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Add the new PGHDR_CLEAN bit to PgHdr.flags in pcache.c. This bit is always

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the opposite of PGHDR_DIRTY.  Use the extra bit to avoid a comparison
for a small performance boost.

FossilOrigin-Name: 8619fc346d9a5a66a3c4566b4cc032b6b6bf73fd
This commit is contained in:
drh
2015-06-29 04:21:15 +00:00
parent 234a93fc9c
commit c78ae916b9
4 changed files with 20 additions and 13 deletions
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16
src/pcache.c
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@@ -328,6 +328,7 @@ static SQLITE_NOINLINE PgHdr *pcacheFetchFinishWithInit(
memset(pPgHdr->pExtra, 0, pCache->szExtra);
pPgHdr->pCache = pCache;
pPgHdr->pgno = pgno;
pPgHdr->flags = PGHDR_CLEAN;
return sqlite3PcacheFetchFinish(pCache,pgno,pPage);
}
@@ -366,7 +367,7 @@ void SQLITE_NOINLINE sqlite3PcacheRelease(PgHdr *p){
p->nRef--;
if( p->nRef==0 ){
p->pCache->nRef--;
if( (p->flags&PGHDR_DIRTY)==0 ){
if( p->flags&PGHDR_CLEAN ){
pcacheUnpin(p);
}else if( p->pDirtyPrev!=0 ){
/* Move the page to the head of the dirty list. */
@@ -402,11 +403,14 @@ void sqlite3PcacheDrop(PgHdr *p){
** 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);
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);
}
}
}
@@ -416,8 +420,10 @@ void sqlite3PcacheMakeDirty(PgHdr *p){
*/
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);
p->flags |= PGHDR_CLEAN;
if( p->nRef==0 ){
pcacheUnpin(p);
}