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Overview
| Comment: | Avoid a race condition in the sqlite3_release_memory() logic within pager.c. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | branch-3.5.9 |
| Files: | files | file ages | folders |
| SHA1: |
a718e6634795a48b5dd5c08833ab561e |
| User & Date: | drh 2010-01-30 19:17:07 |
Context
|
2010-01-30
| ||
| 22:28 | Always hold the MEM2 mutex when initially marking a pager as in use by its database connection. (check-in: 622c1717 user: drh tags: branch-3.5.9) | |
| 19:17 | Avoid a race condition in the sqlite3_release_memory() logic within pager.c. (check-in: a718e663 user: drh tags: branch-3.5.9) | |
| 19:00 | Remove all cache pages from the LRU list prior to removing the pager from the pager list when closing a pager. (check-in: 9d13acc4 user: drh tags: branch-3.5.9) | |
Changes
Changes to src/pager.c.
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*/
for(pPager=sqlite3PagerList; pPager; pPager=pPager->pNext){
pPager->iInUseMM = 1;
}
while( rc==SQLITE_OK && (nReq<0 || nReleased<nReq) ){
PgHdr *pPg;
PgHdr *pRecycled;
/* Try to find a page to recycle that does not require a sync(). If
** this is not possible, find one that does require a sync().
*/
sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU));
pPg = sqlite3LruPageList.pFirstSynced;
while( pPg && (pPg->needSync || pPg->pPager->iInUseDB) ){
................................................................................
/* If pPg==0, then the block above has failed to find a page to
** recycle. In this case return early - no further memory will
** be released.
*/
if( !pPg ) break;
pPager = pPg->pPager;
assert(!pPg->needSync || pPg==pPager->lru.pFirst);
assert(pPg->needSync || pPg==pPager->lru.pFirstSynced);
savedBusy = pPager->pBusyHandler;
pPager->pBusyHandler = 0;
rc = pager_recycle(pPager, &pRecycled);
pPager->pBusyHandler = savedBusy;
assert(pRecycled==pPg || rc!=SQLITE_OK);
if( rc==SQLITE_OK ){
/* We've found a page to free. At this point the page has been
** removed from the page hash-table, free-list and synced-list
** (pFirstSynced). It is still in the all pages (pAll) list.
** Remove it from this list before freeing.
**
** Todo: Check the Pager.pStmt list to make sure this is Ok. It
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*/
for(pPager=sqlite3PagerList; pPager; pPager=pPager->pNext){
pPager->iInUseMM = 1;
}
while( rc==SQLITE_OK && (nReq<0 || nReleased<nReq) ){
PgHdr *pPg;
/* Try to find a page to recycle that does not require a sync(). If
** this is not possible, find one that does require a sync().
*/
sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU));
pPg = sqlite3LruPageList.pFirstSynced;
while( pPg && (pPg->needSync || pPg->pPager->iInUseDB) ){
................................................................................
/* If pPg==0, then the block above has failed to find a page to
** recycle. In this case return early - no further memory will
** be released.
*/
if( !pPg ) break;
pPager = pPg->pPager;
savedBusy = pPager->pBusyHandler;
pPager->pBusyHandler = 0;
rc = pager_recycle(pPager, &pPg);
pPager->pBusyHandler = savedBusy;
if( rc==SQLITE_OK ){
/* We've found a page to free. At this point the page has been
** removed from the page hash-table, free-list and synced-list
** (pFirstSynced). It is still in the all pages (pAll) list.
** Remove it from this list before freeing.
**
** Todo: Check the Pager.pStmt list to make sure this is Ok. It
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