Index: src/pcache1.c ================================================================== --- src/pcache1.c +++ src/pcache1.c @@ -630,29 +630,49 @@ */ static void pcache1TruncateUnsafe( PCache1 *pCache, /* The cache to truncate */ unsigned int iLimit /* Drop pages with this pgno or larger */ ){ - TESTONLY( unsigned int nPage = 0; ) /* To assert pCache->nPage is correct */ - unsigned int h; + TESTONLY( int nPage = 0; ) /* To assert pCache->nPage is correct */ + unsigned int h, iStop; assert( sqlite3_mutex_held(pCache->pGroup->mutex) ); - for(h=0; hnHash; h++){ - PgHdr1 **pp = &pCache->apHash[h]; + assert( pCache->iMaxKey >= iLimit ); + assert( pCache->nHash > 0 ); + if( pCache->iMaxKey - iLimit < pCache->nHash ){ + /* If we are just shaving the last few pages off the end of the + ** cache, then there is no point in scanning the entire hash table. + ** Only scan those hash slots that might contain pages that need to + ** be removed. */ + h = iLimit % pCache->nHash; + iStop = pCache->iMaxKey % pCache->nHash; + TESTONLY( nPage = -10; ) /* Disable the pCache->nPage validity check */ + }else{ + /* This is the general case where many pages are being removed. + ** It is necessary to scan the entire hash table */ + h = pCache->nHash/2; + iStop = h - 1; + } + for(;;){ + PgHdr1 **pp; PgHdr1 *pPage; + assert( hnHash ); + pp = &pCache->apHash[h]; while( (pPage = *pp)!=0 ){ if( pPage->iKey>=iLimit ){ pCache->nPage--; *pp = pPage->pNext; if( !pPage->isPinned ) pcache1PinPage(pPage); pcache1FreePage(pPage); }else{ pp = &pPage->pNext; - TESTONLY( nPage++; ) + TESTONLY( if( nPage>=0 ) nPage++; ) } } + if( h==iStop ) break; + h = (h+1) % pCache->nHash; } - assert( pCache->nPage==nPage ); + assert( nPage<0 || pCache->nPage==(unsigned)nPage ); } /******************************************************************************/ /******** sqlite3_pcache Methods **********************************************/ @@ -1125,11 +1145,11 @@ static void pcache1Destroy(sqlite3_pcache *p){ PCache1 *pCache = (PCache1 *)p; PGroup *pGroup = pCache->pGroup; assert( pCache->bPurgeable || (pCache->nMax==0 && pCache->nMin==0) ); pcache1EnterMutex(pGroup); - pcache1TruncateUnsafe(pCache, 0); + if( pCache->nPage ) pcache1TruncateUnsafe(pCache, 0); assert( pGroup->nMaxPage >= pCache->nMax ); pGroup->nMaxPage -= pCache->nMax; assert( pGroup->nMinPage >= pCache->nMin ); pGroup->nMinPage -= pCache->nMin; pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;