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Overview
Comment: | Microoptimization in pcache1.c makes the code slightly smaller and faster. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA3-256: |
422cd9f39403feeacd70133c7a147e23 |
User & Date: | drh 2017-08-05 15:49:03.201 |
Context
2017-08-05
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16:15 | Fix a segfault in swarmvtab that could occur if there was an error in the SQL statement passed to the constructor. Add other test cases. (check-in: 6ce8b7ca62 user: dan tags: trunk) | |
15:49 | Microoptimization in pcache1.c makes the code slightly smaller and faster. (check-in: 422cd9f394 user: drh tags: trunk) | |
15:30 | Fix memory leak in swarmvtab. (check-in: 002a9c7bac user: dan tags: trunk) | |
Changes
Changes to src/pcache1.c.
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92 93 94 95 96 97 98 | ** structure. Unless SQLITE_PCACHE_SEPARATE_HEADER is defined, a buffer of ** PgHdr1.pCache->szPage bytes is allocated directly before this structure ** in memory. */ struct PgHdr1 { sqlite3_pcache_page page; /* Base class. Must be first. pBuf & pExtra */ unsigned int iKey; /* Key value (page number) */ | < > > > > > > | 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 | ** structure. Unless SQLITE_PCACHE_SEPARATE_HEADER is defined, a buffer of ** PgHdr1.pCache->szPage bytes is allocated directly before this structure ** in memory. */ struct PgHdr1 { sqlite3_pcache_page page; /* Base class. Must be first. pBuf & pExtra */ unsigned int iKey; /* Key value (page number) */ u8 isBulkLocal; /* This page from bulk local storage */ u8 isAnchor; /* This is the PGroup.lru element */ PgHdr1 *pNext; /* Next in hash table chain */ PCache1 *pCache; /* Cache that currently owns this page */ PgHdr1 *pLruNext; /* Next in LRU list of unpinned pages */ PgHdr1 *pLruPrev; /* Previous in LRU list of unpinned pages */ }; /* ** A page is pinned if it is no on the LRU list */ #define PAGE_IS_PINNED(p) ((p)->pLruNext==0) #define PAGE_IS_UNPINNED(p) ((p)->pLruNext!=0) /* Each page cache (or PCache) belongs to a PGroup. A PGroup is a set ** of one or more PCaches that are able to recycle each other's unpinned ** pages when they are under memory pressure. A PGroup is an instance of ** the following object. ** ** This page cache implementation works in one of two modes: ** |
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553 554 555 556 557 558 559 | ** This function is used internally to remove the page pPage from the ** PGroup LRU list, if is part of it. If pPage is not part of the PGroup ** LRU list, then this function is a no-op. ** ** The PGroup mutex must be held when this function is called. */ static PgHdr1 *pcache1PinPage(PgHdr1 *pPage){ | < < | < | < | | | 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 | ** This function is used internally to remove the page pPage from the ** PGroup LRU list, if is part of it. If pPage is not part of the PGroup ** LRU list, then this function is a no-op. ** ** The PGroup mutex must be held when this function is called. */ static PgHdr1 *pcache1PinPage(PgHdr1 *pPage){ assert( pPage!=0 ); assert( PAGE_IS_UNPINNED(pPage) ); assert( pPage->pLruNext ); assert( pPage->pLruPrev ); assert( sqlite3_mutex_held(pPage->pCache->pGroup->mutex) ); pPage->pLruPrev->pLruNext = pPage->pLruNext; pPage->pLruNext->pLruPrev = pPage->pLruPrev; pPage->pLruNext = 0; pPage->pLruPrev = 0; assert( pPage->isAnchor==0 ); assert( pPage->pCache->pGroup->lru.isAnchor==1 ); pPage->pCache->nRecyclable--; return pPage; } /* ** Remove the page supplied as an argument from the hash table ** (PCache1.apHash structure) that it is currently stored in. |
