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Overview
| Comment: | Use tail recursion in pcache1Unpin() to get a small size reduction and speed improvement. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
fde70472aebc09b34a517131f676e684 |
| User & Date: | drh 2015-06-29 00:21:00 |
Context
|
2015-06-29
| ||
| 00:52 | Move an assert() and testcase() into their correct position within getAndInitPage(). check-in: 18115164 user: drh tags: trunk | |
| 00:21 | Use tail recursion in pcache1Unpin() to get a small size reduction and speed improvement. check-in: fde70472 user: drh tags: trunk | |
|
2015-06-28
| ||
| 17:33 | Comment typo fix and minor cleanup in the pager. No logic changes. check-in: 94ef1701 user: drh tags: trunk | |
Changes
Changes to src/pcache1.c.
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return pPage;
}
/*
** Remove the page supplied as an argument from the hash table
** (PCache1.apHash structure) that it is currently stored in.
**
** The PGroup mutex must be held when this function is called.
*/
static void pcache1RemoveFromHash(PgHdr1 *pPage){
unsigned int h;
PCache1 *pCache = pPage->pCache;
PgHdr1 **pp;
assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
h = pPage->iKey % pCache->nHash;
for(pp=&pCache->apHash[h]; (*pp)!=pPage; pp=&(*pp)->pNext);
*pp = (*pp)->pNext;
pCache->nPage--;
}
/*
** If there are currently more than nMaxPage pages allocated, try
** to recycle pages to reduce the number allocated to nMaxPage.
*/
static void pcache1EnforceMaxPage(PGroup *pGroup){
assert( sqlite3_mutex_held(pGroup->mutex) );
while( pGroup->nCurrentPage>pGroup->nMaxPage && pGroup->pLruTail ){
PgHdr1 *p = pGroup->pLruTail;
assert( p->pCache->pGroup==pGroup );
assert( p->isPinned==0 );
pcache1PinPage(p);
pcache1RemoveFromHash(p);
pcache1FreePage(p);
}
}
/*
** Discard all pages from cache pCache with a page number (key value)
** greater than or equal to iLimit. Any pinned pages that meet this
** criteria are unpinned before they are discarded.
................................................................................
(pCache->nPage+1>=pCache->nMax)
|| pGroup->nCurrentPage>=pGroup->nMaxPage
|| pcache1UnderMemoryPressure(pCache)
)){
PCache1 *pOther;
pPage = pGroup->pLruTail;
assert( pPage->isPinned==0 );
pcache1RemoveFromHash(pPage);
pcache1PinPage(pPage);
pOther = pPage->pCache;
/* We want to verify that szPage and szExtra are the same for pOther
** and pCache. Assert that we can verify this by comparing sums. */
assert( (pCache->szPage & (pCache->szPage-1))==0 && pCache->szPage>=512 );
assert( pCache->szExtra<512 );
................................................................................
** part of the PGroup LRU list.
*/
assert( pPage->pLruPrev==0 && pPage->pLruNext==0 );
assert( pGroup->pLruHead!=pPage && pGroup->pLruTail!=pPage );
assert( pPage->isPinned==1 );
if( reuseUnlikely || pGroup->nCurrentPage>pGroup->nMaxPage ){
pcache1RemoveFromHash(pPage);
pcache1FreePage(pPage);
}else{
/* Add the page to the PGroup LRU list. */
if( pGroup->pLruHead ){
pGroup->pLruHead->pLruPrev = pPage;
pPage->pLruNext = pGroup->pLruHead;
pGroup->pLruHead = pPage;
}else{
................................................................................
while( (nReq<0 || nFree<nReq) && ((p=pcache1.grp.pLruTail)!=0) ){
nFree += pcache1MemSize(p->page.pBuf);
#ifdef SQLITE_PCACHE_SEPARATE_HEADER
nFree += sqlite3MemSize(p);
#endif
assert( p->isPinned==0 );
pcache1PinPage(p);
pcache1RemoveFromHash(p);
pcache1FreePage(p);
}
pcache1LeaveMutex(&pcache1.grp);
}
return nFree;
}
#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */
|
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return pPage; } /* ** Remove the page supplied as an argument from the hash table ** (PCache1.apHash structure) that it is currently stored in. ** Also free the page if freePage is true. ** ** The PGroup mutex must be held when this function is called. */ static void pcache1RemoveFromHash(PgHdr1 *pPage, int freeFlag){ unsigned int h; PCache1 *pCache = pPage->pCache; PgHdr1 **pp; assert( sqlite3_mutex_held(pCache->pGroup->mutex) ); h = pPage->iKey % pCache->nHash; for(pp=&pCache->apHash[h]; (*pp)!=pPage; pp=&(*pp)->pNext); *pp = (*pp)->pNext; pCache->nPage--; if( freeFlag ) pcache1FreePage(pPage); } /* ** If there are currently more than nMaxPage pages allocated, try ** to recycle pages to reduce the number allocated to nMaxPage. */ static void pcache1EnforceMaxPage(PGroup *pGroup){ assert( sqlite3_mutex_held(pGroup->mutex) ); while( pGroup->nCurrentPage>pGroup->nMaxPage && pGroup->pLruTail ){ PgHdr1 *p = pGroup->pLruTail; assert( p->pCache->pGroup==pGroup ); assert( p->isPinned==0 ); pcache1PinPage(p); pcache1RemoveFromHash(p, 1); } } /* ** Discard all pages from cache pCache with a page number (key value) ** greater than or equal to iLimit. Any pinned pages that meet this ** criteria are unpinned before they are discarded. ................................................................................ (pCache->nPage+1>=pCache->nMax) || pGroup->nCurrentPage>=pGroup->nMaxPage || pcache1UnderMemoryPressure(pCache) )){ PCache1 *pOther; pPage = pGroup->pLruTail; assert( pPage->isPinned==0 ); pcache1RemoveFromHash(pPage, 0); pcache1PinPage(pPage); pOther = pPage->pCache; /* We want to verify that szPage and szExtra are the same for pOther ** and pCache. Assert that we can verify this by comparing sums. */ assert( (pCache->szPage & (pCache->szPage-1))==0 && pCache->szPage>=512 ); assert( pCache->szExtra<512 ); ................................................................................ ** part of the PGroup LRU list. */ assert( pPage->pLruPrev==0 && pPage->pLruNext==0 ); assert( pGroup->pLruHead!=pPage && pGroup->pLruTail!=pPage ); assert( pPage->isPinned==1 ); if( reuseUnlikely || pGroup->nCurrentPage>pGroup->nMaxPage ){ pcache1RemoveFromHash(pPage, 1); }else{ /* Add the page to the PGroup LRU list. */ if( pGroup->pLruHead ){ pGroup->pLruHead->pLruPrev = pPage; pPage->pLruNext = pGroup->pLruHead; pGroup->pLruHead = pPage; }else{ ................................................................................ while( (nReq<0 || nFree<nReq) && ((p=pcache1.grp.pLruTail)!=0) ){ nFree += pcache1MemSize(p->page.pBuf); #ifdef SQLITE_PCACHE_SEPARATE_HEADER nFree += sqlite3MemSize(p); #endif assert( p->isPinned==0 ); pcache1PinPage(p); pcache1RemoveFromHash(p, 1); } pcache1LeaveMutex(&pcache1.grp); } return nFree; } #endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */ |