/*
** Obtain space for a page. Try to recycle an old page if the limit on the
** number of pages has been reached. If the limit has not been reached or
** there are no pages eligible for recycling, allocate a new page.
**
** Return a pointer to the new page, or NULL if an OOM condition occurs.
*/
static int pcacheRecycleOrAlloc(PCache *pCache, PgHdr **ppPage) {
PgHdr *p = 0;
int szPage = pCache->szPage;
int szExtra = pCache->szExtra;
assert( pcache.isInit );
assert( sqlite3_mutex_held(pcache.mutex) );
*ppPage = 0;
/* If we have reached the limit for pinned/dirty pages, and there is at
** least one dirty page, invoke the xStress callback to cause a page to
** become clean.
*/
expensive_assert( pCache->nPinned==pcachePinnedCount(pCache) );
expensive_assert( pcacheCheckSynced(pCache) );
if( pCache->xStress
&& pCache->pDirty
&& pCache->nPinned>=(pcache.nMaxPage+pCache->nMin-pcache.nMinPage)
) {
PgHdr *pPg;
assert(pCache->pDirtyTail);
for(pPg=pCache->pSynced;
pPg && (pPg->nRef || (pPg->flags&PGHDR_NEED_SYNC));
pPg=pPg->pPrev
);
if( !pPg ) {
for(pPg=pCache->pDirtyTail; pPg && pPg->nRef; pPg=pPg->pPrev);
}
if( pPg ) {
int rc;
pcacheExitMutex();
rc = pCache->xStress(pCache->pStress, pPg);
pcacheEnterMutex();
if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ) {
return rc;
}
}
}
/* If the global page limit has been reached, try to recycle a page. */
if( pCache->bPurgeable && pcache.nCurrentPage>=pcache.nMaxPage ) {
p = pcacheRecyclePage();
}
/* If a page has been recycled but it is the wrong size, free it. */
if( p && (p->pCache->szPage!=szPage || p->pCache->szPage!=szExtra) ) {
pcachePageFree(p);
p = 0;
}
if( !p ) {
p = pcachePageAlloc(pCache);
}
*ppPage = p;
return (p?SQLITE_OK:SQLITE_NOMEM);
}
/*
** Remove page pPage from the list of dirty pages.
*/
static void pcacheRemoveFromDirtyList(PgHdr *pPage){
PCache *p = pPage->pCache;
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;
}
pPage->pDirtyNext = 0;
pPage->pDirtyPrev = 0;
expensive_assert( pcacheCheckSynced(p) );
}
static void pcacheMakeClean(PgHdr *p){
PCache *pCache = p->pCache;
assert( p->flags & PGHDR_DIRTY );
pcacheRemoveFromList(&pCache->pDirty, p);
pcacheAddToList(&pCache->pClean, p);
p->flags &= ~PGHDR_DIRTY;
if( p->nRef==0 ){
pcacheAddToLruList(p);
pCache->nPinned--;
}
expensive_assert( pCache->nPinned==pcachePinnedCount(pCache) );
}
/*
** Insert a page into the hash table
**
** The mutex must be held by the caller.
*/
static void pcacheAddToHash(PgHdr *pPage){
PCache *pCache = pPage->pCache;
u32 h = pPage->pgno % pCache->nHash;
assert( pcacheMutexHeld() );
pPage->pNextHash = pCache->apHash[h];
pPage->pPrevHash = 0;
if( pCache->apHash[h] ){
pCache->apHash[h]->pPrevHash = pPage;
}
pCache->apHash[h] = pPage;
pCache->nPage++;
expensive_assert( pcacheCheckHashCount(pCache) );
}
/*
** Make every page in the cache clean.
*/
void sqlite3PcacheCleanAll(PCache *pCache){
PgHdr *p;
pcacheEnterMutex();
while( (p = pCache->pDirty)!=0 ){
pcacheRemoveFromList(&pCache->pDirty, p);
p->flags &= ~PGHDR_DIRTY;
pcacheAddToList(&pCache->pClean, p);
if( p->nRef==0 ){
pcacheAddToLruList(p);
pCache->nPinned--;
}
}
sqlite3PcacheAssertFlags(pCache, 0, PGHDR_DIRTY);
expensive_assert( pCache->nPinned==pcachePinnedCount(pCache) );
pcacheExitMutex();
