
 
-    void NamespaceDetails::setPaddingFactor( TransactionExperiment* txn, double paddingFactor ) {
+    void NamespaceDetails::setPaddingFactor( OperationContext* txn, double paddingFactor ) {
         if ( paddingFactor == _paddingFactor )
             return;
 
@@ -388,7 +388,7 @@ namespace mongo {
             ((tmp >> (x+1)) << x);
     }
 
-    void NamespaceDetails::_removeIndexFromMe( TransactionExperiment* txn, int idxNumber ) {
+    void NamespaceDetails::_removeIndexFromMe( OperationContext* txn, int idxNumber ) {
 
         // TODO: don't do this whole thing, do it piece meal for readability
         NamespaceDetails* d = writingWithExtra( txn );
@@ -407,7 +407,7 @@ namespace mongo {
         d->idx( getTotalIndexCount() ) = IndexDetails();
     }
 
-    void NamespaceDetails::swapIndex( TransactionExperiment* txn, int a, int b ) {
+    void NamespaceDetails::swapIndex( OperationContext* txn, int a, int b ) {
 
         // flip main meta data
         IndexDetails temp = idx(a);
@@ -420,7 +420,7 @@ namespace mongo {
         setIndexIsMultikey( txn, b, tempMultikey );
     }
 
-    void NamespaceDetails::orphanDeletedList( TransactionExperiment* txn ) {
+    void NamespaceDetails::orphanDeletedList( OperationContext* txn ) {
         for( int i = 0; i < Buckets; i++ ) {
             *txn->writing(&_deletedList[i]) = DiskLoc();
         }
@@ -438,7 +438,7 @@ namespace mongo {
         return -1;
     }
 
-    void NamespaceDetails::Extra::setNext( TransactionExperiment* txn,
+    void NamespaceDetails::Extra::setNext( OperationContext* txn,
                                            long ofs ) {
         *txn->writing(&_next) = ofs;
     }
diff --git a/src/mongo/db/structure/catalog/namespace_details.h b/src/mongo/db/structure/catalog/namespace_details.h
index 90b5d845c21..2c7dc3c6df5 100644
--- a/src/mongo/db/structure/catalog/namespace_details.h
+++ b/src/mongo/db/structure/catalog/namespace_details.h
@@ -37,7 +37,7 @@
 namespace mongo {
 
     class Collection;
-    class TransactionExperiment;
+    class OperationContext;
 
     /* deleted lists -- linked lists of deleted records -- are placed in 'buckets' of various sizes
        so you can look for a deleterecord about the right size.
@@ -130,7 +130,7 @@ namespace mongo {
                 if( _next == 0 ) return 0;
                 return (Extra*) (((char *) d) + _next);
             }
-            void setNext(TransactionExperiment* txn, long ofs);
+            void setNext(OperationContext* txn, long ofs);
             void copy(NamespaceDetails *d, const Extra& e) {
                 memcpy(this, &e, sizeof(Extra));
                 _next = 0;
@@ -141,60 +141,60 @@ namespace mongo {
             return (Extra *) (((char *) this) + _extraOffset);
         }
         /* add extra space for indexes when more than 10 */
-        Extra* allocExtra( TransactionExperiment* txn,
+        Extra* allocExtra( OperationContext* txn,
                            const StringData& ns,
                            NamespaceIndex& ni,
                            int nindexessofar );
 
-        void copyingFrom( TransactionExperiment* txn,
+        void copyingFrom( OperationContext* txn,
                           const char* thisns,
                           NamespaceIndex& ni,
                           NamespaceDetails *src); // must be called when renaming a NS to fix up extra
 
     public:
         const DiskLoc& capExtent() const { return _capExtent; }
-        void setCapExtent( TransactionExperiment* txn, const DiskLoc& loc );
+        void setCapExtent( OperationContext* txn, const DiskLoc& loc );
 
         const DiskLoc& capFirstNewRecord() const { return _capFirstNewRecord; }
-        void setCapFirstNewRecord( TransactionExperiment* txn, const DiskLoc& loc );
+        void setCapFirstNewRecord( OperationContext* txn, const DiskLoc& loc );
 
         bool capLooped() const { return _capFirstNewRecord.isValid(); }
 
     public:
 
         const DiskLoc& firstExtent() const { return _firstExtent; }
-        void setFirstExtent( TransactionExperiment* txn, const DiskLoc& loc );
+        void setFirstExtent( OperationContext* txn, const DiskLoc& loc );
 
         const DiskLoc& lastExtent() const { return _lastExtent; }
-        void setLastExtent( TransactionExperiment* txn, const DiskLoc& loc );
+        void setLastExtent( OperationContext* txn, const DiskLoc& loc );
 
-        void setFirstExtentInvalid( TransactionExperiment* txn );
-        void setLastExtentInvalid( TransactionExperiment* txn );
+        void setFirstExtentInvalid( OperationContext* txn );
+        void setLastExtentInvalid( OperationContext* txn );
 
 
         long long dataSize() const { return _stats.datasize; }
         long long numRecords() const { return _stats.nrecords; }
 
-        void incrementStats( TransactionExperiment* txn,
+        void incrementStats( OperationContext* txn,
                              long long dataSizeIncrement,
                              long long numRecordsIncrement );
 
-        void setStats( TransactionExperiment* txn,
+        void setStats( OperationContext* txn,
                        long long dataSizeIncrement,
                        long long numRecordsIncrement );
 
 
         bool isCapped() const { return _isCapped; }
         long long maxCappedDocs() const;
-        void setMaxCappedDocs( TransactionExperiment* txn, long long max );
+        void setMaxCappedDocs( OperationContext* txn, long long max );
 
         int lastExtentSize() const { return _lastExtentSize; }
-        void setLastExtentSize( TransactionExperiment* txn, int newMax );
+        void setLastExtentSize( OperationContext* txn, int newMax );
 
         const DiskLoc& deletedListEntry( int bucket ) const { return _deletedList[bucket]; }
-        void setDeletedListEntry( TransactionExperiment* txn, int bucket, const DiskLoc& loc );
+        void setDeletedListEntry( OperationContext* txn, int bucket, const DiskLoc& loc );
 
-        void orphanDeletedList( TransactionExperiment* txn );
+        void orphanDeletedList( OperationContext* txn );
 
         /**
          * @param max in and out, will be adjusted
@@ -243,17 +243,17 @@ namespace mongo {
         /**
          * @return - if any state was changed
          */
-        bool setIndexIsMultikey(TransactionExperiment* txn, int i, bool multikey = true);
+        bool setIndexIsMultikey(OperationContext* txn, int i, bool multikey = true);
 
         /**
          * This fetches the IndexDetails for the next empty index slot. The caller must populate
          * returned object.  This handles allocating extra index space, if necessary.
          */
-        IndexDetails& getNextIndexDetails(TransactionExperiment* txn, Collection* collection);
+        IndexDetails& getNextIndexDetails(OperationContext* txn, Collection* collection);
 
         double paddingFactor() const { return _paddingFactor; }
 
-        void setPaddingFactor( TransactionExperiment* txn, double paddingFactor );
+        void setPaddingFactor( OperationContext* txn, double paddingFactor );
 
         /* called to indicate that an update fit in place.  
            fits also called on an insert -- idea there is that if you had some mix and then went to
@@ -264,13 +264,13 @@ namespace mongo {
                  size of documents might be considered -- in some cases smaller ones are more likely 
                  to grow than larger ones in the same collection? (not always)
         */
-        void paddingFits( TransactionExperiment* txn ) {
+        void paddingFits( OperationContext* txn ) {
             MONGO_SOMETIMES(sometimes, 4) { // do this on a sampled basis to journal less
                 double x = max(1.0, _paddingFactor - 0.001 );
                 setPaddingFactor( txn, x );
             }
         }
-        void paddingTooSmall( TransactionExperiment* txn ) {
+        void paddingTooSmall( OperationContext* txn ) {
             MONGO_SOMETIMES(sometimes, 4) { // do this on a sampled basis to journal less       
                 /* the more indexes we have, the higher the cost of a move.  so we take that into 
                    account herein.  note on a move that insert() calls paddingFits(), thus
@@ -297,14 +297,14 @@ namespace mongo {
          }
          * these methods all return true iff only something was modified
          */
-        bool setUserFlag( TransactionExperiment* txn, int flag );
-        bool clearUserFlag( TransactionExperiment* txn, int flag );
-        bool replaceUserFlags( TransactionExperiment* txn, int flags );
+        bool setUserFlag( OperationContext* txn, int flag );
+        bool clearUserFlag( OperationContext* txn, int flag );
+        bool replaceUserFlags( OperationContext* txn, int flags );
 
-        NamespaceDetails *writingWithoutExtra( TransactionExperiment* txn );
+        NamespaceDetails *writingWithoutExtra( OperationContext* txn );
 
         /** Make all linked Extra objects writeable as well */
-        NamespaceDetails *writingWithExtra( TransactionExperiment* txn );
+        NamespaceDetails *writingWithExtra( OperationContext* txn );
 
         /**
          * Returns the offset of the specified index name within the array of indexes. Must be
@@ -318,14 +318,14 @@ namespace mongo {
 
     private:
 
-        void _removeIndexFromMe( TransactionExperiment* txn, int idx );
+        void _removeIndexFromMe( OperationContext* txn, int idx );
 
         /**
          * swaps all meta data for 2 indexes
          * a and b are 2 index ids, whose contents will be swapped
          * must have a lock on the entire collection to do this
          */
-        void swapIndex( TransactionExperiment* txn, int a, int b );
+        void swapIndex( OperationContext* txn, int a, int b );
 
         friend class IndexCatalog;
         friend class IndexCatalogEntry;
diff --git a/src/mongo/db/structure/catalog/namespace_details_rsv1_metadata.h b/src/mongo/db/structure/catalog/namespace_details_rsv1_metadata.h
index 0fd008adf8f..397affa16a3 100644
--- a/src/mongo/db/structure/catalog/namespace_details_rsv1_metadata.h
+++ b/src/mongo/db/structure/catalog/namespace_details_rsv1_metadata.h
@@ -51,7 +51,7 @@ namespace mongo {
             return _details->capExtent();
         }
 
