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Simplifications and performance improvement in pager_write().

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FossilOrigin-Name: ab7aeeead395a05b91a921ef9ebe9252fffad667
This commit is contained in:
drh
2015-06-29 14:11:50 +00:00
parent c78ae916b9
commit 82ef8775c7
5 changed files with 101 additions and 94 deletions
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169
src/pager.c
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@@ -808,7 +808,7 @@ static const unsigned char aJournalMagic[] = {
**
** if( pPager->jfd->pMethods ){ ...
*/
#define isOpen(pFd) ((pFd)->pMethods)
#define isOpen(pFd) ((pFd)->pMethods!=0)
/*
** Return true if this pager uses a write-ahead log instead of the usual
@@ -1031,19 +1031,21 @@ static int subjRequiresPage(PgHdr *pPg){
int i;
for(i=0; i<pPager->nSavepoint; i++){
p = &pPager->aSavepoint[i];
if( p->nOrig>=pgno && 0==sqlite3BitvecTest(p->pInSavepoint, pgno) ){
if( p->nOrig>=pgno && 0==sqlite3BitvecTestNotNull(p->pInSavepoint, pgno) ){
return 1;
}
}
return 0;
}
#ifdef SQLITE_DEBUG
/*
** Return true if the page is already in the journal file.
*/
static int pageInJournal(Pager *pPager, PgHdr *pPg){
return sqlite3BitvecTest(pPager->pInJournal, pPg->pgno);
}
#endif
/*
** Read a 32-bit integer from the given file descriptor. Store the integer
@@ -5648,6 +5650,59 @@ int sqlite3PagerBegin(Pager *pPager, int exFlag, int subjInMemory){
return rc;
}
/*
** Write page pPg onto the end of the rollback journal.
*/
static SQLITE_NOINLINE int pagerAddPageToRollbackJournal(PgHdr *pPg){
Pager *pPager = pPg->pPager;
int rc;
u32 cksum;
char *pData2;
i64 iOff = pPager->journalOff;
/* We should never write to the journal file the page that
** contains the database locks. The following assert verifies
** that we do not. */
assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) );
assert( pPager->journalHdr<=pPager->journalOff );
CODEC2(pPager, pPg->pData, pPg->pgno, 7, return SQLITE_NOMEM, pData2);
cksum = pager_cksum(pPager, (u8*)pData2);
/* Even if an IO or diskfull error occurs while journalling the
** page in the block above, set the need-sync flag for the page.
** Otherwise, when the transaction is rolled back, the logic in
** playback_one_page() will think that the page needs to be restored
** in the database file. And if an IO error occurs while doing so,
** then corruption may follow.
*/
pPg->flags |= PGHDR_NEED_SYNC;
rc = write32bits(pPager->jfd, iOff, pPg->pgno);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3OsWrite(pPager->jfd, pData2, pPager->pageSize, iOff+4);
if( rc!=SQLITE_OK ) return rc;
rc = write32bits(pPager->jfd, iOff+pPager->pageSize+4, cksum);
if( rc!=SQLITE_OK ) return rc;
IOTRACE(("JOUT %p %d %lld %d\n", pPager, pPg->pgno,
pPager->journalOff, pPager->pageSize));
PAGER_INCR(sqlite3_pager_writej_count);
PAGERTRACE(("JOURNAL %d page %d needSync=%d hash(%08x)\n",
PAGERID(pPager), pPg->pgno,
((pPg->flags&PGHDR_NEED_SYNC)?1:0), pager_pagehash(pPg)));
pPager->journalOff += 8 + pPager->pageSize;
pPager->nRec++;
assert( pPager->pInJournal!=0 );
rc = sqlite3BitvecSet(pPager->pInJournal, pPg->pgno);
testcase( rc==SQLITE_NOMEM );
assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
rc |= addToSavepointBitvecs(pPager, pPg->pgno);
assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
return rc;
}
/*
** Mark a single data page as writeable. The page is written into the
** main journal or sub-journal as required. If the page is written into
@@ -5658,7 +5713,6 @@ int sqlite3PagerBegin(Pager *pPager, int exFlag, int subjInMemory){
static int pager_write(PgHdr *pPg){
Pager *pPager = pPg->pPager;
int rc = SQLITE_OK;
int inJournal;
/* This routine is not called unless a write-transaction has already
** been started. The journal file may or may not be open at this point.
@@ -5671,7 +5725,6 @@ static int pager_write(PgHdr *pPg){
assert( assert_pager_state(pPager) );
assert( pPager->errCode==0 );
assert( pPager->readOnly==0 );
CHECK_PAGE(pPg);
/* The journal file needs to be opened. Higher level routines have already
@@ -5690,91 +5743,41 @@ static int pager_write(PgHdr *pPg){
assert( pPager->eState>=PAGER_WRITER_CACHEMOD );
assert( assert_pager_state(pPager) );
