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Change to the pager to avoid opening journal files unnecessarily. This can

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sometimes results in a significant speed improvement. (CVS 791)

FossilOrigin-Name: fa5c042585c601449ede7319d0c5993cd8ba75a4
This commit is contained in:
drh
2002-12-02 04:25:19 +00:00
parent d0d006e29c
commit da47d7748f
11 changed files with 146 additions and 87 deletions
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153
src/pager.c
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@@ -18,7 +18,7 @@
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.59 2002/12/01 02:00:58 drh Exp $
** @(#) $Id: pager.c,v 1.60 2002/12/02 04:25:21 drh Exp $
*/
#include "os.h" /* Must be first to enable large file support */
#include "sqliteInt.h"
@@ -116,8 +116,10 @@ struct Pager {
int mxPage; /* Maximum number of pages to hold in cache */
int nHit, nMiss, nOvfl; /* Cache hits, missing, and LRU overflows */
u8 journalOpen; /* True if journal file descriptors is valid */
u8 useJournal; /* Do not use a rollback journal on this file */
u8 ckptOpen; /* True if the checkpoint journal is open */
u8 ckptInUse; /* True we are in a checkpoint */
u8 ckptAutoopen; /* Open ckpt journal when main journal is opened*/
u8 noSync; /* Do not sync the journal if true */
u8 state; /* SQLITE_UNLOCK, _READLOCK or _WRITELOCK */
u8 errMask; /* One of several kinds of errors */
@@ -348,16 +350,20 @@ static int pager_unwritelock(Pager *pPager){
sqliteOsClose(&pPager->cpfd);
pPager->ckptOpen = 0;
}
sqliteOsClose(&pPager->jfd);
pPager->journalOpen = 0;
sqliteOsDelete(pPager->zJournal);
rc = sqliteOsReadLock(&pPager->fd);
sqliteFree( pPager->aInJournal );
pPager->aInJournal = 0;
for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
pPg->inJournal = 0;
pPg->dirty = 0;
if( pPager->journalOpen ){
sqliteOsClose(&pPager->jfd);
pPager->journalOpen = 0;
sqliteOsDelete(pPager->zJournal);
sqliteFree( pPager->aInJournal );
pPager->aInJournal = 0;
for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
pPg->inJournal = 0;
pPg->dirty = 0;
}
}else{
assert( pPager->dirtyFile==0 || pPager->useJournal==0 );
}
rc = sqliteOsReadLock(&pPager->fd);
if( rc==SQLITE_OK ){
pPager->state = SQLITE_READLOCK;
}else{
@@ -616,7 +622,8 @@ int sqlitepager_open(
Pager **ppPager, /* Return the Pager structure here */
const char *zFilename, /* Name of the database file to open */
int mxPage, /* Max number of in-memory cache pages */
int nExtra /* Extra bytes append to each in-memory page */
int nExtra, /* Extra bytes append to each in-memory page */
int useJournal /* TRUE to use a rollback journal on this file */
){
Pager *pPager;
int nameLen;
@@ -654,6 +661,7 @@ int sqlitepager_open(
strcpy(&pPager->zJournal[nameLen], "-journal");
pPager->fd = fd;
pPager->journalOpen = 0;
pPager->useJournal = useJournal;
pPager->ckptOpen = 0;
pPager->ckptInUse = 0;
pPager->nRef = 0;
@@ -667,7 +675,7 @@ int sqlitepager_open(
pPager->tempFile = tempFile;
pPager->readOnly = readOnly;
pPager->needSync = 0;
pPager->noSync = pPager->tempFile;
pPager->noSync = pPager->tempFile || !useJournal;
pPager->pFirst = 0;
pPager->pLast = 0;
pPager->nExtra = nExtra;
@@ -894,7 +902,7 @@ int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage){
/* If a journal file exists, try to play it back.