-        virtual void setCapExtent( TransactionExperiment* txn, const DiskLoc& loc ) {
+        virtual void setCapExtent( OperationContext* txn, const DiskLoc& loc ) {
             _details->setCapExtent( txn, loc );
         }
 
@@ -59,7 +59,7 @@ namespace mongo {
             return _details->capFirstNewRecord();
         }
 
-        virtual void setCapFirstNewRecord( TransactionExperiment* txn, const DiskLoc& loc ) {
+        virtual void setCapFirstNewRecord( OperationContext* txn, const DiskLoc& loc ) {
             _details->setCapFirstNewRecord( txn, loc );
         }
 
@@ -74,13 +74,13 @@ namespace mongo {
             return _details->numRecords();
         }
 
-        virtual void incrementStats( TransactionExperiment* txn,
+        virtual void incrementStats( OperationContext* txn,
                                      long long dataSizeIncrement,
                                      long long numRecordsIncrement ) {
             _details->incrementStats( txn, dataSizeIncrement, numRecordsIncrement );
         }
 
-        virtual void setStats( TransactionExperiment* txn,
+        virtual void setStats( OperationContext* txn,
                                long long dataSizeIncrement,
                                long long numRecordsIncrement ) {
             _details->setStats( txn,
@@ -92,13 +92,13 @@ namespace mongo {
             return _details->deletedListEntry( bucket );
         }
 
-        virtual void setDeletedListEntry( TransactionExperiment* txn,
+        virtual void setDeletedListEntry( OperationContext* txn,
                                           int bucket,
                                           const DiskLoc& loc ) {
             _details->setDeletedListEntry( txn, bucket, loc );
         }
 
-        virtual void orphanDeletedList(TransactionExperiment* txn) {
+        virtual void orphanDeletedList(OperationContext* txn) {
             _details->orphanDeletedList( txn );
         }
 
@@ -106,7 +106,7 @@ namespace mongo {
             return _details->firstExtent();
         }
 
-        virtual void setFirstExtent( TransactionExperiment* txn, const DiskLoc& loc ) {
+        virtual void setFirstExtent( OperationContext* txn, const DiskLoc& loc ) {
             _details->setFirstExtent( txn, loc );
         }
 
@@ -114,7 +114,7 @@ namespace mongo {
             return _details->lastExtent();
         }
 
-        virtual void setLastExtent( TransactionExperiment* txn, const DiskLoc& loc ) {
+        virtual void setLastExtent( OperationContext* txn, const DiskLoc& loc ) {
             _details->setLastExtent( txn, loc );
         }
 
@@ -130,7 +130,7 @@ namespace mongo {
             return _details->lastExtentSize();
         }
 
-        virtual void setLastExtentSize( TransactionExperiment* txn, int newMax ) {
+        virtual void setLastExtentSize( OperationContext* txn, int newMax ) {
             _details->setLastExtentSize( txn, newMax );
         }
 
@@ -142,7 +142,7 @@ namespace mongo {
             return _details->paddingFactor();
         }
 
-        virtual void setPaddingFactor( TransactionExperiment* txn, double paddingFactor ) {
+        virtual void setPaddingFactor( OperationContext* txn, double paddingFactor ) {
             _details->setPaddingFactor( txn, paddingFactor );
         }
 
diff --git a/src/mongo/db/structure/catalog/namespace_index.cpp b/src/mongo/db/structure/catalog/namespace_index.cpp
index e4f8d58517c..d7863519423 100644
--- a/src/mongo/db/structure/catalog/namespace_index.cpp
+++ b/src/mongo/db/structure/catalog/namespace_index.cpp
@@ -33,7 +33,7 @@
 #include <boost/filesystem/operations.hpp>
 
 #include "mongo/db/d_concurrency.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/db/structure/catalog/namespace_details.h"
 #include "mongo/util/exit.h"
 
@@ -50,19 +50,19 @@ namespace mongo {
         return _ht->get(ns);
     }
 
-    void NamespaceIndex::add_ns( TransactionExperiment* txn,
+    void NamespaceIndex::add_ns( OperationContext* txn,
                                  const StringData& ns, const DiskLoc& loc, bool capped) {
         NamespaceDetails details( loc, capped );
         add_ns( txn, ns, &details );
     }
 
-    void NamespaceIndex::add_ns( TransactionExperiment* txn,
+    void NamespaceIndex::add_ns( OperationContext* txn,
                                  const StringData& ns, const NamespaceDetails* details ) {
         Namespace n(ns);
         add_ns( txn, n, details );
     }
 
-    void NamespaceIndex::add_ns( TransactionExperiment* txn,
+    void NamespaceIndex::add_ns( OperationContext* txn,
                                  const Namespace& ns, const NamespaceDetails* details ) {
         string nsString = ns.toString();
         Lock::assertWriteLocked( nsString );
@@ -71,7 +71,7 @@ namespace mongo {
         uassert( 10081, "too many namespaces/collections", _ht->put(txn, ns, *details));
     }
 
-    void NamespaceIndex::kill_ns( TransactionExperiment* txn, const StringData& ns) {
+    void NamespaceIndex::kill_ns( OperationContext* txn, const StringData& ns) {
         Lock::assertWriteLocked(ns);
         if ( !_ht.get() )
             return;
@@ -132,7 +132,7 @@ namespace mongo {
             MONGO_ASSERT_ON_EXCEPTION_WITH_MSG( boost::filesystem::create_directory( dir ), "create dir for db " );
     }
 
-    NOINLINE_DECL void NamespaceIndex::_init( TransactionExperiment* txn ) {
+    NOINLINE_DECL void NamespaceIndex::_init( OperationContext* txn ) {
         verify( !_ht.get() );
 
         Lock::assertWriteLocked(_database);
diff --git a/src/mongo/db/structure/catalog/namespace_index.h b/src/mongo/db/structure/catalog/namespace_index.h
index b099d92f066..85d05fc861d 100644
--- a/src/mongo/db/structure/catalog/namespace_index.h
+++ b/src/mongo/db/structure/catalog/namespace_index.h
@@ -40,7 +40,7 @@
 namespace mongo {
 
     class NamespaceDetails;
-    class TransactionExperiment;
+    class OperationContext;
 
     /* NamespaceIndex is the ".ns" file you see in the data directory.  It is the "system catalog"
        if you will: at least the core parts.  (Additional info in system.* collections.)
@@ -53,22 +53,22 @@ namespace mongo {
         /* returns true if new db will be created if we init lazily */
         bool exists() const;
 
-        void init( TransactionExperiment* txn ) {
+        void init( OperationContext* txn ) {
             if ( !_ht.get() )
                 _init( txn );
         }
 
-        void add_ns( TransactionExperiment* txn,
+        void add_ns( OperationContext* txn,
                      const StringData& ns, const DiskLoc& loc, bool capped);
-        void add_ns( TransactionExperiment* txn,
+        void add_ns( OperationContext* txn,
                      const StringData& ns, const NamespaceDetails* details );
-        void add_ns( TransactionExperiment* txn,
+        void add_ns( OperationContext* txn,
                      const Namespace& ns, const NamespaceDetails* details );
 
         NamespaceDetails* details(const StringData& ns);
         NamespaceDetails* details(const Namespace& ns);
 
-        void kill_ns( TransactionExperiment* txn,
+        void kill_ns( OperationContext* txn,
                       const StringData& ns);
 
         bool allocated() const { return _ht.get() != 0; }
@@ -80,7 +80,7 @@ namespace mongo {
         unsigned long long fileLength() const { return _f.length(); }
 
     private:
-        void _init( TransactionExperiment* txn );
+        void _init( OperationContext* txn );
         void maybeMkdir() const;
 
         DurableMappedFile _f;
diff --git a/src/mongo/db/structure/collection_compact.cpp b/src/mongo/db/structure/collection_compact.cpp
index 86b75523859..2777d51918e 100644
--- a/src/mongo/db/structure/collection_compact.cpp
+++ b/src/mongo/db/structure/collection_compact.cpp
@@ -44,7 +44,7 @@
 #include "mongo/db/storage/extent.h"
 #include "mongo/db/storage/extent_manager.h"
 #include "mongo/db/storage/record.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/util/touch_pages.h"
 
 namespace mongo {
@@ -104,7 +104,7 @@ namespace mongo {
     }
 
 
-    StatusWith<CompactStats> Collection::compact( TransactionExperiment* txn,
+    StatusWith<CompactStats> Collection::compact( OperationContext* txn,
                                                   const CompactOptions* compactOptions ) {
         if ( !_recordStore->compactSupported() )
             return StatusWith<CompactStats>( ErrorCodes::BadValue,
diff --git a/src/mongo/db/structure/head_manager.h b/src/mongo/db/structure/head_manager.h
index 1df38f56fd6..9460b930210 100644
--- a/src/mongo/db/structure/head_manager.h
+++ b/src/mongo/db/structure/head_manager.h
@@ -32,7 +32,7 @@
 
 namespace mongo {
 
-    class TransactionExperiment;
+    class OperationContext;
 
     /**
      * An abstraction for setting and getting data about the 'head' of an index.  This is the data
@@ -44,7 +44,7 @@ namespace mongo {
 
         virtual const DiskLoc& getHead() const = 0;
 
-        virtual void setHead(TransactionExperiment* txn, const DiskLoc& newHead) = 0;
+        virtual void setHead(OperationContext* txn, const DiskLoc& newHead) = 0;
     };
 
