SERVER-13896 Replace logOp() with a more operation-aware observer interface

54 files changed, 662 insertions, 374 deletions

diff --git a/src/mongo/SConscript b/src/mongo/SConscript
index 3670fafb4dd..404cce94c19 100644
--- a/src/mongo/SConscript
+++ b/src/mongo/SConscript
@@ -750,6 +750,7 @@ serverOnlyFiles = [ "db/background.cpp",
                     "db/introspect.cpp",
                     "db/matcher/expression_where.cpp",
                     "db/operation_context_impl.cpp",
+                    "db/op_observer.cpp",
                     "db/ops/delete.cpp",
                     "db/ops/insert.cpp",
                     "db/ops/parsed_delete.cpp",
diff --git a/src/mongo/db/auth/authorization_manager.cpp b/src/mongo/db/auth/authorization_manager.cpp
index 16485be8015..2a4ef685acb 100644
--- a/src/mongo/db/auth/authorization_manager.cpp
+++ b/src/mongo/db/auth/authorization_manager.cpp
@@ -1014,10 +1014,9 @@ namespace {
             const char* op,
             const char* ns,
             const BSONObj& o,
-            BSONObj* o2,
-            bool* b) {
+            BSONObj* o2) {
 
-        _externalState->logOp(txn, op, ns, o, o2, b);
+        _externalState->logOp(txn, op, ns, o, o2);
         if (appliesToAuthzData(op, ns, o)) {
             _invalidateRelevantCacheData(op, ns, o, o2);
         }
diff --git a/src/mongo/db/auth/authorization_manager.h b/src/mongo/db/auth/authorization_manager.h
index a6b4f4ae068..d430d1e8012 100644
--- a/src/mongo/db/auth/authorization_manager.h
+++ b/src/mongo/db/auth/authorization_manager.h
@@ -438,8 +438,7 @@ namespace mongo {
                    const char* opstr,
                    const char* ns,
                    const BSONObj& obj,
-                   BSONObj* patt,
-                   bool* b);
+                   BSONObj* patt);
 
     private:
         /**
diff --git a/src/mongo/db/auth/authz_manager_external_state.h b/src/mongo/db/auth/authz_manager_external_state.h
index 4c54cabc1aa..87c057b25da 100644
--- a/src/mongo/db/auth/authz_manager_external_state.h
+++ b/src/mongo/db/auth/authz_manager_external_state.h
@@ -233,8 +233,7 @@ namespace mongo {
                 const char* op,
                 const char* ns,
                 const BSONObj& o,
-                BSONObj* o2,
-                bool* b) {}
+                BSONObj* o2) {}
 
 
     protected:
diff --git a/src/mongo/db/auth/authz_manager_external_state_local.cpp b/src/mongo/db/auth/authz_manager_external_state_local.cpp
index ea843a2d4b0..410d3389986 100644
--- a/src/mongo/db/auth/authz_manager_external_state_local.cpp
+++ b/src/mongo/db/auth/authz_manager_external_state_local.cpp
@@ -375,18 +375,14 @@ namespace {
                                  const char* op,
                                  const char* ns,
                                  const BSONObj& o,
-                                 const BSONObj* o2,
-                                 const bool* b):
+                                 const BSONObj* o2):
             _externalState(externalState),
             _op(op),
             _ns(ns),
             _o(o.getOwned()),
 
             _isO2Set(o2 ? true : false),
-            _o2(_isO2Set ? o2->getOwned() : BSONObj()),
-
-            _isBSet(b ? true : false),
-            _b(_isBSet ? *b : false) {
+            _o2(_isO2Set ? o2->getOwned() : BSONObj()) {
 
         }
 
@@ -404,8 +400,6 @@ namespace {
                 oplogEntryBuilder << "op" << _op << "ns" << _ns << "o" << _o;
                 if (_isO2Set)
                     oplogEntryBuilder << "o2" << _o2;
-                if (_isBSet)
-                    oplogEntryBuilder << "b" << _b;
                 error() << "Unsupported modification to roles collection in oplog; "
                     "restart this process to reenable user-defined roles; " << status.reason() <<
                     "; Oplog entry: " << oplogEntryBuilder.done();
@@ -438,9 +432,6 @@ namespace {
 
         const bool _isO2Set;
         const BSONObj _o2;
-
-        const bool _isBSet;
-        const bool _b;
     };
 
     void AuthzManagerExternalStateLocal::logOp(
@@ -448,8 +439,7 @@ namespace {
             const char* op,
             const char* ns,
             const BSONObj& o,
-            BSONObj* o2,
-            bool* b) {
+            BSONObj* o2) {
 
         if (ns == AuthorizationManager::rolesCollectionNamespace.ns() ||
             ns == AuthorizationManager::adminCommandNamespace.ns()) {
@@ -458,8 +448,7 @@ namespace {
                                                                              op,
                                                                              ns,
                                                                              o,
-                                                                             o2,
-                                                                             b));
+                                                                             o2));
         }
     }
 
diff --git a/src/mongo/db/auth/authz_manager_external_state_local.h b/src/mongo/db/auth/authz_manager_external_state_local.h
index 87648b911c0..d5f852ac85d 100644
--- a/src/mongo/db/auth/authz_manager_external_state_local.h
+++ b/src/mongo/db/auth/authz_manager_external_state_local.h
@@ -69,8 +69,7 @@ namespace mongo {
                 const char* op,
                 const char* ns,
                 const BSONObj& o,
-                BSONObj* o2,
-                bool* b);
+                BSONObj* o2);
 
     protected:
         AuthzManagerExternalStateLocal();
diff --git a/src/mongo/db/auth/authz_manager_external_state_mock.cpp b/src/mongo/db/auth/authz_manager_external_state_mock.cpp
index c031cbc52cc..9d9f0cc0955 100644
--- a/src/mongo/db/auth/authz_manager_external_state_mock.cpp
+++ b/src/mongo/db/auth/authz_manager_external_state_mock.cpp
@@ -159,7 +159,6 @@ namespace {
                     "i",
                     collectionName.ns().c_str(),
                     toInsert,
-                    NULL,
                     NULL);
         }
 
@@ -200,8 +199,7 @@ namespace {
                         "u",
                         collectionName.ns().c_str(),
                         logObj,
-                        &idQuery,
-                        NULL);
+                        &idQuery);
             }
 
             return Status::OK();
@@ -256,7 +254,6 @@ namespace {
                         "d",
                         collectionName.ns().c_str(),
                         idQuery,
-                        NULL,
                         NULL);
             }
 
diff --git a/src/mongo/db/catalog/database.cpp b/src/mongo/db/catalog/database.cpp
index b556af32321..9252d6417ab 100644
--- a/src/mongo/db/catalog/database.cpp
+++ b/src/mongo/db/catalog/database.cpp
@@ -53,6 +53,7 @@
 #include "mongo/db/index/index_access_method.h"
 #include "mongo/db/instance.h"
 #include "mongo/db/introspect.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/repl/oplog.h"
 #include "mongo/db/server_parameters.h"
 #include "mongo/db/stats/top.h"
@@ -129,8 +130,8 @@ namespace mongo {
     void Database::close(OperationContext* txn ) {
         // XXX? - Do we need to close database under global lock or just DB-lock is sufficient ?
         invariant(txn->lockState()->isW());
-
-        repl::oplogCheckCloseDatabase(txn, this); // oplog caches some things, dirty its caches
+        // oplog caches some things, dirty its caches
+        repl::oplogCheckCloseDatabase(txn, this);
 
         if ( BackgroundOperation::inProgForDb( _name ) ) {
             log() << "warning: bg op in prog during close db? " << _name << endl;
@@ -271,11 +272,8 @@ namespace mongo {
                     continue;
                 }
 
-                string cmdNs = _name + ".$cmd";
-                repl::logOp( txn,
-                             "c",
-                             cmdNs.c_str(),
-                             BSON( "drop" << nsToCollectionSubstring( ns ) ) );
+                getGlobalEnvironment()->getOpObserver()->onDropCollection(
+                        txn, NamespaceString(ns));
                 wunit.commit();
             }
             catch (const WriteConflictException& exp) {
@@ -624,14 +622,9 @@ namespace mongo {
         invariant( db->createCollection( txn, ns, collectionOptions, true, createDefaultIndexes ) );
 
         if ( logForReplication ) {
-            if ( options.getField( "create" ).eoo() ) {
-                BSONObjBuilder b;
-                b << "create" << nsToCollectionSubstring( ns );
-                b.appendElements( options );
-                options = b.obj();
-            }
-            string logNs = nsToDatabase(ns) + ".$cmd";
-            repl::logOp(txn, "c", logNs.c_str(), options);
+            getGlobalEnvironment()->getOpObserver()->onCreateCollection(txn,
+                                                                        NamespaceString(ns),
+                                                                        collectionOptions);
         }
 
         return Status::OK();
diff --git a/src/mongo/db/catalog/index_create.cpp b/src/mongo/db/catalog/index_create.cpp
index 82d621260a1..c7a2536c3bc 100644
--- a/src/mongo/db/catalog/index_create.cpp
+++ b/src/mongo/db/catalog/index_create.cpp
@@ -46,7 +46,6 @@
 #include "mongo/db/concurrency/write_conflict_exception.h"
 #include "mongo/db/curop.h"
 #include "mongo/db/query/internal_plans.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/db/operation_context.h"
 #include "mongo/util/log.h"
diff --git a/src/mongo/db/cloner.cpp b/src/mongo/db/cloner.cpp
index 90f13bb0094..d22663f1f98 100644
--- a/src/mongo/db/cloner.cpp
+++ b/src/mongo/db/cloner.cpp
@@ -50,11 +50,12 @@
 #include "mongo/db/commands/rename_collection.h"
 #include "mongo/db/dbdirectclient.h"
 #include "mongo/db/dbhelpers.h"
+#include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/index_builder.h"
 #include "mongo/db/jsobj.h"
 #include "mongo/db/namespace_string.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/repl/isself.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/db/server_parameters.h"
 #include "mongo/db/storage_options.h"
@@ -150,10 +151,10 @@ namespace mongo {
                 verify(collection);
 
                 if (logForRepl) {
-                    repl::logOp(txn,
-                                "c",
-                                (_dbName + ".$cmd").c_str(),
-                                BSON("create" << to_collection.coll()));
+                    getGlobalEnvironment()->getOpObserver()->onCreateCollection(
+                            txn,
+                            to_collection,
+                            CollectionOptions());
                 }
                 wunit.commit();
             }
@@ -232,7 +233,7 @@ namespace mongo {
                 }
                 uassertStatusOK( loc.getStatus() );
                 if (logForRepl)
-                    repl::logOp(txn, "i", to_collection.ns().c_str(), js);
+                    getGlobalEnvironment()->getOpObserver()->onInsert(txn, to_collection.ns(), js);
 
                 wunit.commit();
 
@@ -339,10 +340,9 @@ namespace mongo {
             collection = db->createCollection( txn, to_collection.ns() );
             invariant(collection);
             if (logForRepl) {
-                repl::logOp(txn,
-                            "c",
-                            (toDBName + ".$cmd").c_str(),
-                            BSON("create" << to_collection.coll()));
+                getGlobalEnvironment()->getOpObserver()->onCreateCollection(txn,
+                                                                            to_collection,
+                                                                            CollectionOptions());
             }
             wunit.commit();
         }
@@ -371,7 +371,7 @@ namespace mongo {
             const char* createIndexNs = targetSystemIndexesCollectionName.c_str();
             for (vector<BSONObj>::const_iterator it = indexesToBuild.begin();
                     it != indexesToBuild.end(); ++it) {
-                repl::logOp(txn, "i", createIndexNs, *it);
+                getGlobalEnvironment()->getOpObserver()->onInsert(txn, createIndexNs, *it);
             }
         }
         wunit.commit();
@@ -650,7 +650,9 @@ namespace mongo {
 
                         c->deleteDocument(txn, *it, true, true, opts.logForRepl ? &id : NULL);
                         if (opts.logForRepl)
-                            repl::logOp(txn, "d", c->ns().ns().c_str(), id);
+                            getGlobalEnvironment()->getOpObserver()->onDelete(txn,
+                                                                              c->ns().ns(),
+                                                                              id);
                         wunit.commit();
                     }
 
