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Overview
| Comment: | Create and use a new pager interface sqlite3PagerUnrefNotNull() that works just like sqlite3PagerUnref() but guarantees that its argument is not a NULL pointer. |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
e00f37e2333cac5b53e17cf764ab56c4 |
| User & Date: | drh 2013-12-13 19:35:21 |
Context
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2013-12-13
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| 19:48 | Reduce the number of calls to the subjRequiresPage() routine inside of pager. check-in: e50ff39a user: drh tags: trunk | |
| 19:35 | Create and use a new pager interface sqlite3PagerUnrefNotNull() that works just like sqlite3PagerUnref() but guarantees that its argument is not a NULL pointer. check-in: e00f37e2 user: drh tags: trunk | |
| 18:50 | Enhance the pcache1PinPage() routine so that it called much less often and runs much faster in the cases when it is actually called. check-in: a845779c user: drh tags: trunk | |
Changes
Changes to src/btree.c.
1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 |
** Release a MemPage. This should be called once for each prior
** call to btreeGetPage.
*/
static void releasePage(MemPage *pPage){
if( pPage ){
assert( pPage->aData );
assert( pPage->pBt );
assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage );
assert( sqlite3PagerGetData(pPage->pDbPage)==pPage->aData );
assert( sqlite3_mutex_held(pPage->pBt->mutex) );
sqlite3PagerUnref(pPage->pDbPage);
}
}
/*
** During a rollback, when the pager reloads information into the cache
** so that the cache is restored to its original state at the start of
** the transaction, for each page restored this routine is called.
|
> | |
1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 |
** Release a MemPage. This should be called once for each prior
** call to btreeGetPage.
*/
static void releasePage(MemPage *pPage){
if( pPage ){
assert( pPage->aData );
assert( pPage->pBt );
assert( pPage->pDbPage!=0 );
assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage );
assert( sqlite3PagerGetData(pPage->pDbPage)==pPage->aData );
assert( sqlite3_mutex_held(pPage->pBt->mutex) );
sqlite3PagerUnrefNotNull(pPage->pDbPage);
}
}
/*
** During a rollback, when the pager reloads information into the cache
** so that the cache is restored to its original state at the start of
** the transaction, for each page restored this routine is called.
|
Changes to src/pager.c.
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#ifdef SQLITE_CHECK_PAGES
sqlite3PcacheIterateDirty(pPager->pPCache, pager_set_pagehash);
if( pPager->dbSize==0 && sqlite3PcacheRefCount(pPager->pPCache)>0 ){
PgHdr *p = pager_lookup(pPager, 1);
if( p ){
p->pageHash = 0;
sqlite3PagerUnref(p);
}
}
#endif
sqlite3BitvecDestroy(pPager->pInJournal);
pPager->pInJournal = 0;
pPager->nRec = 0;
................................................................................
rc = sqlite3WalFindFrame(pPager->pWal, pPg->pgno, &iFrame);
if( rc==SQLITE_OK ){
rc = readDbPage(pPg, iFrame);
}
if( rc==SQLITE_OK ){
pPager->xReiniter(pPg);
}
sqlite3PagerUnref(pPg);
}
}
/* Normally, if a transaction is rolled back, any backup processes are
** updated as data is copied out of the rollback journal and into the
** database. This is not generally possible with a WAL database, as
** rollback involves simply truncating the log file. Therefore, if one
................................................................................
** Release a page reference.
**
** If the number of references to the page drop to zero, then the
** page is added to the LRU list. When all references to all pages
** are released, a rollback occurs and the lock on the database is
** removed.
*/
void sqlite3PagerUnref(DbPage *pPg){
if( pPg ){
Pager *pPager = pPg->pPager;
if( pPg->flags & PGHDR_MMAP ){
pagerReleaseMapPage(pPg);
}else{
sqlite3PcacheRelease(pPg);
}
pagerUnlockIfUnused(pPager);
}
}
/*
** This function is called at the start of every write transaction.
** There must already be a RESERVED or EXCLUSIVE lock on the database
** file when this routine is called.
**
................................................................................
