| Index: third_party/sqlite/sqlite-src-3080704/src/pcache.c
|
| diff --git a/third_party/sqlite/sqlite-src-3080704/src/pcache.c b/third_party/sqlite/sqlite-src-3080704/src/pcache.c
|
| new file mode 100644
|
| index 0000000000000000000000000000000000000000..191a9d00f41ded328642e71fa5da12138f38bc35
|
| --- /dev/null
|
| +++ b/third_party/sqlite/sqlite-src-3080704/src/pcache.c
|
| @@ -0,0 +1,666 @@
|
| +/*
|
| +** 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 nRef; /* Number of referenced 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 */
|
| + PgHdr *pPage1; /* Reference to page 1 */
|
| +};
|
| +
|
| +/*
|
| +** Some of the assert() macros in this code are too expensive to run
|
| +** even during normal debugging. Use them only rarely on long-running
|
| +** tests. Enable the expensive asserts using the
|
| +** -DSQLITE_ENABLE_EXPENSIVE_ASSERT=1 compile-time option.
|
| +*/
|
| +#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
|
| +# define expensive_assert(X) assert(X)
|
| +#else
|
| +# define expensive_assert(X)
|
| +#endif
|
| +
|
| +/********************************** 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 ){
|
| + if( p->pgno==1 ){
|
| + p->pCache->pPage1 = 0;
|
| + }
|
| + sqlite3GlobalConfig.pcache2.xUnpin(p->pCache->pCache, p->pPage, 0);
|
| + }
|
| +}
|
| +
|
| +/*
|
| +** Compute the number of pages of cache requested.
|
| +*/
|
| +static int numberOfCachePages(PCache *p){
|
| + if( p->szCache>=0 ){
|
| + return p->szCache;
|
| + }else{
|
| + 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->nRef==0 && pCache->pDirty==0 );
|
| + if( pCache->szPage ){
|
| + sqlite3_pcache *pNew;
|
| + pNew = sqlite3GlobalConfig.pcache2.xCreate(
|
| + szPage, pCache->szExtra + 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->pPage1 = 0;
|
| + 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;
|
| + 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;
|
| +
|
| + 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;
|
| + }
|
| + 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->nRef--;
|
| + if( p->nRef==0 ){
|
| + p->pCache->nRef--;
|
| + if( (p->flags&PGHDR_DIRTY)==0 ){
|
| + 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++;
|
| +}
|
| +
|
| +/*
|
| +** 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->nRef--;
|
| + if( p->pgno==1 ){
|
| + p->pCache->pPage1 = 0;
|
| + }
|
| + 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){
|
| + p->flags &= ~PGHDR_DONT_WRITE;
|
| + assert( p->nRef>0 );
|
| + if( 0==(p->flags & PGHDR_DIRTY) ){
|
| + p->flags |= 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) ){
|
| + pcacheManageDirtyList(p, PCACHE_DIRTYLIST_REMOVE);
|
| + p->flags &= ~(PGHDR_DIRTY|PGHDR_NEED_SYNC);
|
| + 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->pPage1 ){
|
| + memset(pCache->pPage1->pData, 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 referenced pages held by the cache.
|
| +*/
|
| +int sqlite3PcacheRefCount(PCache *pCache){
|
| + return pCache->nRef;
|
| +}
|
| +
|
| +/*
|
| +** 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);
|
| +}
|
| +
|
| +#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
|
|
|