-C Add\sa\sVDBE\ssynopsis\scomment\sfor\sclarification.
-D 2014-08-27T17:53:40.315
+C Refactor\sthe\ssqlite3PcacheFetch()\sroutine\sinto\sthree\sseparate\sroutines,\nwhich\sare\ssignificantly\sfaster\soverall\sand\sabout\s100\sbytes\ssmaller\sin\nsize\sas\swell.
+D 2014-08-27T23:18:01.324
F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
F Makefile.in 5eb79e334a5de69c87740edd56af6527dd219308
F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
F src/os_unix.c bd7df3094a60915c148517504c76df4fca24e542
F src/os_win.c d067fce558a5032e6e6afe62899e5397bf63cf3e
F src/os_win.h 09e751b20bbc107ffbd46e13555dc73576d88e21
-F src/pager.c 27fb89e62e0ccf10218805ed31315ccb2d56c0ce
+F src/pager.c 3e732d2bbdd8d8d95fed0c5ae7e718d73153c4c5
F src/pager.h ffd5607f7b3e4590b415b007a4382f693334d428
F src/parse.y 22d6a074e5f5a7258947a1dc55a9bf946b765dd0
-F src/pcache.c c216e4077449be57e9752a348490ffa467b85599
-F src/pcache.h 80a9c3f7d7b7080388e8654717cb45e7b99f14a6
+F src/pcache.c 3b3791297e8977002e56b4a9b8916f2039abad9b
+F src/pcache.h 9b559127b83f84ff76d735c8262f04853be0c59a
F src/pcache1.c c5af6403a55178c9d1c09e4f77b0f9c88822762c
F src/pragma.c d10ef67c4de79f78188b965b4b7988aff1d66f2e
F src/prepare.c 3842c1dfc0b053458e3adcf9f6efc48e03e3fe3d
F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P d8b1c4336145d436241863c3525530e24a24799b
-R 34521287dadc9603bb93e0f806afdcf3
-U mistachkin
-Z d8914cdf39bc88ab4bc7c63f9115cf85
+P 029a6dc744c24e7be482298c678af8a115d6a87b
+R dd4d11ad7a65bf573cc08ce3e7bd3aa7
+U drh
+Z c0c64dee6940e13662884c6ed139ac1a
if( pPager->errCode!=SQLITE_OK ){
rc = pPager->errCode;
}else{
-
if( bMmapOk && pagerUseWal(pPager) ){
rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iFrame);
if( rc!=SQLITE_OK ) goto pager_acquire_err;
if( rc==SQLITE_OK && pData ){
if( pPager->eState>PAGER_READER ){
- (void)sqlite3PcacheFetch(pPager->pPCache, pgno, 0, &pPg);
+ pPg = sqlite3PagerLookup(pPager, pgno);
}
if( pPg==0 ){
rc = pagerAcquireMapPage(pPager, pgno, pData, &pPg);
}
}
- rc = sqlite3PcacheFetch(pPager->pPCache, pgno, 3, ppPage);
+ {
+ sqlite3_pcache_page *pBase;
+ pBase = sqlite3PcacheFetch(pPager->pPCache, pgno, 3);
+ if( pBase==0 ){
+ rc = sqlite3PcacheFetchStress(pPager->pPCache, pgno, &pBase);
+ if( rc!=SQLITE_OK ) goto pager_acquire_err;
+ }
+ pPg = *ppPage = sqlite3PcacheFetchFinish(pPager->pPCache, pgno, pBase);
+ if( pPg==0 ) rc = SQLITE_NOMEM;
+ }
}
if( rc!=SQLITE_OK ){
** has ever happened.
*/
DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno){
- PgHdr *pPg = 0;
+ sqlite3_pcache_page *pPage;
assert( pPager!=0 );
assert( pgno!=0 );
assert( pPager->pPCache!=0 );
- sqlite3PcacheFetch(pPager->pPCache, pgno, 0, &pPg);
- return pPg;
+ pPage = sqlite3PcacheFetch(pPager->pPCache, pgno, 0);
+ return sqlite3PcacheFetchFinish(pPager->pPCache, pgno, pPage);
}
/*
/*
** Try to obtain a page from the cache.
-*/
-int sqlite3PcacheFetch(
+**
+** This routine returns a pointer to an sqlite3_pcache_page object if
+** such an object is already in cache, or if a new one is created.
