SERVER-13641 rename TransactionExperiment to OperationContext

8 files changed, 41 insertions, 313 deletions

diff --git a/src/mongo/db/storage/data_file.cpp b/src/mongo/db/storage/data_file.cpp
index adeaf34b129..b6466fd5b71 100644
--- a/src/mongo/db/storage/data_file.cpp
+++ b/src/mongo/db/storage/data_file.cpp
@@ -37,7 +37,7 @@
 #include "mongo/db/d_concurrency.h"
 #include "mongo/db/storage/mmap_v1/dur.h"
 #include "mongo/db/lockstate.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/util/file_allocator.h"
 
 namespace mongo {
@@ -88,7 +88,7 @@ namespace mongo {
     }
 
     /** @return true if found and opened. if uninitialized (prealloc only) does not open. */
-    Status DataFile::openExisting( TransactionExperiment* txn, const char *filename ) {
+    Status DataFile::openExisting( OperationContext* txn, const char *filename ) {
         verify( _mb == 0 );
         if( !boost::filesystem::exists(filename) )
             return Status( ErrorCodes::InvalidPath, "DataFile::openExisting - file does not exist" );
@@ -118,7 +118,7 @@ namespace mongo {
         return Status::OK();
     }
 
-    void DataFile::open( TransactionExperiment* txn,
+    void DataFile::open( OperationContext* txn,
                          const char *filename,
                          int minSize,
                          bool preallocateOnly ) {
@@ -160,7 +160,7 @@ namespace mongo {
         mmf.flush( sync );
     }
 
-    DiskLoc DataFile::allocExtentArea( TransactionExperiment* txn, int size ) {
+    DiskLoc DataFile::allocExtentArea( OperationContext* txn, int size ) {
 
         massert( 10357, "shutdown in progress", !inShutdown() );
         massert( 10359, "header==0 on new extent: 32 bit mmap space exceeded?", header() ); // null if file open failed
@@ -178,7 +178,7 @@ namespace mongo {
 
     // -------------------------------------------------------------------------------
 
-    void DataFileHeader::init(TransactionExperiment* txn, int fileno, int filelength, const char* filename) {
+    void DataFileHeader::init(OperationContext* txn, int fileno, int filelength, const char* filename) {
         if ( uninitialized() ) {
             DEV log() << "datafileheader::init initializing " << filename << " n:" << fileno << endl;
             if( !(filelength > 32768 ) ) {
@@ -217,7 +217,7 @@ namespace mongo {
         }
     }
 
-    void DataFileHeader::checkUpgrade(TransactionExperiment* txn) {
+    void DataFileHeader::checkUpgrade(OperationContext* txn) {
         if ( freeListStart == minDiskLoc ) {
             // we are upgrading from 2.4 to 2.6
             invariant( freeListEnd == minDiskLoc ); // both start and end should be (0,0) or real
diff --git a/src/mongo/db/storage/data_file.h b/src/mongo/db/storage/data_file.h
index d96d20dffd7..f83e9f8f08f 100644
--- a/src/mongo/db/storage/data_file.h
+++ b/src/mongo/db/storage/data_file.h
@@ -37,7 +37,7 @@
 namespace mongo {
 
     class ExtentManager;
-    class TransactionExperiment;
+    class OperationContext;
 
     /*  a datafile - i.e. the "dbname.<#>" files :
 
@@ -77,9 +77,9 @@ namespace mongo {
 
         bool uninitialized() const { return version == 0; }
 
-        void init(TransactionExperiment* txn, int fileno, int filelength, const char* filename);
+        void init(OperationContext* txn, int fileno, int filelength, const char* filename);
 
-        void checkUpgrade(TransactionExperiment* txn);
+        void checkUpgrade(OperationContext* txn);
 
         bool isEmpty() const {
             return uninitialized() || ( unusedLength == fileLength - HeaderSize - 16 );
@@ -95,15 +95,15 @@ namespace mongo {
         DataFile(int fn) : _mb(0), fileNo(fn) { }
 
         /** @return true if found and opened. if uninitialized (prealloc only) does not open. */
-        Status openExisting( TransactionExperiment* txn, const char *filename );
+        Status openExisting( OperationContext* txn, const char *filename );
 
         /** creates if DNE */
-        void open(TransactionExperiment* txn,
+        void open(OperationContext* txn,
                   const char *filename,
                   int requestedDataSize = 0,
                   bool preallocateOnly = false);
 
-        DiskLoc allocExtentArea( TransactionExperiment* txn, int size );
+        DiskLoc allocExtentArea( OperationContext* txn, int size );
 