if( pg!=PAGER_MJ_PGNO(pPager) ){
rc = sqlite3PagerGet(pPager, pg, &pPage);
if( rc==SQLITE_OK ){
rc = pager_write(pPage);
if( pPage->flags&PGHDR_NEED_SYNC ){
needSync = 1;
}
sqlite3PagerUnref(pPage);
}
}
}else if( (pPage = pager_lookup(pPager, pg))!=0 ){
if( pPage->flags&PGHDR_NEED_SYNC ){
needSync = 1;
}
sqlite3PagerUnref(pPage);
}
}
/* If the PGHDR_NEED_SYNC flag is set for any of the nPage pages
** starting at pg1, then it needs to be set for all of them. Because
** writing to any of these nPage pages may damage the others, the
** journal file must contain sync()ed copies of all of them
................................................................................
*/
if( rc==SQLITE_OK && needSync ){
assert( !MEMDB );
for(ii=0; ii<nPage; ii++){
PgHdr *pPage = pager_lookup(pPager, pg1+ii);
if( pPage ){
pPage->flags |= PGHDR_NEED_SYNC;
sqlite3PagerUnref(pPage);
}
}
}
assert( (pPager->doNotSpill & SPILLFLAG_NOSYNC)!=0 );
pPager->doNotSpill &= ~SPILLFLAG_NOSYNC;
}else{
................................................................................
/* For an in-memory database, make sure the original page continues
** to exist, in case the transaction needs to roll back. Use pPgOld
** as the original page since it has already been allocated.
*/
if( MEMDB ){
assert( pPgOld );
sqlite3PcacheMove(pPgOld, origPgno);
sqlite3PagerUnref(pPgOld);
}
if( needSyncPgno ){
/* If needSyncPgno is non-zero, then the journal file needs to be
** sync()ed before any data is written to database file page needSyncPgno.
** Currently, no such page exists in the page-cache and the
** "is journaled" bitvec flag has been set. This needs to be remedied by
................................................................................
assert( pPager->pTmpSpace!=0 );
sqlite3BitvecClear(pPager->pInJournal, needSyncPgno, pPager->pTmpSpace);
}
return rc;
}
pPgHdr->flags |= PGHDR_NEED_SYNC;
sqlite3PcacheMakeDirty(pPgHdr);
sqlite3PagerUnref(pPgHdr);
}
return SQLITE_OK;
}
#endif
/*
|
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#ifdef SQLITE_CHECK_PAGES
sqlite3PcacheIterateDirty(pPager->pPCache, pager_set_pagehash);
if( pPager->dbSize==0 && sqlite3PcacheRefCount(pPager->pPCache)>0 ){
PgHdr *p = pager_lookup(pPager, 1);
if( p ){
p->pageHash = 0;
sqlite3PagerUnrefNotNull(p);
}
}
#endif
sqlite3BitvecDestroy(pPager->pInJournal);
pPager->pInJournal = 0;
pPager->nRec = 0;
................................................................................
rc = sqlite3WalFindFrame(pPager->pWal, pPg->pgno, &iFrame);
if( rc==SQLITE_OK ){
rc = readDbPage(pPg, iFrame);
}
if( rc==SQLITE_OK ){
pPager->xReiniter(pPg);
}
sqlite3PagerUnrefNotNull(pPg);
}
}
/* Normally, if a transaction is rolled back, any backup processes are
** updated as data is copied out of the rollback journal and into the
** database. This is not generally possible with a WAL database, as
** rollback involves simply truncating the log file. Therefore, if one
................................................................................
** Release a page reference.
**
** If the number of references to the page drop to zero, then the
** page is added to the LRU list. When all references to all pages
** are released, a rollback occurs and the lock on the database is
** removed.
*/
void sqlite3PagerUnrefNotNull(DbPage *pPg){
Pager *pPager;
assert( pPg!=0 );
pPager = pPg->pPager;
if( pPg->flags & PGHDR_MMAP ){
pagerReleaseMapPage(pPg);
}else{
sqlite3PcacheRelease(pPg);
}
pagerUnlockIfUnused(pPager);
}
void sqlite3PagerUnref(DbPage *pPg){
if( pPg ) sqlite3PagerUnrefNotNull(pPg);
}
/*
** This function is called at the start of every write transaction.
** There must already be a RESERVED or EXCLUSIVE lock on the database
** file when this routine is called.
**
................................................................................