+** This routine returns a NULL pointer if the object was not in cache
+** and could not be created.
+**
+** The createFlags should be 0 to check for existing pages and should
+** be 3 (not 1, but 3) to try to create a new page.
+**
+** If the createFlag is 0, then NULL is always returned if the page
+** is not already in the cache. If createFlag is 1, then a new page
+** is created only if that can be done without spilling dirty pages
+** and without exceeding the cache size limit.
+**
+** The caller needs to invoke sqlite3PcacheFetchFinish() to properly
+** initialize the sqlite3_pcache_page object and convert it into a
+** PgHdr object. The sqlite3PcacheFetch() and sqlite3PcacheFetchFinish()
+** routines are split this way for performance reasons. When separated
+** they can both (usually) operate without having to push values to
+** the stack on entry and pop them back off on exit, which saves a
+** lot of pushing and popping.
+*/
+sqlite3_pcache_page *sqlite3PcacheFetch(
PCache *pCache, /* Obtain the page from this cache */
Pgno pgno, /* Page number to obtain */
- int createFlag, /* If true, create page if it does not exist already */
- PgHdr **ppPage /* Write the page here */
+ int createFlag /* If true, create page if it does not exist already */
){
- sqlite3_pcache_page *pPage;
- PgHdr *pPgHdr = 0;
int eCreate;
assert( pCache!=0 );
assert( eCreate==0 || eCreate==1 || eCreate==2 );
assert( createFlag==0 || pCache->eCreate==eCreate );
assert( createFlag==0 || eCreate==1+(!pCache->bPurgeable||!pCache->pDirty) );
- pPage = sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache, pgno, eCreate);
- if( !pPage && eCreate==1 ){
- PgHdr *pPg;
-
- /* Find a dirty page to write-out and recycle. First try to find a
- ** page that does not require a journal-sync (one with PGHDR_NEED_SYNC
- ** cleared), but if that is not possible settle for any other
- ** unreferenced dirty page.
- */
- expensive_assert( pcacheCheckSynced(pCache) );
- for(pPg=pCache->pSynced;
- pPg && (pPg->nRef || (pPg->flags&PGHDR_NEED_SYNC));
- pPg=pPg->pDirtyPrev
- );
- pCache->pSynced = pPg;
- if( !pPg ){
- for(pPg=pCache->pDirtyTail; pPg && pPg->nRef; pPg=pPg->pDirtyPrev);
- }
- if( pPg ){
- int rc;
+ return sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache, pgno, eCreate);
+}
+
+/*
+** If the sqlite3PcacheFetch() routine is unable to allocate a new
+** page because new clean pages are available for reuse and the cache
+** size limit has been reached, then this routine can be invoked to
+** try harder to allocate a page. This routine might invoke the stress
+** callback to spill dirty pages to the journal. It will then try to
+** allocate the new page and will only fail to allocate a new page on
+** an OOM error.
+**
+** This routine should be invoked only after sqlite3PcacheFetch() fails.
+*/
+int sqlite3PcacheFetchStress(
+ PCache *pCache, /* Obtain the page from this cache */
+ Pgno pgno, /* Page number to obtain */
+ sqlite3_pcache_page **ppPage /* Write result here */
+){
+ PgHdr *pPg;
+ if( pCache->eCreate==2 ) return 0;
+
+
+ /* Find a dirty page to write-out and recycle. First try to find a
+ ** page that does not require a journal-sync (one with PGHDR_NEED_SYNC
+ ** cleared), but if that is not possible settle for any other
+ ** unreferenced dirty page.
