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Overview
Comment: | In the pager, cache a pointer to the first page on the freelist that does not need to be synced. This makes a fetch of a page that is not in cache go a lot faster when the cache is full. This check-in also adds some performance instrumentation to the OS layer. (CVS 842) |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
00f08fc0b5b6b9c5efbf15a62f9a1cc1 |
User & Date: | drh 2003-01-21 02:39:37.000 |
Context
2003-01-21
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23:06 | fix a typo on the quickstart.html page. (CVS 843) (check-in: 61869bb51b user: drh tags: trunk) | |
02:39 | In the pager, cache a pointer to the first page on the freelist that does not need to be synced. This makes a fetch of a page that is not in cache go a lot faster when the cache is full. This check-in also adds some performance instrumentation to the OS layer. (CVS 842) (check-in: 00f08fc0b5 user: drh tags: trunk) | |
2003-01-19
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03:59 | Update comments. No changes to code. (CVS 841) (check-in: f6a8706872 user: drh tags: trunk) | |
Changes
Changes to src/os.c.
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48 49 50 51 52 53 54 | #endif /* ** Macros for performance tracing. Normally turned off */ #if 0 static int last_page = 0; | > > > > > > > > > > > | | | | > > > > > > | 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 | #endif /* ** Macros for performance tracing. Normally turned off */ #if 0 static int last_page = 0; __inline__ unsigned long long int hwtime(void){ unsigned long long int x; __asm__("rdtsc\n\t" "mov %%edx, %%ecx\n\t" :"=A" (x)); return x; } static unsigned long long int g_start; static unsigned int elapse; #define TIMER_START g_start=hwtime() #define TIMER_END elapse=hwtime()-g_start #define SEEK(X) last_page=(X) #define TRACE1(X) fprintf(stderr,X) #define TRACE2(X,Y) fprintf(stderr,X,Y) #define TRACE3(X,Y,Z) fprintf(stderr,X,Y,Z) #define TRACE4(X,Y,Z,A) fprintf(stderr,X,Y,Z,A) #define TRACE5(X,Y,Z,A,B) fprintf(stderr,X,Y,Z,A,B) #else #define TIMER_START #define TIMER_END #define SEEK(X) #define TRACE1(X) #define TRACE2(X,Y) #define TRACE3(X,Y,Z) #define TRACE4(X,Y,Z,A) #define TRACE5(X,Y,Z,A,B) #endif #if OS_UNIX /* ** Here is the dirt on POSIX advisory locks: ANSI STD 1003.1 (1996) ** section 6.5.2.2 lines 483 through 490 specify that when a process |
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660 661 662 663 664 665 666 | ** bytes were read successfully and SQLITE_IOERR if anything goes ** wrong. */ int sqliteOsRead(OsFile *id, void *pBuf, int amt){ #if OS_UNIX int got; SimulateIOError(SQLITE_IOERR); | | > > > | 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 | ** bytes were read successfully and SQLITE_IOERR if anything goes ** wrong. */ int sqliteOsRead(OsFile *id, void *pBuf, int amt){ #if OS_UNIX int got; SimulateIOError(SQLITE_IOERR); TIMER_START; got = read(id->fd, pBuf, amt); TIMER_END; TRACE4("READ %-3d %7d %d\n", id->fd, last_page, elapse); SEEK(0); /* if( got<0 ) got = 0; */ if( got==amt ){ return SQLITE_OK; }else{ return SQLITE_IOERR; } #endif |
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708 709 710 711 712 713 714 | ** Write data from a buffer into a file. Return SQLITE_OK on success ** or some other error code on failure. */ int sqliteOsWrite(OsFile *id, const void *pBuf, int amt){ #if OS_UNIX int wrote = 0; SimulateIOError(SQLITE_IOERR); | | > > > | 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 | ** Write data from a buffer into a file. Return SQLITE_OK on success ** or some other error code on failure. */ int sqliteOsWrite(OsFile *id, const void *pBuf, int amt){ #if OS_UNIX int wrote = 0; SimulateIOError(SQLITE_IOERR); TIMER_START; while( amt>0 && (wrote = write(id->fd, pBuf, amt))>0 ){ amt -= wrote; pBuf = &((char*)pBuf)[wrote]; } TIMER_END; TRACE4("WRITE %-3d %7d %d\n", id->fd, last_page, elapse); SEEK(0); if( amt>0 ){ return SQLITE_FULL; } return SQLITE_OK; #endif #if OS_WIN int rc; |
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Changes to src/pager.c.
