Defer opening and writing statement journals until the size reaches a

threshold (currently 64KiB).

FossilOrigin-Name: cb9302cca423de41305719a49208daa392ec09da

5 files changed, 284 insertions, 132 deletions

diff --git a/src/journal.c b/src/journal.c
index a5cf8c8e2..da59db0e5 100644
--- a/src/journal.c
+++ b/src/journal.c
@@ -24,6 +24,7 @@
 **      buffer, or
 **   2) The sqlite3JournalCreate() function is called.
 */
+#if 0 
 #ifdef SQLITE_ENABLE_ATOMIC_WRITE
 #include "sqliteInt.h"
 
@@ -254,3 +255,4 @@ int sqlite3JournalSize(sqlite3_vfs *pVfs){
   return (pVfs->szOsFile+sizeof(JournalFile));
 }
 #endif
+#endif
diff --git a/src/memjournal.c b/src/memjournal.c
index 62594530e..9ecd2a9ba 100644
--- a/src/memjournal.c
+++ b/src/memjournal.c
@@ -21,25 +21,29 @@ typedef struct MemJournal MemJournal;
 typedef struct FilePoint FilePoint;
 typedef struct FileChunk FileChunk;
 
-/* Space to hold the rollback journal is allocated in increments of
-** this many bytes.
-**
-** The size chosen is a little less than a power of two.  That way,
-** the FileChunk object will have a size that almost exactly fills
-** a power-of-two allocation.  This minimizes wasted space in power-of-two
-** memory allocators.
-*/
-#define JOURNAL_CHUNKSIZE ((int)(1024-sizeof(FileChunk*)))
-
 /*
 ** The rollback journal is composed of a linked list of these structures.
+**
+** The zChunk array is always at least 8 bytes in size - usually much more.
+** Its actual size is stored in the MemJournal.nChunkSize variable.
 */
 struct FileChunk {
   FileChunk *pNext;               /* Next chunk in the journal */
-  u8 zChunk[JOURNAL_CHUNKSIZE];   /* Content of this chunk */
+  u8 zChunk[8];                   /* Content of this chunk */
 };
 
 /*
+** By default, allocate this many bytes of memory for each FileChunk object.
+*/
+#define MEMJOURNAL_DFLT_FILECHUNKSIZE 1024
+
+/*
+** For chunk size nChunkSize, return the number of bytes that should
+** be allocated for each FileChunk structure.
+*/
+#define fileChunkSize(nChunkSize) (sizeof(FileChunk) + ((nChunkSize)-8))
+
+/*
 ** An instance of this object serves as a cursor into the rollback journal.
 ** The cursor can be either for reading or writing.
 */
@@ -49,14 +53,23 @@ struct FilePoint {
 };
 
 /*
-** This subclass is a subclass of sqlite3_file.  Each open memory-journal
+** This structure is a subclass of sqlite3_file. Each open memory-journal
 ** is an instance of this class.
 */
 struct MemJournal {
-  sqlite3_io_methods *pMethod;    /* Parent class. MUST BE FIRST */
+  const sqlite3_io_methods *pMethod; /* Parent class. MUST BE FIRST */
+  int nChunkSize;                 /* In-memory chunk-size */
+
+  int nBuf;                       /* Bytes of data before flushing */
+  int nSize;                      /* Bytes of data currently in memory */
   FileChunk *pFirst;              /* Head of in-memory chunk-list */
   FilePoint endpoint;             /* Pointer to the end of the file */
   FilePoint readpoint;            /* Pointer to the end of the last xRead() */
+
+  int flags;                      /* xOpen flags */
+  sqlite3_vfs *pVfs;              /* The "real" underlying VFS */
+  const char *zJournal;           /* Name of the journal file */
+  sqlite3_file *pReal;            /* The "real" underlying file descriptor */
 };
 
