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Merge changes from wal2, including the fix to prevent non-PASSIVE checkpoints from ever taking the writer lock.

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FossilOrigin-Name: eb8449ea9ac8e29425f7127535a1db328d56c86382919fb1fcf42324b71de013
This commit is contained in:
dan
2024-12-14 17:36:12 +00:00
parent cc38dbba4f 686166eb32
commit 8d98a87912
4 changed files with 126 additions and 34 deletions
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74
src/wal.c
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@@ -4947,37 +4947,61 @@ static int walRestartLog(Wal *pWal){
int iApp = walidxGetFile(&pWal->hdr);
u32 nWalSize = WAL_DEFAULT_WALSIZE;
if( pWal->mxWalSize>0 ){
/* mxWalSize is in bytes. Convert this to a number of frames. */
nWalSize = (pWal->mxWalSize-WAL_HDRSIZE+pWal->szPage+WAL_FRAME_HDRSIZE-1)
/ (pWal->szPage+WAL_FRAME_HDRSIZE);
nWalSize = MAX(nWalSize, 1);
}
assert( 1==WAL_LOCK_PART1 );
assert( 4==WAL_LOCK_PART2 );
assert( 1+(iApp*3)==WAL_LOCK_PART1 || 1+(iApp*3)==WAL_LOCK_PART2 );
if( pWal->readLock==1+(iApp*3)
/* With a BEGIN CONCURRENT transaction, it is possible for a connection
** to hold the WAL_LOCK_PART1 lock even if iApp==1 (or WAL_LOCK_PART2
** when iApp==0). This is because a connection running concurrent to this
** one may have switched the wal file after this connection took the
** read lock.
**
** This is not a problem, as if this happens it means the current lock
** is more restrictive, not less, than required. And a BEGIN CONCURRENT
** transaction cannot be committed and downgraded to a read-transaction,
** so there is no chance of continuing while holding the wrong lock.
*/
assert( iApp==0 || pWal->readLock==WAL_LOCK_PART2
|| pWal->readLock==WAL_LOCK_PART2_FULL1
|| pWal->readLock==WAL_LOCK_PART1 );
assert( iApp==1 || pWal->readLock==WAL_LOCK_PART1
|| pWal->readLock==WAL_LOCK_PART1_FULL2
|| pWal->readLock==WAL_LOCK_PART2 );
/* Switch to wal file !iApp if
**
** (a) Wal file iApp (the current wal file) contains >= nWalSize frames.
** (b) This client is not reading from wal file !iApp.
** (c) No other client is reading from wal file !iApp.
**
** Condition (b) guarantees that wal file !iApp is either empty or
** completely checkpointed.
*/
assert( (0*3)+1==WAL_LOCK_PART1 ); /* iApp==0 -> require WAL_LOCK_PART1 */
assert( (1*3)+1==WAL_LOCK_PART2 ); /* iApp==1 -> require WAL_LOCK_PART2 */
if( pWal->readLock==(iApp*3)+1
&& walidxGetMxFrame(&pWal->hdr, iApp)>=nWalSize
){
volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
u32 mxFrame = walidxGetMxFrame(&pWal->hdr, !iApp);
if( mxFrame==0 || pInfo->nBackfill ){
rc = wal2RestartOk(pWal, iApp);
if( rc==SQLITE_OK ){
int iNew = !iApp;
pWal->nCkpt++;
walidxSetFile(&pWal->hdr, iNew);
walidxSetMxFrame(&pWal->hdr, iNew, 0);
sqlite3Put4byte((u8*)&pWal->hdr.aSalt[0], pWal->hdr.aFrameCksum[0]);
sqlite3Put4byte((u8*)&pWal->hdr.aSalt[1], pWal->hdr.aFrameCksum[1]);
walIndexWriteHdr(pWal);
pInfo->nBackfill = 0;
wal2RestartFinished(pWal, iApp);
walUnlockShared(pWal, WAL_READ_LOCK(pWal->readLock));
pWal->readLock = iNew ? WAL_LOCK_PART2_FULL1 : WAL_LOCK_PART1_FULL2;
rc = walLockShared(pWal, WAL_READ_LOCK(pWal->readLock));
}else if( rc==SQLITE_BUSY ){
rc = SQLITE_OK;
}
rc = wal2RestartOk(pWal, iApp);
if( rc==SQLITE_OK ){
volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
int iNew = !iApp;
pWal->nCkpt++;
walidxSetFile(&pWal->hdr, iNew);
walidxSetMxFrame(&pWal->hdr, iNew, 0);
sqlite3Put4byte((u8*)&pWal->hdr.aSalt[0], pWal->hdr.aFrameCksum[0]);
sqlite3Put4byte((u8*)&pWal->hdr.aSalt[1], pWal->hdr.aFrameCksum[1]);
walIndexWriteHdr(pWal);
pInfo->nBackfill = 0;
wal2RestartFinished(pWal, iApp);
walUnlockShared(pWal, WAL_READ_LOCK(pWal->readLock));
pWal->readLock = iNew ? WAL_LOCK_PART2_FULL1 : WAL_LOCK_PART1_FULL2;
rc = walLockShared(pWal, WAL_READ_LOCK(pWal->readLock));
}else if( rc==SQLITE_BUSY ){
rc = SQLITE_OK;
}
}
}else if( pWal->readLock==0 ){
@@ -5504,7 +5528,7 @@ int sqlite3WalCheckpoint(
** writer lock retried until either the busy-handler returns 0 or the
** lock is successfully obtained.
*/
if( eMode!=SQLITE_CHECKPOINT_PASSIVE ){
if( eMode!=SQLITE_CHECKPOINT_PASSIVE && isWalMode2(pWal)==0 ){
rc = walBusyLock(pWal, xBusy2, pBusyArg, WAL_WRITE_LOCK, 1);
if( rc==SQLITE_OK ){
pWal->writeLock = 1;