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First attempt at enhancing the "PRAGMA cache_spill" statement to accept a

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cache threashold size.

FossilOrigin-Name: 549d42be0dac87dc04c3eeccfdc60615c3a6ad3f
This commit is contained in:
drh
2015-11-12 14:57:19 +00:00
parent 3d38cec99a
commit 9b0cf34f81
12 changed files with 257 additions and 140 deletions
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72
src/pcache.c
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@@ -21,6 +21,7 @@ struct PCache {
PgHdr *pSynced; /* Last synced page in dirty page list */
int nRefSum; /* Sum of ref counts over all pages */
int szCache; /* Configured cache size */
int szSpill; /* Size before spilling occurs */
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 */
@@ -110,10 +111,8 @@ static void pcacheUnpin(PgHdr *p){
}
/*
** Compute the number of pages of cache requested. p->szCache is the
** 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 ){
@@ -176,6 +175,7 @@ int sqlite3PcacheOpen(
p->xStress = xStress;
p->pStress = pStress;
p->szCache = 100;
p->szSpill = 1;
return sqlite3PcacheSetPageSize(p, szPage);
}
@@ -271,32 +271,33 @@ int sqlite3PcacheFetchStress(
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;
if( sqlite3PcachePagecount(pCache)>pCache->szSpill ){
/* 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),
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;
}
}
}
*ppPage = sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache, pgno, 2);
@@ -641,6 +642,25 @@ void sqlite3PcacheSetCachesize(PCache *pCache, int mxPage){
numberOfCachePages(pCache));
}
/*
** Set the suggested cache-spill value. Make no changes if if the
** argument is zero. Return the effective cache-spill size, which will
** be the larger of the szSpill and szCache.
*/
int sqlite3PcacheSetSpillsize(PCache *p, int mxPage){
int res;
assert( p->pCache!=0 );
if( mxPage ){
if( mxPage<0 ){
mxPage = (int)((-1024*(i64)p->szCache)/(p->szPage+p->szExtra));
}
p->szSpill = mxPage;
}
res = numberOfCachePages(p);
if( res<p->szSpill ) res = p->szSpill;
return res;
}
/*
** Free up as much memory as possible from the page cache.
*/