 }  // namespace mongo
diff --git a/src/mongo/db/structure/record_store.h b/src/mongo/db/structure/record_store.h
index 3d3b5675123..1b006c464cd 100644
--- a/src/mongo/db/structure/record_store.h
+++ b/src/mongo/db/structure/record_store.h
@@ -45,7 +45,7 @@ namespace mongo {
     class MAdvise;
     class NamespaceDetails;
     class Record;
-    class TransactionExperiment;
+    class OperationContext;
 
     class RecordStoreCompactAdaptor;
     class RecordStore;
@@ -123,14 +123,14 @@ namespace mongo {
 
         virtual Record* recordFor( const DiskLoc& loc ) const = 0;
 
-        virtual void deleteRecord( TransactionExperiment* txn, const DiskLoc& dl ) = 0;
+        virtual void deleteRecord( OperationContext* txn, const DiskLoc& dl ) = 0;
 
-        virtual StatusWith<DiskLoc> insertRecord( TransactionExperiment* txn,
+        virtual StatusWith<DiskLoc> insertRecord( OperationContext* txn,
                                                   const char* data,
                                                   int len,
                                                   int quotaMax ) = 0;
 
-        virtual StatusWith<DiskLoc> insertRecord( TransactionExperiment* txn,
+        virtual StatusWith<DiskLoc> insertRecord( OperationContext* txn,
                                                   const DocWriter* doc,
                                                   int quotaMax ) = 0;
 
@@ -161,11 +161,11 @@ namespace mongo {
         /**
          * removes all Records
          */
-        virtual Status truncate( TransactionExperiment* txn ) = 0;
+        virtual Status truncate( OperationContext* txn ) = 0;
 
         // does this RecordStore support the compact operation
         virtual bool compactSupported() const = 0;
-        virtual Status compact( TransactionExperiment* txn,
+        virtual Status compact( OperationContext* txn,
                                 RecordStoreCompactAdaptor* adaptor,
                                 const CompactOptions* options,
                                 CompactStats* stats ) = 0;
@@ -177,7 +177,7 @@ namespace mongo {
          *         OK will be returned even if corruption is found
          *         deatils will be in result
          */
-        virtual Status validate( TransactionExperiment* txn,
+        virtual Status validate( OperationContext* txn,
                                  bool full, bool scanData,
                                  ValidateAdaptor* adaptor,
                                  ValidateResults* results, BSONObjBuilder* output ) const = 0;
@@ -187,11 +187,11 @@ namespace mongo {
          * What cache depends on implementation.
          * @param output (optional) - where to put detailed stats
          */
-        virtual Status touch( TransactionExperiment* txn, BSONObjBuilder* output ) const = 0;
+        virtual Status touch( OperationContext* txn, BSONObjBuilder* output ) const = 0;
 
         // TODO: this makes me sad, it shouldn't be in the interface
         // do not use this anymore
-        virtual void increaseStorageSize( TransactionExperiment* txn,  int size, int quotaMax ) = 0;
+        virtual void increaseStorageSize( OperationContext* txn,  int size, int quotaMax ) = 0;
 
     protected:
         std::string _ns;
diff --git a/src/mongo/db/structure/record_store_heap.cpp b/src/mongo/db/structure/record_store_heap.cpp
index da56f288867..162c3c69125 100644
--- a/src/mongo/db/structure/record_store_heap.cpp
+++ b/src/mongo/db/structure/record_store_heap.cpp
@@ -70,7 +70,7 @@ namespace mongo {
         return reinterpret_cast<Record*>(it->second.get());
     }
 
-    void HeapRecordStore::deleteRecord(TransactionExperiment* txn, const DiskLoc& loc) {
+    void HeapRecordStore::deleteRecord(OperationContext* txn, const DiskLoc& loc) {
         Record* rec = recordFor(loc);
         _dataSize -= rec->netLength();
         invariant(_records.erase(loc) == 1);
@@ -89,7 +89,7 @@ namespace mongo {
         return false;
     }
 
-    void HeapRecordStore::cappedDeleteAsNeeded(TransactionExperiment* txn) {
+    void HeapRecordStore::cappedDeleteAsNeeded(OperationContext* txn) {
         while (cappedAndNeedDelete()) {
             invariant(!_records.empty());
 
@@ -102,7 +102,7 @@ namespace mongo {
         }
     }
 
-    StatusWith<DiskLoc> HeapRecordStore::insertRecord(TransactionExperiment* txn,
+    StatusWith<DiskLoc> HeapRecordStore::insertRecord(OperationContext* txn,
                                                       const char* data,
                                                       int len,
                                                       int quotaMax) {
@@ -129,7 +129,7 @@ namespace mongo {
         return StatusWith<DiskLoc>(loc);
     }
 
-    StatusWith<DiskLoc> HeapRecordStore::insertRecord(TransactionExperiment* txn,
+    StatusWith<DiskLoc> HeapRecordStore::insertRecord(OperationContext* txn,
                                                       const DocWriter* doc,
                                                       int quotaMax) {
         const int len = doc->documentSize();
@@ -182,7 +182,7 @@ namespace mongo {
         return out;
     }
 
-    Status HeapRecordStore::truncate(TransactionExperiment* txn) {
+    Status HeapRecordStore::truncate(OperationContext* txn) {
         _records.clear();
         _dataSize = 0;
         return Status::OK();
@@ -191,7 +191,7 @@ namespace mongo {
     bool HeapRecordStore::compactSupported() const {
         return false;
     }
-    Status HeapRecordStore::compact(TransactionExperiment* txn,
+    Status HeapRecordStore::compact(OperationContext* txn,
                                     RecordStoreCompactAdaptor* adaptor,
                                     const CompactOptions* options,
                                     CompactStats* stats) {
@@ -199,7 +199,7 @@ namespace mongo {
         invariant(!"compact not yet implemented");
     }
 
-    Status HeapRecordStore::validate(TransactionExperiment* txn,
+    Status HeapRecordStore::validate(OperationContext* txn,
                                      bool full,
                                      bool scanData,
                                      ValidateAdaptor* adaptor,
@@ -225,7 +225,7 @@ namespace mongo {
 
     }
 
-    Status HeapRecordStore::touch(TransactionExperiment* txn, BSONObjBuilder* output) const {
+    Status HeapRecordStore::touch(OperationContext* txn, BSONObjBuilder* output) const {
         if (output) {
             output->append("numRanges", 1);
             output->append("millis", 0);
@@ -233,7 +233,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    void HeapRecordStore::increaseStorageSize(TransactionExperiment* txn,  int size, int quotaMax) {
+    void HeapRecordStore::increaseStorageSize(OperationContext* txn,  int size, int quotaMax) {
         // unclear what this would mean for this class. For now, just error if called.
         invariant(!"increaseStorageSize not yet implemented");
     }
diff --git a/src/mongo/db/structure/record_store_heap.h b/src/mongo/db/structure/record_store_heap.h
index f9d752cbe84..42fc085ea64 100644
--- a/src/mongo/db/structure/record_store_heap.h
+++ b/src/mongo/db/structure/record_store_heap.h
@@ -56,14 +56,14 @@ namespace mongo {
 
         virtual Record* recordFor( const DiskLoc& loc ) const;
 
-        virtual void deleteRecord( TransactionExperiment* txn, const DiskLoc& dl );
+        virtual void deleteRecord( OperationContext* txn, const DiskLoc& dl );
 
-        virtual StatusWith<DiskLoc> insertRecord( TransactionExperiment* txn,
+        virtual StatusWith<DiskLoc> insertRecord( OperationContext* txn,
                                                   const char* data,
                                                   int len,
                                                   int quotaMax );
 
-        virtual StatusWith<DiskLoc> insertRecord( TransactionExperiment* txn,
+        virtual StatusWith<DiskLoc> insertRecord( OperationContext* txn,
                                                   const DocWriter* doc,
                                                   int quotaMax );
 
@@ -74,23 +74,23 @@ namespace mongo {
 
         virtual std::vector<RecordIterator*> getManyIterators() const;
 
-        virtual Status truncate( TransactionExperiment* txn );
+        virtual Status truncate( OperationContext* txn );
 
         virtual bool compactSupported() const;
-        virtual Status compact( TransactionExperiment* txn,
+        virtual Status compact( OperationContext* txn,
                                 RecordStoreCompactAdaptor* adaptor,
                                 const CompactOptions* options,
                                 CompactStats* stats );
 
-        virtual Status validate( TransactionExperiment* txn,
+        virtual Status validate( OperationContext* txn,
                                  bool full,
                                  bool scanData,
                                  ValidateAdaptor* adaptor,
                                  ValidateResults* results, BSONObjBuilder* output ) const;
 
-        virtual Status touch( TransactionExperiment* txn, BSONObjBuilder* output ) const;
+        virtual Status touch( OperationContext* txn, BSONObjBuilder* output ) const;
 
-        virtual void increaseStorageSize( TransactionExperiment* txn,  int size, int quotaMax );
+        virtual void increaseStorageSize( OperationContext* txn,  int size, int quotaMax );
 
         virtual int64_t storageSize(BSONObjBuilder* extraInfo = NULL, int infoLevel = 0) const;
 
@@ -111,7 +111,7 @@ namespace mongo {
     private:
         DiskLoc allocateLoc();
         bool cappedAndNeedDelete() const;
-        void cappedDeleteAsNeeded(TransactionExperiment* txn);
+        void cappedDeleteAsNeeded(OperationContext* txn);
 
         // TODO figure out a proper solution to metadata
         const bool _isCapped;
diff --git a/src/mongo/db/structure/record_store_v1_base.cpp b/src/mongo/db/structure/record_store_v1_base.cpp
index b3c844687e2..97a421de8d0 100644
--- a/src/mongo/db/structure/record_store_v1_base.cpp
+++ b/src/mongo/db/structure/record_store_v1_base.cpp
@@ -34,7 +34,7 @@
 #include "mongo/db/storage/extent.h"
 #include "mongo/db/storage/extent_manager.h"
 #include "mongo/db/storage/record.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/db/structure/record_store_v1_repair_iterator.h"
 #include "mongo/util/timer.h"
 #include "mongo/util/touch_pages.h"
@@ -161,7 +161,7 @@ namespace mongo {
 