if( pg!=PAGER_MJ_PGNO(pPager) ){
rc = sqlite3PagerGet(pPager, pg, &pPage);
if( rc==SQLITE_OK ){
rc = pager_write(pPage);
if( pPage->flags&PGHDR_NEED_SYNC ){
needSync = 1;
}
sqlite3PagerUnrefNotNull(pPage);
}
}
}else if( (pPage = pager_lookup(pPager, pg))!=0 ){
if( pPage->flags&PGHDR_NEED_SYNC ){
needSync = 1;
}
sqlite3PagerUnrefNotNull(pPage);
}
}
/* If the PGHDR_NEED_SYNC flag is set for any of the nPage pages
** starting at pg1, then it needs to be set for all of them. Because
** writing to any of these nPage pages may damage the others, the
** journal file must contain sync()ed copies of all of them
................................................................................
*/
if( rc==SQLITE_OK && needSync ){
assert( !MEMDB );
for(ii=0; ii<nPage; ii++){
PgHdr *pPage = pager_lookup(pPager, pg1+ii);
if( pPage ){
pPage->flags |= PGHDR_NEED_SYNC;
sqlite3PagerUnrefNotNull(pPage);
}
}
}
assert( (pPager->doNotSpill & SPILLFLAG_NOSYNC)!=0 );
pPager->doNotSpill &= ~SPILLFLAG_NOSYNC;
}else{
................................................................................
/* For an in-memory database, make sure the original page continues
** to exist, in case the transaction needs to roll back. Use pPgOld
** as the original page since it has already been allocated.
*/
if( MEMDB ){
assert( pPgOld );
sqlite3PcacheMove(pPgOld, origPgno);
sqlite3PagerUnrefNotNull(pPgOld);
}
if( needSyncPgno ){
/* If needSyncPgno is non-zero, then the journal file needs to be
** sync()ed before any data is written to database file page needSyncPgno.
** Currently, no such page exists in the page-cache and the
** "is journaled" bitvec flag has been set. This needs to be remedied by
................................................................................
assert( pPager->pTmpSpace!=0 );
sqlite3BitvecClear(pPager->pInJournal, needSyncPgno, pPager->pTmpSpace);
}
return rc;
}
pPgHdr->flags |= PGHDR_NEED_SYNC;
sqlite3PcacheMakeDirty(pPgHdr);
sqlite3PagerUnrefNotNull(pPgHdr);
}
return SQLITE_OK;
}
#endif
/*
|
Changes to src/pager.h.
132 133 134 135 136 137 138 139 140 141 142 143 144 145 |
/* Functions used to obtain and release page references. */ int sqlite3PagerAcquire(Pager *pPager, Pgno pgno, DbPage **ppPage, int clrFlag); #define sqlite3PagerGet(A,B,C) sqlite3PagerAcquire(A,B,C,0) DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno); void sqlite3PagerRef(DbPage*); void sqlite3PagerUnref(DbPage*); /* Operations on page references. */ int sqlite3PagerWrite(DbPage*); void sqlite3PagerDontWrite(DbPage*); int sqlite3PagerMovepage(Pager*,DbPage*,Pgno,int); int sqlite3PagerPageRefcount(DbPage*); void *sqlite3PagerGetData(DbPage *); |
> |
132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 |
/* Functions used to obtain and release page references. */
int sqlite3PagerAcquire(Pager *pPager, Pgno pgno, DbPage **ppPage, int clrFlag);
#define sqlite3PagerGet(A,B,C) sqlite3PagerAcquire(A,B,C,0)
DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno);
void sqlite3PagerRef(DbPage*);
void sqlite3PagerUnref(DbPage*);
void sqlite3PagerUnrefNotNull(DbPage*);
/* Operations on page references. */
int sqlite3PagerWrite(DbPage*);
void sqlite3PagerDontWrite(DbPage*);
int sqlite3PagerMovepage(Pager*,DbPage*,Pgno,int);
int sqlite3PagerPageRefcount(DbPage*);
void *sqlite3PagerGetData(DbPage *);
|