+ */
+ expensive_assert( pcacheCheckSynced(pCache) );
+ for(pPg=pCache->pSynced;
+ pPg && (pPg->nRef || (pPg->flags&PGHDR_NEED_SYNC));
+ pPg=pPg->pDirtyPrev
+ );
+ pCache->pSynced = pPg;
+ if( !pPg ){
+ for(pPg=pCache->pDirtyTail; pPg && pPg->nRef; pPg=pPg->pDirtyPrev);
+ }
+ if( pPg ){
+ int rc;
#ifdef SQLITE_LOG_CACHE_SPILL
- sqlite3_log(SQLITE_FULL,
- "spill page %d making room for %d - cache used: %d/%d",
- pPg->pgno, pgno,
- sqlite3GlobalConfig.pcache.xPagecount(pCache->pCache),
- numberOfCachePages(pCache));
+ sqlite3_log(SQLITE_FULL,
+ "spill page %d making room for %d - cache used: %d/%d",
+ pPg->pgno, pgno,
+ sqlite3GlobalConfig.pcache.xPagecount(pCache->pCache),
+ numberOfCachePages(pCache));
#endif
- rc = pCache->xStress(pCache->pStress, pPg);
- if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){
- return rc;
- }
+ rc = pCache->xStress(pCache->pStress, pPg);
+ if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){
+ return rc;
}
-
- pPage = sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache, pgno, 2);
}
+ *ppPage = sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache, pgno, 2);
+ return *ppPage==0 ? SQLITE_NOMEM : SQLITE_OK;
+}
- if( pPage ){
- pPgHdr = (PgHdr *)pPage->pExtra;
-
- if( !pPgHdr->pPage ){
- memset(pPgHdr, 0, sizeof(PgHdr));
- pPgHdr->pPage = pPage;
- pPgHdr->pData = pPage->pBuf;
- pPgHdr->pExtra = (void *)&pPgHdr[1];
- memset(pPgHdr->pExtra, 0, pCache->szExtra);
- pPgHdr->pCache = pCache;
- pPgHdr->pgno = pgno;
- }
- assert( pPgHdr->pCache==pCache );
- assert( pPgHdr->pgno==pgno );
- assert( pPgHdr->pData==pPage->pBuf );
- assert( pPgHdr->pExtra==(void *)&pPgHdr[1] );
+/*
+** This is a helper routine for sqlite3PcacheFetchFinish()
+**
+** In the uncommon case where the page being fetched has not been
+** initialized, this routine is invoked to do the initialization.
+** This routine is broken out into a separate function since it
+** requires extra stack manipulation that can be avoided in the common
+** case.
+*/
+static SQLITE_NOINLINE PgHdr *pcacheFetchFinishWithInit(
+ PCache *pCache, /* Obtain the page from this cache */
+ Pgno pgno, /* Page number obtained */
+ sqlite3_pcache_page *pPage /* Page obtained by prior PcacheFetch() call */
+){
+ PgHdr *pPgHdr;
+ assert( pPage!=0 );
+ pPgHdr = (PgHdr*)pPage->pExtra;
+ assert( pPgHdr->pPage==0 );
+ memset(pPgHdr, 0, sizeof(PgHdr));
+ pPgHdr->pPage = pPage;
+ pPgHdr->pData = pPage->pBuf;
+ pPgHdr->pExtra = (void *)&pPgHdr[1];
+ memset(pPgHdr->pExtra, 0, pCache->szExtra);
+ pPgHdr->pCache = pCache;
+ pPgHdr->pgno = pgno;
+ return sqlite3PcacheFetchFinish(pCache,pgno,pPage);
+}
- if( 0==pPgHdr->nRef ){
- pCache->nRef++;
- }
- pPgHdr->nRef++;
- if( pgno==1 ){
- pCache->pPage1 = pPgHdr;
- }
+/*
+** This routine converts the sqlite3_pcache_page object returned by
+** sqlite3PcacheFetch() into an initialized PgHdr object. This routine
+** must be called after sqlite3PcacheFetch() in order to get a usable
+** result.
+*/
+PgHdr *sqlite3PcacheFetchFinish(
+ PCache *pCache, /* Obtain the page from this cache */
+ Pgno pgno, /* Page number obtained */
+ sqlite3_pcache_page *pPage /* Page obtained by prior PcacheFetch() call */
+){
+ PgHdr *pPgHdr;
+
+ if( pPage==0 ) return 0;
+ pPgHdr = (PgHdr *)pPage->pExtra;
+
+ if( !pPgHdr->pPage ){
+ return pcacheFetchFinishWithInit(pCache, pgno, pPage);
+ }
+ if( 0==pPgHdr->nRef ){
+ pCache->nRef++;
+ }
+ pPgHdr->nRef++;
+ if( pgno==1 ){
+ pCache->pPage1 = pPgHdr;
}
- *ppPage = pPgHdr;
- return (pPgHdr==0 && eCreate) ? SQLITE_NOMEM : SQLITE_OK;
+ return pPgHdr;
}
/*
projects / thirdparty / sqlite.git / commitdiff