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606 607 608 609 610 611 612 | PGroup *pGroup = pCache->pGroup; PgHdr1 *p; assert( sqlite3_mutex_held(pGroup->mutex) ); while( pGroup->nCurrentPage>pGroup->nMaxPage && (p=pGroup->lru.pLruPrev)->isAnchor==0 ){ assert( p->pCache->pGroup==pGroup ); | | | 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 | PGroup *pGroup = pCache->pGroup; PgHdr1 *p; assert( sqlite3_mutex_held(pGroup->mutex) ); while( pGroup->nCurrentPage>pGroup->nMaxPage && (p=pGroup->lru.pLruPrev)->isAnchor==0 ){ assert( p->pCache->pGroup==pGroup ); assert( PAGE_IS_UNPINNED(p) ); pcache1PinPage(p); pcache1RemoveFromHash(p, 1); } if( pCache->nPage==0 && pCache->pBulk ){ sqlite3_free(pCache->pBulk); pCache->pBulk = pCache->pFree = 0; } |
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655 656 657 658 659 660 661 | PgHdr1 *pPage; assert( h<pCache->nHash ); pp = &pCache->apHash[h]; while( (pPage = *pp)!=0 ){ if( pPage->iKey>=iLimit ){ pCache->nPage--; *pp = pPage->pNext; | | | 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 | PgHdr1 *pPage; assert( h<pCache->nHash ); pp = &pCache->apHash[h]; while( (pPage = *pp)!=0 ){ if( pPage->iKey>=iLimit ){ pCache->nPage--; *pp = pPage->pNext; if( PAGE_IS_UNPINNED(pPage) ) pcache1PinPage(pPage); pcache1FreePage(pPage); }else{ pp = &pPage->pNext; TESTONLY( if( nPage>=0 ) nPage++; ) } } if( h==iStop ) break; |
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874 875 876 877 878 879 880 | /* Step 4. Try to recycle a page. */ if( pCache->bPurgeable && !pGroup->lru.pLruPrev->isAnchor && ((pCache->nPage+1>=pCache->nMax) || pcache1UnderMemoryPressure(pCache)) ){ PCache1 *pOther; pPage = pGroup->lru.pLruPrev; | | | 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 | /* Step 4. Try to recycle a page. */ if( pCache->bPurgeable && !pGroup->lru.pLruPrev->isAnchor && ((pCache->nPage+1>=pCache->nMax) || pcache1UnderMemoryPressure(pCache)) ){ PCache1 *pOther; pPage = pGroup->lru.pLruPrev; assert( PAGE_IS_UNPINNED(pPage) ); pcache1RemoveFromHash(pPage, 0); pcache1PinPage(pPage); pOther = pPage->pCache; if( pOther->szAlloc != pCache->szAlloc ){ pcache1FreePage(pPage); pPage = 0; }else{ |
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901 902 903 904 905 906 907 | unsigned int h = iKey % pCache->nHash; pCache->nPage++; pPage->iKey = iKey; pPage->pNext = pCache->apHash[h]; pPage->pCache = pCache; pPage->pLruPrev = 0; pPage->pLruNext = 0; | < | 902 903 904 905 906 907 908 909 910 911 912 913 914 915 | unsigned int h = iKey % pCache->nHash; pCache->nPage++; pPage->iKey = iKey; pPage->pNext = pCache->apHash[h]; pPage->pCache = pCache; pPage->pLruPrev = 0; pPage->pLruNext = 0; *(void **)pPage->page.pExtra = 0; pCache->apHash[h] = pPage; if( iKey>pCache->iMaxKey ){ pCache->iMaxKey = iKey; } } return pPage; |