     }
 
-    DiskLoc RecordStoreV1Base::_findFirstSpot( TransactionExperiment* txn,
+    DiskLoc RecordStoreV1Base::_findFirstSpot( OperationContext* txn,
                                                const DiskLoc& extDiskLoc, Extent* e ) {
         DiskLoc emptyLoc = extDiskLoc;
         emptyLoc.inc( Extent::HeaderSize() );
@@ -205,7 +205,7 @@ namespace mongo {
     }
 
 
-    StatusWith<DiskLoc> RecordStoreV1Base::insertRecord( TransactionExperiment* txn,
+    StatusWith<DiskLoc> RecordStoreV1Base::insertRecord( OperationContext* txn,
                                                          const DocWriter* doc,
                                                          int quotaMax ) {
         int docSize = doc->documentSize();
@@ -235,7 +235,7 @@ namespace mongo {
     }
 
 
-    StatusWith<DiskLoc> RecordStoreV1Base::insertRecord( TransactionExperiment* txn,
+    StatusWith<DiskLoc> RecordStoreV1Base::insertRecord( OperationContext* txn,
                                                          const char* data,
                                                          int len,
                                                          int quotaMax ) {
@@ -265,7 +265,7 @@ namespace mongo {
         return loc;
     }
 
-    void RecordStoreV1Base::deleteRecord( TransactionExperiment* txn, const DiskLoc& dl ) {
+    void RecordStoreV1Base::deleteRecord( OperationContext* txn, const DiskLoc& dl ) {
 
         Record* todelete = recordFor( dl );
         invariant( todelete->netLength() >= 4 ); // this is required for defensive code
@@ -329,7 +329,7 @@ namespace mongo {
         return new RecordStoreV1RepairIterator(this);
     }
 
-    void RecordStoreV1Base::_addRecordToRecListInExtent(TransactionExperiment* txn,
+    void RecordStoreV1Base::_addRecordToRecListInExtent(OperationContext* txn,
                                                         Record *r,
                                                         DiskLoc loc) {
         dassert( recordFor(loc) == r );
@@ -348,7 +348,7 @@ namespace mongo {
         }
     }
 
-    void RecordStoreV1Base::increaseStorageSize( TransactionExperiment* txn,
+    void RecordStoreV1Base::increaseStorageSize( OperationContext* txn,
                                                  int size,
                                                  int quotaMax ) {
         DiskLoc eloc = _extentManager->allocateExtent( txn,
@@ -388,7 +388,7 @@ namespace mongo {
         addDeletedRec(txn, emptyLoc);
     }
 
-    Status RecordStoreV1Base::validate( TransactionExperiment* txn,
+    Status RecordStoreV1Base::validate( OperationContext* txn,
                                         bool full, bool scanData,
                                         ValidateAdaptor* adaptor,
                                         ValidateResults* results, BSONObjBuilder* output ) const {
@@ -693,7 +693,7 @@ namespace mongo {
         };
     }
 
-    Status RecordStoreV1Base::touch( TransactionExperiment* txn, BSONObjBuilder* output ) const {
+    Status RecordStoreV1Base::touch( OperationContext* txn, BSONObjBuilder* output ) const {
         Timer t;
 
         // Note: when this class has document level locking, we'll need a lock to get extents
diff --git a/src/mongo/db/structure/record_store_v1_base.h b/src/mongo/db/structure/record_store_v1_base.h
index d2d989a21e4..3bd569c095a 100644
--- a/src/mongo/db/structure/record_store_v1_base.h
+++ b/src/mongo/db/structure/record_store_v1_base.h
@@ -38,7 +38,7 @@ namespace mongo {
     class DocWriter;
     class ExtentManager;
     class Record;
-    class TransactionExperiment;
+    class OperationContext;
 
     struct Extent;
 
@@ -47,48 +47,48 @@ namespace mongo {
         virtual ~RecordStoreV1MetaData(){}
 
         virtual const DiskLoc& capExtent() const = 0;
-        virtual void setCapExtent( TransactionExperiment* txn, const DiskLoc& loc ) = 0;
+        virtual void setCapExtent( OperationContext* txn, const DiskLoc& loc ) = 0;
 
         virtual const DiskLoc& capFirstNewRecord() const = 0;
-        virtual void setCapFirstNewRecord( TransactionExperiment* txn, const DiskLoc& loc ) = 0;
+        virtual void setCapFirstNewRecord( OperationContext* txn, const DiskLoc& loc ) = 0;
 
         virtual bool capLooped() const = 0;
 
         virtual long long dataSize() const = 0;
         virtual long long numRecords() const = 0;
 
-        virtual void incrementStats( TransactionExperiment* txn,
+        virtual void incrementStats( OperationContext* txn,
                                      long long dataSizeIncrement,
                                      long long numRecordsIncrement ) = 0;
 
-        virtual void setStats( TransactionExperiment* txn,
+        virtual void setStats( OperationContext* txn,
                                long long dataSizeIncrement,
                                long long numRecordsIncrement ) = 0;
 
         virtual const DiskLoc& deletedListEntry( int bucket ) const = 0;
-        virtual void setDeletedListEntry( TransactionExperiment* txn,
+        virtual void setDeletedListEntry( OperationContext* txn,
                                           int bucket,
                                           const DiskLoc& loc ) = 0;
-        virtual void orphanDeletedList(TransactionExperiment* txn) = 0;
+        virtual void orphanDeletedList(OperationContext* txn) = 0;
 
         virtual const DiskLoc& firstExtent() const = 0;
-        virtual void setFirstExtent( TransactionExperiment* txn, const DiskLoc& loc ) = 0;
+        virtual void setFirstExtent( OperationContext* txn, const DiskLoc& loc ) = 0;
 
         virtual const DiskLoc& lastExtent() const = 0;
-        virtual void setLastExtent( TransactionExperiment* txn, const DiskLoc& loc ) = 0;
+        virtual void setLastExtent( OperationContext* txn, const DiskLoc& loc ) = 0;
 
         virtual bool isCapped() const = 0;
 
         virtual bool isUserFlagSet( int flag ) const = 0;
 
         virtual int lastExtentSize() const = 0;
-        virtual void setLastExtentSize( TransactionExperiment* txn, int newMax ) = 0;
+        virtual void setLastExtentSize( OperationContext* txn, int newMax ) = 0;
 
         virtual long long maxCappedDocs() const = 0;
 
         virtual double paddingFactor() const = 0;
 
-        virtual void setPaddingFactor( TransactionExperiment* txn, double paddingFactor ) = 0;
+        virtual void setPaddingFactor( OperationContext* txn, double paddingFactor ) = 0;
 
     };
 
@@ -126,28 +126,28 @@ namespace mongo {
 
         Record* recordFor( const DiskLoc& loc ) const;
 
-        void deleteRecord( TransactionExperiment* txn,
+        void deleteRecord( OperationContext* txn,
                            const DiskLoc& dl );
 
-        StatusWith<DiskLoc> insertRecord( TransactionExperiment* txn,
+        StatusWith<DiskLoc> insertRecord( OperationContext* txn,
                                           const char* data,
                                           int len,
                                           int quotaMax );
 
-        StatusWith<DiskLoc> insertRecord( TransactionExperiment* txn,
+        StatusWith<DiskLoc> insertRecord( OperationContext* txn,
                                           const DocWriter* doc,
                                           int quotaMax );
 
         virtual RecordIterator* getIteratorForRepair() const;
 
-        void increaseStorageSize( TransactionExperiment* txn, int size, int quotaMax );
+        void increaseStorageSize( OperationContext* txn, int size, int quotaMax );
 
-        virtual Status validate( TransactionExperiment* txn,
+        virtual Status validate( OperationContext* txn,
                                  bool full, bool scanData,
                                  ValidateAdaptor* adaptor,
                                  ValidateResults* results, BSONObjBuilder* output ) const;
 
-        virtual Status touch( TransactionExperiment* txn, BSONObjBuilder* output ) const;
+        virtual Status touch( OperationContext* txn, BSONObjBuilder* output ) const;
 
         const DeletedRecord* deletedRecordFor( const DiskLoc& loc ) const;
 
@@ -186,12 +186,12 @@ namespace mongo {
 
         virtual bool isCapped() const = 0;
 
-        virtual StatusWith<DiskLoc> allocRecord( TransactionExperiment* txn,
+        virtual StatusWith<DiskLoc> allocRecord( OperationContext* txn,
                                                  int lengthWithHeaders,
                                                  int quotaMax ) = 0;
 
         // TODO: document, remove, what have you
-        virtual void addDeletedRec( TransactionExperiment* txn, const DiskLoc& dloc) = 0;
+        virtual void addDeletedRec( OperationContext* txn, const DiskLoc& dloc) = 0;
 
         // TODO: another sad one
         virtual DeletedRecord* drec( const DiskLoc& loc ) const;
@@ -211,12 +211,12 @@ namespace mongo {
          * finds the first suitable DiskLoc for data
          * will return the DiskLoc of a newly created DeletedRecord
          */
-        DiskLoc _findFirstSpot( TransactionExperiment* txn, const DiskLoc& extDiskLoc, Extent* e );
+        DiskLoc _findFirstSpot( OperationContext* txn, const DiskLoc& extDiskLoc, Extent* e );
 