         DataFileHeader* getHeader() { return header(); }
         const DataFileHeader* getHeader() const { return header(); }
diff --git a/src/mongo/db/storage/extent_manager.h b/src/mongo/db/storage/extent_manager.h
index 7ebb7b199c4..671f4271698 100644
--- a/src/mongo/db/storage/extent_manager.h
+++ b/src/mongo/db/storage/extent_manager.h
@@ -41,7 +41,7 @@ namespace mongo {
 
     class DataFile;
     class Record;
-    class TransactionExperiment;
+    class OperationContext;
 
     struct Extent;
 
@@ -68,7 +68,7 @@ namespace mongo {
         /**
          * opens all current files
          */
-        virtual Status init(TransactionExperiment* txn) = 0;
+        virtual Status init(OperationContext* txn) = 0;
 
         virtual size_t numFiles() const = 0;
         virtual long long fileSize() const = 0;
@@ -76,7 +76,7 @@ namespace mongo {
         virtual void flushFiles( bool sync ) = 0;
 
         // must call Extent::reuse on the returned extent
-        virtual DiskLoc allocateExtent( TransactionExperiment* txn,
+        virtual DiskLoc allocateExtent( OperationContext* txn,
                                         bool capped,
                                         int size,
                                         int quotaMax ) = 0;
@@ -84,14 +84,14 @@ namespace mongo {
         /**
          * firstExt has to be == lastExt or a chain
          */
-        virtual void freeExtents( TransactionExperiment* txn,
+        virtual void freeExtents( OperationContext* txn,
                                   DiskLoc firstExt, DiskLoc lastExt ) = 0;
 
         /**
          * frees a single extent
          * ignores all fields in the Extent except: magic, myLoc, length
          */
-        virtual void freeExtent( TransactionExperiment* txn, DiskLoc extent ) = 0;
+        virtual void freeExtent( OperationContext* txn, DiskLoc extent ) = 0;
 
         virtual void freeListStats( int* numExtents, int64_t* totalFreeSize ) const = 0;
 
diff --git a/src/mongo/db/storage/mmap_v1/dur_transaction.cpp b/src/mongo/db/storage/mmap_v1/dur_transaction.cpp
deleted file mode 100644
index 8dbf008d5d3..00000000000
--- a/src/mongo/db/storage/mmap_v1/dur_transaction.cpp
+++ /dev/null
@@ -1,69 +0,0 @@
-/**
- *    Copyright (C) 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/db/storage/mmap_v1/dur_transaction.h"
-
-#include "mongo/db/client.h"
-#include "mongo/db/curop.h"
-#include "mongo/db/kill_current_op.h"
-#include "mongo/db/storage/mmap_v1/dur_recovery_unit.h"
-
-namespace mongo {
-
-    DurTransaction::DurTransaction() {
-        _recovery.reset(new DurRecoveryUnit());
-    }
-
-    RecoveryUnit* DurTransaction::recoveryUnit() const {
-        return _recovery.get();
-    }
-
-    ProgressMeter* DurTransaction::setMessage(const char* msg,
-                                              const std::string& name,
-                                              unsigned long long progressMeterTotal,
-                                              int secondsBetween) {
-        return &cc().curop()->setMessage( msg, name, progressMeterTotal, secondsBetween );
-    }
-
-    void DurTransaction::checkForInterrupt(bool heedMutex) const {
-        killCurrentOp.checkForInterrupt(heedMutex);
-    }
-
-    Status DurTransaction::checkForInterruptNoAssert() const {
-        const char* killed = killCurrentOp.checkForInterruptNoAssert();
-        if ( !killed || !killed[0] )
-            return Status::OK();
-
-        return Status( ErrorCodes::Interrupted, killed );
-    }
-
-    TransactionExperiment* DurTransaction::factory() {
-        return new DurTransaction();
-    }
-
-}  // namespace mongo
diff --git a/src/mongo/db/storage/mmap_v1/dur_transaction.h b/src/mongo/db/storage/mmap_v1/dur_transaction.h
deleted file mode 100644
index a0dc1029e6a..00000000000
--- a/src/mongo/db/storage/mmap_v1/dur_transaction.h
+++ /dev/null
@@ -1,67 +0,0 @@
-/**
- *    Copyright (C) 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 <boost/scoped_ptr.hpp>
-#include <string>
-
-#include "mongo/db/storage/transaction.h"
-
-#pragma once
-
-namespace mongo {
-
-    /**
-     * TODO(hk): Move to db/ and rename to OperationContextMongoDImpl or something better?
-     */
-    class DurTransaction : public TransactionExperiment  {
-    public:
-        DurTransaction();
-
-        virtual ~DurTransaction() { }
-
-        virtual RecoveryUnit* recoveryUnit() const;
-
-        virtual ProgressMeter* setMessage(const char* msg,
-                                          const std::string& name ,
-                                          unsigned long long progressMeterTotal,
-                                          int secondsBetween);
-
-        virtual void checkForInterrupt(bool heedMutex = true) const;
-
-        virtual Status checkForInterruptNoAssert() const;
-
-        /**
-         * Returns a DurTransaction. Caller takes ownership.
-         */
-        static TransactionExperiment* factory();
-
-    private:
-        boost::scoped_ptr<RecoveryUnit> _recovery;
-    };
-
-}  // namespace mongo
diff --git a/src/mongo/db/storage/mmap_v1/mmap_v1_extent_manager.cpp b/src/mongo/db/storage/mmap_v1/mmap_v1_extent_manager.cpp
index 84bfae056e7..85ad027b39b 100644
--- a/src/mongo/db/storage/mmap_v1/mmap_v1_extent_manager.cpp
+++ b/src/mongo/db/storage/mmap_v1/mmap_v1_extent_manager.cpp
@@ -40,7 +40,7 @@
 #include "mongo/db/storage/extent.h"
 #include "mongo/db/storage/extent_manager.h"
 #include "mongo/db/storage/record.h"
-#include "mongo/db/storage/transaction.h"
+#include "mongo/db/operation_context.h"
 
 namespace mongo {
 
@@ -74,7 +74,7 @@ namespace mongo {
     }
 
 
-    Status MmapV1ExtentManager::init(TransactionExperiment* txn) {
+    Status MmapV1ExtentManager::init(OperationContext* txn) {
         verify( _files.size() == 0 );
 
         for ( int n = 0; n < DiskLoc::MaxFiles; n++ ) {
@@ -113,7 +113,7 @@ namespace mongo {
 
 
     // todo: this is called a lot. streamline the common case
-    DataFile* MmapV1ExtentManager::getFile( TransactionExperiment* txn,
+    DataFile* MmapV1ExtentManager::getFile( OperationContext* txn,
                                       int n,
                                       int sizeNeeded ,
                                       bool preallocateOnly) {
@@ -174,7 +174,7 @@ namespace mongo {
         return preallocateOnly ? 0 : p;
     }
 
-    DataFile* MmapV1ExtentManager::_addAFile( TransactionExperiment* txn,
+    DataFile* MmapV1ExtentManager::_addAFile( OperationContext* txn,
                                         int sizeNeeded,
                                         bool preallocateNextFile ) {
         DEV Lock::assertWriteLocked( _dbname );
@@ -243,7 +243,7 @@ namespace mongo {
         return DataFile::maxSize() - DataFileHeader::HeaderSize - 16;
     }
 
-    DiskLoc MmapV1ExtentManager::_createExtentInFile( TransactionExperiment* txn,
+    DiskLoc MmapV1ExtentManager::_createExtentInFile( OperationContext* txn,
                                                 int fileNo,
                                                 DataFile* f,
                                                 int size,
@@ -276,7 +276,7 @@ namespace mongo {
     }
 
 
-    DiskLoc MmapV1ExtentManager::_createExtent( TransactionExperiment* txn,
+    DiskLoc MmapV1ExtentManager::_createExtent( OperationContext* txn,
                                           int size,
                                           int maxFileNoForQuota ) {
         size = quantizeExtentSize( size );
@@ -315,7 +315,7 @@ namespace mongo {
         msgasserted(14810, "couldn't allocate space for a new extent" );
     }
 
-    DiskLoc MmapV1ExtentManager::_allocFromFreeList( TransactionExperiment* txn,
+    DiskLoc MmapV1ExtentManager::_allocFromFreeList( OperationContext* txn,
                                                int approxSize,
                                                bool capped ) {
         // setup extent constraints
@@ -400,7 +400,7 @@ namespace mongo {
         return best->myLoc;
     }
 
-    DiskLoc MmapV1ExtentManager::allocateExtent( TransactionExperiment* txn,
+    DiskLoc MmapV1ExtentManager::allocateExtent( OperationContext* txn,
                                            bool capped,
                                            int size,
                                            int quotaMax ) {
@@ -423,7 +423,7 @@ namespace mongo {
         return eloc;
     }
 
