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Diffstat (limited to 'lib/libsqlite3/src/pcache.c')
| -rw-r--r-- | lib/libsqlite3/src/pcache.c | 671 |
1 files changed, 0 insertions, 671 deletions
diff --git a/lib/libsqlite3/src/pcache.c b/lib/libsqlite3/src/pcache.c deleted file mode 100644 index e39262cb8c8..00000000000 --- a/lib/libsqlite3/src/pcache.c +++ /dev/null @@ -1,671 +0,0 @@ -/* -** 2008 August 05 -** -** The author disclaims copyright to this source code. In place of -** a legal notice, here is a blessing: -** -** May you do good and not evil. -** May you find forgiveness for yourself and forgive others. -** May you share freely, never taking more than you give. -** -************************************************************************* -** This file implements that page cache. -*/ -#include "sqliteInt.h" - -/* -** A complete page cache is an instance of this structure. -*/ -struct PCache { - PgHdr *pDirty, *pDirtyTail; /* List of dirty pages in LRU order */ - PgHdr *pSynced; /* Last synced page in dirty page list */ - int nRefSum; /* Sum of ref counts over all pages */ - int szCache; /* Configured cache size */ - int szPage; /* Size of every page in this cache */ - int szExtra; /* Size of extra space for each page */ - u8 bPurgeable; /* True if pages are on backing store */ - u8 eCreate; /* eCreate value for for xFetch() */ - int (*xStress)(void*,PgHdr*); /* Call to try make a page clean */ - void *pStress; /* Argument to xStress */ - sqlite3_pcache *pCache; /* Pluggable cache module */ -}; - -/********************************** Linked List Management ********************/ - -/* Allowed values for second argument to pcacheManageDirtyList() */ -#define PCACHE_DIRTYLIST_REMOVE 1 /* Remove pPage from dirty list */ -#define PCACHE_DIRTYLIST_ADD 2 /* Add pPage to the dirty list */ -#define PCACHE_DIRTYLIST_FRONT 3 /* Move pPage to the front of the list */ - -/* -** Manage pPage's participation on the dirty list. Bits of the addRemove -** argument determines what operation to do. The 0x01 bit means first -** remove pPage from the dirty list. The 0x02 means add pPage back to -** the dirty list. Doing both moves pPage to the front of the dirty list. -*/ -static void pcacheManageDirtyList(PgHdr *pPage, u8 addRemove){ - PCache *p = pPage->pCache; - - if( addRemove & PCACHE_DIRTYLIST_REMOVE ){ - assert( pPage->pDirtyNext || pPage==p->pDirtyTail ); - assert( pPage->pDirtyPrev || pPage==p->pDirty ); - - /* Update the PCache1.pSynced variable if necessary. */ - if( p->pSynced==pPage ){ - PgHdr *pSynced = pPage->pDirtyPrev; - while( pSynced && (pSynced->flags&PGHDR_NEED_SYNC) ){ - pSynced = pSynced->pDirtyPrev; - } - p->pSynced = pSynced; - } - - if( pPage->pDirtyNext ){ - pPage->pDirtyNext->pDirtyPrev = pPage->pDirtyPrev; - }else{ - assert( pPage==p->pDirtyTail ); - p->pDirtyTail = pPage->pDirtyPrev; - } - if( pPage->pDirtyPrev ){ - pPage->pDirtyPrev->pDirtyNext = pPage->pDirtyNext; - }else{ - assert( pPage==p->pDirty ); - p->pDirty = pPage->pDirtyNext; - if( p->pDirty==0 && p->bPurgeable ){ - assert( p->eCreate==1 ); - p->eCreate = 2; - } - } - pPage->pDirtyNext = 0; - pPage->pDirtyPrev = 0; - } - if( addRemove & PCACHE_DIRTYLIST_ADD ){ - assert( pPage->pDirtyNext==0 && pPage->pDirtyPrev==0 && p->pDirty!