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-rw-r--r--lib/libsqlite3/src/wal.c296
1 files changed, 176 insertions, 120 deletions
diff --git a/lib/libsqlite3/src/wal.c b/lib/libsqlite3/src/wal.c
index d134a8b52a3..71f4a3d452f 100644
--- a/lib/libsqlite3/src/wal.c
+++ b/lib/libsqlite3/src/wal.c
@@ -1504,7 +1504,7 @@ static void walMergesort(
** Free an iterator allocated by walIteratorInit().
*/
static void walIteratorFree(WalIterator *p){
- sqlite3ScratchFree(p);
+ sqlite3_free(p);
}
/*
@@ -1539,7 +1539,7 @@ static int walIteratorInit(Wal *pWal, WalIterator **pp){
nByte = sizeof(WalIterator)
+ (nSegment-1)*sizeof(struct WalSegment)
+ iLast*sizeof(ht_slot);
- p = (WalIterator *)sqlite3ScratchMalloc(nByte);
+ p = (WalIterator *)sqlite3_malloc(nByte);
if( !p ){
return SQLITE_NOMEM;
}
@@ -1549,7 +1549,7 @@ static int walIteratorInit(Wal *pWal, WalIterator **pp){
/* Allocate temporary space used by the merge-sort routine. This block
** of memory will be freed before this function returns.
*/
- aTmp = (ht_slot *)sqlite3ScratchMalloc(
+ aTmp = (ht_slot *)sqlite3_malloc(
sizeof(ht_slot) * (iLast>HASHTABLE_NPAGE?HASHTABLE_NPAGE:iLast)
);
if( !aTmp ){
@@ -1586,7 +1586,7 @@ static int walIteratorInit(Wal *pWal, WalIterator **pp){
p->aSegment[i].aPgno = (u32 *)aPgno;
}
}
- sqlite3ScratchFree(aTmp);
+ sqlite3_free(aTmp);
if( rc!=SQLITE_OK ){
walIteratorFree(p);
@@ -1624,6 +1624,38 @@ static int walPagesize(Wal *pWal){
}
/*
+** The following is guaranteed when this function is called:
+**
+** a) the WRITER lock is held,
+** b) the entire log file has been checkpointed, and
+** c) any existing readers are reading exclusively from the database
+** file - there are no readers that may attempt to read a frame from
+** the log file.
+**
+** This function updates the shared-memory structures so that the next
+** client to write to the database (which may be this one) does so by
+** writing frames into the start of the log file.
+**
+** The value of parameter salt1 is used as the aSalt[1] value in the
+** new wal-index header. It should be passed a pseudo-random value (i.e.
+** one obtained from sqlite3_randomness()).
+*/
+static void walRestartHdr(Wal *pWal, u32 salt1){
+ volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
+ int i; /* Loop counter */
+ u32 *aSalt = pWal->hdr.aSalt; /* Big-endian salt values */
+ pWal->nCkpt++;
+ pWal->hdr.mxFrame = 0;
+ sqlite3Put4byte((u8*)&aSalt[0], 1 + sqlite3Get4byte((u8*)&aSalt[0]));
+ memcpy(&pWal->hdr.aSalt[1], &salt1, 4);
+ walIndexWriteHdr(pWal);
+ pInfo->nBackfill = 0;
+ pInfo->aReadMark[1] = 0;
+ for(i=2; i<WAL_NREADER; i++) pInfo->aReadMark[i] = READMARK_NOT_USED;
+ assert( pInfo->aReadMark[0]==0 );