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14 15 16 17 18 19 20 | ** The pager is used to access a database disk file. It implements ** atomic commit and rollback through the use of a journal file that ** is separate from the database file. The pager also implements file ** locking to prevent two processes from writing the same database ** file simultaneously, or one process from reading the database while ** another is writing. ** | | | 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | ** The pager is used to access a database disk file. It implements ** atomic commit and rollback through the use of a journal file that ** is separate from the database file. The pager also implements file ** locking to prevent two processes from writing the same database ** file simultaneously, or one process from reading the database while ** another is writing. ** ** @(#) $Id: pager.c,v 1.69 2003/01/21 02:39:37 drh Exp $ */ #include "os.h" /* Must be first to enable large file support */ #include "sqliteInt.h" #include "pager.h" #include <assert.h> #include <string.h> |
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158 159 160 161 162 163 164 165 166 167 168 169 170 171 | u8 needSync; /* True if an fsync() is needed on the journal */ u8 dirtyFile; /* True if database file has changed in any way */ u8 alwaysRollback; /* Disable dont_rollback() for all pages */ u8 journalFormat; /* Version number of the journal file */ u8 *aInJournal; /* One bit for each page in the database file */ u8 *aInCkpt; /* One bit for each page in the database */ PgHdr *pFirst, *pLast; /* List of free pages */ PgHdr *pAll; /* List of all pages */ PgHdr *pCkpt; /* List of pages in the checkpoint journal */ PgHdr *aHash[N_PG_HASH]; /* Hash table to map page number of PgHdr */ }; /* ** These are bits that can be set in Pager.errMask. | > | 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 | u8 needSync; /* True if an fsync() is needed on the journal */ u8 dirtyFile; /* True if database file has changed in any way */ u8 alwaysRollback; /* Disable dont_rollback() for all pages */ u8 journalFormat; /* Version number of the journal file */ u8 *aInJournal; /* One bit for each page in the database file */ u8 *aInCkpt; /* One bit for each page in the database */ PgHdr *pFirst, *pLast; /* List of free pages */ PgHdr *pFirstSynced; /* First free page with PgHdr.needSync==0 */ PgHdr *pAll; /* List of all pages */ PgHdr *pCkpt; /* List of pages in the checkpoint journal */ PgHdr *aHash[N_PG_HASH]; /* Hash table to map page number of PgHdr */ }; /* ** These are bits that can be set in Pager.errMask. |
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342 343 344 345 346 347 348 349 350 351 352 353 354 355 | static void pager_reset(Pager *pPager){ PgHdr *pPg, *pNext; for(pPg=pPager->pAll; pPg; pPg=pNext){ pNext = pPg->pNextAll; sqliteFree(pPg); } pPager->pFirst = 0; pPager->pLast = 0; pPager->pAll = 0; memset(pPager->aHash, 0, sizeof(pPager->aHash)); pPager->nPage = 0; if( pPager->state>=SQLITE_WRITELOCK ){ sqlitepager_rollback(pPager); } | > | 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 | static void pager_reset(Pager *pPager){ PgHdr *pPg, *pNext; for(pPg=pPager->pAll; pPg; pPg=pNext){ pNext = pPg->pNextAll; sqliteFree(pPg); } pPager->pFirst = 0; pPager->pFirstSynced = 0; pPager->pLast = 0; pPager->pAll = 0; memset(pPager->aHash, 0, sizeof(pPager->aHash)); pPager->nPage = 0; if( pPager->state>=SQLITE_WRITELOCK ){ sqlitepager_rollback(pPager); } |
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733 734 735 736 737 738 739 740 741 742 743 744 745 746 | pPager->state = SQLITE_UNLOCK; pPager->errMask = 0; pPager->tempFile = tempFile; pPager->readOnly = readOnly; pPager->needSync = 0; pPager->noSync = pPager->tempFile || !useJournal; pPager->pFirst = 0; pPager->pLast = 0; pPager->nExtra = nExtra; memset(pPager->aHash, 0, sizeof(pPager->aHash)); *ppPager = pPager; return SQLITE_OK; } | > | 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 | pPager->state = SQLITE_UNLOCK; pPager->errMask = 0; pPager->tempFile = tempFile; pPager->readOnly = readOnly; pPager->needSync = 0; pPager->noSync = pPager->tempFile || !useJournal; pPager->pFirst = 0; pPager->pFirstSynced = 0; pPager->pLast = 0; pPager->nExtra = nExtra; memset(pPager->aHash, 0, sizeof(pPager->aHash)); *ppPager = pPager; return SQLITE_OK; } |
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833 834 835 836 837 838 839 840 841 842 843 844 845 846 | ** currently on the freelist (the reference count is zero) then ** remove it from the freelist. */ #define page_ref(P) ((P)->nRef==0?_page_ref(P):(void)(P)->nRef++) static void _page_ref(PgHdr *pPg){ if( pPg->nRef==0 ){ /* The page is currently on the freelist. Remove it. */ if( pPg->pPrevFree ){ pPg->pPrevFree->pNextFree = pPg->pNextFree; }else{ pPg->pPager->pFirst = pPg->pNextFree; } if( pPg->pNextFree ){ pPg->pNextFree->pPrevFree = pPg->pPrevFree; | > > > > > | 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 | ** currently on the freelist (the reference count is zero) then ** remove it from the freelist. */ #define page_ref(P) ((P)->nRef==0?_page_ref(P):(void)(P)->nRef++) static void _page_ref(PgHdr *pPg){ if( pPg->nRef==0 ){ /* The page is currently on the freelist. Remove it. */ if( pPg==pPg->pPager->pFirstSynced ){ PgHdr *p = pPg->pNextFree; while( p && p->needSync ){ p = p->pNextFree; } pPg->pPager->pFirstSynced = p; } if( pPg->pPrevFree ){ pPg->pPrevFree->pNextFree = pPg->pNextFree; }else{ pPg->pPager->pFirst = pPg->pNextFree; } if( pPg->pNextFree ){ pPg->pNextFree->pPrevFree = pPg->pPrevFree; |
