When a sub-transaction is released, if no pages required by containing sub-transactions were journaled, truncate the statement journal. This prevents out of control statement journal growth in some cases.

Author: danielk-1977

src/memjournal.c

@@ -70,7 +70,6 @@ struct MemJournal {
   int nChunkSize;                 /* In-memory chunk-size */
 
   int nSpill;                     /* 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() */
@@ -131,14 +130,13 @@ static int memjrnlRead(
 /*
 ** Free the list of FileChunk structures headed at MemJournal.pFirst.
 */
-static void memjrnlFreeChunks(MemJournal *p){
+static void memjrnlFreeChunks(FileChunk *pFirst){
   FileChunk *pIter;
   FileChunk *pNext;
-  for(pIter=p->pFirst; pIter; pIter=pNext){
+  for(pIter=pFirst; pIter; pIter=pNext){
     pNext = pIter->pNext;
     sqlite3_free(pIter);
   } 
-  p->pFirst = 0;
 }
 
 /*
@@ -165,7 +163,7 @@ static int memjrnlCreateFile(MemJournal *p){
     }
     if( rc==SQLITE_OK ){
       /* No error has occurred. Free the in-memory buffers. */
-      memjrnlFreeChunks(&copy);
+      memjrnlFreeChunks(copy.pFirst);
     }
   }
   if( rc!=SQLITE_OK ){
@@ -248,30 +246,37 @@ static int memjrnlWrite(
         nWrite -= iSpace;
         p->endpoint.iOffset += iSpace;
       }
-      p->nSize = iAmt + iOfst;
     }
   }
 
   return SQLITE_OK;
 }
 
 /*
-** 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 
+** Truncate the in-memory file.
 */
 static int memjrnlTruncate(sqlite3_file *pJfd, sqlite_int64 size){
   MemJournal *p = (MemJournal *)pJfd;
-  if( ALWAYS(size==0) ){
-    memjrnlFreeChunks(p);
-    p->nSize = 0;
-    p->endpoint.pChunk = 0;
-    p->endpoint.iOffset = 0;
-    p->readpoint.pChunk = 0;
-    p->readpoint.iOffset = 0;
+  FileChunk *pIter = 0;
+
+  if( size==0 ){
+    memjrnlFreeChunks(p->pFirst);
+    p->pFirst = 0;
+  }else{
+    i64 iOff = p->nChunkSize;
+    for(pIter=p->pFirst; ALWAYS(pIter) && iOff<=size; pIter=pIter->pNext){
+      iOff += p->nChunkSize;
+    }
+    if( pIter ){
+      memjrnlFreeChunks(pIter->pNext);
+      pIter->pNext = 0;
+    }
   }
+
+  p->endpoint.pChunk = pIter;
+  p->endpoint.iOffset = size;
+  p->readpoint.pChunk = 0;
+  p->readpoint.iOffset = 0;
   return SQLITE_OK;
 }
 
@@ -280,7 +285,7 @@ static int memjrnlTruncate(sqlite3_file *pJfd, sqlite_int64 size){
 */
 static int memjrnlClose(sqlite3_file *pJfd){
   MemJournal *p = (MemJournal *)pJfd;
-  memjrnlFreeChunks(p);
+  memjrnlFreeChunks(p->pFirst);
   return SQLITE_OK;
 }
 

src/pager.c

@@ -435,6 +435,7 @@ struct PagerSavepoint {
   Bitvec *pInSavepoint;        /* Set of pages in this savepoint */
   Pgno nOrig;                  /* Original number of pages in file */
   Pgno iSubRec;                /* Index of first record in sub-journal */
+  int bTruncateOnRelease;      /* If stmt journal may be truncated on RELEASE */
 #ifndef SQLITE_OMIT_WAL
   u32 aWalData[WAL_SAVEPOINT_NDATA];        /* WAL savepoint context */
 #endif
@@ -1070,6 +1071,9 @@ static int subjRequiresPage(PgHdr *pPg){
   for(i=0; i<pPager->nSavepoint; i++){
     p = &pPager->aSavepoint[i];
     if( p->nOrig>=pgno && 0==sqlite3BitvecTestNotNull(p->pInSavepoint, pgno) ){
+      for(i=i+1; i<pPager->nSavepoint; i++){
+        pPager->aSavepoint[i].bTruncateOnRelease = 0;
+      }
       return 1;
     }
   }
@@ -6848,6 +6852,7 @@ static SQLITE_NOINLINE int pagerOpenSavepoint(Pager *pPager, int nSavepoint){
     }
     aNew[ii].iSubRec = pPager->nSubRec;
     aNew[ii].pInSavepoint = sqlite3BitvecCreate(pPager->dbSize);
+    aNew[ii].bTruncateOnRelease = 1;
     if( !aNew[ii].pInSavepoint ){
       return SQLITE_NOMEM_BKPT;
     }
@@ -6929,13 +6934,15 @@ int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint){
     /* If this is a release of the outermost savepoint, truncate 
     ** the sub-journal to zero bytes in size. */
     if( op==SAVEPOINT_RELEASE ){
-      if( nNew==0 && isOpen(pPager->sjfd) ){
+      PagerSavepoint *pRel = &pPager->aSavepoint[nNew];
+      if( pRel->bTruncateOnRelease && isOpen(pPager->sjfd) ){
         /* Only truncate if it is an in-memory sub-journal. */
         if( sqlite3JournalIsInMemory(pPager->sjfd) ){
-          rc = sqlite3OsTruncate(pPager->sjfd, 0);
+          i64 sz = (pPager->pageSize+4)*pRel->iSubRec;
+          rc = sqlite3OsTruncate(pPager->sjfd, sz);
           assert( rc==SQLITE_OK );
         }
-        pPager->nSubRec = 0;
+        pPager->nSubRec = pRel->iSubRec;
       }
     }
     /* Else this is a rollback operation, playback the specified savepoint.