 /*
@@ -70,42 +83,97 @@ static int memjrnlRead(
   sqlite_int64 iOfst     /* Begin reading at this offset */
 ){
   MemJournal *p = (MemJournal *)pJfd;
-  u8 *zOut = zBuf;
-  int nRead = iAmt;
-  int iChunkOffset;
-  FileChunk *pChunk;
-
-  /* SQLite never tries to read past the end of a rollback journal file */
-  assert( iOfst+iAmt<=p->endpoint.iOffset );
-
-  if( p->readpoint.iOffset!=iOfst || iOfst==0 ){
-    sqlite3_int64 iOff = 0;
-    for(pChunk=p->pFirst; 
-        ALWAYS(pChunk) && (iOff+JOURNAL_CHUNKSIZE)<=iOfst;
-        pChunk=pChunk->pNext
-    ){
-      iOff += JOURNAL_CHUNKSIZE;
-    }
+  if( p->pReal ){
+    return sqlite3OsRead(p->pReal, zBuf, iAmt, iOfst);
+  }else if( (iAmt+iOfst)>p->endpoint.iOffset ){
+    return SQLITE_IOERR_SHORT_READ;
   }else{
-    pChunk = p->readpoint.pChunk;
-  }
+    u8 *zOut = zBuf;
+    int nRead = iAmt;
+    int iChunkOffset;
+    FileChunk *pChunk;
+
+    if( p->readpoint.iOffset!=iOfst || iOfst==0 ){
+      sqlite3_int64 iOff = 0;
+      for(pChunk=p->pFirst; 
+          ALWAYS(pChunk) && (iOff+p->nChunkSize)<=iOfst;
+          pChunk=pChunk->pNext
+      ){
+        iOff += p->nChunkSize;
+      }
+    }else{
+      pChunk = p->readpoint.pChunk;
+    }
 
-  iChunkOffset = (int)(iOfst%JOURNAL_CHUNKSIZE);
-  do {
-    int iSpace = JOURNAL_CHUNKSIZE - iChunkOffset;
-    int nCopy = MIN(nRead, (JOURNAL_CHUNKSIZE - iChunkOffset));
-    memcpy(zOut, &pChunk->zChunk[iChunkOffset], nCopy);
-    zOut += nCopy;
-    nRead -= iSpace;
-    iChunkOffset = 0;
-  } while( nRead>=0 && (pChunk=pChunk->pNext)!=0 && nRead>0 );
-  p->readpoint.iOffset = iOfst+iAmt;
-  p->readpoint.pChunk = pChunk;
+    iChunkOffset = (int)(iOfst%p->nChunkSize);
+    do {
+      int iSpace = p->nChunkSize - iChunkOffset;
+      int nCopy = MIN(nRead, (p->nChunkSize - iChunkOffset));
+      memcpy(zOut, &pChunk->zChunk[iChunkOffset], nCopy);
+      zOut += nCopy;
+      nRead -= iSpace;
+      iChunkOffset = 0;
+    } while( nRead>=0 && (pChunk=pChunk->pNext)!=0 && nRead>0 );
+    p->readpoint.iOffset = iOfst+iAmt;
+    p->readpoint.pChunk = pChunk;
+  }
 
   return SQLITE_OK;
 }
 
 /*
+** Free the list of FileChunk structures headed at MemJournal.pFirst.
+*/
+static void memjrnlFreeChunks(MemJournal *p){
+  FileChunk *pIter;
+  FileChunk *pNext;
+  for(pIter=p->pFirst; pIter; pIter=pNext){
+    pNext = pIter->pNext;
+    sqlite3_free(pIter);
+  } 
+  p->pFirst = 0;
+}
+
+/*
+** Flush the contents of memory to a real file on disk.
+*/
+static int createFile(MemJournal *p){
+  int rc = SQLITE_OK;
+  if( !p->pReal ){
+    sqlite3_file *pReal = (sqlite3_file *)&p[1];
+    rc = sqlite3OsOpen(p->pVfs, p->zJournal, pReal, p->flags, 0);
+    if( rc==SQLITE_OK ){
+      int nChunk = p->nChunkSize;
+      i64 iOff = 0;
+      FileChunk *pIter;
+      p->pReal = pReal;
+      for(pIter=p->pFirst; pIter && rc==SQLITE_OK; pIter=pIter->pNext){
+        int nWrite = nChunk;
+        if( pIter==p->endpoint.pChunk ){
+          nWrite = p->endpoint.iOffset % p->nChunkSize;
+          if( nWrite==0 ) nWrite = p->nChunkSize;
+        }
+        rc = sqlite3OsWrite(pReal, pIter->zChunk, nWrite, iOff);
+        iOff += nWrite;
+      }
+      if( rc!=SQLITE_OK ){
+        /* If an error occurred while writing to the file, close it before
+        ** returning. This way, SQLite uses the in-memory journal data to 
+        ** roll back changes made to the internal page-cache before this
+        ** function was called.  */
+        sqlite3OsClose(pReal);
+        p->pReal = 0;
+      }else{
+        /* No error has occurred. Free the in-memory buffers. */
+        memjrnlFreeChunks(p);
+      }
+    }
+  }
+  return rc;
+}
+
+
+/*
 ** Write data to the file.
 */
 static int memjrnlWrite(
@@ -118,38 +186,61 @@ static int memjrnlWrite(
   int nWrite = iAmt;
   u8 *zWrite = (u8 *)zBuf;
 