         /** add a record to the end of the linked list chain within this extent.
             require: you must have already declared write intent for the record header.
         */
-        void _addRecordToRecListInExtent(TransactionExperiment* txn, Record* r, DiskLoc loc);
+        void _addRecordToRecListInExtent(OperationContext* txn, Record* r, DiskLoc loc);
 
         scoped_ptr<RecordStoreV1MetaData> _details;
         ExtentManager* _extentManager;
diff --git a/src/mongo/db/structure/record_store_v1_capped.cpp b/src/mongo/db/structure/record_store_v1_capped.cpp
index 9e5455dccbc..9b1d4d3f3e4 100644
--- a/src/mongo/db/structure/record_store_v1_capped.cpp
+++ b/src/mongo/db/structure/record_store_v1_capped.cpp
@@ -32,7 +32,7 @@
 
 #include "mongo/db/storage/extent.h"
 #include "mongo/db/storage/extent_manager.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/db/storage/record.h"
 #include "mongo/db/structure/record_store_v1_capped_iterator.h"
 #include "mongo/util/mmap.h"
@@ -58,7 +58,7 @@
 
 namespace mongo {
 
-    CappedRecordStoreV1::CappedRecordStoreV1( TransactionExperiment* txn,
+    CappedRecordStoreV1::CappedRecordStoreV1( OperationContext* txn,
                                               CappedDocumentDeleteCallback* collection,
                                               const StringData& ns,
                                               RecordStoreV1MetaData* details,
@@ -82,7 +82,7 @@ namespace mongo {
     CappedRecordStoreV1::~CappedRecordStoreV1() {
     }
 
-    StatusWith<DiskLoc> CappedRecordStoreV1::allocRecord( TransactionExperiment* txn,
+    StatusWith<DiskLoc> CappedRecordStoreV1::allocRecord( OperationContext* txn,
                                                           int lenToAlloc,
                                                           int quotaMax ) {
         {
@@ -215,7 +215,7 @@ namespace mongo {
         return StatusWith<DiskLoc>( loc );
     }
 
-    Status CappedRecordStoreV1::truncate(TransactionExperiment* txn) {
+    Status CappedRecordStoreV1::truncate(OperationContext* txn) {
         setLastDelRecLastExtent( txn, DiskLoc() );
         setListOfAllDeletedRecords( txn, DiskLoc() );
 
@@ -248,7 +248,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    void CappedRecordStoreV1::temp_cappedTruncateAfter( TransactionExperiment* txn,
+    void CappedRecordStoreV1::temp_cappedTruncateAfter( OperationContext* txn,
                                                         DiskLoc end,
                                                         bool inclusive ) {
         cappedTruncateAfter( txn, _ns.c_str(), end, inclusive );
@@ -259,7 +259,7 @@ namespace mongo {
        this is O(n^2) but we call it for capped tables where typically n==1 or 2!
        (or 3...there will be a little unused sliver at the end of the extent.)
     */
-    void CappedRecordStoreV1::compact(TransactionExperiment* txn) {
+    void CappedRecordStoreV1::compact(OperationContext* txn) {
         DDD( "CappedRecordStoreV1::compact enter" );
 
         vector<DiskLoc> drecs;
@@ -314,7 +314,7 @@ namespace mongo {
             return drec(cappedLastDelRecLastExtent())->nextDeleted();
     }
 
-    void CappedRecordStoreV1::setFirstDeletedInCurExtent( TransactionExperiment* txn,
+    void CappedRecordStoreV1::setFirstDeletedInCurExtent( OperationContext* txn,
                                                           const DiskLoc& loc ) {
         if ( cappedLastDelRecLastExtent().isNull() )
             setListOfAllDeletedRecords( txn, loc );
@@ -322,7 +322,7 @@ namespace mongo {
             *txn->writing( &drec(cappedLastDelRecLastExtent())->nextDeleted() ) = loc;
     }
 
-    void CappedRecordStoreV1::cappedCheckMigrate(TransactionExperiment* txn) {
+    void CappedRecordStoreV1::cappedCheckMigrate(OperationContext* txn) {
         // migrate old RecordStoreV1MetaData format
         if ( _details->capExtent().a() == 0 && _details->capExtent().getOfs() == 0 ) {
             _details->setCapFirstNewRecord( txn, DiskLoc().setInvalid() );
@@ -366,7 +366,7 @@ namespace mongo {
         return inCapExtent( next );
     }
 
-    void CappedRecordStoreV1::advanceCapExtent( TransactionExperiment* txn, const StringData& ns ) {
+    void CappedRecordStoreV1::advanceCapExtent( OperationContext* txn, const StringData& ns ) {
         // We want cappedLastDelRecLastExtent() to be the last DeletedRecord of the prev cap extent
         // (or DiskLoc() if new capExtent == firstExtent)
         if ( _details->capExtent() == _details->lastExtent() )
@@ -388,7 +388,7 @@ namespace mongo {
         _details->setCapFirstNewRecord( txn, DiskLoc() );
     }
 
-    DiskLoc CappedRecordStoreV1::__capAlloc( TransactionExperiment* txn, int len ) {
+    DiskLoc CappedRecordStoreV1::__capAlloc( OperationContext* txn, int len ) {
         DiskLoc prev = cappedLastDelRecLastExtent();
         DiskLoc i = cappedFirstDeletedInCurExtent();
         DiskLoc ret;
@@ -414,7 +414,7 @@ namespace mongo {
         return ret;
     }
 
-    void CappedRecordStoreV1::cappedTruncateLastDelUpdate(TransactionExperiment* txn) {
+    void CappedRecordStoreV1::cappedTruncateLastDelUpdate(OperationContext* txn) {
         if ( _details->capExtent() == _details->firstExtent() ) {
             // Only one extent of the collection is in use, so there
             // is no deleted record in a previous extent, so nullify
@@ -440,7 +440,7 @@ namespace mongo {
         }
     }
 
-    void CappedRecordStoreV1::cappedTruncateAfter(TransactionExperiment* txn,
+    void CappedRecordStoreV1::cappedTruncateAfter(OperationContext* txn,
                                                   const char* ns,
                                                   DiskLoc end,
                                                   bool inclusive) {
@@ -545,7 +545,7 @@ namespace mongo {
         return _details->deletedListEntry(0);
     }
 
-    void CappedRecordStoreV1::setListOfAllDeletedRecords( TransactionExperiment* txn,
+    void CappedRecordStoreV1::setListOfAllDeletedRecords( OperationContext* txn,
                                                           const DiskLoc& loc ) {
         return _details->setDeletedListEntry(txn, 0, loc);
     }
@@ -554,7 +554,7 @@ namespace mongo {
         return _details->deletedListEntry(1);
     }
 
-    void CappedRecordStoreV1::setLastDelRecLastExtent( TransactionExperiment* txn,
+    void CappedRecordStoreV1::setLastDelRecLastExtent( OperationContext* txn,
                                                        const DiskLoc& loc ) {
         return _details->setDeletedListEntry(txn, 1, loc);
     }
@@ -567,7 +567,7 @@ namespace mongo {
         return _extentManager->getExtent(_details->capExtent());
     }
 
-    void CappedRecordStoreV1::addDeletedRec( TransactionExperiment* txn, const DiskLoc& dloc ) {
+    void CappedRecordStoreV1::addDeletedRec( OperationContext* txn, const DiskLoc& dloc ) {
         DeletedRecord* d = txn->writing( drec( dloc ) );
 
         DEBUGGING log() << "TEMP: add deleted rec " << dloc.toString() << ' ' << hex << d->extentOfs() << endl;
@@ -647,7 +647,7 @@ namespace mongo {
         return iterators.release();
     }
 
-    Status CappedRecordStoreV1::compact( TransactionExperiment* txn,
+    Status CappedRecordStoreV1::compact( OperationContext* txn,
                                          RecordStoreCompactAdaptor* adaptor,
                                          const CompactOptions* options,
                                          CompactStats* stats ) {
diff --git a/src/mongo/db/structure/record_store_v1_capped.h b/src/mongo/db/structure/record_store_v1_capped.h
index b0483230f20..a84b8884ded 100644
--- a/src/mongo/db/structure/record_store_v1_capped.h
+++ b/src/mongo/db/structure/record_store_v1_capped.h
@@ -40,7 +40,7 @@ namespace mongo {
 
     class CappedRecordStoreV1 : public RecordStoreV1Base {
     public:
-        CappedRecordStoreV1( TransactionExperiment* txn,
+        CappedRecordStoreV1( OperationContext* txn,
                              CappedDocumentDeleteCallback* collection,
                              const StringData& ns,
                              RecordStoreV1MetaData* details,
@@ -51,7 +51,7 @@ namespace mongo {
 
         const char* name() const { return "CappedRecordStoreV1"; }
 
-        virtual Status truncate(TransactionExperiment* txn);
+        virtual Status truncate(OperationContext* txn);
 
         /**
          * Truncate documents newer than the document at 'end' from the capped
@@ -60,7 +60,7 @@ namespace mongo {
          * @param inclusive - Truncate 'end' as well iff true
          * XXX: this will go away soon, just needed to move for now
          */
-        void temp_cappedTruncateAfter( TransactionExperiment* txn, DiskLoc end, bool inclusive );
+        void temp_cappedTruncateAfter( OperationContext* txn, DiskLoc end, bool inclusive );
 
         virtual RecordIterator* getIterator( const DiskLoc& start, bool tailable,
                                              const CollectionScanParams::Direction& dir) const;
@@ -69,7 +69,7 @@ namespace mongo {
 
         virtual bool compactSupported() const { return false; }
 
-        virtual Status compact( TransactionExperiment* txn,
+        virtual Status compact( OperationContext* txn,
                                 RecordStoreCompactAdaptor* adaptor,
                                 const CompactOptions* options,
                                 CompactStats* stats );
@@ -83,29 +83,29 @@ namespace mongo {
 
         virtual bool isCapped() const { return true; }
 
-        virtual StatusWith<DiskLoc> allocRecord( TransactionExperiment* txn,
+        virtual StatusWith<DiskLoc> allocRecord( OperationContext* txn,
                                                  int lengthWithHeaders,
                                                  int quotaMax );
 