+}
+
+/*
** Copy as much content as we can from the WAL back into the database file
** in response to an sqlite3_wal_checkpoint() request or the equivalent.
**
@@ -1657,12 +1689,12 @@ static int walPagesize(Wal *pWal){
static int walCheckpoint(
Wal *pWal, /* Wal connection */
int eMode, /* One of PASSIVE, FULL or RESTART */
- int (*xBusyCall)(void*), /* Function to call when busy */
+ int (*xBusy)(void*), /* Function to call when busy */
void *pBusyArg, /* Context argument for xBusyHandler */
int sync_flags, /* Flags for OsSync() (or 0) */
u8 *zBuf /* Temporary buffer to use */
){
- int rc; /* Return code */
+ int rc = SQLITE_OK; /* Return code */
int szPage; /* Database page-size */
WalIterator *pIter = 0; /* Wal iterator context */
u32 iDbpage = 0; /* Next database page to write */
@@ -1671,123 +1703,146 @@ static int walCheckpoint(
u32 mxPage; /* Max database page to write */
int i; /* Loop counter */
volatile WalCkptInfo *pInfo; /* The checkpoint status information */
- int (*xBusy)(void*) = 0; /* Function to call when waiting for locks */
szPage = walPagesize(pWal);
testcase( szPage<=32768 );
testcase( szPage>=65536 );
pInfo = walCkptInfo(pWal);
- if( pInfo->nBackfill>=pWal->hdr.mxFrame ) return SQLITE_OK;
+ if( pInfo->nBackfill<pWal->hdr.mxFrame ){
- /* Allocate the iterator */
- rc = walIteratorInit(pWal, &pIter);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- assert( pIter );
+ /* Allocate the iterator */
+ rc = walIteratorInit(pWal, &pIter);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ assert( pIter );
- if( eMode!=SQLITE_CHECKPOINT_PASSIVE ) xBusy = xBusyCall;
+ /* EVIDENCE-OF: R-62920-47450 The busy-handler callback is never invoked
+ ** in the SQLITE_CHECKPOINT_PASSIVE mode. */
+ assert( eMode!=SQLITE_CHECKPOINT_PASSIVE || xBusy==0 );
- /* Compute in mxSafeFrame the index of the last frame of the WAL that is
- ** safe to write into the database. Frames beyond mxSafeFrame might
- ** overwrite database pages that are in use by active readers and thus
- ** cannot be backfilled from the WAL.
- */
- mxSafeFrame = pWal->hdr.mxFrame;
- mxPage = pWal->hdr.nPage;
- for(i=1; i<WAL_NREADER; i++){
- u32 y = pInfo->aReadMark[i];
- if( mxSafeFrame>y ){
- assert( y<=pWal->hdr.mxFrame );
- rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(i), 1);
- if( rc==SQLITE_OK ){
- pInfo->aReadMark[i] = (i==1 ? mxSafeFrame : READMARK_NOT_USED);
- walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
- }else if( rc==SQLITE_BUSY ){
- mxSafeFrame = y;
- xBusy = 0;
- }else{
- goto walcheckpoint_out;
+ /* Compute in mxSafeFrame the index of the last frame of the WAL that is
+ ** safe to write into the database. Frames beyond mxSafeFrame might
+ ** overwrite database pages that are in use by active readers and thus
+ ** cannot be backfilled from the WAL.
+ */
+ mxSafeFrame = pWal->hdr.mxFrame;
+ mxPage = pWal->hdr.nPage;
+ for(i=1; i<WAL_NREADER; i++){
+ u32 y = pInfo->aReadMark[i];
+ if( mxSafeFrame>y ){
+ assert( y<=pWal->hdr.mxFrame );
+ rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(i), 1);
+ if( rc==SQLITE_OK ){
+ pInfo->aReadMark[i] = (i==1 ? mxSafeFrame : READMARK_NOT_USED);
+ walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
+ }else if( rc==SQLITE_BUSY ){
+ mxSafeFrame = y;
+ xBusy = 0;
+ }else{
+ goto walcheckpoint_out;
+ }
}
}
- }
- if( pInfo->nBackfill<mxSafeFrame
- && (rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(0), 1))==SQLITE_OK
- ){
- i64 nSize; /* Current size of database file */
- u32 nBackfill = pInfo->nBackfill;
-
- /* Sync the WAL to disk */
- if( sync_flags ){
- rc = sqlite3OsSync(pWal->pWalFd, sync_flags);
- }
+ if( pInfo->nBackfill<mxSafeFrame
+ && (rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(0),1))==SQLITE_OK
+ ){
+ i64 nSize; /* Current size of database file */
+ u32 nBackfill = pInfo->nBackfill;
- /* If the database may grow as a result of this checkpoint, hint
- ** about the eventual size of the db file to the VFS layer.