@@ -661,10 +663,10 @@ namespace mongo {
                     WriteUnitOfWork wunit(txn);
                     indexer.commit();
                     if (opts.logForRepl) {
-                        repl::logOp(txn,
-                                    "i",
-                                    c->ns().getSystemIndexesCollection().c_str(),
-                                    c->getIndexCatalog()->getDefaultIdIndexSpec());
+                        getGlobalEnvironment()->getOpObserver()->onCreateIndex(
+                                txn,
+                                c->ns().getSystemIndexesCollection().c_str(),
+                                c->getIndexCatalog()->getDefaultIdIndexSpec());
                     }
                     wunit.commit();
                 }
diff --git a/src/mongo/db/commands/apply_ops.cpp b/src/mongo/db/commands/apply_ops.cpp
index dc8e09c22d6..69641f16c43 100644
--- a/src/mongo/db/commands/apply_ops.cpp
+++ b/src/mongo/db/commands/apply_ops.cpp
@@ -44,9 +44,11 @@
 #include "mongo/db/commands/dbhash.h"
 #include "mongo/db/concurrency/write_conflict_exception.h"
 #include "mongo/db/dbdirectclient.h"
+#include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/jsobj.h"
 #include "mongo/db/matcher/matcher.h"
 #include "mongo/db/operation_context_impl.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/util/log.h"
@@ -221,7 +223,9 @@ namespace mongo {
                 while (true) {
                     try {
                         WriteUnitOfWork wunit(txn);
-                        repl::logOp(txn, "c", tempNS.c_str(), cmdRewritten);
+                        getGlobalEnvironment()->getOpObserver()->onApplyOps(txn,
+                                                                            tempNS,
+                                                                            cmdRewritten);
                         wunit.commit();
                         break;
                     }
diff --git a/src/mongo/db/commands/clone.cpp b/src/mongo/db/commands/clone.cpp
index 63b8ae2679d..00efcfcf5c1 100644
--- a/src/mongo/db/commands/clone.cpp
+++ b/src/mongo/db/commands/clone.cpp
@@ -45,7 +45,6 @@
 #include "mongo/db/instance.h"
 #include "mongo/db/jsobj.h"
 #include "mongo/db/namespace_string.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/operation_context_impl.h"
 #include "mongo/db/storage_options.h"
 
diff --git a/src/mongo/db/commands/clone_collection.cpp b/src/mongo/db/commands/clone_collection.cpp
index afb048a7d4a..952044bc747 100644
--- a/src/mongo/db/commands/clone_collection.cpp
+++ b/src/mongo/db/commands/clone_collection.cpp
@@ -49,7 +49,6 @@
 #include "mongo/db/jsobj.h"
 #include "mongo/db/namespace_string.h"
 #include "mongo/db/repl/isself.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/operation_context_impl.h"
 #include "mongo/db/storage_options.h"
 #include "mongo/util/log.h"
diff --git a/src/mongo/db/commands/collection_to_capped.cpp b/src/mongo/db/commands/collection_to_capped.cpp
index 14e817840fa..9d15d3df794 100644
--- a/src/mongo/db/commands/collection_to_capped.cpp
+++ b/src/mongo/db/commands/collection_to_capped.cpp
@@ -35,10 +35,11 @@
 #include "mongo/db/background.h"
 #include "mongo/db/client.h"
 #include "mongo/db/commands.h"
+#include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/index_builder.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/query/internal_plans.h"
 #include "mongo/db/query/find.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/db/operation_context_impl.h"
 
@@ -123,8 +124,9 @@ namespace {
 
                 WriteUnitOfWork wunit(txn);
                 toCollection->insertDocument( txn, obj, true );
-                if ( logForReplication )
-                    repl::logOp(txn, "i", toNs.c_str(), obj);
+                if ( logForReplication ) {
+                    getGlobalEnvironment()->getOpObserver()->onInsert(txn, toNs, obj);
+                }
                 wunit.commit();
             }
         }
@@ -296,8 +298,12 @@ namespace {
             if ( !status.isOK() )
                 return appendCommandStatus( result, status );
 
-            if (!fromRepl)
-                repl::logOp(txn, "c",(dbname + ".$cmd").c_str(), jsobj);
+            if (!fromRepl) {
+                getGlobalEnvironment()->getOpObserver()->onConvertToCapped(
+                        txn,
+                        NamespaceString(longSource),
+                        size);
+            }
 
             wunit.commit();
             return true;
diff --git a/src/mongo/db/commands/copydb.cpp b/src/mongo/db/commands/copydb.cpp
index 29f28e305f0..d043f717ddd 100644
--- a/src/mongo/db/commands/copydb.cpp
+++ b/src/mongo/db/commands/copydb.cpp
@@ -49,7 +49,6 @@
 #include "mongo/db/instance.h"
 #include "mongo/db/jsobj.h"
 #include "mongo/db/namespace_string.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/operation_context_impl.h"
 #include "mongo/db/storage_options.h"
 
diff --git a/src/mongo/db/commands/copydb_start_commands.cpp b/src/mongo/db/commands/copydb_start_commands.cpp
index 56f430a5fb1..18979fa6022 100644
--- a/src/mongo/db/commands/copydb_start_commands.cpp
+++ b/src/mongo/db/commands/copydb_start_commands.cpp
@@ -50,7 +50,6 @@
 #include "mongo/db/instance.h"
 #include "mongo/db/jsobj.h"
 #include "mongo/db/namespace_string.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/operation_context_impl.h"
 #include "mongo/db/storage_options.h"
 #include "mongo/util/log.h"
diff --git a/src/mongo/db/commands/create_indexes.cpp b/src/mongo/db/commands/create_indexes.cpp
index 7da1cc30dd0..eed2eb96a13 100644
--- a/src/mongo/db/commands/create_indexes.cpp
+++ b/src/mongo/db/commands/create_indexes.cpp
@@ -42,9 +42,10 @@
 #include "mongo/db/commands.h"
 #include "mongo/db/concurrency/write_conflict_exception.h"
 #include "mongo/db/curop.h"
+#include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/operation_context_impl.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/ops/insert.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/s/d_state.h"
 #include "mongo/s/shard_key_pattern.h"
@@ -161,8 +162,10 @@ namespace mongo {
                     collection = db->createCollection( txn, ns.ns() );
                     invariant( collection );
                     if (!fromRepl) {
-                        repl::logOp(txn, "c", (dbname + ".$cmd").c_str(),
-                                    BSON("create" << ns.coll()));
+                        getGlobalEnvironment()->getOpObserver()->onCreateCollection(
+                                txn,
+                                ns,
+                                CollectionOptions());
                     }
                     wunit.commit();
                 } MONGO_WRITE_CONFLICT_RETRY_LOOP_END(txn, "createIndexes", ns.ns());
@@ -271,7 +274,9 @@ namespace mongo {
                 if ( !fromRepl ) {
                     for ( size_t i = 0; i < specs.size(); i++ ) {
                         std::string systemIndexes = ns.getSystemIndexesCollection();
-                        repl::logOp(txn, "i", systemIndexes.c_str(), specs[i]);
+                        getGlobalEnvironment()->getOpObserver()->onCreateIndex(txn,
+                                                                               systemIndexes,
+                                                                               specs[i]);
                     }
                 }
 
diff --git a/src/mongo/db/commands/drop_indexes.cpp b/src/mongo/db/commands/drop_indexes.cpp
index c2c2f05d6c1..e861204c1c4 100644
--- a/src/mongo/db/commands/drop_indexes.cpp
+++ b/src/mongo/db/commands/drop_indexes.cpp
@@ -40,6 +40,7 @@
 #include "mongo/db/commands.h"
 #include "mongo/db/curop.h"
 #include "mongo/db/dbdirectclient.h"
+#include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/index_builder.h"
 #include "mongo/db/index/index_descriptor.h"
 #include "mongo/db/catalog/collection.h"
@@ -49,7 +50,7 @@
 #include "mongo/db/catalog/index_create.h"
 #include "mongo/db/catalog/index_key_validate.h"
 #include "mongo/db/concurrency/write_conflict_exception.h"
-#include "mongo/db/repl/oplog.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/db/operation_context_impl.h"
 #include "mongo/util/log.h"
@@ -130,7 +131,9 @@ namespace mongo {
                     return false;
                 }
                 if (!fromRepl) {
-                    repl::logOp(txn, "c",(dbname + ".$cmd").c_str(), jsobj);
+                    getGlobalEnvironment()->getOpObserver()->onDropIndex(txn,
+                                                                         dbname + ".$cmd",
+                                                                         jsobj);
                 }
                 wunit.commit();
             } MONGO_WRITE_CONFLICT_RETRY_LOOP_END(txn, "dropIndexes", dbname);
diff --git a/src/mongo/db/commands/find_and_modify.cpp b/src/mongo/db/commands/find_and_modify.cpp
index acd9dbed9b1..2cba4a3960f 100644
--- a/src/mongo/db/commands/find_and_modify.cpp
+++ b/src/mongo/db/commands/find_and_modify.cpp
@@ -39,12 +39,13 @@
 #include "mongo/db/dbhelpers.h"
 #include "mongo/db/exec/update.h"
 #include "mongo/db/exec/working_set_common.h"
+#include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/projection.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/ops/delete.h"
 #include "mongo/db/ops/update.h"
 #include "mongo/db/ops/update_lifecycle_impl.h"
 #include "mongo/db/query/get_executor.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/util/log.h"
 
@@ -430,7 +431,9 @@ namespace mongo {
 
                         // This is the last thing we do before the WriteUnitOfWork commits (except
                         // for some BSON manipulation).
-                        repl::logOp(txn, "i", collection->ns().ns().c_str(), newDoc);
+                        getGlobalEnvironment()->getOpObserver()->onInsert(txn,
+                                                                          collection->ns().ns(),
+                                                                          newDoc); 
 
                         // Must commit the write and logOp() before doing anything that could throw.
                         wuow.commit();
diff --git a/src/mongo/db/commands/mr.cpp b/src/mongo/db/commands/mr.cpp
index cd0be7674c7..c3349c814eb 100644
--- a/src/mongo/db/commands/mr.cpp
+++ b/src/mongo/db/commands/mr.cpp
@@ -44,12 +44,13 @@
 #include "mongo/db/commands.h"
 #include "mongo/db/db.h"
 #include "mongo/db/dbhelpers.h"
+#include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/instance.h"
 #include "mongo/db/index/index_descriptor.h"
 #include "mongo/db/matcher/matcher.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/query/get_executor.h"
 #include "mongo/db/query/query_planner.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/db/range_preserver.h"
 #include "mongo/db/namespace_string.h"
@@ -439,7 +440,10 @@ namespace mongo {
                 b.append( "create", nsToCollectionSubstring( _config.tempNamespace ));
                 b.appendElements( options.toBSON() );
                 string logNs = nsToDatabase( _config.tempNamespace ) + ".$cmd";
-                repl::logOp(_txn, "c", logNs.c_str(), b.obj());
+                getGlobalEnvironment()->getOpObserver()->onCreateCollection(
+                        _txn,
+                        NamespaceString(_config.tempNamespace),
+                        options);
 
                 for ( vector<BSONObj>::iterator it = indexesToInsert.begin();
                         it != indexesToInsert.end(); ++it ) {
@@ -453,7 +457,7 @@ namespace mongo {
                     }
                     // Log the createIndex operation.
                     string logNs = nsToDatabase( _config.tempNamespace ) + ".system.indexes";
-                    repl::logOp(_txn, "i", logNs.c_str(), *it);
+                    getGlobalEnvironment()->getOpObserver()->onInsert(_txn, logNs, *it);
                 }
                 wuow.commit();
             }
@@ -690,7 +694,7 @@ namespace mongo {
             BSONObj bo = b.obj();
 
             uassertStatusOK( coll->insertDocument( _txn, bo, true ).getStatus() );
-            repl::logOp(_txn, "i", ns.c_str(), bo);
+            getGlobalEnvironment()->getOpObserver()->onInsert(_txn, ns, bo);
             wuow.commit();
         }
 
diff --git a/src/mongo/db/commands/oplog_note.cpp b/src/mongo/db/commands/oplog_note.cpp
index 00b34ead0da..bc41c2a1409 100644
--- a/src/mongo/db/commands/oplog_note.cpp
+++ b/src/mongo/db/commands/oplog_note.cpp
@@ -32,9 +32,11 @@
 #include "mongo/db/auth/action_type.h"
 #include "mongo/db/auth/authorization_session.h"
 #include "mongo/db/auth/resource_pattern.h"
+#include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/commands.h"
 #include "mongo/db/jsobj.h"
 #include "mongo/db/operation_context.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 
@@ -82,7 +84,7 @@ namespace mongo {
             Lock::GlobalWrite globalWrite(txn->lockState());
 
