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Store the page number for the PENDING_BYTE page in the Pager object, rather

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than computing the page number every time it is needed, because it turns out
that number is needed quite frequently.  This saves a few hundred thousand
CPU cycles and a few bytes of code space.

FossilOrigin-Name: 5aa9c3eb45514d5eb7b32696d25a9aeb7dad485e1ea5adb833fac6d1f2105f1a
This commit is contained in:
drh
2022-02-23 17:00:44 +00:00
parent f2a777fa5d
commit 584bfcaeb6
5 changed files with 24 additions and 21 deletions
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20
src/pager.c
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@@ -681,6 +681,7 @@ struct Pager {
u32 vfsFlags; /* Flags for sqlite3_vfs.xOpen() */
u32 sectorSize; /* Assumed sector size during rollback */
Pgno mxPgno; /* Maximum allowed size of the database */
Pgno lckPgno; /* Page number for the locking page */
i64 pageSize; /* Number of bytes in a page */
i64 journalSizeLimit; /* Size limit for persistent journal files */
char *zFilename; /* Name of the database file */
@@ -1667,7 +1668,7 @@ static int readJournalHdr(
** journal file descriptor is advanced to the next sector boundary before
** anything is written. The format is:
**
** + 4 bytes: PAGER_MJ_PGNO.
** + 4 bytes: PAGER_SJ_PGNO.
** + N bytes: super-journal filename in utf-8.
** + 4 bytes: N (length of super-journal name in bytes, no nul-terminator).
** + 4 bytes: super-journal name checksum.
@@ -1715,7 +1716,7 @@ static int writeSuperJournal(Pager *pPager, const char *zSuper){
/* Write the super-journal data to the end of the journal file. If
** an error occurs, return the error code to the caller.
*/
if( (0 != (rc = write32bits(pPager->jfd, iHdrOff, PAGER_MJ_PGNO(pPager))))
if( (0 != (rc = write32bits(pPager->jfd, iHdrOff, PAGER_SJ_PGNO(pPager))))
|| (0 != (rc = sqlite3OsWrite(pPager->jfd, zSuper, nSuper, iHdrOff+4)))
|| (0 != (rc = write32bits(pPager->jfd, iHdrOff+4+nSuper, nSuper)))
|| (0 != (rc = write32bits(pPager->jfd, iHdrOff+4+nSuper+4, cksum)))
@@ -2225,7 +2226,7 @@ static u32 pager_cksum(Pager *pPager, const u8 *aData){
** corrupted, SQLITE_DONE is returned. Data is considered corrupted in
** two circumstances:
**
** * If the record page-number is illegal (0 or PAGER_MJ_PGNO), or
** * If the record page-number is illegal (0 or PAGER_SJ_PGNO), or
** * If the record is being rolled back from the main journal file
** and the checksum field does not match the record content.
**
@@ -2285,7 +2286,7 @@ static int pager_playback_one_page(
** it could cause invalid data to be written into the journal. We need to
** detect this invalid data (with high probability) and ignore it.
*/
if( pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){
if( pgno==0 || pgno==PAGER_SJ_PGNO(pPager) ){
assert( !isSavepnt );
return SQLITE_DONE;
}
@@ -3740,6 +3741,7 @@ int sqlite3PagerSetPagesize(Pager *pPager, u32 *pPageSize, int nReserve){
pPager->pTmpSpace = pNew;
pPager->dbSize = (Pgno)((nByte+pageSize-1)/pageSize);
pPager->pageSize = pageSize;
pPager->lckPgno = (Pgno)(PENDING_BYTE/pageSize) + 1;
}else{
sqlite3PageFree(pNew);
}
@@ -5509,7 +5511,7 @@ static int getPageNormal(
if( pPg->pPager && !noContent ){
/* In this case the pcache already contains an initialized copy of
** the page. Return without further ado. */
assert( pgno!=PAGER_MJ_PGNO(pPager) );
assert( pgno!=PAGER_SJ_PGNO(pPager) );
pPager->aStat[PAGER_STAT_HIT]++;
return SQLITE_OK;
@@ -5520,7 +5522,7 @@ static int getPageNormal(
** (*) obsolete. Was: maximum page number is 2^31
** (2) Never try to fetch the locking page
*/
if( pgno==PAGER_MJ_PGNO(pPager) ){
if( pgno==PAGER_SJ_PGNO(pPager) ){
rc = SQLITE_CORRUPT_BKPT;
goto pager_acquire_err;
}
@@ -5919,7 +5921,7 @@ static SQLITE_NOINLINE int pagerAddPageToRollbackJournal(PgHdr *pPg){
/* 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( pPg->pgno!=PAGER_SJ_PGNO(pPager) );
assert( pPager->journalHdr<=pPager->journalOff );
pData2 = pPg->pData;
@@ -6098,7 +6100,7 @@ static SQLITE_NOINLINE int pagerWriteLargeSector(PgHdr *pPg){
Pgno pg = pg1+ii;
PgHdr *pPage;
if( pg==pPg->pgno || !sqlite3BitvecTest(pPager->pInJournal, pg) ){
if( pg!=PAGER_MJ_PGNO(pPager) ){
if( pg!=PAGER_SJ_PGNO(pPager) ){
rc = sqlite3PagerGet(pPager, pg, &pPage, 0);
if( rc==SQLITE_OK ){
rc = pager_write(pPage);
@@ -6576,7 +6578,7 @@ int sqlite3PagerCommitPhaseOne(
** last page is never written out to disk, leaving the database file
** undersized. Fix this now if it is the case. */
if( pPager->dbSize>pPager->dbFileSize ){
Pgno nNew = pPager->dbSize - (pPager->dbSize==PAGER_MJ_PGNO(pPager));
Pgno nNew = pPager->dbSize - (pPager->dbSize==PAGER_SJ_PGNO(pPager));
assert( pPager->eState==PAGER_WRITER_DBMOD );
rc = pager_truncate(pPager, nNew);
if( rc!=SQLITE_OK ) goto commit_phase_one_exit;