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Changes so that WAL and exclusive-locking mode work together.

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FossilOrigin-Name: 71e7b1cf9f4cd02a2a9bc8a3e58acd7a7e3c7e60
This commit is contained in:
dan
2010-05-11 12:19:26 +00:00
parent a10069dd22
commit 5543759b1b
6 changed files with 321 additions and 35 deletions
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39
src/pager.c
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@@ -1404,8 +1404,8 @@ static int pager_end_transaction(Pager *pPager, int hasMaster){
}
pPager->journalOff = 0;
pPager->journalStarted = 0;
}else if( pPager->exclusiveMode
|| pPager->journalMode==PAGER_JOURNALMODE_PERSIST
}else if( pPager->journalMode==PAGER_JOURNALMODE_PERSIST
|| (pPager->exclusiveMode && pPager->journalMode!=PAGER_JOURNALMODE_WAL)
){
rc = zeroJournalHdr(pPager, hasMaster);
pager_error(pPager, rc);
@@ -1439,6 +1439,17 @@ static int pager_end_transaction(Pager *pPager, int hasMaster){
if( pagerUseWal(pPager) ){
rc2 = sqlite3WalWriteLock(pPager->pWal, 0);
pPager->state = PAGER_SHARED;
/* If the connection was in locking_mode=exclusive mode but is no longer,
** drop the EXCLUSIVE lock held on the database file.
*/
if( rc2==SQLITE_OK
&& !pPager->exclusiveMode
&& sqlite3WalExclusiveMode(pPager->pWal, -1)
){
sqlite3WalExclusiveMode(pPager->pWal, 0);
rc2 = osUnlock(pPager->fd, SHARED_LOCK);
}
}else if( !pPager->exclusiveMode ){
rc2 = osUnlock(pPager->fd, SHARED_LOCK);
pPager->state = PAGER_SHARED;
@@ -4509,15 +4520,34 @@ int sqlite3PagerBegin(Pager *pPager, int exFlag, int subjInMemory){
int rc = SQLITE_OK;
assert( pPager->state!=PAGER_UNLOCK );
pPager->subjInMemory = (u8)subjInMemory;
if( pPager->state==PAGER_SHARED ){
assert( pPager->pInJournal==0 );
assert( !MEMDB && !pPager->tempFile );
if( pagerUseWal(pPager) ){
/* If the pager is configured to use locking_mode=exclusive, and an
** exclusive lock on the database is not already held, obtain it now.
*/
if( pPager->exclusiveMode && !sqlite3WalExclusiveMode(pPager->pWal, -1) ){
rc = sqlite3OsLock(pPager->fd, EXCLUSIVE_LOCK);
pPager->state = PAGER_SHARED;
if( rc!=SQLITE_OK ){
return rc;
}
sqlite3WalExclusiveMode(pPager->pWal, 1);
}
/* Grab the write lock on the log file. If successful, upgrade to
** PAGER_EXCLUSIVE state. Otherwise, return an error code to the caller.
** PAGER_RESERVED state. Otherwise, return an error code to the caller.
** The busy-handler is not invoked if another connection already
** holds the write-lock. If possible, the upper layer will call it.
**
** WAL mode sets Pager.state to PAGER_RESERVED when it has an open
** transaction, but never to PAGER_EXCLUSIVE. This is because in
** PAGER_EXCLUSIVE state the code to roll back savepoint transactions
** may copy data from the sub-journal into the database file as well
** as into the page cache. Which would be incorrect in WAL mode.
*/
rc = sqlite3WalWriteLock(pPager->pWal, 1);
if( rc==SQLITE_OK ){
@@ -4525,6 +4555,9 @@ int sqlite3PagerBegin(Pager *pPager, int exFlag, int subjInMemory){
pPager->state = PAGER_RESERVED;
pPager->journalOff = 0;
}
assert( rc!=SQLITE_OK || pPager->state==PAGER_RESERVED );
assert( rc==SQLITE_OK || pPager->state==PAGER_SHARED );
}else{
/* Obtain a RESERVED lock on the database file. If the exFlag parameter
** is true, then immediately upgrade this to an EXCLUSIVE lock. The