-    void MmapV1ExtentManager::freeExtent(TransactionExperiment* txn, DiskLoc firstExt ) {
+    void MmapV1ExtentManager::freeExtent(OperationContext* txn, DiskLoc firstExt ) {
         Extent* e = getExtent( firstExt );
         txn->writing( &e->xnext )->Null();
         txn->writing( &e->xprev )->Null();
@@ -445,7 +445,7 @@ namespace mongo {
 
     }
 
-    void MmapV1ExtentManager::freeExtents(TransactionExperiment* txn, DiskLoc firstExt, DiskLoc lastExt) {
+    void MmapV1ExtentManager::freeExtents(OperationContext* txn, DiskLoc firstExt, DiskLoc lastExt) {
 
         if ( firstExt.isNull() && lastExt.isNull() )
             return;
@@ -488,13 +488,13 @@ namespace mongo {
         return file->header()->freeListEnd;
     }
 
-    void MmapV1ExtentManager::_setFreeListStart( TransactionExperiment* txn, DiskLoc loc ) {
+    void MmapV1ExtentManager::_setFreeListStart( OperationContext* txn, DiskLoc loc ) {
         invariant( !_files.empty() );
         DataFile* file = _files[0];
         *txn->writing( &file->header()->freeListStart ) = loc;
     }
 
-    void MmapV1ExtentManager::_setFreeListEnd( TransactionExperiment* txn, DiskLoc loc ) {
+    void MmapV1ExtentManager::_setFreeListEnd( OperationContext* txn, DiskLoc loc ) {
         invariant( !_files.empty() );
         DataFile* file = _files[0];
         *txn->writing( &file->header()->freeListEnd ) = loc;
diff --git a/src/mongo/db/storage/mmap_v1/mmap_v1_extent_manager.h b/src/mongo/db/storage/mmap_v1/mmap_v1_extent_manager.h
index c045a075df4..47a35d3eb91 100644
--- a/src/mongo/db/storage/mmap_v1/mmap_v1_extent_manager.h
+++ b/src/mongo/db/storage/mmap_v1/mmap_v1_extent_manager.h
@@ -44,7 +44,7 @@ namespace mongo {
 
     class DataFile;
     class Record;
-    class TransactionExperiment;
+    class OperationContext;
 
     struct Extent;
 
@@ -83,13 +83,13 @@ namespace mongo {
         /**
          * opens all current files
          */
-        Status init(TransactionExperiment* txn);
+        Status init(OperationContext* txn);
 
         size_t numFiles() const;
         long long fileSize() const;
 
         // TODO: make private
-        DataFile* getFile( TransactionExperiment* txn,
+        DataFile* getFile( OperationContext* txn,
                            int n,
                            int sizeNeeded = 0,
                            bool preallocateOnly = false );
@@ -97,7 +97,7 @@ namespace mongo {
         void flushFiles( bool sync );
 
         // must call Extent::reuse on the returned extent
-        DiskLoc allocateExtent( TransactionExperiment* txn,
+        DiskLoc allocateExtent( OperationContext* txn,
                                 bool capped,
                                 int size,
                                 int quotaMax );
@@ -105,13 +105,13 @@ namespace mongo {
         /**
          * firstExt has to be == lastExt or a chain
          */
-        void freeExtents( TransactionExperiment* txn, DiskLoc firstExt, DiskLoc lastExt );
+        void freeExtents( OperationContext* txn, DiskLoc firstExt, DiskLoc lastExt );
 
         /**
          * frees a single extent
          * ignores all fields in the Extent except: magic, myLoc, length
          */
-        void freeExtent( TransactionExperiment* txn, DiskLoc extent );
+        void freeExtent( OperationContext* txn, DiskLoc extent );
 
         void printFreeList() const;
 
@@ -153,23 +153,23 @@ namespace mongo {
         /**
          * will return NULL if nothing suitable in free list
          */
-        DiskLoc _allocFromFreeList( TransactionExperiment* txn, int approxSize, bool capped );
+        DiskLoc _allocFromFreeList( OperationContext* txn, int approxSize, bool capped );
 
         /* allocate a new Extent, does not check free list
          * @param maxFileNoForQuota - 0 for unlimited
         */
-        DiskLoc _createExtent( TransactionExperiment* txn, int approxSize, int maxFileNoForQuota );
+        DiskLoc _createExtent( OperationContext* txn, int approxSize, int maxFileNoForQuota );
 
-        DataFile* _addAFile( TransactionExperiment* txn, int sizeNeeded, bool preallocateNextFile );
+        DataFile* _addAFile( OperationContext* txn, int sizeNeeded, bool preallocateNextFile );
 