-        virtual void addDeletedRec(TransactionExperiment* txn, const DiskLoc& dloc);
+        virtual void addDeletedRec(OperationContext* txn, const DiskLoc& dloc);
 
     private:
         // -- start copy from cap.cpp --
-        void compact(TransactionExperiment* txn);
+        void compact(OperationContext* txn);
         const DiskLoc& cappedFirstDeletedInCurExtent() const;
-        void setFirstDeletedInCurExtent( TransactionExperiment* txn, const DiskLoc& loc );
-        void cappedCheckMigrate(TransactionExperiment* txn);
-        DiskLoc __capAlloc( TransactionExperiment* txn, int len );
+        void setFirstDeletedInCurExtent( OperationContext* txn, const DiskLoc& loc );
+        void cappedCheckMigrate(OperationContext* txn);
+        DiskLoc __capAlloc( OperationContext* txn, int len );
         bool inCapExtent( const DiskLoc &dl ) const;
         const DiskLoc& cappedListOfAllDeletedRecords() const;
         const DiskLoc& cappedLastDelRecLastExtent() const;
-        void setListOfAllDeletedRecords( TransactionExperiment* txn, const DiskLoc& loc );
-        void setLastDelRecLastExtent( TransactionExperiment* txn, const DiskLoc& loc );
+        void setListOfAllDeletedRecords( OperationContext* txn, const DiskLoc& loc );
+        void setLastDelRecLastExtent( OperationContext* txn, const DiskLoc& loc );
         bool capLooped() const;
         Extent *theCapExtent() const;
         bool nextIsInCapExtent( const DiskLoc &dl ) const;
-        void advanceCapExtent( TransactionExperiment* txn, const StringData& ns );
-        void cappedTruncateLastDelUpdate(TransactionExperiment* txn);
+        void advanceCapExtent( OperationContext* txn, const StringData& ns );
+        void cappedTruncateLastDelUpdate(OperationContext* txn);
 
         /**
          * Truncate documents newer than the document at 'end' from the capped
@@ -113,7 +113,7 @@ namespace mongo {
          * function.  An assertion will be thrown if that is attempted.
          * @param inclusive - Truncate 'end' as well iff true
          */
-        void cappedTruncateAfter(TransactionExperiment* txn,
+        void cappedTruncateAfter(OperationContext* txn,
                                  const char* ns,
                                  DiskLoc end,
                                  bool inclusive);
diff --git a/src/mongo/db/structure/record_store_v1_capped_test.cpp b/src/mongo/db/structure/record_store_v1_capped_test.cpp
index eefe8803d82..9bf2cdd8ea1 100644
--- a/src/mongo/db/structure/record_store_v1_capped_test.cpp
+++ b/src/mongo/db/structure/record_store_v1_capped_test.cpp
@@ -40,7 +40,7 @@ namespace {
 
     class DummyCappedDocumentDeleteCallback : public CappedDocumentDeleteCallback {
     public:
-        Status aboutToDeleteCapped( TransactionExperiment* txn, const DiskLoc& loc ) {
+        Status aboutToDeleteCapped( OperationContext* txn, const DiskLoc& loc ) {
             deleted.push_back( loc );
             return Status::OK();
         }
@@ -49,7 +49,7 @@ namespace {
 
     void simpleInsertTest( const char* buf, int size ) {
 
-        DummyTransactionExperiment txn;
+        DummyOperationContext txn;
         DummyExtentManager em;
         DummyRecordStoreV1MetaData* md = new DummyRecordStoreV1MetaData( true, 0 );
         DummyCappedDocumentDeleteCallback cb;
diff --git a/src/mongo/db/structure/record_store_v1_simple.cpp b/src/mongo/db/structure/record_store_v1_simple.cpp
index 87c8b28cd1e..fa43a2087a7 100644
--- a/src/mongo/db/structure/record_store_v1_simple.cpp
+++ b/src/mongo/db/structure/record_store_v1_simple.cpp
@@ -36,7 +36,7 @@
 #include "mongo/db/storage/extent.h"
 #include "mongo/db/storage/extent_manager.h"
 #include "mongo/db/storage/record.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/db/structure/record_store_v1_simple_iterator.h"
 #include "mongo/util/progress_meter.h"
 #include "mongo/util/timer.h"
@@ -57,7 +57,7 @@ namespace mongo {
     static ServerStatusMetricField<Counter64> dFreelist3( "storage.freelist.search.scanned",
                                                           &freelistIterations );
 
-    SimpleRecordStoreV1::SimpleRecordStoreV1( TransactionExperiment* txn,
+    SimpleRecordStoreV1::SimpleRecordStoreV1( OperationContext* txn,
                                               const StringData& ns,
                                               RecordStoreV1MetaData* details,
                                               ExtentManager* em,
@@ -76,7 +76,7 @@ namespace mongo {
     SimpleRecordStoreV1::~SimpleRecordStoreV1() {
     }
 
-    DiskLoc SimpleRecordStoreV1::_allocFromExistingExtents( TransactionExperiment* txn,
+    DiskLoc SimpleRecordStoreV1::_allocFromExistingExtents( OperationContext* txn,
                                                             int lenToAlloc ) {
         // align very slightly.
         lenToAlloc = (lenToAlloc + 3) & 0xfffffffc;
@@ -219,7 +219,7 @@ namespace mongo {
 
     }
 
-    StatusWith<DiskLoc> SimpleRecordStoreV1::allocRecord( TransactionExperiment* txn,
+    StatusWith<DiskLoc> SimpleRecordStoreV1::allocRecord( OperationContext* txn,
                                                           int lengthWithHeaders,
                                                           int quotaMax ) {
         DiskLoc loc = _allocFromExistingExtents( txn, lengthWithHeaders );
@@ -259,12 +259,12 @@ namespace mongo {
         return StatusWith<DiskLoc>( ErrorCodes::InternalError, "cannot allocate space" );
     }
 
-    Status SimpleRecordStoreV1::truncate(TransactionExperiment* txn) {
+    Status SimpleRecordStoreV1::truncate(OperationContext* txn) {
         return Status( ErrorCodes::InternalError,
                        "SimpleRecordStoreV1::truncate not implemented" );
     }
 
-    void SimpleRecordStoreV1::addDeletedRec( TransactionExperiment* txn, const DiskLoc& dloc ) {
+    void SimpleRecordStoreV1::addDeletedRec( OperationContext* txn, const DiskLoc& dloc ) {
         DeletedRecord* d = drec( dloc );
 
         DEBUGGING log() << "TEMP: add deleted rec " << dloc.toString() << ' ' << hex << d->extentOfs() << endl;
@@ -324,7 +324,7 @@ namespace mongo {
         size_t _allocationSize;
     };
 
-    void SimpleRecordStoreV1::_compactExtent(TransactionExperiment* txn,
+    void SimpleRecordStoreV1::_compactExtent(OperationContext* txn,
                                              const DiskLoc diskloc,
                                              int extentNumber,
                                              RecordStoreCompactAdaptor* adaptor,
@@ -446,7 +446,7 @@ namespace mongo {
 
     }
 
-    Status SimpleRecordStoreV1::compact( TransactionExperiment* txn,
+    Status SimpleRecordStoreV1::compact( OperationContext* txn,
                                          RecordStoreCompactAdaptor* adaptor,
                                          const CompactOptions* options,
                                          CompactStats* stats ) {
diff --git a/src/mongo/db/structure/record_store_v1_simple.h b/src/mongo/db/structure/record_store_v1_simple.h
index 79139d93437..5e32f390938 100644
--- a/src/mongo/db/structure/record_store_v1_simple.h
+++ b/src/mongo/db/structure/record_store_v1_simple.h
@@ -40,7 +40,7 @@ namespace mongo {
     // used by index and original collections
     class SimpleRecordStoreV1 : public RecordStoreV1Base {
     public:
-        SimpleRecordStoreV1( TransactionExperiment* txn,
+        SimpleRecordStoreV1( OperationContext* txn,
                              const StringData& ns,
                              RecordStoreV1MetaData* details,
                              ExtentManager* em,
@@ -55,10 +55,10 @@ namespace mongo {
 
         virtual std::vector<RecordIterator*> getManyIterators() const;
 
-        virtual Status truncate(TransactionExperiment* txn);
+        virtual Status truncate(OperationContext* txn);
 
         virtual bool compactSupported() const { return true; }
-        virtual Status compact( TransactionExperiment* txn,
+        virtual Status compact( OperationContext* txn,
                                 RecordStoreCompactAdaptor* adaptor,
                                 const CompactOptions* options,
                                 CompactStats* stats );
@@ -66,17 +66,17 @@ namespace mongo {
     protected:
         virtual bool isCapped() const { return false; }
 
-        virtual StatusWith<DiskLoc> allocRecord( TransactionExperiment* txn,
+        virtual StatusWith<DiskLoc> allocRecord( OperationContext* txn,
                                                  int lengthWithHeaders,
                                                  int quotaMax );
 
-        virtual void addDeletedRec(TransactionExperiment* txn,
+        virtual void addDeletedRec(OperationContext* txn,
                                    const DiskLoc& dloc);
     private:
-        DiskLoc _allocFromExistingExtents( TransactionExperiment* txn,
+        DiskLoc _allocFromExistingExtents( OperationContext* txn,
                                            int lengthWithHeaders );
 
-        void _compactExtent(TransactionExperiment* txn,
+        void _compactExtent(OperationContext* txn,
                             const DiskLoc diskloc,
                             int extentNumber,
                             RecordStoreCompactAdaptor* adaptor,
diff --git a/src/mongo/db/structure/record_store_v1_simple_test.cpp b/src/mongo/db/structure/record_store_v1_simple_test.cpp
index c515cde0d8d..08a32c5d137 100644
--- a/src/mongo/db/structure/record_store_v1_simple_test.cpp
+++ b/src/mongo/db/structure/record_store_v1_simple_test.cpp
@@ -149,7 +149,7 @@ namespace {
 