- */
- if( rc==SQLITE_OK ){
- i64 nReq = ((i64)mxPage * szPage);
- rc = sqlite3OsFileSize(pWal->pDbFd, &nSize);
- if( rc==SQLITE_OK && nSize<nReq ){
- sqlite3OsFileControlHint(pWal->pDbFd, SQLITE_FCNTL_SIZE_HINT, &nReq);
+ /* Sync the WAL to disk */
+ if( sync_flags ){
+ rc = sqlite3OsSync(pWal->pWalFd, sync_flags);
}
- }
+ /* If the database may grow as a result of this checkpoint, hint
+ ** about the eventual size of the db file to the VFS layer.
+ */
+ if( rc==SQLITE_OK ){
+ i64 nReq = ((i64)mxPage * szPage);
+ rc = sqlite3OsFileSize(pWal->pDbFd, &nSize);
+ if( rc==SQLITE_OK && nSize<nReq ){
+ sqlite3OsFileControlHint(pWal->pDbFd, SQLITE_FCNTL_SIZE_HINT, &nReq);
+ }
+ }
- /* Iterate through the contents of the WAL, copying data to the db file. */
- while( rc==SQLITE_OK && 0==walIteratorNext(pIter, &iDbpage, &iFrame) ){
- i64 iOffset;
- assert( walFramePgno(pWal, iFrame)==iDbpage );
- if( iFrame<=nBackfill || iFrame>mxSafeFrame || iDbpage>mxPage ) continue;
- iOffset = walFrameOffset(iFrame, szPage) + WAL_FRAME_HDRSIZE;
- /* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL file */
- rc = sqlite3OsRead(pWal->pWalFd, zBuf, szPage, iOffset);
- if( rc!=SQLITE_OK ) break;
- iOffset = (iDbpage-1)*(i64)szPage;
- testcase( IS_BIG_INT(iOffset) );
- rc = sqlite3OsWrite(pWal->pDbFd, zBuf, szPage, iOffset);
- if( rc!=SQLITE_OK ) break;
- }
- /* If work was actually accomplished... */
- if( rc==SQLITE_OK ){
- if( mxSafeFrame==walIndexHdr(pWal)->mxFrame ){
- i64 szDb = pWal->hdr.nPage*(i64)szPage;
- testcase( IS_BIG_INT(szDb) );
- rc = sqlite3OsTruncate(pWal->pDbFd, szDb);
- if( rc==SQLITE_OK && sync_flags ){
- rc = sqlite3OsSync(pWal->pDbFd, sync_flags);
+ /* Iterate through the contents of the WAL, copying data to the db file */
+ while( rc==SQLITE_OK && 0==walIteratorNext(pIter, &iDbpage, &iFrame) ){
+ i64 iOffset;
+ assert( walFramePgno(pWal, iFrame)==iDbpage );
+ if( iFrame<=nBackfill || iFrame>mxSafeFrame || iDbpage>mxPage ){
+ continue;
}
+ iOffset = walFrameOffset(iFrame, szPage) + WAL_FRAME_HDRSIZE;
+ /* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL file */
+ rc = sqlite3OsRead(pWal->pWalFd, zBuf, szPage, iOffset);
+ if( rc!=SQLITE_OK ) break;
+ iOffset = (iDbpage-1)*(i64)szPage;
+ testcase( IS_BIG_INT(iOffset) );
+ rc = sqlite3OsWrite(pWal->pDbFd, zBuf, szPage, iOffset);
+ if( rc!=SQLITE_OK ) break;
}
+
+ /* If work was actually accomplished... */
if( rc==SQLITE_OK ){
- pInfo->nBackfill = mxSafeFrame;
+ if( mxSafeFrame==walIndexHdr(pWal)->mxFrame ){
+ i64 szDb = pWal->hdr.nPage*(i64)szPage;
+ testcase( IS_BIG_INT(szDb) );
+ rc = sqlite3OsTruncate(pWal->pDbFd, szDb);
+ if( rc==SQLITE_OK && sync_flags ){
+ rc = sqlite3OsSync(pWal->pDbFd, sync_flags);
+ }
+ }
+ if( rc==SQLITE_OK ){
+ pInfo->nBackfill = mxSafeFrame;
+ }
}
- }
- /* Release the reader lock held while backfilling */
- walUnlockExclusive(pWal, WAL_READ_LOCK(0), 1);
- }
+ /* Release the reader lock held while backfilling */
+ walUnlockExclusive(pWal, WAL_READ_LOCK(0), 1);
+ }
- if( rc==SQLITE_BUSY ){
- /* Reset the return code so as not to report a checkpoint failure
- ** just because there are active readers. */
- rc = SQLITE_OK;
+ if( rc==SQLITE_BUSY ){
+ /* Reset the return code so as not to report a checkpoint failure
+ ** just because there are active readers. */
+ rc = SQLITE_OK;
+ }
}
- /* If this is an SQLITE_CHECKPOINT_RESTART operation, and the entire wal
- ** file has been copied into the database file, then block until all
- ** readers have finished using the wal file. This ensures that the next
- ** process to write to the database restarts the wal file.