             WriteUnitOfWork wuow(txn);
-            repl::logOpComment(txn, dataElement.Obj());
+            getGlobalEnvironment()->getOpObserver()->onOpMessage(txn, dataElement.Obj());
             wuow.commit();
             return true;
         }
diff --git a/src/mongo/db/commands/rename_collection.cpp b/src/mongo/db/commands/rename_collection.cpp
index fdbf6ce220e..a9da366eb74 100644
--- a/src/mongo/db/commands/rename_collection.cpp
+++ b/src/mongo/db/commands/rename_collection.cpp
@@ -38,12 +38,13 @@
 #include "mongo/db/commands.h"
 #include "mongo/db/commands/rename_collection.h"
 #include "mongo/db/dbhelpers.h"
+#include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/index/index_descriptor.h"
 #include "mongo/db/index_builder.h"
 #include "mongo/db/namespace_string.h"
 #include "mongo/db/operation_context_impl.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/ops/insert.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/util/scopeguard.h"
 
@@ -245,7 +246,12 @@ namespace mongo {
                     }
 
                     if (!fromRepl) {
-                        repl::logOp(txn, "c", (dbname + ".$cmd").c_str(), cmdObj);
+                        getGlobalEnvironment()->getOpObserver()->onRenameCollection(
+                                txn,
+                                NamespaceString(source),
+                                NamespaceString(target),
+                                cmdObj["dropTarget"].trueValue(),
+                                cmdObj["stayTemp"].trueValue());
                     }
 
                     wunit.commit();
@@ -344,7 +350,12 @@ namespace mongo {
                 indexer.commit();
 
                 if (!fromRepl) {
-                    repl::logOp(txn, "c", (dbname + ".$cmd").c_str(), cmdObj);
+                    getGlobalEnvironment()->getOpObserver()->onRenameCollection(
+                            txn,
+                            NamespaceString(source),
+                            NamespaceString(target),
+                            cmdObj["dropTarget"].trueValue(),
+                            cmdObj["stayTemp"].trueValue());
                 }
 
                 wunit.commit();
diff --git a/src/mongo/db/commands/test_commands.cpp b/src/mongo/db/commands/test_commands.cpp
index de121a73002..34151c96303 100644
--- a/src/mongo/db/commands/test_commands.cpp
+++ b/src/mongo/db/commands/test_commands.cpp
@@ -36,10 +36,11 @@
 #include "mongo/base/initializer_context.h"
 #include "mongo/db/client.h"
 #include "mongo/db/commands.h"
+#include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/index_builder.h"
 #include "mongo/db/query/internal_plans.h"
 #include "mongo/db/catalog/collection.h"
-#include "mongo/db/repl/oplog.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/db/operation_context_impl.h"
 #include "mongo/util/log.h"
@@ -233,7 +234,7 @@ namespace mongo {
             IndexBuilder::restoreIndexes(txn, indexes);
 
             if (!fromRepl) {
-                repl::logOp(txn, "c", (dbname + ".$cmd").c_str(), cmdObj);
+                getGlobalEnvironment()->getOpObserver()->onEmptyCapped(txn, collection->ns());
             }
 
             wuow.commit();
diff --git a/src/mongo/db/commands/write_commands/batch_executor.cpp b/src/mongo/db/commands/write_commands/batch_executor.cpp
index 34f4a448021..ae0c16e30f6 100644
--- a/src/mongo/db/commands/write_commands/batch_executor.cpp
+++ b/src/mongo/db/commands/write_commands/batch_executor.cpp
@@ -39,6 +39,7 @@
 #include "mongo/db/catalog/database.h"
 #include "mongo/db/clientcursor.h"
 #include "mongo/db/commands.h"
+#include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/instance.h"
 #include "mongo/db/introspect.h"
 #include "mongo/db/lasterror.h"
@@ -48,6 +49,7 @@
 #include "mongo/db/concurrency/write_conflict_exception.h"
 #include "mongo/db/exec/delete.h"
 #include "mongo/db/exec/update.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/ops/delete_request.h"
 #include "mongo/db/ops/parsed_delete.h"
 #include "mongo/db/ops/parsed_update.h"
@@ -57,6 +59,7 @@
 #include "mongo/db/query/plan_executor.h"
 #include "mongo/db/query/query_knobs.h"
 #include "mongo/db/repl/oplog.h"
+#include "mongo/db/repl/repl_settings.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/db/server_parameters.h"
 #include "mongo/db/stats/counters.h"
@@ -1037,10 +1040,10 @@ namespace mongo {
                                             request->getTargetingNS())));
                 return false;
             }
-            repl::logOp(txn,
-                        "c",
-                        (database->name() + ".$cmd").c_str(),
-                        BSON("create" << nsToCollectionSubstring(request->getTargetingNS())));
+            getGlobalEnvironment()->getOpObserver()->onCreateCollection(
+                    txn,
+                    NamespaceString(request->getTargetingNS()),
+                    CollectionOptions());
             wunit.commit();
         }
         return true;
@@ -1156,7 +1159,7 @@ namespace mongo {
             result->setError(toWriteError(status.getStatus()));
         }
         else {
-            repl::logOp( txn, "i", insertNS.c_str(), docToInsert );
+            getGlobalEnvironment()->getOpObserver()->onInsert(txn, insertNS, docToInsert);
             result->getStats().n = 1;
             wunit.commit();
         }
diff --git a/src/mongo/db/db.cpp b/src/mongo/db/db.cpp
index 981c927b486..2fbee0bc850 100644
--- a/src/mongo/db/db.cpp
+++ b/src/mongo/db/db.cpp
@@ -71,10 +71,12 @@
 #include "mongo/db/log_process_details.h"
 #include "mongo/db/mongod_options.h"
 #include "mongo/db/operation_context_impl.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/query/internal_plans.h"
 #include "mongo/db/range_deleter_service.h"
 #include "mongo/db/repair_database.h"
 #include "mongo/db/repl/network_interface_impl.h"
+#include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/repl_settings.h"
 #include "mongo/db/repl/replication_coordinator_external_state_impl.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
@@ -462,6 +464,7 @@ namespace mongo {
         }
 
         getGlobalEnvironment()->setGlobalStorageEngine(storageGlobalParams.engine);
+        getGlobalEnvironment()->setOpObserver(std::unique_ptr<OpObserver>(new OpObserver));
 
         const repl::ReplSettings& replSettings =
                 repl::getGlobalReplicationCoordinator()->getSettings();
@@ -801,6 +804,7 @@ MONGO_INITIALIZER_WITH_PREREQUISITES(CreateReplicationManager, ("SetGlobalEnviro
             new repl::TopologyCoordinatorImpl(Seconds(repl::maxSyncSourceLagSecs)),
             static_cast<int64_t>(curTimeMillis64()));
     repl::setGlobalReplicationCoordinator(replCoord);
+    repl::setOplogCollectionName();
     getGlobalEnvironment()->registerKillOpListener(replCoord);
     return Status::OK();
 }
diff --git a/src/mongo/db/dbcommands.cpp b/src/mongo/db/dbcommands.cpp
index d5e246a43aa..add67a02143 100644
--- a/src/mongo/db/dbcommands.cpp
+++ b/src/mongo/db/dbcommands.cpp
@@ -58,6 +58,7 @@
 #include "mongo/db/db.h"
 #include "mongo/db/dbdirectclient.h"
 #include "mongo/db/dbhelpers.h"
+#include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/global_environment_d.h"
 #include "mongo/db/index_builder.h"
 #include "mongo/db/instance.h"
@@ -66,6 +67,7 @@
 #include "mongo/db/json.h"
 #include "mongo/db/lasterror.h"
 #include "mongo/db/namespace_string.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/ops/insert.h"
 #include "mongo/db/query/get_executor.h"
 #include "mongo/db/query/internal_plans.h"
@@ -73,7 +75,6 @@
 #include "mongo/db/repair_database.h"
 #include "mongo/db/repl/repl_settings.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/storage/storage_engine.h"
 #include "mongo/db/storage/mmap_v1/dur_stats.h"
 #include "mongo/db/write_concern.h"
@@ -217,7 +218,7 @@ namespace mongo {
                 WriteUnitOfWork wunit(txn);
 
                 if (!fromRepl) {
-                    repl::logOp(txn, "c", (dbname + ".$cmd").c_str(), cmdObj);
+                    getGlobalEnvironment()->getOpObserver()->onDropDatabase(txn, dbname + ".$cmd");
                 }
 
                 wunit.commit();
@@ -527,7 +528,9 @@ namespace mongo {
                 }
 
                 if ( !fromRepl ) {
-                    repl::logOp(txn, "c",(dbname + ".$cmd").c_str(), cmdObj);
+                    getGlobalEnvironment()->getOpObserver()->onDropCollection(
+                            txn,
+                            NamespaceString(nsToDrop));
                 }
                 wunit.commit();
             } MONGO_WRITE_CONFLICT_RETRY_LOOP_END(txn, "drop", nsToDrop);
@@ -1166,7 +1169,9 @@ namespace mongo {
             }
 
             if (!fromRepl) {
-                repl::logOp(txn, "c",(dbname + ".$cmd").c_str(), jsobj);
+                getGlobalEnvironment()->getOpObserver()->onCollMod(txn,
+                                                                   (dbname + ".$cmd").c_str(),
+                                                                   jsobj);
             }
 
             wunit.commit();
diff --git a/src/mongo/db/dbhelpers.cpp b/src/mongo/db/dbhelpers.cpp
index da3adfbc961..92f82960e3e 100644
--- a/src/mongo/db/dbhelpers.cpp
+++ b/src/mongo/db/dbhelpers.cpp
@@ -41,9 +41,11 @@
 #include "mongo/db/catalog/index_create.h"
 #include "mongo/db/db.h"
 #include "mongo/db/exec/working_set_common.h"
+#include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/json.h"
 #include "mongo/db/keypattern.h"
 #include "mongo/db/index/btree_access_method.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/ops/delete.h"
 #include "mongo/db/ops/update.h"
 #include "mongo/db/ops/update_lifecycle_impl.h"
@@ -53,7 +55,6 @@
 #include "mongo/db/query/internal_plans.h"
 #include "mongo/db/query/query_planner.h"
 #include "mongo/db/range_arithmetic.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/db/write_concern.h"
 #include "mongo/db/write_concern_options.h"
@@ -451,7 +452,7 @@ namespace mongo {
                 BSONObj deletedId;
                 collection->deleteDocument( txn, rloc, false, false, &deletedId );
                 // The above throws on failure, and so is not logged
-                repl::logOp(txn, "d", ns.c_str(), deletedId, 0, 0, fromMigrate);
+                getGlobalEnvironment()->getOpObserver()->onDelete(txn, ns, deletedId, fromMigrate);
                 wuow.commit();
                 numDeleted++;
             }
diff --git a/src/mongo/db/exec/delete.cpp b/src/mongo/db/exec/delete.cpp
index a2184a87b41..a6d8a967704 100644
--- a/src/mongo/db/exec/delete.cpp
+++ b/src/mongo/db/exec/delete.cpp
@@ -37,8 +37,8 @@
 #include "mongo/db/exec/scoped_timer.h"
 #include "mongo/db/exec/working_set_common.h"
 #include "mongo/db/global_environment_experiment.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/query/canonical_query.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/util/log.h"
 #include "mongo/util/scopeguard.h"
@@ -164,9 +164,11 @@ namespace mongo {
                             << ", not logging.";
                         }
                         else {
-                            bool replJustOne = true;
-                            repl::logOp(_txn, "d", _collection->ns().ns().c_str(), deletedDoc, 0,
-                                        &replJustOne, _params.fromMigrate);
+                            getGlobalEnvironment()->getOpObserver()->onDelete(
+                                    _txn,
+                                    _collection->ns().ns(),
+                                    deletedDoc,
+                                    _params.fromMigrate);
                         }
                     }
 
diff --git a/src/mongo/db/exec/update.cpp b/src/mongo/db/exec/update.cpp
index 04d7813cb47..0da9981261f 100644
--- a/src/mongo/db/exec/update.cpp
+++ b/src/mongo/db/exec/update.cpp
@@ -37,10 +37,10 @@
 #include "mongo/db/exec/scoped_timer.h"
 #include "mongo/db/exec/working_set_common.h"
 #include "mongo/db/global_environment_experiment.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/ops/update_lifecycle.h"
 #include "mongo/db/query/explain.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/util/log.h"
 #include "mongo/util/scopeguard.h"
 
