database/sqlite
1
0
Fork 0
mirror of https://github.com/sqlite/sqlite.git synced 2025-08-05 15:55:57 +03:00
Code Activity

Allow a wal mode recovery to proceed even if there are readers.

Browse Source 
FossilOrigin-Name: 74374aebf9abf3d6b6a3920967a079ceaa4c6276dc6c177682742c2be405b7b7
This commit is contained in:
dan
2020-07-25 20:16:27 +00:00
parent 8adc8f1ecb
commit d3e38b7c0e
3 changed files with 70 additions and 43 deletions
Download Patch File Download Diff File Expand all files Collapse all files

94
src/wal.c
View File

@@ -1161,12 +1161,6 @@ static int walIndexRecover(Wal *pWal){
assert( pWal->writeLock );
iLock = WAL_ALL_BUT_WRITE + pWal->ckptLock;
rc = walLockExclusive(pWal, iLock, WAL_READ_LOCK(0)-iLock);
if( rc==SQLITE_OK ){
rc = walLockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
if( rc!=SQLITE_OK ){
walUnlockExclusive(pWal, iLock, WAL_READ_LOCK(0)-iLock);
}
}
if( rc ){
return rc;
}
@@ -1182,15 +1176,16 @@ static int walIndexRecover(Wal *pWal){
if( nSize>WAL_HDRSIZE ){
u8 aBuf[WAL_HDRSIZE]; /* Buffer to load WAL header into */
u32 *aPrivate = 0; /* Heap copy of *-shm hash being populated */
u8 *aFrame = 0; /* Malloc'd buffer to load entire frame */
int szFrame; /* Number of bytes in buffer aFrame[] */
u8 *aData; /* Pointer to data part of aFrame buffer */
int iFrame; /* Index of last frame read */
i64 iOffset; /* Next offset to read from log file */
int szPage; /* Page size according to the log */
u32 magic; /* Magic value read from WAL header */
u32 version; /* Magic value read from WAL header */
int isValid; /* True if this frame is valid */
int iPg; /* Current 32KB wal-index page */
int iLastFrame; /* Last frame in wal, based on nSize alone */
/* Read in the WAL header. */
rc = sqlite3OsRead(pWal->pWalFd, aBuf, WAL_HDRSIZE, 0);
@@ -1237,38 +1232,59 @@ static int walIndexRecover(Wal *pWal){
/* Malloc a buffer to read frames into. */
szFrame = szPage + WAL_FRAME_HDRSIZE;
aFrame = (u8 *)sqlite3_malloc64(szFrame);
aFrame = (u8 *)sqlite3_malloc64(szFrame + WALINDEX_PGSZ);
if( !aFrame ){
rc = SQLITE_NOMEM_BKPT;
goto recovery_error;
}
aData = &aFrame[WAL_FRAME_HDRSIZE];
aPrivate = (u32*)&aData[szPage];
/* Read all frames from the log file. */
iFrame = 0;
for(iOffset=WAL_HDRSIZE; (iOffset+szFrame)<=nSize; iOffset+=szFrame){
u32 pgno; /* Database page number for frame */
u32 nTruncate; /* dbsize field from frame header */
iLastFrame = (nSize - WAL_HDRSIZE) / szFrame;
for(iPg=0; iPg<=walFramePage(iLastFrame); iPg++){
u32 *aShare;
int iFrame; /* Index of last frame read */
int iLast = MIN(iLastFrame, HASHTABLE_NPAGE_ONE+iPg*HASHTABLE_NPAGE);
int iFirst = 1 + (iPg==0?0:HASHTABLE_NPAGE_ONE+(iPg-1)*HASHTABLE_NPAGE);
rc = walIndexPage(pWal, iPg, (volatile u32**)&aShare);
if( rc ) break;
pWal->apWiData[iPg] = aPrivate;
for(iFrame=iFirst; iFrame<=iLast; iFrame++){
i64 iOffset = walFrameOffset(iFrame, szPage);