         DiskLoc _getFreeListStart() const;
         DiskLoc _getFreeListEnd() const;
-        void _setFreeListStart( TransactionExperiment* txn, DiskLoc loc );
-        void _setFreeListEnd( TransactionExperiment* txn, DiskLoc loc );
+        void _setFreeListStart( OperationContext* txn, DiskLoc loc );
+        void _setFreeListEnd( OperationContext* txn, DiskLoc loc );
 
         const DataFile* _getOpenFile( int n ) const;
 
-        DiskLoc _createExtentInFile( TransactionExperiment* txn,
+        DiskLoc _createExtentInFile( OperationContext* txn,
                                      int fileNo,
                                      DataFile* f,
                                      int size,
diff --git a/src/mongo/db/storage/transaction.h b/src/mongo/db/storage/transaction.h
deleted file mode 100644
index e76e1ab49ca..00000000000
--- a/src/mongo/db/storage/transaction.h
+++ /dev/null
@@ -1,136 +0,0 @@
-/**
- *    Copyright (C) 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.
- */
-
-#pragma once
-
-#include <stdlib.h>
-
-#include "mongo/base/disallow_copying.h"
-#include "mongo/base/status.h"
-#include "mongo/db/storage/recovery_unit.h"
-
-namespace mongo {
-
-    class ProgressMeter;
-
-    /**
-     * This name and this class are both a work in progress.
-     *
-     * TODO(hk): move up a level, rename to OperationContext (or OpCtx if you're into the whole
-     * brevity thing)
-     */
-    class TransactionExperiment  {
-        MONGO_DISALLOW_COPYING(TransactionExperiment);
-    public:
-        virtual ~TransactionExperiment() { }
-
-        /**
-         * Interface for durability.  Caller DOES NOT own pointer.
-         *
-         * XXX: what's a better name for this
-         */
-        virtual RecoveryUnit* recoveryUnit() const = 0;
-
-        // XXX: migrate callers use the recoveryUnit() directly
-        template <typename T>
-        T* writing(T* x) {
-            return recoveryUnit()->writing(x);
-        }
-
-        int& writingInt(int& d) {
-            return recoveryUnit()->writingInt(d);
-        }
-
-        void syncDataAndTruncateJournal() {
-            recoveryUnit()->syncDataAndTruncateJournal();
-        }
-
-        void createdFile(const std::string& filename, unsigned long long len) {
-            recoveryUnit()->createdFile(filename, len);
-        }
-
-        void* writingPtr(void* data, size_t len) {
-            return recoveryUnit()->writingPtr(data, len);
-        }
-
-        bool isCommitNeeded() const {
-            return recoveryUnit()->isCommitNeeded();
-        }
-
-        bool commitIfNeeded(bool force = false) {
-            return recoveryUnit()->commitIfNeeded(force);
-        }
-        // XXX: migrate callers use the recoveryUnit() directly
-
-
-        // --- operation level info? ---
-
-        /**
-         * TODO: Get rid of this and just have one interrupt func?
-         * throws an exception if the operation is interrupted
-         * @param heedMutex if true and have a write lock, won't kill op since it might be unsafe
-         */
-        virtual void checkForInterrupt(bool heedMutex = true) const = 0;
-
-        /**
-         * TODO: Where do I go
-         * @return Status::OK() if not interrupted
-         *         otherwise returns reasons
-         */
-        virtual Status checkForInterruptNoAssert() const = 0;
-
-        /**
-         * TODO(ERH): this should move to some CurOp like context.
-         */
-        virtual ProgressMeter* setMessage(const char* msg,
-                                          const std::string& name = "Progress",
-                                          unsigned long long progressMeterTotal = 0,
-                                          int secondsBetween = 3) = 0;
-
-        /**
-         * Returns a TransactionExperiment. Caller takes ownership.
-         *
-         * This interface is used for functions that need to create transactions (aka OpCtx), but
-         * don't know which implementation they should create. It allows the calling code to make
-         * that decision for them.
-         *
-         * TODO come up with a better Factory API once we split this class up (SERVER-13931).
-         */
-        typedef TransactionExperiment* (*Factory)();
-
-        /**
-         * A TransactionExperiment::Factory that always returns NULL. For things that shouldn't be
-         * touching their txns such as mongos or some unittests.
-         */
-        static TransactionExperiment* factoryNULL() { return NULL; }
-
-    protected:
-        TransactionExperiment() {}
-    };
-
-}  // namespace mongo