@@ -590,13 +590,12 @@ namespace mongo {
             // Call logOp if requested, and we're not an explain.
             if (request->shouldCallLogOp() && !logObj.isEmpty() && !request->isExplain()) {
                 BSONObj idQuery = driver->makeOplogEntryQuery(newObj, request->isMulti());
-                repl::logOp(_txn,
-                            "u",
-                            request->getNamespaceString().ns().c_str(),
-                            logObj,
-                            &idQuery,
-                            NULL,
-                            request->isFromMigration());
+                getGlobalEnvironment()->getOpObserver()->onUpdate(
+                        _txn,
+                        request->getNamespaceString().ns().c_str(),
+                        logObj,
+                        idQuery,
+                        request->isFromMigration());
             }
 
             invariant(oldObj.snapshotId() == _txn->recoveryUnit()->getSnapshotId());
@@ -743,13 +742,10 @@ namespace mongo {
                                                                  !request->isGod()/*enforceQuota*/);
         uassertStatusOK(newLoc.getStatus());
         if (request->shouldCallLogOp()) {
-            repl::logOp(_txn,
-                        "i",
-                        request->getNamespaceString().ns().c_str(),
-                        newObj,
-                        NULL,
-                        NULL,
-                        request->isFromMigration());
+            getGlobalEnvironment()->getOpObserver()->onInsert(_txn,
+                                                              request->getNamespaceString().ns(),
+                                                              newObj,
+                                                              request->isFromMigration());
         }
 
         // Technically, we should save/restore state here, but since we are going to return EOF
diff --git a/src/mongo/db/global_environment_d.cpp b/src/mongo/db/global_environment_d.cpp
index 6f94d2a0f11..420f9c0779f 100644
--- a/src/mongo/db/global_environment_d.cpp
+++ b/src/mongo/db/global_environment_d.cpp
@@ -35,6 +35,7 @@
 #include "mongo/db/client.h"
 #include "mongo/db/curop.h"
 #include "mongo/db/operation_context_impl.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/storage/storage_engine.h"
 #include "mongo/db/storage/storage_engine_lock_file.h"
 #include "mongo/db/storage/storage_engine_metadata.h"
@@ -261,4 +262,12 @@ namespace mongo {
         return new OperationContextImpl();
     }
 
+    void GlobalEnvironmentMongoD::setOpObserver(std::unique_ptr<OpObserver> opObserver) {
+        _opObserver.reset(opObserver.get());
+    }
+
+    OpObserver* GlobalEnvironmentMongoD::getOpObserver() {
+        return _opObserver.get();
+    }
+
 }  // namespace mongo
diff --git a/src/mongo/db/global_environment_d.h b/src/mongo/db/global_environment_d.h
index d1bb679eee5..6c94098b03d 100644
--- a/src/mongo/db/global_environment_d.h
+++ b/src/mongo/db/global_environment_d.h
@@ -75,6 +75,9 @@ namespace mongo {
 
         OperationContext* newOpCtx();
 
+        void setOpObserver(std::unique_ptr<OpObserver> opObserver);
+
+        OpObserver* getOpObserver();
 
     private:
 
@@ -90,6 +93,9 @@ namespace mongo {
         // logically owned here, but never deleted by anyone.
         StorageEngine* _storageEngine;
 
+        // logically owned here.
+        std::unique_ptr<OpObserver> _opObserver;
+
         // All possible storage engines are registered here through MONGO_INIT.
         FactoryMap _storageFactories;
     };
diff --git a/src/mongo/db/global_environment_experiment.h b/src/mongo/db/global_environment_experiment.h
index b32fcce9f73..3c72a235aff 100644
--- a/src/mongo/db/global_environment_experiment.h
+++ b/src/mongo/db/global_environment_experiment.h
@@ -35,6 +35,7 @@
 namespace mongo {
 
     class OperationContext;
+    class OpObserver;
 
     /**
      * Classes that implement this interface can receive notification on killOp.
@@ -157,6 +158,20 @@ namespace mongo {
          */
         virtual OperationContext* newOpCtx() = 0;
 
+        //
+        // Global OpObserver.
+        //
+
+        /**
+         * Set the OpObserver.
+         */
+        virtual void setOpObserver(std::unique_ptr<OpObserver> opObserver) = 0;
+
+        /**
+         * Return the OpObserver instance we're using.
+         */
+        virtual OpObserver* getOpObserver() = 0;
+
     protected:
         GlobalEnvironmentExperiment() { }
     };
diff --git a/src/mongo/db/global_environment_noop.cpp b/src/mongo/db/global_environment_noop.cpp
index 498df1ff0e1..2170420a00e 100644
--- a/src/mongo/db/global_environment_noop.cpp
+++ b/src/mongo/db/global_environment_noop.cpp
@@ -31,6 +31,7 @@
 #include "mongo/db/global_environment_noop.h"
 
 #include "mongo/db/operation_context_noop.h"
+#include "mongo/db/op_observer.h"
 
 namespace mongo {
 
@@ -84,4 +85,10 @@ namespace mongo {
         return new OperationContextNoop();
     }
 
+    void GlobalEnvironmentNoop::setOpObserver(std::unique_ptr<OpObserver> opObserver) {
+    }
+
+    OpObserver* GlobalEnvironmentNoop::getOpObserver() {
+        return nullptr;
+    }
 }  // namespace mongo
diff --git a/src/mongo/db/global_environment_noop.h b/src/mongo/db/global_environment_noop.h
index 0bacdf8b009..dc946f28b7d 100644
--- a/src/mongo/db/global_environment_noop.h
+++ b/src/mongo/db/global_environment_noop.h
@@ -58,6 +58,10 @@ namespace mongo {
         void registerKillOpListener(KillOpListenerInterface* listener);
 
         OperationContext* newOpCtx();
+
+        void setOpObserver(std::unique_ptr<OpObserver> opObserver);
+
+        OpObserver* getOpObserver();
     };
 
 }  // namespace mongo
diff --git a/src/mongo/db/instance.cpp b/src/mongo/db/instance.cpp
index 96a9fa496b8..aa1cf74a859 100644
--- a/src/mongo/db/instance.cpp
+++ b/src/mongo/db/instance.cpp
@@ -67,6 +67,7 @@
 #include "mongo/db/catalog/index_create.h"
 #include "mongo/db/exec/delete.h"
 #include "mongo/db/exec/update.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/ops/delete_request.h"
 #include "mongo/db/ops/insert.h"
 #include "mongo/db/ops/parsed_delete.h"
@@ -880,15 +881,15 @@ namespace mongo {
                 if ( !collection ) {
                     collection = ctx.db()->createCollection( txn, ns );
                     verify( collection );
-                    repl::logOp(txn,
-                                "c",
-                                (ctx.db()->name() + ".$cmd").c_str(),
-                                BSON("create" << nsToCollectionSubstring(ns)));
+                    getGlobalEnvironment()->getOpObserver()->onCreateCollection(
+                            txn,
+                            NamespaceString(ns),
+                            CollectionOptions());
                 }
 