-  /* An in-memory journal file should only ever be appended to. Random
-  ** access writes are not required by sqlite.
-  */
-  assert( iOfst==p->endpoint.iOffset );
-  UNUSED_PARAMETER(iOfst);
-
-  while( nWrite>0 ){
-    FileChunk *pChunk = p->endpoint.pChunk;
-    int iChunkOffset = (int)(p->endpoint.iOffset%JOURNAL_CHUNKSIZE);
-    int iSpace = MIN(nWrite, JOURNAL_CHUNKSIZE - iChunkOffset);
-
-    if( iChunkOffset==0 ){
-      /* New chunk is required to extend the file. */
-      FileChunk *pNew = sqlite3_malloc(sizeof(FileChunk));
-      if( !pNew ){
-        return SQLITE_IOERR_NOMEM_BKPT;
-      }
-      pNew->pNext = 0;
-      if( pChunk ){
-        assert( p->pFirst );
-        pChunk->pNext = pNew;
-      }else{
-        assert( !p->pFirst );
-        p->pFirst = pNew;
-      }
-      p->endpoint.pChunk = pNew;
+  /* If the file has already been created on disk. */
+  if( p->pReal ){
+    return sqlite3OsWrite(p->pReal, zBuf, iAmt, iOfst);
+  }
+
+  /* If the file should be created now. */
+  else if( p->nBuf>0 && (iAmt+iOfst)>p->nBuf ){
+    int rc = createFile(p);
+    if( rc==SQLITE_OK ){
+      rc = memjrnlWrite(pJfd, zBuf, iAmt, iOfst);
     }
+    return rc;
+  }
+
+  /* If the contents of this write should be stored in memory */
+  else{
+    /* An in-memory journal file should only ever be appended to. Random
+    ** access writes are not required. The only exception to this is when
+    ** the in-memory journal is being used by a connection using the
+    ** atomic-write optimization. In this case the first 28 bytes of the
+    ** journal file may be written as part of committing the transaction. */ 
+    assert( iOfst==p->endpoint.iOffset || iOfst==0 );
+    if( iOfst==0 && p->pFirst ){
+      assert( p->nChunkSize>iAmt );
+      memcpy(p->pFirst->zChunk, zBuf, iAmt);
+    }else{
+      while( nWrite>0 ){
+        FileChunk *pChunk = p->endpoint.pChunk;
+        int iChunkOffset = (int)(p->endpoint.iOffset%p->nChunkSize);
+        int iSpace = MIN(nWrite, p->nChunkSize - iChunkOffset);
 
