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Overview
| Comment: | Always hold the MEM2 mutex when initially marking a pager as in use by its database connection. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | branch-3.5.9 |
| Files: | files | file ages | folders |
| SHA1: |
622c17177af6851fec11bdec8fb6246c |
| User & Date: | drh 2010-01-30 22:28:47 |
Context
|
2010-01-30
| ||
| 23:08 | The iInUseDB and iInUseMM variables do not need to be volatile. (Leaf check-in: bb18f578 user: drh tags: branch-3.5.9) | |
| 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) | |
Changes
Changes to src/pager.c.
515 515 ** 516 516 ** The pagerMutexHeld(X) macro is for sanity checking. This macro verifies 517 517 ** that the database-connection mutex is held for pager X and asserts if it 518 518 ** is not. 519 519 */ 520 520 #ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT 521 521 static void pagerEnter(Pager *p){ 522 - p->iInUseDB++; 523 - if( p->iInUseMM && p->iInUseDB==1 ){ 522 + if( p->iInUseDB>0 ){ 523 + p->iInUseDB++; 524 + }else{ 524 525 #ifndef SQLITE_MUTEX_NOOP 525 526 sqlite3_mutex *mutex; 526 527 mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MEM2); 527 528 #endif 528 - p->iInUseDB = 0; 529 529 sqlite3_mutex_enter(mutex); 530 530 assert( p->iInUseMM==0 ); 531 531 p->iInUseDB = 1; 532 532 sqlite3_mutex_leave(mutex); 533 533 } 534 534 } 535 535 static void pagerLeave(Pager *p){ ................................................................................ 3314 3314 /* If pPg==0, then the block above has failed to find a page to 3315 3315 ** recycle. In this case return early - no further memory will 3316 3316 ** be released. 3317 3317 */ 3318 3318 if( !pPg ) break; 3319 3319 3320 3320 pPager = pPg->pPager; 3321 + assert( pPager->iInUseDB==0 ); 3321 3322 savedBusy = pPager->pBusyHandler; 3322 3323 pPager->pBusyHandler = 0; 3323 3324 rc = pager_recycle(pPager, &pPg); 3325 + assert( pPager->iInUseDB==0 ); 3324 3326 pPager->pBusyHandler = savedBusy; 3325 3327 if( rc==SQLITE_OK ){ 3326 3328 /* We've found a page to free. At this point the page has been 3327 3329 ** removed from the page hash-table, free-list and synced-list 3328 3330 ** (pFirstSynced). It is still in the all pages (pAll) list. 3329 3331 ** Remove it from this list before freeing. 3330 3332 **