                 StatusWith<RecordId> status = collection->insertDocument( txn, js, true );
                 uassertStatusOK( status.getStatus() );
-                repl::logOp(txn, "i", ns, js);
+                getGlobalEnvironment()->getOpObserver()->onInsert(txn, std::string(ns), js);
                 wunit.commit();
                 break;
             }
diff --git a/src/mongo/db/op_observer.cpp b/src/mongo/db/op_observer.cpp
new file mode 100644
index 00000000000..25aa20b35a7
--- /dev/null
+++ b/src/mongo/db/op_observer.cpp
@@ -0,0 +1,235 @@
+/**
+*    Copyright (C) 2008-2014 MongoDB Inc.
+*
+*    This program is free software: you can redistribute it and/or  modify
+*    it under the terms of the GNU Affero General Public License, version 3,
+*    as published by the Free Software Foundation.
+*
+*    This program is distributed in the hope that it will be useful,
+*    but WITHOUT ANY WARRANTY; without even the implied warranty of
+*    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+*    GNU Affero General Public License for more details.
+*
+*    You should have received a copy of the GNU Affero General Public License
+*    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*
+*    As a special exception, the copyright holders give permission to link the
+*    code of portions of this program with the OpenSSL library under certain
+*    conditions as described in each individual source file and distribute
+*    linked combinations including the program with the OpenSSL library. You
+*    must comply with the GNU Affero General Public License in all respects for
+*    all of the code used other than as permitted herein. If you modify file(s)
+*    with this exception, you may extend this exception to your version of the
+*    file(s), but you are not obligated to do so. If you do not wish to do so,
+*    delete this exception statement from your version. If you delete this
+*    exception statement from all source files in the program, then also delete
+*    it in the license file.
+*/
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/op_observer.h"
+
+#include "mongo/db/auth/authorization_manager_global.h"
+#include "mongo/db/catalog/collection_options.h"
+#include "mongo/db/commands/dbhash.h"
+#include "mongo/db/dbdirectclient.h"
+#include "mongo/db/global_environment_experiment.h"
+#include "mongo/db/namespace_string.h"
+#include "mongo/db/repl/oplog.h"
+#include "mongo/db/repl/replication_coordinator_global.h"
+#include "mongo/s/d_state.h"
+#include "mongo/scripting/engine.h"
+
+namespace mongo {
+
+    void OpObserver::onCreateIndex(OperationContext* txn,
+                                   const std::string& ns,
+                                   BSONObj indexDoc,
+                                   bool fromMigrate) {
+        if (repl::getGlobalReplicationCoordinator()->isReplEnabled()) {
+            repl::_logOp(txn, "i", ns.c_str(), indexDoc, nullptr, fromMigrate);
+        }
+
+        getGlobalAuthorizationManager()->logOp(txn, "i", ns.c_str(), indexDoc, nullptr);
+        logOpForSharding(txn, "i", ns.c_str(), indexDoc, nullptr, fromMigrate);
+        logOpForDbHash(txn, ns.c_str());
+    }
+
+    void OpObserver::onInsert(OperationContext* txn,
+                              const std::string& ns,
+                              BSONObj doc,
+                              bool fromMigrate) {
+        if ( repl::getGlobalReplicationCoordinator()->isReplEnabled() ) {
+            repl::_logOp(txn, "i", ns.c_str(), doc, nullptr, fromMigrate);
+        }
+
+        getGlobalAuthorizationManager()->logOp(txn, "i", ns.c_str(), doc, nullptr);
+        logOpForSharding(txn, "i", ns.c_str(), doc, nullptr, fromMigrate);
+        logOpForDbHash(txn, ns.c_str());
+        if ( strstr( ns.c_str(), ".system.js" ) ) {
+            Scope::storedFuncMod(txn);
+        }
+    }
+
+    void OpObserver::onUpdate(OperationContext* txn,
+                              const std::string& ns,
+                              const BSONObj& update,
+                              BSONObj& criteria,
+                              bool fromMigrate) {
+        if ( repl::getGlobalReplicationCoordinator()->isReplEnabled() ) {
+            repl::_logOp(txn, "u", ns.c_str(), update, &criteria, fromMigrate);
+        }
+
+        getGlobalAuthorizationManager()->logOp(txn, "u", ns.c_str(), update, &criteria);
+        logOpForSharding(txn, "u", ns.c_str(), update, &criteria, fromMigrate);
+        logOpForDbHash(txn, ns.c_str());
+        if ( strstr( ns.c_str(), ".system.js" ) ) {
+            Scope::storedFuncMod(txn);
+        }
+    }
+
+    void OpObserver::onDelete(OperationContext* txn,
+                              const std::string& ns,
+                              const BSONObj& idDoc,
+                              bool fromMigrate) {
+
+        if ( repl::getGlobalReplicationCoordinator()->isReplEnabled() ) {
+            repl::_logOp(txn, "d", ns.c_str(), idDoc, nullptr, fromMigrate);
+        }
+
+        getGlobalAuthorizationManager()->logOp(txn, "d", ns.c_str(), idDoc, nullptr);
+        logOpForSharding(txn, "d", ns.c_str(), idDoc, nullptr, fromMigrate);
+        logOpForDbHash(txn, ns.c_str());
+        if ( strstr( ns.c_str(), ".system.js" ) ) {
+            Scope::storedFuncMod(txn);
+        }
+    }
+
+    void OpObserver::onOpMessage(OperationContext* txn, const BSONObj& msgObj) {
+        if ( repl::getGlobalReplicationCoordinator()->isReplEnabled() ) {
+            repl::_logOp(txn, "n", "", msgObj, nullptr, false);
+        }
+    }
+
+    void OpObserver::onCreateCollection(OperationContext* txn,
+                                        const NamespaceString& collectionName,
+                                        const CollectionOptions& options) {
+        std::string dbName = collectionName.db().toString() + ".$cmd";
+        BSONObjBuilder b;
+        b.append("create", collectionName.coll().toString());
+        b.appendElements(options.toBSON());
+        BSONObj cmdObj = b.obj();
+
+        if ( repl::getGlobalReplicationCoordinator()->isReplEnabled() ) {
+            repl::_logOp(txn, "c", dbName.c_str(), cmdObj, nullptr, false);
+        }
+
+        getGlobalAuthorizationManager()->logOp(txn, "c", dbName.c_str(), cmdObj, nullptr);
+        logOpForDbHash(txn, dbName.c_str());
+    }
+
+    void OpObserver::onCollMod(OperationContext* txn,
+                               const std::string& dbName,
+                               const BSONObj& collModCmd) {
+        if ( repl::getGlobalReplicationCoordinator()->isReplEnabled() ) {
+            repl::_logOp(txn, "c", dbName.c_str(), collModCmd, nullptr, false);
+        }
+
+        getGlobalAuthorizationManager()->logOp(txn, "c", dbName.c_str(), collModCmd, nullptr);
+        logOpForDbHash(txn, dbName.c_str());
+    }
+
+    void OpObserver::onDropDatabase(OperationContext* txn,
+                                    const std::string& dbName) {
+        BSONObj cmdObj = BSON("dropDatabase" << 1);
+
+        if ( repl::getGlobalReplicationCoordinator()->isReplEnabled() ) {
+            repl::_logOp(txn, "c", dbName.c_str(), cmdObj, nullptr, false);
+        }
+
+        getGlobalAuthorizationManager()->logOp(txn, "c", dbName.c_str(), cmdObj, nullptr);
+        logOpForDbHash(txn, dbName.c_str());
+    }
+
+    void OpObserver::onDropCollection(OperationContext* txn,
+                                      const NamespaceString& collectionName) {
+        std::string dbName = collectionName.db().toString() + ".$cmd";
+        BSONObj cmdObj = BSON("drop" << collectionName.coll().toString());
+
+        if ( repl::getGlobalReplicationCoordinator()->isReplEnabled() ) {
+            repl::_logOp(txn, "c", dbName.c_str(), cmdObj, nullptr, false);
+        }
+
+        getGlobalAuthorizationManager()->logOp(txn, "c", dbName.c_str(), cmdObj, nullptr);
+        logOpForDbHash(txn, dbName.c_str());
+    }
+
+    void OpObserver::onDropIndex(OperationContext* txn,
+                                 const std::string& dbName,
+                                 const BSONObj& idxDescriptor) {
+        if ( repl::getGlobalReplicationCoordinator()->isReplEnabled() ) {
+            repl::_logOp(txn, "c", dbName.c_str(), idxDescriptor, nullptr, false);
+        }
+
+        getGlobalAuthorizationManager()->logOp(txn, "c", dbName.c_str(), idxDescriptor, nullptr);
+        logOpForDbHash(txn, dbName.c_str());
+    }
+
+    void OpObserver::onRenameCollection(OperationContext* txn,
+                                        const NamespaceString& fromCollection,
+                                        const NamespaceString& toCollection,
+                                        bool dropTarget,
+                                        bool stayTemp) {
+        std::string dbName = fromCollection.db().toString() + ".$cmd";
+        BSONObj cmdObj = BSON("renameCollection" << fromCollection <<
+                              "to" << toCollection <<
+                              "stayTemp" << stayTemp <<
+                              "dropTarget" << dropTarget);
+
+        if ( repl::getGlobalReplicationCoordinator()->isReplEnabled() ) {
+            repl::_logOp(txn, "c", dbName.c_str(), cmdObj, nullptr, false);
+        }
+
+        getGlobalAuthorizationManager()->logOp(txn, "c", dbName.c_str(), cmdObj, nullptr);
+        logOpForDbHash(txn, dbName.c_str());
+    }
+
+    void OpObserver::onApplyOps(OperationContext* txn,
+                                const std::string& dbName,
+                                const BSONObj& applyOpCmd) {
+        if ( repl::getGlobalReplicationCoordinator()->isReplEnabled() ) {
+            repl::_logOp(txn, "c", dbName.c_str(), applyOpCmd, nullptr, false);
+        }
+
+        getGlobalAuthorizationManager()->logOp(txn, "c", dbName.c_str(), applyOpCmd, nullptr);
+        logOpForDbHash(txn, dbName.c_str());
+    }
+
+    void OpObserver::onConvertToCapped(OperationContext* txn,
+                                       const NamespaceString& collectionName,
+                                       double size) {
+        std::string dbName = collectionName.db().toString() + ".$cmd";
+        BSONObj cmdObj = BSON("convertToCapped" << collectionName.coll() << "size" << size);
+
+        if ( repl::getGlobalReplicationCoordinator()->isReplEnabled() ) {
+            repl::_logOp(txn, "c", dbName.c_str(), cmdObj, nullptr, false);
+        }
+
+        getGlobalAuthorizationManager()->logOp(txn, "c", dbName.c_str(), cmdObj, nullptr);
+        logOpForDbHash(txn, dbName.c_str());
+    }
+
+    void OpObserver::onEmptyCapped(OperationContext* txn, const NamespaceString& collectionName) {
+        std::string dbName = collectionName.db().toString() + ".$cmd";
+        BSONObj cmdObj = BSON("emptycapped" << collectionName.coll());
+
+        if ( repl::getGlobalReplicationCoordinator()->isReplEnabled() ) {
+            repl::_logOp(txn, "c", dbName.c_str(), cmdObj, nullptr, false);
+        }
+
+        getGlobalAuthorizationManager()->logOp(txn, "c", dbName.c_str(), cmdObj, nullptr);
+        logOpForDbHash(txn, dbName.c_str());
+    }
+
+} // namespace mongo
diff --git a/src/mongo/db/op_observer.h b/src/mongo/db/op_observer.h
new file mode 100644
index 00000000000..ebc296acf13
--- /dev/null
+++ b/src/mongo/db/op_observer.h
@@ -0,0 +1,88 @@
+/**
+ *    Copyright 2015 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#pragma once
+
+#include <string>
+
+#include "mongo/base/disallow_copying.h"
+
+namespace mongo {
+    class BSONObj;
+    struct CollectionOptions;
+    class NamespaceString;
+    class OperationContext;
+
+    class OpObserver {
+        MONGO_DISALLOW_COPYING(OpObserver);
+
+    public:
+        OpObserver() {}
+        ~OpObserver() {}
+        void onCreateIndex(OperationContext* txn,
+                           const std::string& ns,
+                           BSONObj indexDoc,
+                           bool fromMigrate = false);
+        void onInsert(OperationContext* txn,
+                      const std::string& ns,
+                      BSONObj doc,
+                      bool fromMigrate = false);
+        void onUpdate(OperationContext* txn,
+                      const std::string& ns,
+                      const BSONObj& update,
+                      BSONObj& criteria,
+                      bool fromMigrate);
+        void onDelete(OperationContext* txn,
+                      const std::string& ns,
+                      const BSONObj& idDoc,
+                      bool fromMigrate = false);
+        void onOpMessage(OperationContext* txn, const BSONObj& msgObj);
+        void onCreateCollection(OperationContext* txn,
+                                const NamespaceString& collectionName,
+                                const CollectionOptions& options);
+        void onCollMod(OperationContext* txn, const std::string& dbName, const BSONObj& collModCmd);
+        void onDropDatabase(OperationContext* txn, const std::string& dbName);
+        void onDropCollection(OperationContext* txn, const NamespaceString& collectionName);
+        void onDropIndex(OperationContext* txn,
+                         const std::string& dbName,
+                         const BSONObj& idxDescriptor);
+        void onRenameCollection(OperationContext* txn,
+                                const NamespaceString& fromCollection,
+                                const NamespaceString& toCollection,
+                                bool dropTarget,
+                                bool stayTemp);
+        void onApplyOps(OperationContext* txn,
+                        const std::string& dbName,
+                        const BSONObj& applyOpCmd);
+        void onEmptyCapped(OperationContext* txn, const NamespaceString& collectionName);
+        void onConvertToCapped(OperationContext* txn,
+                               const NamespaceString& collectionName,
+                               double size);
+    };
+
+} // namespace mongo
diff --git a/src/mongo/db/ops/update.cpp b/src/mongo/db/ops/update.cpp
index 9aeb9946a45..b92aa821bb3 100644
--- a/src/mongo/db/ops/update.cpp
+++ b/src/mongo/db/ops/update.cpp
@@ -40,12 +40,13 @@
 #include "mongo/db/clientcursor.h"
 #include "mongo/db/concurrency/d_concurrency.h"
 #include "mongo/db/exec/update.h"
+#include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/operation_context_impl.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/ops/update_driver.h"
 #include "mongo/db/ops/update_lifecycle.h"
 #include "mongo/db/query/explain.h"
 #include "mongo/db/query/get_executor.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/db/update_index_data.h"
 #include "mongo/util/log.h"
@@ -90,10 +91,10 @@ namespace mongo {
             invariant(collection);
 
             if (!request.isFromReplication()) {
-                repl::logOp(txn,
-                            "c",
-                            (db->name() + ".$cmd").c_str(),
-                            BSON("create" << (nsString.coll())));
+                getGlobalEnvironment()->getOpObserver()->onCreateCollection(
+                        txn,
+                        NamespaceString(nsString),
+                        CollectionOptions());
             }
             wuow.commit();
         }
diff --git a/src/mongo/db/repl/bgsync.cpp b/src/mongo/db/repl/bgsync.cpp
index 81a1a373264..ad2833df368 100644
--- a/src/mongo/db/repl/bgsync.cpp
+++ b/src/mongo/db/repl/bgsync.cpp
@@ -251,7 +251,7 @@ namespace {
             _replCoord->signalUpstreamUpdater();
         }
 
-        _syncSourceReader.tailingQueryGTE(rsoplog, lastOpTimeFetched);
+        _syncSourceReader.tailingQueryGTE(rsOplogName.c_str(), lastOpTimeFetched);
 