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897 898 899 900 901 902 903 | #ifndef NDEBUG rc = sqliteOsFileSize(&pPager->jfd, &pPager->syncJSize); if( rc!=0 ) return rc; #endif pPager->journalStarted = 1; } pPager->needSync = 0; | | < | | | | | > > > > > > > > > > > > > > > > > | 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 | #ifndef NDEBUG rc = sqliteOsFileSize(&pPager->jfd, &pPager->syncJSize); if( rc!=0 ) return rc; #endif pPager->journalStarted = 1; } pPager->needSync = 0; /* Erase the needSync flag from every page. */ for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){ pPg->needSync = 0; } pPager->pFirstSynced = pPager->pFirst; } #ifndef NDEBUG /* If the Pager.needSync flag is clear then the PgHdr.needSync ** flag must also be clear for all pages. Verify that this ** invariant is true. */ else{ for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){ assert( pPg->needSync==0 ); } assert( pPager->pFirstSynced==pPager->pFirst ); } #endif return rc; } /* ** Acquire a page. ** |
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1028 1029 1030 1031 1032 1033 1034 | pPg->pPrevAll = 0; pPager->pAll = pPg; pPager->nPage++; }else{ /* Find a page to recycle. Try to locate a page that does not ** require us to do an fsync() on the journal. */ | | < < < | 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 | pPg->pPrevAll = 0; pPager->pAll = pPg; pPager->nPage++; }else{ /* Find a page to recycle. Try to locate a page that does not ** require us to do an fsync() on the journal. */ pPg = pPager->pFirstSynced; /* If we could not find a page that does not require an fsync() ** on the journal file then fsync the journal file. This is a ** very slow operation, so we work hard to avoid it. But sometimes ** it can't be helped. */ if( pPg==0 ){ |
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1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 | */ if( pPg->alwaysRollback ){ pPager->alwaysRollback = 1; } /* Unlink the old page from the free list and the hash table */ if( pPg->pPrevFree ){ pPg->pPrevFree->pNextFree = pPg->pNextFree; }else{ assert( pPager->pFirst==pPg ); pPager->pFirst = pPg->pNextFree; } if( pPg->pNextFree ){ | > > > > > | 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 | */ if( pPg->alwaysRollback ){ pPager->alwaysRollback = 1; } /* Unlink the old page from the free list and the hash table */ if( pPg==pPager->pFirstSynced ){ PgHdr *p = pPg->pNextFree; while( p && p->needSync ){ p = p->pNextFree; } pPager->pFirstSynced = p; } if( pPg->pPrevFree ){ pPg->pPrevFree->pNextFree = pPg->pNextFree; }else{ assert( pPager->pFirst==pPg ); pPager->pFirst = pPg->pNextFree; } if( pPg->pNextFree ){ |
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1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 | pPg->pNextFree = 0; pPg->pPrevFree = pPager->pLast; pPager->pLast = pPg; if( pPg->pPrevFree ){ pPg->pPrevFree->pNextFree = pPg; }else{ pPager->pFirst = pPg; } if( pPager->xDestructor ){ pPager->xDestructor(pData); } /* When all pages reach the freelist, drop the read lock from ** the database file. | > > > | 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 | pPg->pNextFree = 0; pPg->pPrevFree = pPager->pLast; pPager->pLast = pPg; if( pPg->pPrevFree ){ pPg->pPrevFree->pNextFree = pPg; }else{ pPager->pFirst = pPg; } if( pPg->needSync==0 && pPager->pFirstSynced==0 ){ pPager->pFirstSynced = pPg; } if( pPager->xDestructor ){ pPager->xDestructor(pData); } /* When all pages reach the freelist, drop the read lock from ** the database file. |
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1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 | if( pPager->state!=SQLITE_WRITELOCK ){ return SQLITE_ERROR; } TRACE1("COMMIT\n"); if( pPager->dirtyFile==0 ){ /* Exit early (without doing the time-consuming sqliteOsSync() calls) ** if there have been no changes to the database file. */ rc = pager_unwritelock(pPager); pPager->dbSize = -1; return rc; } assert( pPager->journalOpen ); | > < < | 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 | if( pPager->state!=SQLITE_WRITELOCK ){ return SQLITE_ERROR; } TRACE1("COMMIT\n"); if( pPager->dirtyFile==0 ){ /* Exit early (without doing the time-consuming sqliteOsSync() calls) ** if there have been no changes to the database file. */ assert( pPager->needSync==0 ); rc = pager_unwritelock(pPager); pPager->dbSize = -1; return rc; } assert( pPager->journalOpen ); if( pPager->needSync && sqliteOsSync(&pPager->jfd)!=SQLITE_OK ){ goto commit_abort; } dbChanged = 0; for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){ if( pPg->dirty==0 ) continue; TRACE2("COMMIT-PAGE %d\n", pPg->pgno); |
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