-    memcpy(&p->endpoint.pChunk->zChunk[iChunkOffset], zWrite, iSpace);
-    zWrite += iSpace;
-    nWrite -= iSpace;
-    p->endpoint.iOffset += iSpace;
+        if( iChunkOffset==0 ){
+          /* New chunk is required to extend the file. */
+          FileChunk *pNew = sqlite3_malloc(fileChunkSize(p->nChunkSize));
+          if( !pNew ){
+            return SQLITE_IOERR_NOMEM_BKPT;
+          }
+          pNew->pNext = 0;
+          if( pChunk ){
+            assert( p->pFirst );
+            pChunk->pNext = pNew;
+          }else{
+            assert( !p->pFirst );
+            p->pFirst = pNew;
+          }
+          p->endpoint.pChunk = pNew;
+        }
+
+        memcpy(&p->endpoint.pChunk->zChunk[iChunkOffset], zWrite, iSpace);
+        zWrite += iSpace;
+        nWrite -= iSpace;
+        p->endpoint.iOffset += iSpace;
+      }
+      p->nSize = iAmt + iOfst;
+    }
   }
 
   return SQLITE_OK;
@@ -157,19 +248,23 @@ static int memjrnlWrite(
 
 /*
 ** Truncate the file.
+**
+** If the journal file is already on disk, truncate it there. Or, if it
+** is still in main memory but is being truncated to zero bytes in size,
+** ignore 
 */
 static int memjrnlTruncate(sqlite3_file *pJfd, sqlite_int64 size){
   MemJournal *p = (MemJournal *)pJfd;
-  FileChunk *pChunk;
-  assert(size==0);
-  UNUSED_PARAMETER(size);
-  pChunk = p->pFirst;
-  while( pChunk ){
-    FileChunk *pTmp = pChunk;
-    pChunk = pChunk->pNext;
-    sqlite3_free(pTmp);
+  if( p->pReal ){
+    return sqlite3OsTruncate(p->pReal, size);
+  }else if( size==0 ){
+    memjrnlFreeChunks(p);
+    p->nSize = 0;
+    p->endpoint.pChunk = 0;
+    p->endpoint.iOffset = 0;
+    p->readpoint.pChunk = 0;
+    p->readpoint.iOffset = 0;
   }
-  sqlite3MemJournalOpen(pJfd);
   return SQLITE_OK;
 }
 
@@ -177,21 +272,23 @@ static int memjrnlTruncate(sqlite3_file *pJfd, sqlite_int64 size){
 ** Close the file.
 */
 static int memjrnlClose(sqlite3_file *pJfd){
-  memjrnlTruncate(pJfd, 0);
+  MemJournal *p = (MemJournal *)pJfd;
+  memjrnlFreeChunks(p);
+  if( p->pReal ) sqlite3OsClose(p->pReal);
   return SQLITE_OK;
 }
 
-
 /*
 ** Sync the file.
 **
-** Syncing an in-memory journal is a no-op.  And, in fact, this routine
-** is never called in a working implementation.  This implementation
-** exists purely as a contingency, in case some malfunction in some other
-** part of SQLite causes Sync to be called by mistake.
+** If the real file has been created, call its xSync method. Otherwise, 
+** syncing an in-memory journal is a no-op. 
 */
-static int memjrnlSync(sqlite3_file *NotUsed, int NotUsed2){
-  UNUSED_PARAMETER2(NotUsed, NotUsed2);
+static int memjrnlSync(sqlite3_file *pJfd, int flags){
+  MemJournal *p = (MemJournal *)pJfd;
+  if( p->pReal ){
+    return sqlite3OsSync(p->pReal, flags);
+  }
   return SQLITE_OK;
 }
 
@@ -200,6 +297,9 @@ static int memjrnlSync(sqlite3_file *NotUsed, int NotUsed2){
 */
 static int memjrnlFileSize(sqlite3_file *pJfd, sqlite_int64 *pSize){
   MemJournal *p = (MemJournal *)pJfd;
+  if( p->pReal ){
+    return sqlite3OsFileSize(p->pReal, pSize);
+  }
   *pSize = (sqlite_int64) p->endpoint.iOffset;
   return SQLITE_OK;
 }
@@ -230,26 +330,86 @@ static const struct sqlite3_io_methods MemJournalMethods = {
 };
 
 /* 
-** Open a journal file.
+** Open a journal file. 
+**
+** The behaviour of the journal file depends on the value of parameter 
+** nBuf. If nBuf is 0, then the journal file is always create and 
+** accessed using the underlying VFS. If nBuf is less than zero, then
+** all content is always stored in main-memory. Finally, if nBuf is a
+** positive value, then the journal file is initially created in-memory
+** but may be flushed to disk later on. In this case the journal file is
+** flushed to disk either when it grows larger than nBuf bytes in size,
+** or when sqlite3JournalCreate() is called.
+*/
+int sqlite3JournalOpen(
+  sqlite3_vfs *pVfs,         /* The VFS to use for actual file I/O */
+  const char *zName,         /* Name of the journal file */
+  sqlite3_file *pJfd,        /* Preallocated, blank file handle */
+  int flags,                 /* Opening flags */
+  int nBuf                   /* Bytes buffered before opening the file */
+){
+  MemJournal *p = (MemJournal*)pJfd;
+
+  /* Zero the file-handle object. If nBuf was passed zero, initialize
+  ** it using the sqlite3OsOpen() function of the underlying VFS. In this
+  ** case none of the code in this module is executed as a result of calls
+  ** made on the journal file-handle.  */
+  memset(p, 0, sizeof(MemJournal) + (pVfs ? pVfs->szOsFile : 0));
+  if( nBuf==0 ){
+    return sqlite3OsOpen(pVfs, zName, pJfd, flags, 0);
+  }
+
+  if( nBuf>0 ){
+    p->nChunkSize = nBuf;
+  }else{
+    p->nChunkSize = 8 + MEMJOURNAL_DFLT_FILECHUNKSIZE - sizeof(FileChunk);
+    assert( MEMJOURNAL_DFLT_FILECHUNKSIZE==fileChunkSize(p->nChunkSize) );
+  }
+
+  p->pMethod = (const sqlite3_io_methods*)&MemJournalMethods;
+  p->nBuf = nBuf;
+  p->flags = flags;
+  p->zJournal = zName;
+  p->pVfs = pVfs;
+  return SQLITE_OK;
+}
+
+/*
+** Open an in-memory journal file.
 */
 void sqlite3MemJournalOpen(sqlite3_file *pJfd){
-  MemJournal *p = (MemJournal *)pJfd;
-  assert( EIGHT_BYTE_ALIGNMENT(p) );
-  memset(p, 0, sqlite3MemJournalSize());
-  p->pMethod = (sqlite3_io_methods*)&MemJournalMethods;
+  sqlite3JournalOpen(0, 0, pJfd, 0, -1);
+}
+
+#ifdef SQLITE_ENABLE_ATOMIC_WRITE
+/*
+** If the argument p points to a MemJournal structure that is not an 
+** in-memory-only journal file (i.e. is one that was opened with a +ve
+** nBuf parameter), and the underlying file has not yet been created, 
+** create it now.
+*/
+int sqlite3JournalCreate(sqlite3_file *p){
+  int rc = SQLITE_OK;
+  if( p->pMethods==&MemJournalMethods && ((MemJournal*)p)->nBuf>0 ){
+    rc = createFile((MemJournal*)p);
+  }
+  return rc;
 }
+#endif
 
 /*
-** Return true if the file-handle passed as an argument is 
-** an in-memory journal 
+** The file-handle passed as the only argument is open on a journal file.
+** Return true if this "journal file" is currently stored in heap memory,
+** or false otherwise.
 */
-int sqlite3IsMemJournal(sqlite3_file *pJfd){
-  return pJfd->pMethods==&MemJournalMethods;
+int sqlite3JournalIsInMemory(sqlite3_file *p){
+  return p->pMethods==&MemJournalMethods && ((MemJournal*)p)->pReal==0;
 }
 