+ /* If this is an SQLITE_CHECKPOINT_RESTART or TRUNCATE operation, and the
+ ** entire wal file has been copied into the database file, then block
+ ** until all readers have finished using the wal file. This ensures that
+ ** the next process to write to the database restarts the wal file.
*/
if( rc==SQLITE_OK && eMode!=SQLITE_CHECKPOINT_PASSIVE ){
assert( pWal->writeLock );
if( pInfo->nBackfill<pWal->hdr.mxFrame ){
rc = SQLITE_BUSY;
- }else if( eMode==SQLITE_CHECKPOINT_RESTART ){
- assert( mxSafeFrame==pWal->hdr.mxFrame );
+ }else if( eMode>=SQLITE_CHECKPOINT_RESTART ){
+ u32 salt1;
+ sqlite3_randomness(4, &salt1);
+ assert( pInfo->nBackfill==pWal->hdr.mxFrame );
rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(1), WAL_NREADER-1);
if( rc==SQLITE_OK ){
+ if( eMode==SQLITE_CHECKPOINT_TRUNCATE ){
+ /* IMPLEMENTATION-OF: R-44699-57140 This mode works the same way as
+ ** SQLITE_CHECKPOINT_RESTART with the addition that it also
+ ** truncates the log file to zero bytes just prior to a
+ ** successful return.
+ **
+ ** In theory, it might be safe to do this without updating the
+ ** wal-index header in shared memory, as all subsequent reader or
+ ** writer clients should see that the entire log file has been
+ ** checkpointed and behave accordingly. This seems unsafe though,
+ ** as it would leave the system in a state where the contents of
+ ** the wal-index header do not match the contents of the
+ ** file-system. To avoid this, update the wal-index header to
+ ** indicate that the log file contains zero valid frames. */
+ walRestartHdr(pWal, salt1);
+ rc = sqlite3OsTruncate(pWal->pWalFd, 0);
+ }
walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
}
}
@@ -2360,7 +2415,7 @@ int sqlite3WalFindFrame(
for(iKey=walHash(pgno); aHash[iKey]; iKey=walNextHash(iKey)){
u32 iFrame = aHash[iKey] + iZero;
if( iFrame<=iLast && aPgno[aHash[iKey]]==pgno ){
- /* assert( iFrame>iRead ); -- not true if there is corruption */
+ assert( iFrame>iRead || CORRUPT_DB );
iRead = iFrame;
}
if( (nCollide--)==0 ){
@@ -2573,7 +2628,6 @@ int sqlite3WalSavepointUndo(Wal *pWal, u32 *aWalData){
return rc;
}
-
/*
** This function is called just before writing a set of frames to the log
** file (see sqlite3WalFrames()). It checks to see if, instead of appending
@@ -2606,20 +2660,8 @@ static int walRestartLog(Wal *pWal){
** In theory it would be Ok to update the cache of the header only
** at this point. But updating the actual wal-index header is also
** safe and means there is no special case for sqlite3WalUndo()
- ** to handle if this transaction is rolled back.