         // if target cut connections between connecting and querying (for
         // example, because it stepped down) we might not have a cursor
@@ -396,7 +396,7 @@ namespace {
 
         if (!r.more()) {
             try {
-                BSONObj theirLastOp = r.getLastOp(rsoplog);
+                BSONObj theirLastOp = r.getLastOp(rsOplogName.c_str());
                 if (theirLastOp.isEmpty()) {
                     error() << "empty query result from " << hn << " oplog";
                     sleepsecs(2);
@@ -497,7 +497,7 @@ namespace {
         try {
             ScopedTransaction transaction(txn, MODE_IX);
             Lock::DBLock lk(txn->lockState(), "local", MODE_X);
-            bool success = Helpers::getLast(txn, rsoplog, oplogEntry);
+            bool success = Helpers::getLast(txn, rsOplogName.c_str(), oplogEntry);
             if (!success) {
                 // This can happen when we are to do an initial sync.  lastHash will be set
                 // after the initial sync is complete.
@@ -505,18 +505,18 @@ namespace {
             }
         }
         catch (const DBException& ex) {
-            severe() << "Problem reading " << rsoplog << ": " << ex.toStatus();
+            severe() << "Problem reading " << rsOplogName << ": " << ex.toStatus();
             fassertFailed(18904);
         }
         BSONElement hashElement = oplogEntry[hashFieldName];
         if (hashElement.eoo()) {
-            severe() << "Most recent entry in " << rsoplog << " missing \"" << hashFieldName <<
+            severe() << "Most recent entry in " << rsOplogName << " missing \"" << hashFieldName <<
                 "\" field";
             fassertFailed(18902);
         }
         if (hashElement.type() != NumberLong) {
             severe() << "Expected type of \"" << hashFieldName << "\" in most recent " << 
-                rsoplog << " entry to have type NumberLong, but found " << 
+                rsOplogName << " entry to have type NumberLong, but found " << 
                 typeName(hashElement.type());
             fassertFailed(18903);
         }
diff --git a/src/mongo/db/repl/initial_sync.cpp b/src/mongo/db/repl/initial_sync.cpp
index 2f976f5ce5d..7e48453ae4e 100644
--- a/src/mongo/db/repl/initial_sync.cpp
+++ b/src/mongo/db/repl/initial_sync.cpp
@@ -33,7 +33,6 @@
 #include "mongo/db/repl/initial_sync.h"
 
 #include "mongo/db/operation_context_impl.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/replset_commands.h"
 #include "mongo/util/log.h"
 
diff --git a/src/mongo/db/repl/master_slave.cpp b/src/mongo/db/repl/master_slave.cpp
index e2873a7ea86..2782061bce3 100644
--- a/src/mongo/db/repl/master_slave.cpp
+++ b/src/mongo/db/repl/master_slave.cpp
@@ -55,6 +55,8 @@
 #include "mongo/db/commands.h"
 #include "mongo/db/dbdirectclient.h"
 #include "mongo/db/dbhelpers.h"
+#include "mongo/db/global_environment_experiment.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/ops/update.h"
 #include "mongo/db/query/internal_plans.h"
 #include "mongo/db/repl/handshake_args.h"
@@ -1281,7 +1283,7 @@ namespace repl {
 
                 try {
                     WriteUnitOfWork wuow(&txn);
-                    logKeepalive(&txn);
+                    getGlobalEnvironment()->getOpObserver()->onOpMessage(&txn, BSONObj());
                     wuow.commit();
                 }
                 catch (...) {
@@ -1326,8 +1328,6 @@ namespace repl {
 
     void startMasterSlave(OperationContext* txn) {
 
-        oldRepl();
-
         const ReplSettings& replSettings = getGlobalReplicationCoordinator()->getSettings();
         if( !replSettings.slave && !replSettings.master )
             return;
diff --git a/src/mongo/db/repl/oplog.cpp b/src/mongo/db/repl/oplog.cpp
index abda0997a35..76ba3f7ec20 100644
--- a/src/mongo/db/repl/oplog.cpp
+++ b/src/mongo/db/repl/oplog.cpp
@@ -53,6 +53,7 @@
 #include "mongo/db/global_optime.h"
 #include "mongo/db/index_builder.h"
 #include "mongo/db/namespace_string.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/ops/update.h"
 #include "mongo/db/ops/update_lifecycle_impl.h"
 #include "mongo/db/ops/delete.h"
@@ -79,18 +80,22 @@ namespace mongo {
     using std::stringstream;
 
 namespace repl {
+    std::string rsOplogName = "local.oplog.rs";
+    std::string masterSlaveOplogName = "local.oplog.$main";
+    int OPLOG_VERSION = 2;
 
 namespace {
     // cached copies of these...so don't rename them, drop them, etc.!!!
-    Database* localDB = NULL;
-    Collection* localOplogMainCollection = 0;
-    Collection* localOplogRSCollection = 0;
+    Database* _localDB = nullptr;
+    Collection* _localOplogCollection = nullptr;
 
     // Synchronizes the section where a new OpTime is generated and when it actually
     // appears in the oplog.
     mongo::mutex newOpMutex("oplogNewOp");
     boost::condition newOptimeNotifier;
 
+    static std::string _oplogCollectionName;
+
     // so we can fail the same way
     void checkOplogInsert( StatusWith<RecordId> result ) {
         massert( 17322,
@@ -98,7 +103,6 @@ namespace {
                  result.isOK() );
     }
 
-
     /**
      * Allocates an optime for a new entry in the oplog, and updates the replication coordinator to
      * reflect that new optime.  Returns the new optime and the correct value of the "h" field for
@@ -189,6 +193,18 @@ namespace {
         BSONObj _oField;
     };
 
+} // namespace
+
+    void setOplogCollectionName() {
+        if (getGlobalReplicationCoordinator()->getReplicationMode() ==
+                    ReplicationCoordinator::modeReplSet) {
+            _oplogCollectionName = rsOplogName;
+        }
+        else {
+            _oplogCollectionName = masterSlaveOplogName;
+        }
+    }
+
     /* we write to local.oplog.rs:
          { ts : ..., h: ..., v: ..., op: ..., etc }
        ts: an OpTime timestamp
@@ -208,40 +224,41 @@ namespace {
 
     */
 
-    void _logOpRS(OperationContext* txn,
-                         const char *opstr,
-                         const char *ns,
-                         const char *logNS,
-                         const BSONObj& obj,
-                         BSONObj *o2,
-                         bool *bb,
-                         bool fromMigrate ) {
+    void _logOp(OperationContext* txn,
+                const char *opstr,
+                const char *ns,
+                const BSONObj& obj,
+                BSONObj *o2,
+                bool fromMigrate) {
         if ( strncmp(ns, "local.", 6) == 0 ) {
             return;
         }
 
         Lock::DBLock lk(txn->lockState(), "local", MODE_IX);
-        Lock::OplogIntentWriteLock oplogLk(txn->lockState());
 
-        DEV verify( logNS == 0 ); // check this was never a master/slave master
+        ReplicationCoordinator* replCoord = getGlobalReplicationCoordinator();
 
-        if ( localOplogRSCollection == 0 ) {
-            Client::Context ctx(txn, rsoplog);
-            localDB = ctx.db();
-            invariant( localDB );
-            localOplogRSCollection = localDB->getCollection( rsoplog );
-            massert(13347, "local.oplog.rs missing. did you drop it? if so restart server", localOplogRSCollection);
+        if (ns[0] && replCoord->getReplicationMode() == ReplicationCoordinator::modeReplSet &&
+                    !replCoord->canAcceptWritesForDatabase(nsToDatabaseSubstring(ns))) {
+                severe() << "logOp() but can't accept write to collection " << ns;
+                fassertFailed(17405);
         }
-
-        ReplicationCoordinator* replCoord = getGlobalReplicationCoordinator();
-        if (ns[0] && !replCoord->canAcceptWritesForDatabase(nsToDatabaseSubstring(ns))) {
-            severe() << "logOp() but can't accept write to collection " << ns;
-            fassertFailed(17405);
+        Lock::CollectionLock lk2(txn->lockState(), _oplogCollectionName, MODE_IX);
+
+
+        if (_localOplogCollection == nullptr) {
+            Client::Context ctx(txn, _oplogCollectionName);
+            _localDB = ctx.db();
+            invariant(_localDB);
+            _localOplogCollection = _localDB->getCollection(_oplogCollectionName);
+            massert(13347,
+                    "the oplog collection " + _oplogCollectionName +
+                            " missing. did you drop it? if so, restart the server",
+                    _localOplogCollection);
         }
 
-        oplogLk.serializeIfNeeded();
         std::pair<OpTime, long long> slot = getNextOpTime(txn,
-                                                          localOplogRSCollection,
+                                                          _localOplogCollection,
                                                           ns,
                                                           replCoord,
                                                           opstr);
@@ -258,129 +275,16 @@ namespace {
         b.append("ns", ns);
         if (fromMigrate)
             b.appendBool("fromMigrate", true);
-        if ( bb )
-            b.appendBool("b", *bb);
         if ( o2 )
             b.append("o2", *o2);
         BSONObj partial = b.done();
 
         OplogDocWriter writer( partial, obj );
-        checkOplogInsert( localOplogRSCollection->insertDocument( txn, &writer, false ) );
+        checkOplogInsert( _localOplogCollection->insertDocument( txn, &writer, false ) );
 
         txn->getClient()->setLastOp( slot.first );
     }
 
-    void _logOpOld(OperationContext* txn,
-                          const char *opstr,
-                          const char *ns,
-                          const char *logNS,
-                          const BSONObj& obj,
-                          BSONObj *o2,
-                          bool *bb,
-                          bool fromMigrate ) {
-
-
-        if ( strncmp(ns, "local.", 6) == 0 ) {
-            return;
-        }
-
-        Lock::DBLock lk(txn->lockState(), "local", MODE_IX);
-
-        if( logNS == 0 ) {
-            logNS = "local.oplog.$main";
-        }
-
-        Lock::CollectionLock lk2(txn->lockState(), logNS, MODE_IX);
-
-        if (localOplogMainCollection == 0) {
-            Client::Context ctx(txn, logNS);
-            localDB = ctx.db();
-            invariant(localDB);
-            localOplogMainCollection = localDB->getCollection(logNS);
-            invariant(localOplogMainCollection);
-        }
-
-        ReplicationCoordinator* replCoord = getGlobalReplicationCoordinator();
-        std::pair<OpTime,long long> slot = getNextOpTime(txn,
-                                                         localOplogMainCollection,
-                                                         ns,
-                                                         replCoord,
-                                                         opstr);
-
-        /* we jump through a bunch of hoops here to avoid copying the obj buffer twice --
-           instead we do a single copy to the destination position in the memory mapped file.
-        */
-
-        BSONObjBuilder b(256);
-        b.appendTimestamp("ts", slot.first.asDate());
-        b.append("op", opstr);
-        b.append("ns", ns);
-        if (fromMigrate) 
-            b.appendBool("fromMigrate", true);
-        if ( bb )
-            b.appendBool("b", *bb);
-        if ( o2 )
-            b.append("o2", *o2);
-        BSONObj partial = b.done(); // partial is everything except the o:... part.
-
-        OplogDocWriter writer( partial, obj );
-        checkOplogInsert( localOplogMainCollection->insertDocument( txn, &writer, false ) );
-
-        txn->getClient()->setLastOp(slot.first);
-    }
-
-    void (*_logOp)(OperationContext* txn,
-                          const char *opstr,
-                          const char *ns,
-                          const char *logNS,
-                          const BSONObj& obj,
-                          BSONObj *o2,
-                          bool *bb,
-                          bool fromMigrate ) = _logOpRS;
-}  // namespace
-
-    void oldRepl() { _logOp = _logOpOld; }
-
-    void logKeepalive(OperationContext* txn) {
-        _logOp(txn, "n", "", 0, BSONObj(), 0, 0, false);
-    }
-    void logOpComment(OperationContext* txn, const BSONObj& obj) {
-        _logOp(txn, "n", "", 0, obj, 0, 0, false);
-    }
-    void logOpInitiate(OperationContext* txn, const BSONObj& obj) {
-        _logOpRS(txn, "n", "", 0, obj, 0, 0, false);
-    }
-
-    /*@ @param opstr:
-          c userCreateNS
-          i insert
-          n no-op / keepalive
-          d delete / remove
-          u update
-    */
-    void logOp(OperationContext* txn,
-               const char* opstr,
-               const char* ns,
-               const BSONObj& obj,
-               BSONObj* patt,
-               bool* b,
-               bool fromMigrate) {
-
-        if ( getGlobalReplicationCoordinator()->isReplEnabled() ) {
-            _logOp(txn, opstr, ns, 0, obj, patt, b, fromMigrate);
-        }
-
-        //
-        // rollback-safe logOp listeners
-        //
-        getGlobalAuthorizationManager()->logOp(txn, opstr, ns, obj, patt, b);
-        logOpForSharding(txn, opstr, ns, obj, patt, fromMigrate);
-        logOpForDbHash(txn, ns);
-        if ( strstr( ns, ".system.js" ) ) {
-            Scope::storedFuncMod(txn);
-        }
-    }
-
     OpTime writeOpsToOplog(OperationContext* txn, const std::deque<BSONObj>& ops) {
         ReplicationCoordinator* replCoord = getGlobalReplicationCoordinator();
         OpTime lastOptime = replCoord->getMyLastOptime();
@@ -391,18 +295,18 @@ namespace {
                 ScopedTransaction transaction(txn, MODE_IX);
                 Lock::DBLock lk(txn->lockState(), "local", MODE_X);
 
