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Overview
| Comment: | Correctly record the fact that the SHM lock reached PENDING if it did so but failed to reach CHECKPOINT. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | wal |
| Files: | files | file ages | folders |
| SHA1: |
d9250e84ac1fc6590f8670e1d8016306 |
| User & Date: | drh 2010-04-30 16:12:04 |
Context
|
2010-04-30
| ||
| 16:19 | Add xShmXXX() methods to the test VFS in test_devsym.test. (check-in: 1d203424 user: dan tags: wal) | |
| 16:12 | Correctly record the fact that the SHM lock reached PENDING if it did so but failed to reach CHECKPOINT. (check-in: d9250e84 user: drh tags: wal) | |
| 15:54 | Fix a couple uninitialized variables in the xShmLock method of the unix VFS. Improved debugging logic for xShmLock. (check-in: 69567c5f user: drh tags: wal) | |
Changes
Changes to src/wal.c.
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** type of reader lock (either SQLITE_SHM_READ or SQLITE_SHM_READ_FULL)
** in pWal->readerType.
*/
static int walSetLock(Wal *pWal, int desiredStatus){
int rc, got;
if( pWal->lockState==desiredStatus ) return SQLITE_OK;
rc = pWal->pVfs->xShmLock(pWal->pWIndex, desiredStatus, &got);
if( rc==SQLITE_OK ){
pWal->lockState = desiredStatus;
if( desiredStatus==SQLITE_SHM_READ ){
pWal->readerType = got;
}
}
return rc;
}
/*
** Update the header of the wal-index file.
*/
................................................................................
Wal *pWal, /* Wal to close */
sqlite3_file *pFd, /* Database file */
int sync_flags, /* Flags to pass to OsSync() (or 0) */
u8 *zBuf /* Buffer of at least page-size bytes */
){
int rc = SQLITE_OK;
if( pWal ){
int isDelete = 0; /* True to unlink wal and wal-index files */
/* If an EXCLUSIVE lock can be obtained on the database file (using the
** ordinary, rollback-mode locking methods, this guarantees that the
** connection associated with this log file is the only connection to
** the database. In this case checkpoint the database and unlink both
** the wal and wal-index files.
**
** The EXCLUSIVE lock is not released before returning.
*/
rc = sqlite3OsLock(pFd, SQLITE_LOCK_EXCLUSIVE);
if( rc==SQLITE_OK ){
rc = walCheckpoint(pWal, pFd, sync_flags, zBuf);
if( rc==SQLITE_OK ){
isDelete = 1;
}
walIndexUnmap(pWal);
}
pWal->pVfs->xShmClose(pWal->pWIndex);
sqlite3OsClose(pWal->pFd);
if( isDelete ){
int nWal;
char *zWal = &((char *)pWal->pFd)[pWal->pVfs->szOsFile];
sqlite3OsDelete(pWal->pVfs, zWal, 0);
nWal = sqlite3Strlen30(zWal);
memcpy(&zWal[nWal], "-index", 7);
pWal->pVfs->xShmDelete(pWal->pVfs, zWal);
}
sqlite3_free(pWal);
}
return rc;
}
/*
** Try to read the wal-index header. Attempt to verify the header
................................................................................
** been overwritten by another writer, SQLITE_BUSY is returned.
*/
int sqlite3WalWriteLock(Wal *pWal, int op){
int rc;
if( op ){
assert( pWal->lockState == SQLITE_SHM_READ );
rc = walSetLock(pWal, SQLITE_SHM_WRITE);
/* If this connection is not reading the most recent database snapshot,
** it is not possible to write to the database. In this case release
** the write locks and return SQLITE_BUSY.
*/
if( rc==SQLITE_OK ){
rc = walIndexMap(pWal, -1);
if( rc==SQLITE_OK
&& memcmp(&pWal->hdr, pWal->pWiData, sizeof(WalIndexHdr))
){
rc = SQLITE_BUSY;
}
walIndexUnmap(pWal);
if( rc!=SQLITE_OK ){
walSetLock(pWal, SQLITE_SHM_READ);
}
}
}else if( pWal->lockState==SQLITE_SHM_WRITE ){
rc = walSetLock(pWal, SQLITE_SHM_READ);
}
return rc;
}
/*
|
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** type of reader lock (either SQLITE_SHM_READ or SQLITE_SHM_READ_FULL)
** in pWal->readerType.
*/
static int walSetLock(Wal *pWal, int desiredStatus){
int rc, got;
if( pWal->lockState==desiredStatus ) return SQLITE_OK;
rc = pWal->pVfs->xShmLock(pWal->pWIndex, desiredStatus, &got);
pWal->lockState = got;
if( got==SQLITE_SHM_READ_FULL || got==SQLITE_SHM_READ ){
pWal->readerType = got;
pWal->lockState = SQLITE_SHM_READ;
}
return rc;
}
/*
** Update the header of the wal-index file.
*/
................................................................................
Wal *pWal, /* Wal to close */
sqlite3_file *pFd, /* Database file */
int sync_flags, /* Flags to pass to OsSync() (or 0) */
u8 *zBuf /* Buffer of at least page-size bytes */
){
int rc = SQLITE_OK;
if( pWal ){
pWal->pVfs->xShmClose(pWal->pWIndex);
sqlite3OsClose(pWal->pFd);
sqlite3_free(pWal);
}
return rc;
}
/*
** Try to read the wal-index header. Attempt to verify the header
................................................................................
** been overwritten by another writer, SQLITE_BUSY is returned.
*/
int sqlite3WalWriteLock(Wal *pWal, int op){
int rc;
if( op ){
assert( pWal->lockState == SQLITE_SHM_READ );
rc = walSetLock(pWal, SQLITE_SHM_WRITE);
}else if( pWal->lockState==SQLITE_SHM_WRITE ){
rc = walSetLock(pWal, SQLITE_SHM_READ);
}
return rc;
}
/*
|