u32 pgno; /* Database page number for frame */
u32 nTruncate; /* dbsize field from frame header */
/* Read and decode the next log frame. */
iFrame++;
rc = sqlite3OsRead(pWal->pWalFd, aFrame, szFrame, iOffset);
if( rc!=SQLITE_OK ) break;
isValid = walDecodeFrame(pWal, &pgno, &nTruncate, aData, aFrame);
if( !isValid ) break;
rc = walIndexAppend(pWal, iFrame, pgno);
if( rc!=SQLITE_OK ) break;
/* Read and decode the next log frame. */
rc = sqlite3OsRead(pWal->pWalFd, aFrame, szFrame, iOffset);
if( rc!=SQLITE_OK ) break;
isValid = walDecodeFrame(pWal, &pgno, &nTruncate, aData, aFrame);
if( !isValid ) break;
rc = walIndexAppend(pWal, iFrame, pgno);
if( rc!=SQLITE_OK ) break;
/* If nTruncate is non-zero, this is a commit record. */
if( nTruncate ){
pWal->hdr.mxFrame = iFrame;
pWal->hdr.nPage = nTruncate;
pWal->hdr.szPage = (u16)((szPage&0xff00) | (szPage>>16));
testcase( szPage<=32768 );
testcase( szPage>=65536 );
aFrameCksum[0] = pWal->hdr.aFrameCksum[0];
aFrameCksum[1] = pWal->hdr.aFrameCksum[1];
/* If nTruncate is non-zero, this is a commit record. */
if( nTruncate ){
pWal->hdr.mxFrame = iFrame;
pWal->hdr.nPage = nTruncate;
pWal->hdr.szPage = (u16)((szPage&0xff00) | (szPage>>16));
testcase( szPage<=32768 );
testcase( szPage>=65536 );
aFrameCksum[0] = pWal->hdr.aFrameCksum[0];
aFrameCksum[1] = pWal->hdr.aFrameCksum[1];
}
}
pWal->apWiData[iPg] = aShare;
{
int nHdr = (iPg==0 ? WALINDEX_HDR_SIZE : 0);
int nHdr32 = nHdr / sizeof(u32);
if( memcpy(&aShare[nHdr32], &aPrivate[nHdr32], WALINDEX_PGSZ-nHdr) ){
memcpy(&aShare[nHdr32], &aPrivate[nHdr32], WALINDEX_PGSZ-nHdr);
}
}
if( iFrame<=iLast ) break;
}
sqlite3_free(aFrame);
@@ -1283,15 +1299,24 @@ finished:
walIndexWriteHdr(pWal);
/* Reset the checkpoint-header. This is safe because this thread is
** currently holding locks that exclude all other readers, writers and
** checkpointers.
** currently holding locks that exclude all other writers and
** checkpointers. Then set the values of read-mark slots 1 through N.
*/
pInfo = walCkptInfo(pWal);
pInfo->nBackfill = 0;
pInfo->nBackfillAttempted = pWal->hdr.mxFrame;
pInfo->aReadMark[0] = 0;
for(i=1; i<WAL_NREADER; i++) pInfo->aReadMark[i] = READMARK_NOT_USED;
if( pWal->hdr.mxFrame ) pInfo->aReadMark[1] = pWal->hdr.mxFrame;
for(i=1; i<WAL_NREADER; i++){
rc = walLockExclusive(pWal, WAL_READ_LOCK(i), 1);
if( rc==SQLITE_OK ){
if( i==1 && pWal->hdr.mxFrame ){
pInfo->aReadMark[i] = pWal->hdr.mxFrame;
}else{
pInfo->aReadMark[i] = READMARK_NOT_USED;
}
walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
}
}
/* If more than one frame was recovered from the log file, report an
** event via sqlite3_log(). This is to help with identifying performance
@@ -1309,7 +1334,6 @@ finished:
recovery_error:
WALTRACE(("WAL%p: recovery %s\n", pWal, rc ? "failed" : "ok"));
walUnlockExclusive(pWal, iLock, WAL_READ_LOCK(0)-iLock);
walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
return rc;
}