-                if ( localOplogRSCollection == 0 ) {
-                    Client::Context ctx(txn, rsoplog);
+                if ( _localOplogCollection == 0 ) {
+                    Client::Context ctx(txn, rsOplogName);
 
-                    localDB = ctx.db();
-                    verify( localDB );
-                    localOplogRSCollection = localDB->getCollection(rsoplog);
+                    _localDB = ctx.db();
+                    verify( _localDB );
+                    _localOplogCollection = _localDB->getCollection(rsOplogName);
                     massert(13389,
                             "local.oplog.rs missing. did you drop it? if so restart server",
-                            localOplogRSCollection);
+                            _localOplogCollection);
                 }
 
-                Client::Context ctx(txn, rsoplog, localDB);
+                Client::Context ctx(txn, rsOplogName, _localDB);
                 WriteUnitOfWork wunit(txn);
 
                 for (std::deque<BSONObj>::const_iterator it = ops.begin();
@@ -411,7 +315,7 @@ namespace {
                     const BSONObj& op = *it;
                     const OpTime ts = op["ts"]._opTime();
 
-                    checkOplogInsert(localOplogRSCollection->insertDocument(txn, op, false));
+                    checkOplogInsert(_localOplogCollection->insertDocument(txn, op, false));
 
                     if (!(lastOptime < ts)) {
                         severe() << "replication oplog stream went back in time. "
@@ -445,15 +349,11 @@ namespace {
         ScopedTransaction transaction(txn, MODE_X);
         Lock::GlobalWrite lk(txn->lockState());
 
-        const char * ns = "local.oplog.$main";
-
         const ReplSettings& replSettings = getGlobalReplicationCoordinator()->getSettings();
         bool rs = !replSettings.replSet.empty();
-        if( rs )
-            ns = rsoplog;
 
-        Client::Context ctx(txn, ns);
-        Collection* collection = ctx.db()->getCollection( ns );
+        Client::Context ctx(txn, _oplogCollectionName);
+        Collection* collection = ctx.db()->getCollection( _oplogCollectionName );
 
         if ( collection ) {
 
@@ -472,7 +372,7 @@ namespace {
             }
 
             if ( !rs )
-                initOpTimeFromOplog(txn, ns);
+                initOpTimeFromOplog(txn, _oplogCollectionName);
             return;
         }
 
@@ -512,9 +412,9 @@ namespace {
         options.autoIndexId = CollectionOptions::NO;
 
         WriteUnitOfWork uow( txn );
-        invariant(ctx.db()->createCollection(txn, ns, options));
+        invariant(ctx.db()->createCollection(txn, _oplogCollectionName, options));
         if( !rs )
-            logOp(txn, "n", "", BSONObj() );
+            getGlobalEnvironment()->getOpObserver()->onOpMessage(txn, BSONObj());
         uow.commit();
 
         /* sync here so we don't get any surprising lag later when we try to sync */
@@ -570,7 +470,7 @@ namespace {
             }
         }
         Collection* collection = db->getCollection( ns );
-        IndexCatalog* indexCatalog = collection == NULL ? NULL : collection->getIndexCatalog();
+        IndexCatalog* indexCatalog = collection == nullptr ? nullptr : collection->getIndexCatalog();
 
         // operation type -- see logOp() comments for types
         const char *opType = fieldOp.valuestrsafe();
@@ -758,8 +658,7 @@ namespace {
                 opType,
                 ns,
                 o,
-                fieldO2.isABSONObj() ? &o2 : NULL,
-                !fieldB.eoo() ? &valueB : NULL );
+                fieldO2.isABSONObj() ? &o2 : NULL);
         wuow.commit();
 
         return Status::OK();
@@ -797,9 +696,8 @@ namespace {
     void oplogCheckCloseDatabase(OperationContext* txn, Database* db) {
         invariant(txn->lockState()->isW());
 
-        localDB = NULL;
-        localOplogMainCollection = NULL;
-        localOplogRSCollection = NULL;
+        _localDB = nullptr;
+        _localOplogCollection = nullptr;
     }
 
 } // namespace repl
diff --git a/src/mongo/db/repl/oplog.h b/src/mongo/db/repl/oplog.h
index c84dfefb3d8..f2705bb2673 100644
--- a/src/mongo/db/repl/oplog.h
+++ b/src/mongo/db/repl/oplog.h
@@ -33,18 +33,22 @@
 #include <string>
 
 #include "mongo/base/status.h"
+#include "mongo/base/disallow_copying.h"
+#include "mongo/util/concurrency/mutex.h"
 
 namespace mongo {
     class BSONObj;
+    class Collection;
+    struct CollectionOptions;
     class Database;
+    class NamespaceString;
     class OperationContext;
     class OpTime;
+    class RecordId;
 
 namespace repl {
-
-    // Redefines the function for logOp() to master/slave.
-    void oldRepl();  // master-slave
-
+    class ReplicationCoordinator;
+ 
     // Create a new capped collection for the oplog if it doesn't yet exist.
     // This will be either local.oplog.rs (replica sets) or local.oplog.$main (master/slave)
     // If the collection already exists, set the 'last' OpTime if master/slave (side effect!)
@@ -56,44 +60,30 @@ namespace repl {
     // Returns the optime for the last op inserted.
     OpTime writeOpsToOplog(OperationContext* txn, const std::deque<BSONObj>& ops);
 
-    const char rsoplog[] = "local.oplog.rs";
-    static const int OPLOG_VERSION = 2;
-
-    /** Log an operation to the local oplog 
-
-       @param opstr
-        "i" insert
-        "u" update
-        "d" delete
-        "c" db cmd
-        "n" no-op
-        "db" declares presence of a database (ns is set to the db name + '.')
+    extern std::string rsOplogName;
+    extern std::string masterSlaveOplogName;
 
-       For 'u' records, 'obj' captures the mutation made to the object but not
-       the object itself. In that case, we provide also 'fullObj' which is the
-       image of the object _after_ the mutation logged here was applied.
+    extern int OPLOG_VERSION;
 
-       See _logOp() in oplog.cpp for more details.
-    */
-    void logOp( OperationContext* txn,
+    /** Log an operation to the local oplog 
+     *
+     * @param opstr
+     *  "i" insert
+     *  "u" update
+     *  "d" delete
+     *  "c" db cmd
+     *  "n" no-op
+     *  "db" declares presence of a database (ns is set to the db name + '.')
+     *
+     * For 'u' records, 'obj' captures the mutation made to the object but not
+     * the object itself. 'o2' captures the the criteria for the object that will be modified.
+     */
+    void _logOp(OperationContext* txn,
                 const char *opstr,
                 const char *ns,
                 const BSONObj& obj,
-                BSONObj *patt = NULL,
-                bool *b = NULL,
-                bool fromMigrate = false);
-
-    // Log an empty no-op operation to the local oplog
-    void logKeepalive(OperationContext* txn);
-
-    /** puts obj in the oplog as a comment (a no-op).  Just for diags.
-        convention is
-          { msg : "text", ... }
-    */
-    void logOpComment(OperationContext* txn, const BSONObj& obj);
-    
-    // Same as logOpComment, except only works for replsets
-    void logOpInitiate(OperationContext* txn, const BSONObj& obj);
+                BSONObj *o2,
+                bool fromMigrate);
 
     // Flush out the cached pointers to the local database and oplog.
     // Used by the closeDatabase command to ensure we don't cache closed things.
@@ -126,5 +116,10 @@ namespace repl {
      * Sets the global OpTime to be 'newTime'.
      */
     void setNewOptime(const OpTime& newTime);
+
+    /**
+     * Detects the current replication mode and sets the "_oplogCollectionName" accordingly.
+     */
+    void setOplogCollectionName();
 } // namespace repl
 } // namespace mongo
diff --git a/src/mongo/db/repl/oplogreader.cpp b/src/mongo/db/repl/oplogreader.cpp
index 90c8e449c08..9746d975fda 100644
--- a/src/mongo/db/repl/oplogreader.cpp
+++ b/src/mongo/db/repl/oplogreader.cpp
@@ -188,7 +188,7 @@ namespace repl {
             }
             // Read the first (oldest) op and confirm that it's not newer than our last
             // fetched op. Otherwise, we have fallen off the back of that source's oplog.
-            BSONObj remoteOldestOp(findOne(rsoplog, Query()));
+            BSONObj remoteOldestOp(findOne(rsOplogName.c_str(), Query()));
             BSONElement tsElem(remoteOldestOp["ts"]);
             if (tsElem.type() != Timestamp) {
                 // This member's got a bad op in its oplog.
diff --git a/src/mongo/db/repl/oplogreader.h b/src/mongo/db/repl/oplogreader.h
index 527452fd5fc..d8639ee8530 100644
--- a/src/mongo/db/repl/oplogreader.h
+++ b/src/mongo/db/repl/oplogreader.h
@@ -77,8 +77,8 @@ namespace repl {
         BSONObj findOne(const char *ns, const Query& q) {
             return conn()->findOne(ns, q, 0, QueryOption_SlaveOk);
         }
-        BSONObj getLastOp(const char *ns) {
-            return findOne(ns, Query().sort(reverseNaturalObj));
+        BSONObj getLastOp(const std::string& ns) {
+            return findOne(ns.c_str(), Query().sort(reverseNaturalObj));
         }
 
         /* SO_TIMEOUT (send/recv time out) for our DBClientConnections */
diff --git a/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp b/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp
index c1e3ac4b10d..9d5ba123213 100644
--- a/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp
+++ b/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp
@@ -45,6 +45,7 @@
 #include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/jsobj.h"
 #include "mongo/db/operation_context_impl.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/repl/bgsync.h"
 #include "mongo/db/repl/isself.h"
 #include "mongo/db/repl/master_slave.h"
@@ -115,7 +116,7 @@ namespace {
         Lock::GlobalWrite globalWrite(txn->lockState());
 
         WriteUnitOfWork wuow(txn);
-        logOpInitiate(txn, BSON("msg" << "initiating set"));
+        getGlobalEnvironment()->getOpObserver()->onOpMessage(txn, BSON("msg" << "initiating set"));
         wuow.commit();
     }
 
@@ -193,23 +194,23 @@ namespace {
 
         try {
             BSONObj oplogEntry;
-            if (!Helpers::getLast(txn, rsoplog, oplogEntry)) {
+            if (!Helpers::getLast(txn, rsOplogName.c_str(), oplogEntry)) {
                 return StatusWith<OpTime>(
                         ErrorCodes::NoMatchingDocument,
-                        str::stream() << "Did not find any entries in " << rsoplog);
+                        str::stream() << "Did not find any entries in " << rsOplogName);
             }
             BSONElement tsElement = oplogEntry[tsFieldName];
             if (tsElement.eoo()) {
                 return StatusWith<OpTime>(
                         ErrorCodes::NoSuchKey,
-                        str::stream() << "Most recent entry in " << rsoplog << " missing \"" <<
+                        str::stream() << "Most recent entry in " << rsOplogName << " missing \"" <<
                         tsFieldName << "\" field");
             }
             if (tsElement.type() != Timestamp) {
                 return StatusWith<OpTime>(
                         ErrorCodes::TypeMismatch,
                         str::stream() << "Expected type of \"" << tsFieldName <<
-                        "\" in most recent " << rsoplog <<
+                        "\" in most recent " << rsOplogName <<
                         " entry to have type Timestamp, but found " << typeName(tsElement.type()));
             }
             return StatusWith<OpTime>(tsElement._opTime());
diff --git a/src/mongo/db/repl/replication_info.cpp b/src/mongo/db/repl/replication_info.cpp
index cf7ff0faabb..a836ef84cc6 100644
--- a/src/mongo/db/repl/replication_info.cpp
+++ b/src/mongo/db/repl/replication_info.cpp
@@ -178,13 +178,13 @@ namespace repl {
             BSONObjBuilder result;
             result.append("latestOptime", replCoord->getMyLastOptime());
 