- */
- int i; /* Loop counter */
- u32 *aSalt = pWal->hdr.aSalt; /* Big-endian salt values */
-
- pWal->nCkpt++;
- pWal->hdr.mxFrame = 0;
- sqlite3Put4byte((u8*)&aSalt[0], 1 + sqlite3Get4byte((u8*)&aSalt[0]));
- aSalt[1] = salt1;
- walIndexWriteHdr(pWal);
- pInfo->nBackfill = 0;
- pInfo->aReadMark[1] = 0;
- for(i=2; i<WAL_NREADER; i++) pInfo->aReadMark[i] = READMARK_NOT_USED;
- assert( pInfo->aReadMark[0]==0 );
+ ** to handle if this transaction is rolled back. */
+ walRestartHdr(pWal, salt1);
walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
}else if( rc!=SQLITE_BUSY ){
return rc;
@@ -2907,7 +2949,7 @@ int sqlite3WalFrames(
*/
int sqlite3WalCheckpoint(
Wal *pWal, /* Wal connection */
- int eMode, /* PASSIVE, FULL or RESTART */
+ int eMode, /* PASSIVE, FULL, RESTART, or TRUNCATE */
int (*xBusy)(void*), /* Function to call when busy */
void *pBusyArg, /* Context argument for xBusyHandler */
int sync_flags, /* Flags to sync db file with (or 0) */
@@ -2919,29 +2961,42 @@ int sqlite3WalCheckpoint(
int rc; /* Return code */
int isChanged = 0; /* True if a new wal-index header is loaded */
int eMode2 = eMode; /* Mode to pass to walCheckpoint() */
+ int (*xBusy2)(void*) = xBusy; /* Busy handler for eMode2 */
assert( pWal->ckptLock==0 );
assert( pWal->writeLock==0 );
+ /* EVIDENCE-OF: R-62920-47450 The busy-handler callback is never invoked
+ ** in the SQLITE_CHECKPOINT_PASSIVE mode. */
+ assert( eMode!=SQLITE_CHECKPOINT_PASSIVE || xBusy==0 );
+
if( pWal->readOnly ) return SQLITE_READONLY;
WALTRACE(("WAL%p: checkpoint begins\n", pWal));
+
+ /* IMPLEMENTATION-OF: R-62028-47212 All calls obtain an exclusive
+ ** "checkpoint" lock on the database file. */
rc = walLockExclusive(pWal, WAL_CKPT_LOCK, 1);
if( rc ){
- /* Usually this is SQLITE_BUSY meaning that another thread or process
- ** is already running a checkpoint, or maybe a recovery. But it might
- ** also be SQLITE_IOERR. */
+ /* EVIDENCE-OF: R-10421-19736 If any other process is running a
+ ** checkpoint operation at the same time, the lock cannot be obtained and
+ ** SQLITE_BUSY is returned.
+ ** EVIDENCE-OF: R-53820-33897 Even if there is a busy-handler configured,
+ ** it will not be invoked in this case.
+ */
+ testcase( rc==SQLITE_BUSY );
+ testcase( xBusy!=0 );
return rc;
}
pWal->ckptLock = 1;
- /* If this is a blocking-checkpoint, then obtain the write-lock as well
- ** to prevent any writers from running while the checkpoint is underway.
- ** This has to be done before the call to walIndexReadHdr() below.
+ /* IMPLEMENTATION-OF: R-59782-36818 The SQLITE_CHECKPOINT_FULL, RESTART and
+ ** TRUNCATE modes also obtain the exclusive "writer" lock on the database
+ ** file.
**
- ** If the writer lock cannot be obtained, then a passive checkpoint is
- ** run instead. Since the checkpointer is not holding the writer lock,
- ** there is no point in blocking waiting for any readers. Assuming no
- ** other error occurs, this function will return SQLITE_BUSY to the caller.
+ ** EVIDENCE-OF: R-60642-04082 If the writer lock cannot be obtained
+ ** immediately, and a busy-handler is configured, it is invoked and the
+ ** writer lock retried until either the busy-handler returns 0 or the
+ ** lock is successfully obtained.
*/
if( eMode!=SQLITE_CHECKPOINT_PASSIVE ){
rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_WRITE_LOCK, 1);
@@ -2949,6 +3004,7 @@ int sqlite3WalCheckpoint(
pWal->writeLock = 1;
}else if( rc==SQLITE_BUSY ){
eMode2 = SQLITE_CHECKPOINT_PASSIVE;
+ xBusy2 = 0;
rc = SQLITE_OK;
}
}
@@ -2966,7 +3022,7 @@ int sqlite3WalCheckpoint(
if( pWal->hdr.mxFrame && walPagesize(pWal)!=nBuf ){
rc = SQLITE_CORRUPT_BKPT;
}else{
- rc = walCheckpoint(pWal, eMode2, xBusy, pBusyArg, sync_flags, zBuf);
+ rc = walCheckpoint(pWal, eMode2, xBusy2, pBusyArg, sync_flags, zBuf);
}
/* If no error occurred, set the output variables. */
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.