     /** alloc() quantizes the requested size using quantizeAllocationSpace() rules. */
     TEST(SimpleRecordStoreV1, AllocQuantized) {
-        DummyTransactionExperiment txn;
+        DummyOperationContext txn;
         DummyExtentManager em;
         DummyRecordStoreV1MetaData* md = new DummyRecordStoreV1MetaData( false, 0 );
 
@@ -169,7 +169,7 @@ namespace {
      * rules.
      */
     TEST(SimpleRecordStoreV1, AllocIndexNamespaceNotQuantized) {
-        DummyTransactionExperiment txn;
+        DummyOperationContext txn;
         DummyExtentManager em;
         DummyRecordStoreV1MetaData* md = new DummyRecordStoreV1MetaData( false, 0 );
 
@@ -187,7 +187,7 @@ namespace {
 
     /** alloc() quantizes records in index collections to the nearest multiple of 4. */
     TEST(SimpleRecordStoreV1, AllocIndexNamespaceSlightlyQuantized) {
-        DummyTransactionExperiment txn;
+        DummyOperationContext txn;
         DummyExtentManager em;
         DummyRecordStoreV1MetaData* md = new DummyRecordStoreV1MetaData( false, 0 );
 
@@ -205,7 +205,7 @@ namespace {
      * 'cook' the deletedList by shrinking the smallest deleted record to size
      * 'newDeletedRecordSize'.
      */
-    void cookDeletedList(TransactionExperiment* txn,
+    void cookDeletedList(OperationContext* txn,
                          RecordStoreV1Base* rs,
                          RecordStoreV1MetaData* md,
                          int newDeletedRecordSize) {
@@ -247,7 +247,7 @@ namespace {
 
     /** alloc() returns a non quantized record larger than the requested size. */
     TEST(SimpleRecordStoreV1, AllocUseNonQuantizedDeletedRecord) {
-        DummyTransactionExperiment txn;
+        DummyOperationContext txn;
         DummyExtentManager em;
         DummyRecordStoreV1MetaData* md = new DummyRecordStoreV1MetaData( false, 0 );
         SimpleRecordStoreV1 rs( &txn, "test.foo", md, &em, false );
@@ -266,7 +266,7 @@ namespace {
 
     /** alloc() returns a non quantized record equal to the requested size. */
     TEST(SimpleRecordStoreV1, AllocExactSizeNonQuantizedDeletedRecord) {
-        DummyTransactionExperiment txn;
+        DummyOperationContext txn;
         DummyExtentManager em;
         DummyRecordStoreV1MetaData* md = new DummyRecordStoreV1MetaData( false, 0 );
         SimpleRecordStoreV1 rs( &txn, "test.foo", md, &em, false );
@@ -288,7 +288,7 @@ namespace {
      * too small to make a DeletedRecord.
      */
     TEST(SimpleRecordStoreV1, AllocQuantizedWithExtra) {
-        DummyTransactionExperiment txn;
+        DummyOperationContext txn;
         DummyExtentManager em;
         DummyRecordStoreV1MetaData* md = new DummyRecordStoreV1MetaData( false, 0 );
         SimpleRecordStoreV1 rs( &txn, "test.foo", md, &em, false );
@@ -310,7 +310,7 @@ namespace {
      * is large enough to form a new deleted record.
      */
     TEST(SimpleRecordStoreV1, AllocQuantizedWithoutExtra) {
-        DummyTransactionExperiment txn;
+        DummyOperationContext txn;
         DummyExtentManager em;
         DummyRecordStoreV1MetaData* md = new DummyRecordStoreV1MetaData( false, 0 );
         SimpleRecordStoreV1 rs( &txn, "test.foo", md, &em, false );
@@ -335,7 +335,7 @@ namespace {
      * if a quantized portion of the deleted record could be used instead.
      */
     TEST(SimpleRecordStoreV1, AllocNotQuantizedNearDeletedSize) {
-        DummyTransactionExperiment txn;
+        DummyOperationContext txn;
         DummyExtentManager em;
         DummyRecordStoreV1MetaData* md = new DummyRecordStoreV1MetaData( false, 0 );
         SimpleRecordStoreV1 rs( &txn, "test.foo", md, &em, false );
@@ -356,7 +356,7 @@ namespace {
 
     /** getRecordAllocationSize() returns its argument when the padding factor is 1.0. */
     TEST(SimpleRecordStoreV1, GetRecordAllocationSizeNoPadding) {
-        DummyTransactionExperiment txn;
+        DummyOperationContext txn;
         DummyExtentManager em;
         DummyRecordStoreV1MetaData* md = new DummyRecordStoreV1MetaData( false, 0 );
         SimpleRecordStoreV1 rs( &txn, "test.foo", md, &em, false );
@@ -366,7 +366,7 @@ namespace {
 
     /** getRecordAllocationSize() multiplies by a padding factor > 1.0. */
     TEST(SimpleRecordStoreV1, GetRecordAllocationSizeWithPadding) {
-        DummyTransactionExperiment txn;
+        DummyOperationContext txn;
         DummyExtentManager em;
         DummyRecordStoreV1MetaData* md = new DummyRecordStoreV1MetaData( false, 0 );
         SimpleRecordStoreV1 rs( &txn, "test.foo", md, &em, false );
@@ -381,7 +381,7 @@ namespace {
      * is set.
      */
     TEST(SimpleRecordStoreV1, GetRecordAllocationSizePowerOf2) {
-        DummyTransactionExperiment txn;
+        DummyOperationContext txn;
         DummyExtentManager em;
         DummyRecordStoreV1MetaData* md = new DummyRecordStoreV1MetaData(
                                                 false,
@@ -396,7 +396,7 @@ namespace {
      * is set, ignoring the padding factor.
      */
     TEST(SimpleRecordStoreV1, GetRecordAllocationSizePowerOf2PaddingIgnored) {
-        DummyTransactionExperiment txn;
+        DummyOperationContext txn;
         DummyExtentManager em;
         DummyRecordStoreV1MetaData* md = new DummyRecordStoreV1MetaData(
                                                 false,
@@ -412,7 +412,7 @@ namespace {
     // -----------------
 
     TEST( SimpleRecordStoreV1, FullSimple1 ) {
-        DummyTransactionExperiment txn;
+        DummyOperationContext txn;
         DummyExtentManager em;
         DummyRecordStoreV1MetaData* md = new DummyRecordStoreV1MetaData( false, 0 );
         SimpleRecordStoreV1 rs( &txn,
@@ -436,7 +436,7 @@ namespace {
      * Inserts take the first deleted record with the correct size.
      */
     TEST( SimpleRecordStoreV1, InsertTakesFirstDeletedWithExactSize ) {
-        DummyTransactionExperiment txn;
+        DummyOperationContext txn;
         DummyExtentManager em;
         DummyRecordStoreV1MetaData* md = new DummyRecordStoreV1MetaData( false, 0 );
         SimpleRecordStoreV1 rs( &txn, "test.foo", md, &em, false );
diff --git a/src/mongo/db/structure/record_store_v1_test_help.cpp b/src/mongo/db/structure/record_store_v1_test_help.cpp
index 486251821ff..95cd609e6cf 100644
--- a/src/mongo/db/structure/record_store_v1_test_help.cpp
+++ b/src/mongo/db/structure/record_store_v1_test_help.cpp
@@ -59,21 +59,21 @@ namespace mongo {
     void DummyRecoveryUnit::syncDataAndTruncateJournal() {
     }
 
-    DummyTransactionExperiment::DummyTransactionExperiment() {
+    DummyOperationContext::DummyOperationContext() {
         _recoveryUnit.reset(new DummyRecoveryUnit());
     }
 
-    ProgressMeter* DummyTransactionExperiment::setMessage(const char* msg,
+    ProgressMeter* DummyOperationContext::setMessage(const char* msg,
                                                           const std::string& name ,
                                                           unsigned long long progressMeterTotal,
                                                           int secondsBetween) {
         invariant( false );
     }
 
-    void DummyTransactionExperiment::checkForInterrupt(bool heedMutex ) const {
+    void DummyOperationContext::checkForInterrupt(bool heedMutex ) const {
     }
 
-    Status DummyTransactionExperiment::checkForInterruptNoAssert() const {
+    Status DummyOperationContext::checkForInterruptNoAssert() const {
         return Status::OK();
     }
 
@@ -98,7 +98,7 @@ namespace mongo {
         return _capExtent;
     }
 
-    void DummyRecordStoreV1MetaData::setCapExtent( TransactionExperiment* txn,
+    void DummyRecordStoreV1MetaData::setCapExtent( OperationContext* txn,
                                                    const DiskLoc& loc ) {
         _capExtent = loc;
     }
@@ -107,7 +107,7 @@ namespace mongo {
         return _capFirstNewRecord;
     }
 
-    void DummyRecordStoreV1MetaData::setCapFirstNewRecord( TransactionExperiment* txn,
+    void DummyRecordStoreV1MetaData::setCapFirstNewRecord( OperationContext* txn,
                                                            const DiskLoc& loc ) {
         _capFirstNewRecord = loc;
     }
@@ -124,14 +124,14 @@ namespace mongo {
         return _numRecords;
     }
 
-    void DummyRecordStoreV1MetaData::incrementStats( TransactionExperiment* txn,
+    void DummyRecordStoreV1MetaData::incrementStats( OperationContext* txn,
                                                      long long dataSizeIncrement,
                                                      long long numRecordsIncrement ) {
         _dataSize += dataSizeIncrement;
         _numRecords += numRecordsIncrement;
     }
 