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987 988 989 990 991 992 993 | while( pPage && pPage->iKey!=iKey ){ pPage = pPage->pNext; } /* Step 2: If the page was found in the hash table, then return it. ** If the page was not in the hash table and createFlag is 0, abort. ** Otherwise (page not in hash and createFlag!=0) continue with ** subsequent steps to try to create the page. */ if( pPage ){ | | | 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 | while( pPage && pPage->iKey!=iKey ){ pPage = pPage->pNext; } /* Step 2: If the page was found in the hash table, then return it. ** If the page was not in the hash table and createFlag is 0, abort. ** Otherwise (page not in hash and createFlag!=0) continue with ** subsequent steps to try to create the page. */ if( pPage ){ if( PAGE_IS_UNPINNED(pPage) ){ return pcache1PinPage(pPage); }else{ return pPage; } }else if( createFlag ){ /* Steps 3, 4, and 5 implemented by this subroutine */ return pcache1FetchStage2(pCache, iKey, createFlag); |
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1062 1063 1064 1065 1066 1067 1068 | assert( pPage->pCache==pCache ); pcache1EnterMutex(pGroup); /* It is an error to call this function if the page is already ** part of the PGroup LRU list. */ assert( pPage->pLruPrev==0 && pPage->pLruNext==0 ); | | < | 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 | assert( pPage->pCache==pCache ); pcache1EnterMutex(pGroup); /* It is an error to call this function if the page is already ** part of the PGroup LRU list. */ assert( pPage->pLruPrev==0 && pPage->pLruNext==0 ); assert( PAGE_IS_PINNED(pPage) ); if( reuseUnlikely || pGroup->nCurrentPage>pGroup->nMaxPage ){ pcache1RemoveFromHash(pPage, 1); }else{ /* Add the page to the PGroup LRU list. */ PgHdr1 **ppFirst = &pGroup->lru.pLruNext; pPage->pLruPrev = &pGroup->lru; (pPage->pLruNext = *ppFirst)->pLruPrev = pPage; *ppFirst = pPage; pCache->nRecyclable++; } pcache1LeaveMutex(pCache->pGroup); } /* ** Implementation of the sqlite3_pcache.xRekey method. |
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1217 1218 1219 1220 1221 1222 1223 | && (p=pcache1.grp.lru.pLruPrev)!=0 && p->isAnchor==0 ){ nFree += pcache1MemSize(p->page.pBuf); #ifdef SQLITE_PCACHE_SEPARATE_HEADER nFree += sqlite3MemSize(p); #endif | | | 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 | && (p=pcache1.grp.lru.pLruPrev)!=0 && p->isAnchor==0 ){ nFree += pcache1MemSize(p->page.pBuf); #ifdef SQLITE_PCACHE_SEPARATE_HEADER nFree += sqlite3MemSize(p); #endif assert( PAGE_IS_UNPINNED(p) ); pcache1PinPage(p); pcache1RemoveFromHash(p, 1); } pcache1LeaveMutex(&pcache1.grp); } return nFree; } |
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1241 1242 1243 1244 1245 1246 1247 | int *pnMax, /* OUT: Global maximum cache size */ int *pnMin, /* OUT: Sum of PCache1.nMin for purgeable caches */ int *pnRecyclable /* OUT: Total number of pages available for recycling */ ){ PgHdr1 *p; int nRecyclable = 0; for(p=pcache1.grp.lru.pLruNext; p && !p->isAnchor; p=p->pLruNext){ | | | 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 | int *pnMax, /* OUT: Global maximum cache size */ int *pnMin, /* OUT: Sum of PCache1.nMin for purgeable caches */ int *pnRecyclable /* OUT: Total number of pages available for recycling */ ){ PgHdr1 *p; int nRecyclable = 0; for(p=pcache1.grp.lru.pLruNext; p && !p->isAnchor; p=p->pLruNext){ assert( PAGE_IS_UNPINNED(p) ); nRecyclable++; } *pnCurrent = pcache1.grp.nCurrentPage; *pnMax = (int)pcache1.grp.nMaxPage; *pnMin = (int)pcache1.grp.nMinPage; *pnRecyclable = nRecyclable; } #endif |