 /* 
-** Return the number of bytes required to store a MemJournal file descriptor.
+** Return the number of bytes required to store a JournalFile that uses vfs
+** pVfs to create the underlying on-disk files.
 */
-int sqlite3MemJournalSize(void){
-  return sizeof(MemJournal);
+int sqlite3JournalSize(sqlite3_vfs *pVfs){
+  return pVfs->szOsFile + sizeof(MemJournal);
 }
diff --git a/src/os.c b/src/os.c
index 2fd44abf8..eed782853 100644
--- a/src/os.c
+++ b/src/os.c
@@ -66,7 +66,7 @@ int sqlite3_open_file_count = 0;
 #if defined(SQLITE_TEST)
 int sqlite3_memdebug_vfs_oom_test = 1;
   #define DO_OS_MALLOC_TEST(x)                                       \
-  if (sqlite3_memdebug_vfs_oom_test && (!x || !sqlite3IsMemJournal(x))) {  \
+  if (sqlite3_memdebug_vfs_oom_test && (!x || !sqlite3JournalIsInMemory(x))) { \
     void *pTstAlloc = sqlite3Malloc(10);                             \
     if (!pTstAlloc) return SQLITE_IOERR_NOMEM_BKPT;                  \
     sqlite3_free(pTstAlloc);                                         \
diff --git a/src/pager.c b/src/pager.c
index 51bd45e48..c74748c8e 100644
--- a/src/pager.c
+++ b/src/pager.c
@@ -1343,6 +1343,7 @@ static i64 journalHdrOffset(Pager *pPager){
 static int zeroJournalHdr(Pager *pPager, int doTruncate){
   int rc = SQLITE_OK;                               /* Return code */
   assert( isOpen(pPager->jfd) );
+  assert( !sqlite3JournalIsInMemory(pPager->jfd) );
   if( pPager->journalOff ){
     const i64 iLimit = pPager->journalSizeLimit;    /* Local cache of jsl */
 
@@ -1724,7 +1725,7 @@ static void releaseAllSavepoints(Pager *pPager){
   for(ii=0; ii<pPager->nSavepoint; ii++){
     sqlite3BitvecDestroy(pPager->aSavepoint[ii].pInSavepoint);
   }
-  if( !pPager->exclusiveMode || sqlite3IsMemJournal(pPager->sjfd) ){
+  if( !pPager->exclusiveMode || sqlite3JournalIsInMemory(pPager->sjfd) ){
     sqlite3OsClose(pPager->sjfd);
   }
   sqlite3_free(pPager->aSavepoint);
@@ -1962,8 +1963,8 @@ static int pager_end_transaction(Pager *pPager, int hasMaster, int bCommit){
     assert( !pagerUseWal(pPager) );
 
     /* Finalize the journal file. */
-    if( sqlite3IsMemJournal(pPager->jfd) ){
-      assert( pPager->journalMode==PAGER_JOURNALMODE_MEMORY );
+    if( sqlite3JournalIsInMemory(pPager->jfd) ){
+      /* assert( pPager->journalMode==PAGER_JOURNALMODE_MEMORY ); */
       sqlite3OsClose(pPager->jfd);
     }else if( pPager->journalMode==PAGER_JOURNALMODE_TRUNCATE ){
       if( pPager->journalOff==0 ){
@@ -1989,9 +1990,10 @@ static int pager_end_transaction(Pager *pPager, int hasMaster, int bCommit){
       /* This branch may be executed with Pager.journalMode==MEMORY if
       ** a hot-journal was just rolled back. In this case the journal
       ** file should be closed and deleted. If this connection writes to
-      ** the database file, it will do so using an in-memory journal. 
+      ** the database file, it will do so using an in-memory journal.
       */
-      int bDelete = (!pPager->tempFile && sqlite3JournalExists(pPager->jfd));
+      int bDelete = !pPager->tempFile;
+      assert( sqlite3JournalIsInMemory(pPager->jfd)==0 );
       assert( pPager->journalMode==PAGER_JOURNALMODE_DELETE 
            || pPager->journalMode==PAGER_JOURNALMODE_MEMORY 
            || pPager->journalMode==PAGER_JOURNALMODE_WAL 
@@ -2729,7 +2731,7 @@ static int pager_playback(Pager *pPager, int isHot){
   ** TODO: Technically the following is an error because it assumes that
   ** buffer Pager.pTmpSpace is (mxPathname+1) bytes or larger. i.e. that
   ** (pPager->pageSize >= pPager->pVfs->mxPathname+1). Using os_unix.c,
-  **  mxPathname is 512, which is the same as the minimum allowable value
+  ** mxPathname is 512, which is the same as the minimum allowable value
   ** for pageSize.
   */
   zMaster = pPager->pTmpSpace;
@@ -4353,11 +4355,14 @@ static int pager_write_pagelist(Pager *pPager, PgHdr *pList){
 static int openSubJournal(Pager *pPager){
   int rc = SQLITE_OK;
   if( !isOpen(pPager->sjfd) ){
+    const int flags =  SQLITE_OPEN_SUBJOURNAL | SQLITE_OPEN_READWRITE 
+      | SQLITE_OPEN_CREATE | SQLITE_OPEN_EXCLUSIVE 
+      | SQLITE_OPEN_DELETEONCLOSE;
+    int nBuf = 64*1024;
     if( pPager->journalMode==PAGER_JOURNALMODE_MEMORY || pPager->subjInMemory ){
-      sqlite3MemJournalOpen(pPager->sjfd);
-    }else{
-      rc = pagerOpentemp(pPager, pPager->sjfd, SQLITE_OPEN_SUBJOURNAL);
+      nBuf = -1;
     }
+    rc = sqlite3JournalOpen(pPager->pVfs, 0, pPager->sjfd, flags, nBuf);
   }
   return rc;
 }
@@ -4578,18 +4583,8 @@ int sqlite3PagerOpen(
   int nUri = 0;            /* Number of bytes of URI args at *zUri */
 