=pPage ); - - pPage->pDirtyNext = p->pDirty; - if( pPage->pDirtyNext ){ - assert( pPage->pDirtyNext->pDirtyPrev==0 ); - pPage->pDirtyNext->pDirtyPrev = pPage; - }else{ - p->pDirtyTail = pPage; - if( p->bPurgeable ){ - assert( p->eCreate==2 ); - p->eCreate = 1; - } - } - p->pDirty = pPage; - if( !p->pSynced && 0==(pPage->flags&PGHDR_NEED_SYNC) ){ - p->pSynced = pPage; - } - } -} - -/* -** Wrapper around the pluggable caches xUnpin method. If the cache is -** being used for an in-memory database, this function is a no-op. -*/ -static void pcacheUnpin(PgHdr *p){ - if( p->pCache->bPurgeable ){ - sqlite3GlobalConfig.pcache2.xUnpin(p->pCache->pCache, p->pPage, 0); - } -} - -/* -** Compute the number of pages of cache requested. p->szCache is the -** cache size requested by the "PRAGMA cache_size" statement. -** -** -*/ -static int numberOfCachePages(PCache *p){ - if( p->szCache>=0 ){ - /* IMPLEMENTATION-OF: R-42059-47211 If the argument N is positive then the - ** suggested cache size is set to N. */ - return p->szCache; - }else{ - /* IMPLEMENTATION-OF: R-61436-13639 If the argument N is negative, then - ** the number of cache pages is adjusted to use approximately abs(N*1024) - ** bytes of memory. */ - return (int)((-1024*(i64)p->szCache)/(p->szPage+p->szExtra)); - } -} - -/*************************************************** General Interfaces ****** -** -** Initialize and shutdown the page cache subsystem. Neither of these -** functions are threadsafe. -*/ -int sqlite3PcacheInitialize(void){ - if( sqlite3GlobalConfig.pcache2.xInit==0 ){ - /* IMPLEMENTATION-OF: R-26801-64137 If the xInit() method is NULL, then the - ** built-in default page cache is used instead of the application defined - ** page cache. */ - sqlite3PCacheSetDefault(); - } - return sqlite3GlobalConfig.pcache2.xInit(sqlite3GlobalConfig.pcache2.pArg); -} -void sqlite3PcacheShutdown(void){ - if( sqlite3GlobalConfig.pcache2.xShutdown ){ - /* IMPLEMENTATION-OF: R-26000-56589 The xShutdown() method may be NULL. */ - sqlite3GlobalConfig.pcache2.xShutdown(sqlite3GlobalConfig.pcache2.pArg); - } -} - -/* -** Return the size in bytes of a PCache object. -*/ -int sqlite3PcacheSize(void){ return sizeof(PCache); } - -/* -** Create a new PCache object. Storage space to hold the object -** has already been allocated and is passed in as the p pointer. -** The caller discovers how much space needs to be allocated by -** calling sqlite3PcacheSize(). -*/ -int sqlite3PcacheOpen( - int szPage, /* Size of every page */ - int szExtra, /* Extra space associated with each page */ - int bPurgeable, /* True if pages are on backing store */ - int (*xStress)(void*,PgHdr*),/* Call to try to make pages clean */ - void *pStress, /* Argument to xStress */ - PCache *p /* Preallocated space for the PCache */ -){ - memset(p, 0, sizeof(PCache)); - p->szPage = 1; - p->szExtra = szExtra; - p->bPurgeable = bPurgeable; - p->eCreate = 2; - p->xStress = xStress; - p->pStress = pStress; - p->szCache = 100; - return sqlite3PcacheSetPageSize(p, szPage); -} - -/* -** Change the page size for PCache object. The caller must ensure that there -** are no outstanding page references when this function is called. -*/ -int sqlite3PcacheSetPageSize(PCache *pCache, int szPage){ - assert( pCache->nRefSum==0 && pCache->pDirty==0 ); - if( pCache->szPage ){ - sqlite3_pcache *pNew; - pNew = sqlite3GlobalConfig.pcache2.xCreate( - szPage, pCache->szExtra + ROUND8(sizeof(PgHdr)), - pCache->bPurgeable - ); - if( pNew==0 ) return SQLITE_NOMEM; - sqlite3GlobalConfig.pcache2.xCachesize(pNew, numberOfCachePages(pCache)); - if( pCache->pCache ){ - sqlite3GlobalConfig.pcache2.xDestroy(pCache->pCache); - } - pCache->pCache = pNew; - pCache->szPage = szPage; - } - return SQLITE_OK; -} - -/* -** Try to obtain a page from the cache. -** -** 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 */ -){ - int eCreate; - - assert( pCache!