*/
if( sqliteOsFileExists(pPager->zJournal) ){
if( pPager->useJournal && sqliteOsFileExists(pPager->zJournal) ){
int rc, dummy;
/* Get a write lock on the database
@@ -1164,6 +1172,58 @@ int sqlitepager_unref(void *pData){
return SQLITE_OK;
}
/*
** Create a journal file for pPager. There should already be a write
** lock on the database file when this routine is called.
**
** Return SQLITE_OK if everything. Return an error code and release the
** write lock if anything goes wrong.
*/
static int pager_open_journal(Pager *pPager){
int rc;
assert( pPager->state==SQLITE_WRITELOCK );
assert( pPager->journalOpen==0 );
assert( pPager->useJournal );
pPager->aInJournal = sqliteMalloc( pPager->dbSize/8 + 1 );
if( pPager->aInJournal==0 ){
sqliteOsReadLock(&pPager->fd);
pPager->state = SQLITE_READLOCK;
return SQLITE_NOMEM;
}
rc = sqliteOsOpenExclusive(pPager->zJournal, &pPager->jfd,pPager->tempFile);
if( rc!=SQLITE_OK ){
sqliteFree(pPager->aInJournal);
pPager->aInJournal = 0;
sqliteOsReadLock(&pPager->fd);
pPager->state = SQLITE_READLOCK;
return SQLITE_CANTOPEN;
}
pPager->journalOpen = 1;
pPager->needSync = 0;
pPager->alwaysRollback = 0;
sqlitepager_pagecount(pPager);
pPager->origDbSize = pPager->dbSize;
if( pager_old_format ){
rc = sqliteOsWrite(&pPager->jfd, aOldJournalMagic,
sizeof(aOldJournalMagic));
}else{
rc = sqliteOsWrite(&pPager->jfd, aJournalMagic, sizeof(aJournalMagic));
}
if( rc==SQLITE_OK ){
rc = write32bits(&pPager->jfd, pPager->dbSize);
}
if( pPager->ckptAutoopen && rc==SQLITE_OK ){
rc = sqlitepager_ckpt_begin(pPager);
}
if( rc!=SQLITE_OK ){
rc = pager_unwritelock(pPager);
if( rc==SQLITE_OK ){
rc = SQLITE_FULL;
}
}
return rc;
}
/*
** Acquire a write-lock on the database. The lock is removed when
** the any of the following happen:
@@ -1178,6 +1238,10 @@ int sqlitepager_unref(void *pData){
** to acquire a pointer to the Pager structure and as proof that there
** is already a read-lock on the database.
**
** A journal file is opened if this is not a temporary file. For
** temporary files, the opening of the journal file is deferred until
** there is an actual need to write to the journal.
**
** If the database is already write-locked, this routine is a no-op.
*/
int sqlitepager_begin(void *pData){
@@ -1192,39 +1256,10 @@ int sqlitepager_begin(void *pData){
if( rc!=SQLITE_OK ){
return rc;
}
pPager->aInJournal = sqliteMalloc( pPager->dbSize/8 + 1 );
if( pPager->aInJournal==0 ){
sqliteOsReadLock(&pPager->fd);
return SQLITE_NOMEM;
}
rc = sqliteOsOpenExclusive(pPager->zJournal, &pPager->jfd,pPager->tempFile);
if( rc!=SQLITE_OK ){
sqliteFree(pPager->aInJournal);
pPager->aInJournal = 0;
sqliteOsReadLock(&pPager->fd);
return SQLITE_CANTOPEN;
}
pPager->journalOpen = 1;
pPager->needSync = 0;
pPager->dirtyFile = 0;
pPager->alwaysRollback = 0;
pPager->state = SQLITE_WRITELOCK;
sqlitepager_pagecount(pPager);
pPager->origDbSize = pPager->dbSize;