-            const char* oplogNS =
+            const std::string& oplogNS =
                 replCoord->getReplicationMode() == ReplicationCoordinator::modeReplSet ?
-                    rsoplog : "local.oplog.$main";
+                    rsOplogName : masterSlaveOplogName;
             BSONObj o;
             uassert(17347,
                     "Problem reading earliest entry from oplog",
-                    Helpers::getSingleton(txn, oplogNS, o));
+                    Helpers::getSingleton(txn, oplogNS.c_str(), o));
             result.append("earliestOptime", o["ts"]._opTime());
             return result.obj();
         }
diff --git a/src/mongo/db/repl/replset_commands.cpp b/src/mongo/db/repl/replset_commands.cpp
index a67b8ca6480..f3ad62ead42 100644
--- a/src/mongo/db/repl/replset_commands.cpp
+++ b/src/mongo/db/repl/replset_commands.cpp
@@ -41,6 +41,7 @@
 #include "mongo/db/commands.h"
 #include "mongo/db/dbhelpers.h"
 #include "mongo/db/global_environment_experiment.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/repl_set_heartbeat_args.h"
 #include "mongo/db/repl/repl_set_heartbeat_response.h"
@@ -318,8 +319,10 @@ namespace {
 
             WriteUnitOfWork wuow(txn);
             if (status.isOK() && !parsedArgs.force) {
-                logOpInitiate(txn, BSON("msg" << "Reconfig set" <<
-                                        "version" << parsedArgs.newConfigObj["version"]));
+                getGlobalEnvironment()->getOpObserver()->onOpMessage(
+                        txn,
+                        BSON("msg" << "Reconfig set" <<
+                             "version" << parsedArgs.newConfigObj["version"]));
             }
             wuow.commit();
 
@@ -553,7 +556,7 @@ namespace {
 
             // we have a local database.  return true if oplog isn't empty
             BSONObj o;
-            if (Helpers::getSingleton(txn, repl::rsoplog, o)) {
+            if (Helpers::getSingleton(txn, repl::rsOplogName.c_str(), o)) {
                 return true;
             }
         }
diff --git a/src/mongo/db/repl/rs_initialsync.cpp b/src/mongo/db/repl/rs_initialsync.cpp
index 47b30ee5543..1d3f17b1536 100644
--- a/src/mongo/db/repl/rs_initialsync.cpp
+++ b/src/mongo/db/repl/rs_initialsync.cpp
@@ -39,8 +39,10 @@
 #include "mongo/db/client.h"
 #include "mongo/db/cloner.h"
 #include "mongo/db/dbhelpers.h"
+#include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/operation_context_impl.h"
 #include "mongo/db/operation_context_impl.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/repl/bgsync.h"
 #include "mongo/db/repl/initial_sync.h"
 #include "mongo/db/repl/minvalid.h"
@@ -70,7 +72,7 @@ namespace {
                                BackgroundSync* bgsync) {
         AutoGetDb autoDb(txn, "local", MODE_X);
         massert(28585, "no local database found", autoDb.getDb());
-        invariant(txn->lockState()->isCollectionLockedForMode(rsoplog, MODE_X));
+        invariant(txn->lockState()->isCollectionLockedForMode(rsOplogName, MODE_X));
         // Note: the following order is important.
         // The bgsync thread uses an empty optime as a sentinel to know to wait
         // for initial sync; thus, we must
@@ -83,7 +85,7 @@ namespace {
         replCoord->clearSyncSourceBlacklist();
 
         // Truncate the oplog in case there was a prior initial sync that failed.
-        Collection* collection = autoDb.getDb()->getCollection(rsoplog);
+        Collection* collection = autoDb.getDb()->getCollection(rsOplogName);
         fassert(28565, collection);
         WriteUnitOfWork wunit(txn);
         Status status = collection->truncate(txn);
@@ -153,7 +155,7 @@ namespace {
             // A common problem is that TCP keepalives are set too infrequent, and thus
             // our connection here is terminated by a firewall due to inactivity.
             // Solution is to increase the TCP keepalive frequency.
-            lastOp = r->getLastOp(rsoplog);
+            lastOp = r->getLastOp(rsOplogName);
         } catch ( SocketException & ) {
             HostAndPort host = r->getHost();
             log() << "connection lost to " << host.toString() << 
@@ -163,7 +165,7 @@ namespace {
                 throw;
             }
             // retry
-            lastOp = r->getLastOp(rsoplog);
+            lastOp = r->getLastOp(rsOplogName);
         }
 
         if (lastOp.isEmpty()) {
@@ -292,7 +294,7 @@ namespace {
         InitialSync init(bgsync);
         init.setHostname(r.getHost().toString());
 
-        BSONObj lastOp = r.getLastOp(rsoplog);
+        BSONObj lastOp = r.getLastOp(rsOplogName);
         if ( lastOp.isEmpty() ) {
             std::string msg = "initial sync couldn't read remote oplog";
             log() << msg;
diff --git a/src/mongo/db/repl/rs_rollback.cpp b/src/mongo/db/repl/rs_rollback.cpp
index d1444ab6ac4..aba19c1e1f8 100644
--- a/src/mongo/db/repl/rs_rollback.cpp
+++ b/src/mongo/db/repl/rs_rollback.cpp
@@ -259,12 +259,12 @@ namespace {
     void syncRollbackFindCommonPoint(OperationContext* txn, 
                                      DBClientConnection* them, 
                                      FixUpInfo& fixUpInfo) {
-        Client::Context ctx(txn, rsoplog);
+        Client::Context ctx(txn, rsOplogName);
 
         boost::scoped_ptr<PlanExecutor> exec(
                 InternalPlanner::collectionScan(txn,
-                                                rsoplog,
-                                                ctx.db()->getCollection(rsoplog),
+                                                rsOplogName,
+                                                ctx.db()->getCollection(rsOplogName),
                                                 InternalPlanner::BACKWARD));
 
         BSONObj ourObj;
@@ -277,10 +277,10 @@ namespace {
         const Query query = Query().sort(reverseNaturalObj);
         const BSONObj fields = BSON("ts" << 1 << "h" << 1);
 
-        //auto_ptr<DBClientCursor> u = us->query(rsoplog, query, 0, 0, &fields, 0, 0);
+        //auto_ptr<DBClientCursor> u = us->query(rsOplogName, query, 0, 0, &fields, 0, 0);
 
         fixUpInfo.rbid = getRBID(them);
-        auto_ptr<DBClientCursor> oplogCursor = them->query(rsoplog, query, 0, 0, &fields, 0, 0);
+        auto_ptr<DBClientCursor> oplogCursor = them->query(rsOplogName, query, 0, 0, &fields, 0, 0);
 
         if (oplogCursor.get() == NULL || !oplogCursor->more())
             throw RSFatalException("remote oplog empty or unreadable");
@@ -418,7 +418,7 @@ namespace {
                     goodVersions.push_back(pair<DocID, BSONObj>(doc,good));
                 }
             }
-            newMinValid = oplogreader->getLastOp(rsoplog);
+            newMinValid = oplogreader->getLastOp(rsOplogName);
             if (newMinValid.isEmpty()) {
                 error() << "rollback error newMinValid empty?";
                 return;
@@ -493,7 +493,7 @@ namespace {
 
             string err;
             try {
-                newMinValid = oplogreader->getLastOp(rsoplog);
+                newMinValid = oplogreader->getLastOp(rsOplogName);
                 if (newMinValid.isEmpty()) {
                     err = "can't get minvalid from sync source";
                 }
@@ -539,10 +539,10 @@ namespace {
         }
 
         log() << "rollback 4.7";
-        Client::Context ctx(txn, rsoplog);
-        Collection* oplogCollection = ctx.db()->getCollection(rsoplog);
+        Client::Context ctx(txn, rsOplogName);
+        Collection* oplogCollection = ctx.db()->getCollection(rsOplogName);
         uassert(13423,
-                str::stream() << "replSet error in rollback can't find " << rsoplog,
+                str::stream() << "replSet error in rollback can't find " << rsOplogName,
                 oplogCollection);
 
         map<string,shared_ptr<Helpers::RemoveSaver> > removeSavers;
diff --git a/src/mongo/db/repl/rs_sync.cpp b/src/mongo/db/repl/rs_sync.cpp
index ca95eec0442..174147fb078 100644
--- a/src/mongo/db/repl/rs_sync.cpp
+++ b/src/mongo/db/repl/rs_sync.cpp
@@ -46,7 +46,6 @@
 #include "mongo/db/namespace_string.h"
 #include "mongo/db/repl/bgsync.h"
 #include "mongo/db/repl/minvalid.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/repl_settings.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/db/repl/rs_initialsync.h"
diff --git a/src/mongo/dbtests/oplogstarttests.cpp b/src/mongo/dbtests/oplogstarttests.cpp
index ff907f964e9..a3b67efac51 100644
--- a/src/mongo/dbtests/oplogstarttests.cpp
+++ b/src/mongo/dbtests/oplogstarttests.cpp
@@ -30,7 +30,6 @@
 #include "mongo/db/exec/working_set.h"
 #include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/query/canonical_query.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/repl_settings.h"
 #include "mongo/db/operation_context_impl.h"
 #include "mongo/db/catalog/collection.h"
diff --git a/src/mongo/dbtests/repltests.cpp b/src/mongo/dbtests/repltests.cpp
index 9b4d67608db..483d3e6d9c9 100644
--- a/src/mongo/dbtests/repltests.cpp
+++ b/src/mongo/dbtests/repltests.cpp
@@ -79,7 +79,6 @@ namespace ReplTests {
             ReplicationCoordinatorMock* replCoord = new ReplicationCoordinatorMock(replSettings);
             setGlobalReplicationCoordinator(replCoord);
 
-            oldRepl();
             createOplog(&_txn);
 
             Client::WriteContext ctx(&_txn, ns());
diff --git a/src/mongo/s/d_migrate.cpp b/src/mongo/s/d_migrate.cpp
index 8d2df1535fb..64486cc827d 100644
--- a/src/mongo/s/d_migrate.cpp
+++ b/src/mongo/s/d_migrate.cpp
@@ -61,13 +61,14 @@
 #include "mongo/db/exec/plan_stage.h"
 #include "mongo/db/storage/mmap_v1/dur.h"
 #include "mongo/db/field_parser.h"
+#include "mongo/db/global_environment_experiment.h"
 #include "mongo/db/hasher.h"
 #include "mongo/db/jsobj.h"
+#include "mongo/db/op_observer.h"
 #include "mongo/db/ops/delete.h"
 #include "mongo/db/query/internal_plans.h"
 #include "mongo/db/query/query_knobs.h"
 #include "mongo/db/range_deleter_service.h"
-#include "mongo/db/repl/oplog.h"
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/db/operation_context_impl.h"
 #include "mongo/db/write_concern.h"
@@ -2050,8 +2051,11 @@ namespace mongo {
 
                     for (size_t i = 0; i < indexSpecs.size(); i++) {
                         // make sure to create index on secondaries as well
-                        repl::logOp(txn, "i", db->getSystemIndexesName().c_str(), indexSpecs[i],
-                                       NULL, NULL, true /* fromMigrate */);
+                        getGlobalEnvironment()->getOpObserver()->onCreateIndex(
+                                txn,
+                                db->getSystemIndexesName(),
+                                indexSpecs[i],
+                                true /* fromMigrate */);
                     }
 
                     wunit.commit();