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Overview
| Comment: | Make sure the wal-index mapping is always large enough to cover the entire active area of the wal-index. |
|---|---|
| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
42705babba0e9d2ef078845854bebbd1 |
| User & Date: | drh 2010-05-26 17:31:59.000 |
Context
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2010-05-28
| ||
| 11:16 | Add a test to walcksum.test to stress the checksum calculation. (check-in: 778d0c1768 user: dan tags: trunk) | |
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2010-05-26
| ||
| 17:31 | Make sure the wal-index mapping is always large enough to cover the entire active area of the wal-index. (check-in: 42705babba user: drh tags: trunk) | |
| 15:06 | Change the semantics of xShmGet() such that it will never increase the size of shared memory. xShmSize() must be used to grow the size of shared memory. A shared memory segment size cannot be shrunk (except by dropping it). (check-in: 72de007312 user: drh tags: trunk) | |
Changes
Changes to src/wal.c.
| ︙ | ︙ | |||
1384 1385 1386 1387 1388 1389 1390 | ** ** A dirty read of the wal-index header occurs if another thread or ** process happens to be writing to the wal-index header at roughly ** the same time as this thread is reading it. In this case it is ** possible that an inconsistent header is read (which is detected ** using the header checksum mechanism). */ | | < | < | | | | | | | | | | | | | | | | | | | | | | > > > > > > > > > | 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 |
**
** A dirty read of the wal-index header occurs if another thread or
** process happens to be writing to the wal-index header at roughly
** the same time as this thread is reading it. In this case it is
** possible that an inconsistent header is read (which is detected
** using the header checksum mechanism).
*/
if( walIndexTryHdr(pWal, pChanged)!=0 ){
/* If the first attempt to read the header failed, lock the wal-index
** file with an exclusive lock and try again. If the header checksum
** verification fails again, we can be sure that it is not simply a
** dirty read, but that the wal-index really does need to be
** reconstructed by running log recovery.
**
** In the paragraph above, an "exclusive lock" may be any of WRITE,
** PENDING, CHECKPOINT or RECOVER. If any of these are already held,
** no locking operations are required. If the caller currently holds
** a READ lock, then upgrade to a RECOVER lock before re-reading the
** wal-index header and revert to a READ lock before returning.
*/
lockState = pWal->lockState;
if( lockState>SQLITE_SHM_READ
|| SQLITE_OK==(rc = walSetLock(pWal, SQLITE_SHM_RECOVER))
){
if( walIndexTryHdr(pWal, pChanged) ){
*pChanged = 1;
rc = walIndexRecover(pWal);
}
if( lockState==SQLITE_SHM_READ ){
walSetLock(pWal, SQLITE_SHM_READ);
}
}
}
/* Make sure the mapping is large enough to cover the entire wal-index */
if( rc==SQLITE_OK ){
int szWanted = walMappingSize(pWal->hdr.mxFrame);
if( pWal->szWIndex<szWanted ){
rc = walIndexMap(pWal, szWanted);
}
}
return rc;
}
/*
|
| ︙ | ︙ | |||
1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 |
if( pWal->lockState==SQLITE_SHM_WRITE ){
int unused;
Pgno iMax = pWal->hdr.mxFrame;
Pgno iFrame;
assert( pWal->pWiData==0 );
rc = walIndexReadHdr(pWal, &unused);
if( rc==SQLITE_OK ){
for(iFrame=pWal->hdr.mxFrame+1; rc==SQLITE_OK && iFrame<=iMax; iFrame++){
assert( pWal->lockState==SQLITE_SHM_WRITE );
rc = xUndo(pUndoCtx, pWal->pWiData[walIndexEntry(iFrame)]);
}
walCleanupHash(pWal);
}
| > > > | 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 |
if( pWal->lockState==SQLITE_SHM_WRITE ){
int unused;
Pgno iMax = pWal->hdr.mxFrame;
Pgno iFrame;
assert( pWal->pWiData==0 );
rc = walIndexReadHdr(pWal, &unused);
if( rc==SQLITE_OK ){
rc = walIndexMap(pWal, walMappingSize(iMax));
}
if( rc==SQLITE_OK ){
for(iFrame=pWal->hdr.mxFrame+1; rc==SQLITE_OK && iFrame<=iMax; iFrame++){
assert( pWal->lockState==SQLITE_SHM_WRITE );
rc = xUndo(pUndoCtx, pWal->pWiData[walIndexEntry(iFrame)]);
}
walCleanupHash(pWal);
}
|
| ︙ | ︙ |