if( pager_old_format ){
rc = sqliteOsWrite(&pPager->jfd, aOldJournalMagic,
sizeof(aOldJournalMagic));
}else{
rc = sqliteOsWrite(&pPager->jfd, aJournalMagic, sizeof(aJournalMagic));
}
if( rc==SQLITE_OK ){
rc = write32bits(&pPager->jfd, pPager->dbSize);
}
if( rc!=SQLITE_OK ){
rc = pager_unwritelock(pPager);
if( rc==SQLITE_OK ){
rc = SQLITE_FULL;
}
pPager->dirtyFile = 0;
if( pPager->useJournal && !pPager->tempFile ){
rc = pager_open_journal(pPager);
}
}
return rc;
@@ -1279,16 +1314,23 @@ int sqlitepager_write(void *pData){
*/
assert( pPager->state!=SQLITE_UNLOCK );
rc = sqlitepager_begin(pData);
pPager->dirtyFile = 1;
if( rc!=SQLITE_OK ) return rc;
if( rc!=SQLITE_OK ){
return rc;
}
assert( pPager->state==SQLITE_WRITELOCK );
assert( pPager->journalOpen );
if( !pPager->journalOpen && pPager->useJournal ){
rc = pager_open_journal(pPager);
if( rc!=SQLITE_OK ) return rc;
}
assert( pPager->journalOpen || !pPager->useJournal );
pPager->dirtyFile = 1;
/* The transaction journal now exists and we have a write lock on the
** main database file. Write the current page to the transaction
** journal if it is not there already.
*/
if( !pPg->inJournal && (int)pPg->pgno <= pPager->origDbSize ){
if( !pPg->inJournal && pPager->useJournal
&& (int)pPg->pgno <= pPager->origDbSize ){
rc = write32bits(&pPager->jfd, pPg->pgno);
if( rc==SQLITE_OK ){
rc = sqliteOsWrite(&pPager->jfd, pData, SQLITE_PAGE_SIZE);
@@ -1444,7 +1486,6 @@ int sqlitepager_commit(Pager *pPager){
if( pPager->state!=SQLITE_WRITELOCK ){
return SQLITE_ERROR;
}
assert( pPager->journalOpen );
if( pPager->dirtyFile==0 ){
/* Exit early (without doing the time-consuming sqliteOsSync() calls)
** if there have been no changes to the database file. */
@@ -1452,6 +1493,7 @@ int sqlitepager_commit(Pager *pPager){
pPager->dbSize = -1;
return rc;
}
assert( pPager->journalOpen );
if( pPager->needSync && sqliteOsSync(&pPager->jfd)!=SQLITE_OK ){
goto commit_abort;
}
@@ -1493,6 +1535,11 @@ commit_abort:
*/
int sqlitepager_rollback(Pager *pPager){
int rc;
if( !pPager->dirtyFile || !pPager->journalOpen ){
rc = pager_unwritelock(pPager);
pPager->dbSize = -1;
return rc;
}
if( pPager->errMask!=0 && pPager->errMask!=PAGER_ERR_FULL ){
if( pPager->state>=SQLITE_WRITELOCK ){
pager_playback(pPager);
@@ -1546,6 +1593,10 @@ int *sqlitepager_stats(Pager *pPager){
int sqlitepager_ckpt_begin(Pager *pPager){
int rc;
char zTemp[SQLITE_TEMPNAME_SIZE];
if( !pPager->journalOpen ){
pPager->ckptAutoopen = 1;
return SQLITE_OK;
}
assert( pPager->journalOpen );
assert( !pPager->ckptInUse );
pPager->aInCkpt = sqliteMalloc( pPager->dbSize/8 + 1 );
@@ -1591,6 +1642,7 @@ int sqlitepager_ckpt_commit(Pager *pPager){
}
pPager->pCkpt = 0;
}
pPager->ckptAutoopen = 0;
return SQLITE_OK;
}
@@ -1605,6 +1657,7 @@ int sqlitepager_ckpt_rollback(Pager *pPager){
}else{
rc = SQLITE_OK;
}
pPager->ckptAutoopen = 0;
return rc;
}