}
/*
** Remove a page from its hash table (PCache.apHash[]).
*/
static void pcacheRemoveFromHash(PgHdr *pPage){
assert( pcacheMutexHeld() );
if( pPage->pPrevHash ){
pPage->pPrevHash->pNextHash = pPage->pNextHash;
}else{
PCache *pCache = pPage->pCache;
u32 h = pPage->pgno % pCache->nHash;
assert( pCache->apHash[h]==pPage );
pCache->apHash[h] = pPage->pNextHash;
}
if( pPage->pNextHash ){
pPage->pNextHash->pPrevHash = pPage->pPrevHash;
}
pPage->pCache->nPage--;
expensive_assert( pcacheCheckHashCount(pPage->pCache) );
}
/*
** Add page pPage to the head of the dirty list (PCache1.pDirty is set to
** pPage).
*/
static void pcacheAddToDirtyList(PgHdr *pPage){
PCache *p = pPage->pCache;
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;
}
p->pDirty = pPage;
if( !p->pDirtyTail ){
p->pDirtyTail = pPage;
}
if( !p->pSynced && 0==(pPage->flags&PGHDR_NEED_SYNC) ){
p->pSynced = pPage;
}
expensive_assert( pcacheCheckSynced(p) );
}
/*
** Try to obtain a page from the cache.
*/
int 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 rc = SQLITE_OK;
PgHdr *pPage = 0;
assert( pcache_g.isInit );
assert( pCache!=0 );
assert( pgno>0 );
expensive_assert( pCache->nPinned==pcachePinnedCount(pCache) );
pcacheEnterMutex();
/* Search the hash table for the requested page. Exit early if it is found. */
if( pCache->apHash ){
u32 h = pgno % pCache->nHash;
for(pPage=pCache->apHash[h]; pPage; pPage=pPage->pNextHash){
if( pPage->pgno==pgno ){
if( pPage->nRef==0 ){
if( 0==(pPage->flags&PGHDR_DIRTY) ){
pcacheRemoveFromLruList(pPage);
pCache->nPinned++;
}
pCache->nRef++;
}
pPage->nRef++;
break;
}
}
}
if( !pPage && createFlag ){
if( pCache->nHash<=pCache->nPage ){
rc = pcacheResizeHash(pCache, pCache->nHash<256 ? 256 : pCache->nHash*2);
}
if( rc==SQLITE_OK ){
rc = pcacheRecycleOrAlloc(pCache, &pPage);
}
if( rc==SQLITE_OK ){
pPage->pPager = 0;
pPage->flags = 0;
pPage->pDirty = 0;
pPage->pgno = pgno;
pPage->pCache = pCache;
pPage->nRef = 1;
pCache->nRef++;
pCache->nPinned++;
pcacheAddToList(&pCache->pClean, pPage);
pcacheAddToHash(pPage);
}
}
pcacheExitMutex();
*ppPage = pPage;
expensive_assert( pCache->nPinned==pcachePinnedCount(pCache) );
assert( pPage || !createFlag || rc!=SQLITE_OK );
return rc;
}
/*
** Try to obtain a page from the cache.
*/
int 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 */
){
PgHdr *pPage = 0;
int eCreate;
assert( pCache!=0 );
assert( createFlag==1 || createFlag==0 );
assert( pgno>0 );