-    void DummyRecordStoreV1MetaData::setStats( TransactionExperiment* txn,
+    void DummyRecordStoreV1MetaData::setStats( OperationContext* txn,
                                                long long dataSizeIncrement,
                                                long long numRecordsIncrement ) {
         _dataSize = dataSizeIncrement;
@@ -149,7 +149,7 @@ namespace mongo {
         return _deletedLists[bucket];
     }
 
-    void DummyRecordStoreV1MetaData::setDeletedListEntry( TransactionExperiment* txn,
+    void DummyRecordStoreV1MetaData::setDeletedListEntry( OperationContext* txn,
                                                           int bucket,
                                                           const DiskLoc& loc ) {
         invariant( bucket >= 0 );
@@ -159,7 +159,7 @@ namespace mongo {
         _deletedLists[bucket] = loc;
     }
 
-    void DummyRecordStoreV1MetaData::orphanDeletedList(TransactionExperiment* txn) {
+    void DummyRecordStoreV1MetaData::orphanDeletedList(OperationContext* txn) {
         invariant( false );
     }
 
@@ -167,7 +167,7 @@ namespace mongo {
         return _firstExtent;
     }
 
-    void DummyRecordStoreV1MetaData::setFirstExtent( TransactionExperiment* txn,
+    void DummyRecordStoreV1MetaData::setFirstExtent( OperationContext* txn,
                                                      const DiskLoc& loc ) {
         _firstExtent = loc;
     }
@@ -176,7 +176,7 @@ namespace mongo {
         return _lastExtent;
     }
 
-    void DummyRecordStoreV1MetaData::setLastExtent( TransactionExperiment* txn,
+    void DummyRecordStoreV1MetaData::setLastExtent( OperationContext* txn,
                                                     const DiskLoc& loc ) {
         _lastExtent = loc;
     }
@@ -193,7 +193,7 @@ namespace mongo {
         return _lastExtentSize;
     }
 
-    void DummyRecordStoreV1MetaData::setLastExtentSize( TransactionExperiment* txn, int newMax ) {
+    void DummyRecordStoreV1MetaData::setLastExtentSize( OperationContext* txn, int newMax ) {
         _lastExtentSize = newMax;
     }
 
@@ -205,7 +205,7 @@ namespace mongo {
         return _paddingFactor;
     }
 
-    void DummyRecordStoreV1MetaData::setPaddingFactor( TransactionExperiment* txn,
+    void DummyRecordStoreV1MetaData::setPaddingFactor( OperationContext* txn,
                                                        double paddingFactor ) {
         _paddingFactor = paddingFactor;
     }
@@ -219,7 +219,7 @@ namespace mongo {
         }
     }
 
-    Status DummyExtentManager::init(TransactionExperiment* txn) {
+    Status DummyExtentManager::init(OperationContext* txn) {
         return Status::OK();
     }
 
@@ -235,7 +235,7 @@ namespace mongo {
     void DummyExtentManager::flushFiles( bool sync ) {
     }
 
-    DiskLoc DummyExtentManager::allocateExtent( TransactionExperiment* txn,
+    DiskLoc DummyExtentManager::allocateExtent( OperationContext* txn,
                                                 bool capped,
                                                 int size,
                                                 int quotaMax ) {
@@ -261,12 +261,12 @@ namespace mongo {
 
     }
 
-    void DummyExtentManager::freeExtents( TransactionExperiment* txn,
+    void DummyExtentManager::freeExtents( OperationContext* txn,
                                           DiskLoc firstExt, DiskLoc lastExt ) {
         // XXX
     }
 
-    void DummyExtentManager::freeExtent( TransactionExperiment* txn, DiskLoc extent ) {
+    void DummyExtentManager::freeExtent( OperationContext* txn, DiskLoc extent ) {
         // XXX
     }
     void DummyExtentManager::freeListStats( int* numExtents, int64_t* totalFreeSize ) const {
@@ -372,7 +372,7 @@ namespace {
     }
 }
 
-    void initializeV1RS(TransactionExperiment* txn,
+    void initializeV1RS(OperationContext* txn,
                         const LocAndSize* records,
                         const LocAndSize* drecs,
                         DummyExtentManager* em,
diff --git a/src/mongo/db/structure/record_store_v1_test_help.h b/src/mongo/db/structure/record_store_v1_test_help.h
index 55feadb449f..0de1350c1c3 100644
--- a/src/mongo/db/structure/record_store_v1_test_help.h
+++ b/src/mongo/db/structure/record_store_v1_test_help.h
@@ -33,7 +33,7 @@
 #include <vector>
 
 #include "mongo/db/storage/extent_manager.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/db/structure/record_store_v1_base.h"
 
 namespace mongo {
@@ -51,11 +51,11 @@ namespace mongo {
         virtual void syncDataAndTruncateJournal();
     };
 
-    class DummyTransactionExperiment : public TransactionExperiment {
+    class DummyOperationContext : public OperationContext {
     public:
-        DummyTransactionExperiment();
+        DummyOperationContext();
 
-        virtual ~DummyTransactionExperiment() { }
+        virtual ~DummyOperationContext() { }
 
         virtual RecoveryUnit* recoveryUnit() const {
             return _recoveryUnit.get();
@@ -80,48 +80,48 @@ namespace mongo {
         virtual ~DummyRecordStoreV1MetaData(){}
 
         virtual const DiskLoc& capExtent() const;
-        virtual void setCapExtent( TransactionExperiment* txn, const DiskLoc& loc );
+        virtual void setCapExtent( OperationContext* txn, const DiskLoc& loc );
 
         virtual const DiskLoc& capFirstNewRecord() const;
-        virtual void setCapFirstNewRecord( TransactionExperiment* txn, const DiskLoc& loc );
+        virtual void setCapFirstNewRecord( OperationContext* txn, const DiskLoc& loc );
 
         virtual bool capLooped() const;
 
         virtual long long dataSize() const;
         virtual long long numRecords() const;
 
-        virtual void incrementStats( TransactionExperiment* txn,
+        virtual void incrementStats( OperationContext* txn,
                                      long long dataSizeIncrement,
                                      long long numRecordsIncrement );
 
-        virtual void setStats( TransactionExperiment* txn,
+        virtual void setStats( OperationContext* txn,
                                long long dataSizeIncrement,
                                long long numRecordsIncrement );
 
         virtual const DiskLoc& deletedListEntry( int bucket ) const;
-        virtual void setDeletedListEntry( TransactionExperiment* txn,
+        virtual void setDeletedListEntry( OperationContext* txn,
                                           int bucket,
                                           const DiskLoc& loc );
-        virtual void orphanDeletedList(TransactionExperiment* txn);
+        virtual void orphanDeletedList(OperationContext* txn);
 
         virtual const DiskLoc& firstExtent() const;
-        virtual void setFirstExtent( TransactionExperiment* txn, const DiskLoc& loc );
+        virtual void setFirstExtent( OperationContext* txn, const DiskLoc& loc );
 
         virtual const DiskLoc& lastExtent() const;
-        virtual void setLastExtent( TransactionExperiment* txn, const DiskLoc& loc );
+        virtual void setLastExtent( OperationContext* txn, const DiskLoc& loc );
 
         virtual bool isCapped() const;
 
         virtual bool isUserFlagSet( int flag ) const;
 
         virtual int lastExtentSize() const;
-        virtual void setLastExtentSize( TransactionExperiment* txn, int newMax );
+        virtual void setLastExtentSize( OperationContext* txn, int newMax );
 
         virtual long long maxCappedDocs() const;
 
         virtual double paddingFactor() const;
 
-        virtual void setPaddingFactor( TransactionExperiment* txn, double paddingFactor );
+        virtual void setPaddingFactor( OperationContext* txn, double paddingFactor );
 
     protected:
 
@@ -148,22 +148,22 @@ namespace mongo {
     public:
         virtual ~DummyExtentManager();
 
-        virtual Status init(TransactionExperiment* txn);
+        virtual Status init(OperationContext* txn);
 
         virtual size_t numFiles() const;
         virtual long long fileSize() const;
 
         virtual void flushFiles( bool sync );
 
-        virtual DiskLoc allocateExtent( TransactionExperiment* txn,
+        virtual DiskLoc allocateExtent( OperationContext* txn,
                                         bool capped,
                                         int size,
                                         int quotaMax );
 
-        virtual void freeExtents( TransactionExperiment* txn,
+        virtual void freeExtents( OperationContext* txn,
                                   DiskLoc firstExt, DiskLoc lastExt );
 
-        virtual void freeExtent( TransactionExperiment* txn, DiskLoc extent );
+        virtual void freeExtent( OperationContext* txn, DiskLoc extent );
 
         virtual void freeListStats( int* numExtents, int64_t* totalFreeSize ) const;
 
@@ -209,7 +209,7 @@ namespace mongo {
      *
      * ExtentManager and MetaData must both be empty.
      */
-    void initializeV1RS(TransactionExperiment* txn,
+    void initializeV1RS(OperationContext* txn,
                         const LocAndSize* records,
                         const LocAndSize* drecs,
                         DummyExtentManager* em,
diff --git a/src/mongo/db/ttl.cpp b/src/mongo/db/ttl.cpp
index affef462400..f1d7e9cd8e2 100644
--- a/src/mongo/db/ttl.cpp
+++ b/src/mongo/db/ttl.cpp
@@ -43,7 +43,7 @@
 #include "mongo/db/ops/delete.h"
 #include "mongo/db/repl/is_master.h"
 #include "mongo/db/server_parameters.h"
-#include "mongo/db/storage/mmap_v1/dur_transaction.h"
+#include "mongo/db/operation_context_impl.h"
 #include "mongo/util/background.h"
 
 namespace mongo {
@@ -115,7 +115,7 @@ namespace mongo {
                 {
                     string ns = idx["ns"].String();
                     Client::WriteContext ctx( ns );
-                    DurTransaction txn;
+                    OperationContextImpl txn;
                     Collection* collection = ctx.ctx().db()->getCollection( ns );
                     if ( !collection ) {
                         // collection was dropped