/*
** Try to obtain a page from the cache.
*/
static int sqlite3PcacheFetch(
PCache pCache, /* Obtain the page from this cache */
u32 pgno, /* Page number to obtain */
int createFlag, /* If true, create page if it does not exist already */
ref PgHdr ppPage /* Write the page here */
)
{
PgHdr pPage = null;
int eCreate;
Debug.Assert( pCache != null );
Debug.Assert( createFlag == 1 || createFlag == 0 );
Debug.Assert( pgno > 0 );
/* If the pluggable cache (sqlite3_pcache*) has not been allocated,
** allocate it now.
*/
if ( null == pCache.pCache && createFlag != 0 )
{
sqlite3_pcache p;
int nByte;
nByte = pCache.szPage + pCache.szExtra + 0;// sizeof( PgHdr );
p = sqlite3GlobalConfig.pcache.xCreate( nByte, pCache.bPurgeable );
//if ( null == p )
//{
// return SQLITE_NOMEM;
//}
sqlite3GlobalConfig.pcache.xCachesize( p, pCache.nMax );
pCache.pCache = p;
}
eCreate = createFlag * ( 1 + ( ( !pCache.bPurgeable || null == pCache.pDirty ) ? 1 : 0 ) );
if ( pCache.pCache != null )
{
pPage = sqlite3GlobalConfig.pcache.xFetch( pCache.pCache, pgno, eCreate );
}
if ( null == 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.
*/
#if SQLITE_ENABLE_EXPENSIVE_ASSERT
expensive_assert( pcacheCheckSynced(pCache) );
#endif
for ( pPg = pCache.pSynced;
pPg != null && ( pPg.nRef != 0 || ( pPg.flags & PGHDR_NEED_SYNC ) != 0 );
pPg = pPg.pDirtyPrev
)
;
pCache.pSynced = pPg;
if ( null == pPg )
{
for ( pPg = pCache.pDirtyTail; pPg != null && pPg.nRef != 0; pPg = pPg.pDirtyPrev )
;
}
if ( pPg != null )
{
int rc;
#if 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),
pCache->nMax);
#endif
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 != null )
{
if ( null == pPage.pData )
{
// memset(pPage, 0, sizeof(PgHdr));
pPage.pData = sqlite3Malloc( pCache.szPage );// 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;
}
Debug.Assert( pPage.pCache == pCache );
Debug.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 == null && eCreate != 0 ) ? SQLITE_NOMEM : SQLITE_OK;
}
/*
** Try to obtain a page from the cache.
*/
static int sqlite3PcacheFetch(
PCache pCache, /* Obtain the page from this cache */
u32 pgno, /* Page number to obtain */
int createFlag, /* If true, create page if it does not exist already */
ref PgHdr ppPage /* Write the page here */
)
{
PgHdr pPage = null;
int eCreate;
Debug.Assert(pCache != null);
Debug.Assert(createFlag == 1 || createFlag == 0);
Debug.Assert(pgno > 0);
/* If the pluggable cache (sqlite3_pcache*) has not been allocated,
** allocate it now.
*/
if (null == pCache.pCache && createFlag != 0)
{
sqlite3_pcache p;
int nByte;
nByte = pCache.szPage + pCache.szExtra + 0;// sizeof( PgHdr );
p = sqlite3GlobalConfig.pcache.xCreate(nByte, pCache.bPurgeable);
if (null == p)
{
return(SQLITE_NOMEM);
}
sqlite3GlobalConfig.pcache.xCachesize(p, pCache.nMax);
pCache.pCache = p;
}
eCreate = createFlag * (1 + ((!pCache.bPurgeable || null == pCache.pDirty) ? 1 : 0));
if (pCache.pCache != null)
{
pPage = sqlite3GlobalConfig.pcache.xFetch(pCache.pCache, pgno, eCreate);
}
if (null == 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.
*/
#if SQLITE_ENABLE_EXPENSIVE_ASSERT
expensive_assert(pcacheCheckSynced(pCache));
#endif
for (pPg = pCache.pSynced;
pPg != null && (pPg.nRef != 0 || (pPg.flags & PGHDR_NEED_SYNC) != 0);
pPg = pPg.pDirtyPrev
)
{
;
}
pCache.pSynced = pPg;
if (null == pPg)
{
for (pPg = pCache.pDirtyTail; pPg != null && pPg.nRef != 0; pPg = pPg.pDirtyPrev)
{
;
}
}
if (pPg != null)
{
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 != null)
{
if (null == pPage.pData)
{
// memset(pPage, 0, sizeof(PgHdr));
pPage.pData = sqlite3Malloc(pCache.szPage);// 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;
}
Debug.Assert(pPage.pCache == pCache);
Debug.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 == null && eCreate != 0) ? SQLITE_NOMEM : SQLITE_OK);
}