/* Mark the page as dirty. If the page has already been written
** to the journal then we can return right away.
*/
/* Mark the page that is about to be modified as dirty. */
sqlite3PcacheMakeDirty(pPg);
inJournal = pageInJournal(pPager, pPg);
if( inJournal && (pPager->nSavepoint==0 || !subjRequiresPage(pPg)) ){
assert( !pagerUseWal(pPager) );
}else{
/* The transaction journal now exists and we have a RESERVED or an
** EXCLUSIVE lock on the main database file. Write the current page to
** the transaction journal if it is not there already.
*/
if( !inJournal && !pagerUseWal(pPager) ){
assert( pagerUseWal(pPager)==0 );
if( pPg->pgno<=pPager->dbOrigSize && isOpen(pPager->jfd) ){
u32 cksum;
char *pData2;
i64 iOff = pPager->journalOff;
/* We should never write to the journal file the page that
** contains the database locks. The following assert verifies
** that we do not. */
assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) );
assert( pPager->journalHdr<=pPager->journalOff );
CODEC2(pPager, pPg->pData, pPg->pgno, 7, return SQLITE_NOMEM, pData2);
cksum = pager_cksum(pPager, (u8*)pData2);
/* Even if an IO or diskfull error occurs while journalling the
** page in the block above, set the need-sync flag for the page.
** Otherwise, when the transaction is rolled back, the logic in
** playback_one_page() will think that the page needs to be restored
** in the database file. And if an IO error occurs while doing so,
** then corruption may follow.
*/
pPg->flags |= PGHDR_NEED_SYNC;
rc = write32bits(pPager->jfd, iOff, pPg->pgno);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3OsWrite(pPager->jfd, pData2, pPager->pageSize, iOff+4);
if( rc!=SQLITE_OK ) return rc;
rc = write32bits(pPager->jfd, iOff+pPager->pageSize+4, cksum);
if( rc!=SQLITE_OK ) return rc;
IOTRACE(("JOUT %p %d %lld %d\n", pPager, pPg->pgno,
pPager->journalOff, pPager->pageSize));
PAGER_INCR(sqlite3_pager_writej_count);
PAGERTRACE(("JOURNAL %d page %d needSync=%d hash(%08x)\n",
PAGERID(pPager), pPg->pgno,
((pPg->flags&PGHDR_NEED_SYNC)?1:0), pager_pagehash(pPg)));
pPager->journalOff += 8 + pPager->pageSize;
pPager->nRec++;
assert( pPager->pInJournal!=0 );
rc = sqlite3BitvecSet(pPager->pInJournal, pPg->pgno);
testcase( rc==SQLITE_NOMEM );
assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
rc |= addToSavepointBitvecs(pPager, pPg->pgno);
if( rc!=SQLITE_OK ){
assert( rc==SQLITE_NOMEM );
return rc;
}
}else{
if( pPager->eState!=PAGER_WRITER_DBMOD ){
pPg->flags |= PGHDR_NEED_SYNC;
}
PAGERTRACE(("APPEND %d page %d needSync=%d\n",
PAGERID(pPager), pPg->pgno,
((pPg->flags&PGHDR_NEED_SYNC)?1:0)));
/* If a rollback journal is in use, them make sure the page that is about
** to change is in the rollback journal, or if the page is a new page off
** then end of the file, make sure it is marked as PGHDR_NEED_SYNC.
*/
assert( (pPager->pInJournal!=0) == isOpen(pPager->jfd) );
if( pPager->pInJournal!=0 /* Journal open */
&& sqlite3BitvecTestNotNull(pPager->pInJournal, pPg->pgno)==0 /* pPg not in jrnl */
){
assert( pagerUseWal(pPager)==0 );
if( pPg->pgno<=pPager->dbOrigSize ){
rc = pagerAddPageToRollbackJournal(pPg);
if( rc!=SQLITE_OK ){
return rc;
}
}
/* If the statement journal is open and the page is not in it,
** then write the current page to the statement journal. Note that
** the statement journal format differs from the standard journal format
** in that it omits the checksums and the header.
*/
if( pPager->nSavepoint>0 && subjRequiresPage(pPg) ){
rc = subjournalPage(pPg);
}else{
if( pPager->eState!=PAGER_WRITER_DBMOD ){
pPg->flags |= PGHDR_NEED_SYNC;
}
PAGERTRACE(("APPEND %d page %d needSync=%d\n",
PAGERID(pPager), pPg->pgno,
((pPg->flags&PGHDR_NEED_SYNC)?1:0)));
}
}
/* Update the database size and return.
/* If the statement journal is open and the page is not in it,
** then write the page into the statement journal.
*/
if( pPager->nSavepoint>0 && subjRequiresPage(pPg) ){
rc = subjournalPage(pPg);
}
/* Update the database size and return. */
if( pPager->dbSize<pPg->pgno ){
pPager->dbSize = pPg->pgno;
}