/* If the pluggable cache (sqlite3_pcache*) has not been allocated,
** allocate it now.
*/
if( !pCache->pCache && createFlag ){
sqlite3_pcache *p;
int nByte;
nByte = pCache->szPage + pCache->szExtra + sizeof(PgHdr);
p = sqlite3GlobalConfig.pcache.xCreate(nByte, pCache->bPurgeable);
if( !p ){
return SQLITE_NOMEM;
}
sqlite3GlobalConfig.pcache.xCachesize(p, pCache->nMax);
pCache->pCache = p;
}
eCreate = createFlag * (1 + (!pCache->bPurgeable || !pCache->pDirty));
if( pCache->pCache ){
pPage = sqlite3GlobalConfig.pcache.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;
rc = pCache->xStress(pCache->pStress, pPg);
if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){
return rc;
}
}
pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, 2);
}
if( pPage ){
if( !pPage->pData ){
memset(pPage, 0, sizeof(PgHdr) + pCache->szExtra);
pPage->pExtra = (void*)&pPage[1];
pPage->pData = (void *)&((char *)pPage)[sizeof(PgHdr) + pCache->szExtra];
pPage->pCache = pCache;
pPage->pgno = pgno;
}
assert( pPage->pCache==pCache );
assert( pPage->pgno==pgno );
assert( pPage->pExtra==(void *)&pPage[1] );
if( 0==pPage->nRef ){
pCache->nRef++;
}
pPage->nRef++;
if( pgno==1 ){
pCache->pPage1 = pPage;
}
}
*ppPage = pPage;
return (pPage==0 && eCreate) ? SQLITE_NOMEM : SQLITE_OK;
}
/*
** Try to obtain a page from the cache.
*/
SQLITE_PRIVATE int 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 */
){
sqlite3_pcache_page *pPage = 0;
PgHdr *pPgHdr = 0;
int eCreate;
assert( pCache!=0 );
assert( createFlag==1 || createFlag==0 );
assert( pgno>0 );
/* If the pluggable cache (sqlite3_pcache*) has not been allocated,
** allocate it now.
*/
if( !pCache->pCache && createFlag ){
sqlite3_pcache *p;
p = sqlite3GlobalConfig.pcache2.xCreate(
pCache->szPage, pCache->szExtra + sizeof(PgHdr), pCache->bPurgeable
);
if( !p ){
return SQLITE_NOMEM;
}
sqlite3GlobalConfig.pcache2.xCachesize(p, numberOfCachePages(pCache));
pCache->pCache = p;
}
eCreate = createFlag * (1 + (!pCache->bPurgeable || !pCache->pDirty));
if( pCache->pCache ){
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;
#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;
}
}
pPage = sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache, pgno, 2);
}
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] );
if( 0==pPgHdr->nRef ){
pCache->nRef++;
}
pPgHdr->nRef++;
if( pgno==1 ){
pCache->pPage1 = pPgHdr;
}
}
*ppPage = pPgHdr;
return (pPgHdr==0 && eCreate) ? SQLITE_NOMEM : SQLITE_OK;
}
int sqlite3PcacheFetch(
PCache *pCache,
Pgno pgno,
int createFlag,
PgHdr **ppPage
){
PgHdr *pPage = 0;
int eCreate;
assert( pCache!=0 );
assert( createFlag==1 || createFlag==0 );
assert( pgno>0 );
if( !pCache->pCache && createFlag ){
sqlite3_pcache *p;
int nByte;
nByte = pCache->szPage + pCache->szExtra + sizeof(PgHdr);
p = sqlite3GlobalConfig.pcache.xCreate(nByte, pCache->bPurgeable);
if( !p ){
return SQLITE_NOMEM;
}
sqlite3GlobalConfig.pcache.xCachesize(p, pCache->nMax);
pCache->pCache = p;
}
eCreate = createFlag * (1 + (!pCache->bPurgeable || !pCache->pDirty));
if( pCache->pCache ){
pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, eCreate);
}
if( !pPage && eCreate==1 ){
PgHdr *pPg;
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;
rc = pCache->xStress(pCache->pStress, pPg);
if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){
return rc;
}
}
pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, 2);
}
if( pPage ){
if( !pPage->pData ){
memset(pPage, 0, sizeof(PgHdr));
pPage->pData = (void *)&pPage[1];
pPage->pExtra = (void*)&((char *)pPage->pData)[pCache->szPage];
memset(pPage->pExtra, 0, pCache->szExtra);
pPage->pCache = pCache;
pPage->pgno = pgno;
}
assert( pPage->pCache==pCache );
assert( pPage->pgno==pgno );
assert( pPage->pData==(void *)&pPage[1] );
assert( pPage->pExtra==(void *)&((char *)&pPage[1])[pCache->szPage] );
if( 0==pPage->nRef ){
pCache->nRef++;
}
pPage->nRef++;
if( pgno==1 ){
pCache->pPage1 = pPage;
}
}
*ppPage = pPage;
return (pPage==0 && eCreate) ? SQLITE_NOMEM : SQLITE_OK;
}
