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Overview
| Comment: | Comment improvements in pcache1.c. No changes to code. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
9660a0a22547656cc3765b673d0cee9e |
| User & Date: | drh 2011-01-19 21:58:56 |
Context
|
2011-01-21
| ||
| 15:52 | Add options to test command [do_faultsim_test] to support testing VFS implementations. check-in: 503ad889 user: dan tags: trunk | |
|
2011-01-20
| ||
| 02:56 | The first of a planned series of enhancements to the query planner that enable it to make better use of sqlite_stat2 histograms when the table has many repeated values. check-in: 2cd374cd user: drh tags: stat2-enhancement | |
|
2011-01-19
| ||
| 21:58 | Comment improvements in pcache1.c. No changes to code. check-in: 9660a0a2 user: drh tags: trunk | |
|
2011-01-18
| ||
| 17:03 | Do not use mutexes in the pcache implementation unless SQLITE_ENABLE_MEMORY_MANAGMENT is defined. This is a performance enhancement. A side effect is that pcaches will not steal pages from one another unless ENABLE_MEMORY_MANAGEMENT is set, or unless SQLITE_THREADSAFE=0. check-in: e5ca59e6 user: drh tags: trunk | |
Changes
Changes to src/pcache1.c.
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PGroup *pGroup = pCache->pGroup;
PgHdr1 *pPage = 0;
assert( pCache->bPurgeable || createFlag!=1 );
pcache1EnterMutex(pGroup);
if( createFlag==1 ) sqlite3BeginBenignMalloc();
/* Search the hash table for an existing entry. */
if( pCache->nHash>0 ){
unsigned int h = iKey % pCache->nHash;
for(pPage=pCache->apHash[h]; pPage&&pPage->iKey!=iKey; pPage=pPage->pNext);
}
if( pPage || createFlag==0 ){
pcache1PinPage(pPage);
goto fetch_out;
}
/* Step 3 of header comment. */
nPinned = pCache->nPage - pCache->nRecyclable;
if( createFlag==1 && (
nPinned>=(pGroup->nMaxPage+pCache->nMin-pGroup->nMinPage)
|| nPinned>=(pCache->nMax * 9 / 10)
|| pcache1UnderMemoryPressure(pCache)
)){
goto fetch_out;
}
if( pCache->nPage>=pCache->nHash && pcache1ResizeHash(pCache) ){
goto fetch_out;
}
/* Step 4. Try to recycle a page buffer if appropriate. */
if( pCache->bPurgeable && pGroup->pLruTail && (
(pCache->nPage+1>=pCache->nMax)
|| pGroup->nCurrentPage>=pGroup->nMaxPage
|| pcache1UnderMemoryPressure(pCache)
)){
pPage = pGroup->pLruTail;
pcache1RemoveFromHash(pPage);
|
| > | | |
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PGroup *pGroup = pCache->pGroup; PgHdr1 *pPage = 0; assert( pCache->bPurgeable || createFlag!=1 ); pcache1EnterMutex(pGroup); if( createFlag==1 ) sqlite3BeginBenignMalloc(); /* Step 1: Search the hash table for an existing entry. */ if( pCache->nHash>0 ){ unsigned int h = iKey % pCache->nHash; for(pPage=pCache->apHash[h]; pPage&&pPage->iKey!=iKey; pPage=pPage->pNext); } /* Step 2: Abort if no existing page is found and createFlag is 0 */ if( pPage || createFlag==0 ){ pcache1PinPage(pPage); goto fetch_out; } /* Step 3: Abort if createFlag is 1 but the cache is nearly full */ nPinned = pCache->nPage - pCache->nRecyclable; if( createFlag==1 && ( nPinned>=(pGroup->nMaxPage+pCache->nMin-pGroup->nMinPage) || nPinned>=(pCache->nMax * 9 / 10) || pcache1UnderMemoryPressure(pCache) )){ goto fetch_out; } if( pCache->nPage>=pCache->nHash && pcache1ResizeHash(pCache) ){ goto fetch_out; } /* Step 4. Try to recycle a page. */ if( pCache->bPurgeable && pGroup->pLruTail && ( (pCache->nPage+1>=pCache->nMax) || pGroup->nCurrentPage>=pGroup->nMaxPage || pcache1UnderMemoryPressure(pCache) )){ pPage = pGroup->pLruTail; pcache1RemoveFromHash(pPage); |