=0 ); - assert( pCache->pCache!=0 ); - assert( createFlag==3 || createFlag==0 ); - assert( pgno>0 ); - - /* eCreate defines what to do if the page does not exist. - ** 0 Do not allocate a new page. (createFlag==0) - ** 1 Allocate a new page if doing so is inexpensive. - ** (createFlag==1 AND bPurgeable AND pDirty) - ** 2 Allocate a new page even it doing so is difficult. - ** (createFlag==1 AND !(bPurgeable AND pDirty) - */ - eCreate = createFlag & pCache->eCreate; - assert( eCreate==0 || eCreate==1 || eCreate==2 ); - assert( createFlag==0 || pCache->eCreate==eCreate ); - assert( createFlag==0 || eCreate==1+(!pCache->bPurgeable||!pCache->pDirty) ); - 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. - */ - 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)); -#endif - rc = pCache->xStress(pCache->pStress, pPg); - if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){ - return rc; - } - } - *ppPage = sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache, pgno, 2); - return *ppPage==0 ? SQLITE_NOMEM : SQLITE_OK; -} - -/* -** 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; - pPgHdr->flags = PGHDR_CLEAN; - return sqlite3PcacheFetchFinish(pCache,pgno,pPage); -} - -/* -** 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; - - assert( pPage!=0 ); - pPgHdr = (PgHdr *)pPage->pExtra; - - if( !pPgHdr->pPage ){ - return pcacheFetchFinishWithInit(pCache, pgno, pPage); - } - pCache->nRefSum++; - pPgHdr->nRef++; - return pPgHdr; -} - -/* -** Decrement the reference count on a page. If the page is clean and the -** reference count drops to 0, then it is made eligible for recycling. -*/ -void SQLITE_NOINLINE sqlite3PcacheRelease(PgHdr *p){ - assert( p->nRef>0 ); - p->pCache->nRefSum--; - if( (--p->nRef)==0 ){ - if( p->flags&PGHDR_CLEAN ){ - pcacheUnpin(p); - }else if( p->pDirtyPrev!=0 ){ - /* Move the page to the head of the dirty list. */ - pcacheManageDirtyList(p, PCACHE_DIRTYLIST_FRONT); - } - } -} - -/* -** Increase the reference count of a supplied page by 1. -*/ -void sqlite3PcacheRef(PgHdr *p){ - assert(p->nRef>0); - p->nRef++; - p->pCache->nRefSum++; -} - -/* -** Drop a page from the cache. There must be exactly one reference to the -** page. This function deletes that reference, so after it returns the -** page pointed to by p is invalid. -*/ -void sqlite3PcacheDrop(PgHdr *p){ - assert( p->nRef==1 ); - if( p->flags&PGHDR_DIRTY ){ - pcacheManageDirtyList(p, PCACHE_DIRTYLIST_REMOVE); - } - p->pCache->nRefSum--; - sqlite3GlobalConfig.pcache2.xUnpin(p->pCache->pCache, p->pPage, 1); -} - -/* -** Make sure the page is marked as dirty. If it isn't dirty already, -** make it so. -*/ -void sqlite3PcacheMakeDirty(PgHdr *p){ - assert( p->nRef>0 ); - if( p->flags & (PGHDR_CLEAN|PGHDR_DONT_WRITE) ){ - p->flags &= ~PGHDR_DONT_WRITE; - if( p->flags & PGHDR_CLEAN ){ - p->flags ^= (PGHDR_DIRTY|PGHDR_CLEAN); - assert( (p->flags & (PGHDR_DIRTY|PGHDR_CLEAN))==PGHDR_DIRTY ); - pcacheManageDirtyList(p, PCACHE_DIRTYLIST_ADD); - } - } -} - -/* -** Make sure the page is marked as clean. If it isn't clean already, -** make it so. -*/ -void sqlite3PcacheMakeClean(PgHdr *p){ - if( (p->flags & PGHDR_DIRTY) ){ - assert( (p->flags & PGHDR_CLEAN)==0 ); - pcacheManageDirtyList(p, PCACHE_DIRTYLIST_REMOVE); - p->flags &= ~(PGHDR_DIRTY|PGHDR_NEED_SYNC|PGHDR_WRITEABLE); - p->flags |= PGHDR_CLEAN; - if( p->nRef==0 ){ - pcacheUnpin(p); - } - } -} - -/* -** Make every page in the cache clean. -*/ -void sqlite3PcacheCleanAll(PCache *pCache){ - PgHdr *p; - while( (p = pCache->pDirty)!=0 ){ - sqlite3PcacheMakeClean(p); - } -} - -/* -** Clear the PGHDR_NEED_SYNC flag from all dirty pages. -*/ -void sqlite3PcacheClearSyncFlags(PCache *pCache){ - PgHdr *p; - for(p=pCache->pDirty; p; p=p->pDirtyNext){ - p->flags &= ~PGHDR_NEED_SYNC; - } - pCache->pSynced = pCache->pDirtyTail; -} - -/* -** Change the page number of page p to newPgno. -*/ -void sqlite3PcacheMove(PgHdr *p, Pgno newPgno){ - PCache *pCache = p->pCache; - assert( p->nRef>0 ); - assert( newPgno>0 ); - sqlite3GlobalConfig.pcache2.xRekey(pCache->pCache, p->pPage, p->pgno,newPgno); - p->pgno = newPgno; - if( (p->flags&PGHDR_DIRTY) && (p->flags&PGHDR_NEED_SYNC) ){ - pcacheManageDirtyList(p, PCACHE_DIRTYLIST_FRONT); - } -} - -/* -** Drop every cache entry whose page number is greater than "pgno". The -** caller must ensure that there are no outstanding references to any pages -** other than page 1 with a page number greater than pgno. -** -** If there is a reference to page 1 and the pgno parameter passed to this -** function is 0, then the data area associated with page 1 is zeroed, but -** the page object is not dropped. -*/ -void sqlite3PcacheTruncate(PCache *pCache, Pgno pgno){ - if( pCache->pCache ){ - PgHdr *p; - PgHdr *pNext; - for(p=pCache->pDirty; p; p=pNext){ - pNext = p->pDirtyNext; - /* This routine never gets call with a positive pgno except right - ** after sqlite3PcacheCleanAll(). So if there are dirty pages, - ** it must be that pgno==0. - */ - assert( p->pgno>0 ); - if( ALWAYS(p->pgno>pgno) ){ - assert( p->flags&PGHDR_DIRTY ); - sqlite3PcacheMakeClean(p); - } - } - if( pgno==0 && pCache->nRefSum ){ - sqlite3_pcache_page *pPage1; - pPage1 = sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache,1,0); - if( ALWAYS(pPage1) ){ /* Page 1 is always available in cache, because - ** pCache->nRefSum>0 */ - memset(pPage1->pBuf, 0, pCache->szPage); - pgno = 1; - } - } - sqlite3GlobalConfig.pcache2.xTruncate(pCache->pCache, pgno+1); - } -} - -/* -** Close a cache. -*/ -void sqlite3PcacheClose(PCache *pCache){ - assert( pCache->pCache!=0 ); - sqlite3GlobalConfig.pcache2.xDestroy(pCache->pCache); -} - -/* -** Discard the contents of the cache. -*/ -void sqlite3PcacheClear(PCache *pCache){ - sqlite3PcacheTruncate(pCache, 0); -} - -/* -** Merge two lists of pages connected by pDirty and in pgno order. -** Do not both fixing the pDirtyPrev pointers. -*/ -static PgHdr *pcacheMergeDirtyList(PgHdr *pA, PgHdr *pB){ - PgHdr result, *pTail; - pTail = &result; - while( pA && pB ){ - if( pA->pgno<pB->pgno ){ - pTail->pDirty = pA; - pTail = pA; - pA = pA->pDirty; - }else{ - pTail->pDirty = pB; - pTail = pB; - pB = pB->pDirty; - } - } - if( pA ){ - pTail->pDirty = pA; - }else if( pB ){ - pTail->pDirty = pB; - }else{ - pTail->pDirty = 0; - } - return result.pDirty; -} - -/* -** Sort the list of pages in accending order by pgno. Pages are -** connected by pDirty pointers. The pDirtyPrev pointers are -** corrupted by this sort. -** -** Since there cannot be more than 2^31 distinct pages in a database, -** there cannot be more than 31 buckets required by the merge sorter. -** One extra bucket is added to catch overflow in case something -** ever changes to make the previous sentence incorrect. -*/ -#define N_SORT_BUCKET 32 -static PgHdr *pcacheSortDirtyList(PgHdr *pIn){ - PgHdr *a[N_SORT_BUCKET], *p; - int i; - memset(a, 0, sizeof(a)); - while( pIn ){ - p = pIn; - pIn = p->pDirty; - p->pDirty = 0; - for(i=0; ALWAYS(i<N_SORT_BUCKET-1); i++){ - if( a[i]==0 ){ - a[i] = p; - break; - }else{ - p = pcacheMergeDirtyList(a[i], p); - a[i] = 0; - } - } - if( NEVER(i==N_SORT_BUCKET-1) ){ - /* To get here, there need to be 2^(N_SORT_BUCKET) elements in - ** the input list. But that is impossible. - */ - a[i] = pcacheMergeDirtyList(a[i], p); - } - } - p = a[0]; - for(i=1; i<N_SORT_BUCKET; i++){ - p = pcacheMergeDirtyList(p, a[i]); - } - return p; -} - -/* -** Return a list of all dirty pages in the cache, sorted by page number. -*/ -PgHdr *sqlite3PcacheDirtyList(PCache *pCache){ - PgHdr *p; - for(p=pCache->pDirty; p; p=p->pDirtyNext){ - p->pDirty = p->pDirtyNext; - } - return pcacheSortDirtyList(pCache->pDirty); -} - -/* -** Return the total number of references to all pages held by the cache. -** -** This is not the total number of pages referenced, but the sum of the -** reference count for all pages. -*/ -int sqlite3PcacheRefCount(PCache *pCache){ - return pCache->nRefSum; -} - -/* -** Return the number of references to the page supplied as an argument. -*/ -int sqlite3PcachePageRefcount(PgHdr *p){ - return p->nRef; -} - -/* -** Return the total number of pages in the cache. -*/ -int sqlite3PcachePagecount(PCache *pCache){ - assert( pCache->pCache!=0 ); - return sqlite3GlobalConfig.pcache2.xPagecount(pCache->pCache); -} - -#ifdef SQLITE_TEST -/* -** Get the suggested cache-size value. -*/ -int sqlite3PcacheGetCachesize(PCache *pCache){ - return numberOfCachePages(pCache); -} -#endif - -/* -** Set the suggested cache-size value. -*/ -void sqlite3PcacheSetCachesize(PCache *pCache, int mxPage){ - assert( pCache->pCache!=0 ); - pCache->szCache = mxPage; - sqlite3GlobalConfig.pcache2.xCachesize(pCache->pCache, - numberOfCachePages(pCache)); -} - -/* -** Free up as much memory as possible from the page cache. -*/ -void sqlite3PcacheShrink(PCache *pCache){ - assert( pCache->pCache!=0 ); - sqlite3GlobalConfig.pcache2.xShrink(pCache->pCache); -} - -/* -** Return the size of the header added by this middleware layer -** in the page-cache hierarchy. -*/ -int sqlite3HeaderSizePcache(void){ return ROUND8(sizeof(PgHdr)); } - - -#if defined(SQLITE_CHECK_PAGES) || defined(SQLITE_DEBUG) -/* -** For all dirty pages currently in the cache, invoke the specified -** callback. This is only used if the SQLITE_CHECK_PAGES macro is -** defined. -*/ -void sqlite3PcacheIterateDirty(PCache *pCache, void (*xIter)(PgHdr *)){ - PgHdr *pDirty; - for(pDirty=pCache->pDirty; pDirty; pDirty=pDirty->pDirtyNext){ - xIter(pDirty); - } -} -#endif |