   /* Figure out how much space is required for each journal file-handle
-  ** (there are two of them, the main journal and the sub-journal). This
-  ** is the maximum space required for an in-memory journal file handle 
-  ** and a regular journal file-handle. Note that a "regular journal-handle"
-  ** may be a wrapper capable of caching the first portion of the journal
-  ** file in memory to implement the atomic-write optimization (see 
-  ** source file journal.c).
-  */
-  if( sqlite3JournalSize(pVfs)>sqlite3MemJournalSize() ){
-    journalFileSize = ROUND8(sqlite3JournalSize(pVfs));
-  }else{
-    journalFileSize = ROUND8(sqlite3MemJournalSize());
-  }
+  ** (there are two of them, the main journal and the sub-journal).  */
+  journalFileSize = ROUND8(sqlite3JournalSize(pVfs));
 
   /* Set the output variable to NULL in case an error occurs. */
   *ppPager = 0;
@@ -6667,7 +6662,7 @@ int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint){
     if( op==SAVEPOINT_RELEASE ){
       if( nNew==0 && isOpen(pPager->sjfd) ){
         /* Only truncate if it is an in-memory sub-journal. */
-        if( sqlite3IsMemJournal(pPager->sjfd) ){
+        if( sqlite3JournalIsInMemory(pPager->sjfd) ){
           rc = sqlite3OsTruncate(pPager->sjfd, 0);
           assert( rc==SQLITE_OK );
         }
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index a37da33ed..387bb7436 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -3998,19 +3998,14 @@ const char *sqlite3JournalModename(int);
 #define IN_INDEX_LOOP        0x0004  /* IN operator used as a loop */
 int sqlite3FindInIndex(Parse *, Expr *, u32, int*);
 
+int sqlite3JournalOpen(sqlite3_vfs *, const char *, sqlite3_file *, int, int);
+int sqlite3JournalSize(sqlite3_vfs *);
 #ifdef SQLITE_ENABLE_ATOMIC_WRITE
-  int sqlite3JournalOpen(sqlite3_vfs *, const char *, sqlite3_file *, int, int);
-  int sqlite3JournalSize(sqlite3_vfs *);
   int sqlite3JournalCreate(sqlite3_file *);
-  int sqlite3JournalExists(sqlite3_file *p);
-#else
-  #define sqlite3JournalSize(pVfs) ((pVfs)->szOsFile)
-  #define sqlite3JournalExists(p) 1
 #endif
 
+int sqlite3JournalIsInMemory(sqlite3_file *p);
 void sqlite3MemJournalOpen(sqlite3_file *);
-int sqlite3MemJournalSize(void);
-int sqlite3IsMemJournal(sqlite3_file *);
 
 void sqlite3ExprSetHeightAndFlags(Parse *pParse, Expr *p);
 #if SQLITE_MAX_EXPR_DEPTH>0