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Add the ability to turn of calls to fsync() using the "synchronous" pragma.

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Increased the default cache size from 100 to 2000 and made the "cache_size"
pragma persistent. (CVS 418)

FossilOrigin-Name: 414da4af1f4aebc3936ca339fbc7932add081912
This commit is contained in:
drh
2002-03-05 01:11:12 +00:00
parent ef2daf547d
commit 603240cf5d
11 changed files with 395 additions and 63 deletions
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40
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 1.41 2002/03/02 20:41:59 drh Exp $
** @(#) $Id: pager.c,v 1.42 2002/03/05 01:11:14 drh Exp $
*/
#include "sqliteInt.h"
#include "pager.h"
@@ -93,7 +93,7 @@ struct PgHdr {
** How big to make the hash table used for locating in-memory pages
** by page number. Knuth says this should be a prime number.
*/
#define N_PG_HASH 373
#define N_PG_HASH 2003
/*
** A open page cache is an instance of the following structure.
@@ -103,8 +103,6 @@ struct Pager {
char *zJournal; /* Name of the journal file */
OsFile fd, jfd; /* File descriptors for database and journal */
OsFile cpfd; /* File descriptor for the checkpoint journal */
int journalOpen; /* True if journal file descriptors is valid */
int ckptOpen; /* True if the checkpoint journal is open */
int dbSize; /* Number of pages in the file */
int origDbSize; /* dbSize before the current change */
int ckptSize, ckptJSize; /* Size of database and journal at ckpt_begin() */
@@ -114,13 +112,16 @@ struct Pager {
int nRef; /* Number of in-memory pages with PgHdr.nRef>0 */
int mxPage; /* Maximum number of pages to hold in cache */
int nHit, nMiss, nOvfl; /* Cache hits, missing, and LRU overflows */
unsigned char state; /* SQLITE_UNLOCK, _READLOCK or _WRITELOCK */
unsigned char errMask; /* One of several kinds of errors */
unsigned char tempFile; /* zFilename is a temporary file */
unsigned char readOnly; /* True for a read-only database */
unsigned char needSync; /* True if an fsync() is needed on the journal */
unsigned char *aInJournal; /* One bit for each page in the database file */
unsigned char *aInCkpt; /* One bit for each page in the database */
u8 journalOpen; /* True if journal file descriptors is valid */
u8 ckptOpen; /* True if the checkpoint journal is open */
u8 noSync; /* Do not sync the journal if true */
u8 state; /* SQLITE_UNLOCK, _READLOCK or _WRITELOCK */
u8 errMask; /* One of several kinds of errors */
u8 tempFile; /* zFilename is a temporary file */
u8 readOnly; /* True for a read-only database */
u8 needSync; /* True if an fsync() is needed on the journal */
u8 *aInJournal; /* One bit for each page in the database file */
u8 *aInCkpt; /* One bit for each page in the database */
PgHdr *pFirst, *pLast; /* List of free pages */
PgHdr *pAll; /* List of all pages */
PgHdr *aHash[N_PG_HASH]; /* Hash table to map page number of PgHdr */
@@ -435,6 +436,12 @@ end_ckpt_playback:
** Change the maximum number of in-memory pages that are allowed.
*/
void sqlitepager_set_cachesize(Pager *pPager, int mxPage){
if( mxPage>=0 ){
pPager->noSync = 0;
}else{
pPager->noSync = 1;
mxPage = -mxPage;
}
if( mxPage>10 ){
pPager->mxPage = mxPage;
}
@@ -800,9 +807,8 @@ int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage){
/* Recycle an older page. First locate the page to be recycled.
** Try to find one that is not dirty and is near the head of
** of the free list */
int cnt = pPager->mxPage/2;
pPg = pPager->pFirst;
while( pPg->dirty && 0<cnt-- && pPg->pNextFree ){
while( pPg && pPg->dirty ){
pPg = pPg->pNextFree;
}
@@ -818,7 +824,7 @@ int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage){
** near future. That is way we write all dirty pages after a
** sync.
*/
if( pPg==0 || pPg->dirty ){
if( pPg==0 ){
int rc = syncAllPages(pPager);
if( rc!=0 ){
sqlitepager_rollback(pPager);
@@ -1081,7 +1087,7 @@ int sqlitepager_write(void *pData){
}
assert( pPager->aInJournal!=0 );
pPager->aInJournal[pPg->pgno/8] |= 1<<(pPg->pgno&7);
pPager->needSync = 1;
pPager->needSync = !pPager->noSync;
pPg->inJournal = 1;
if( pPager->ckptOpen ){
pPager->aInCkpt[pPg->pgno/8] |= 1<<(pPg->pgno&7);
@@ -1209,7 +1215,9 @@ int sqlitepager_commit(Pager *pPager){
rc = sqliteOsWrite(&pPager->fd, PGHDR_TO_DATA(pPg), SQLITE_PAGE_SIZE);
if( rc!=SQLITE_OK ) goto commit_abort;
}
if( sqliteOsSync(&pPager->fd)!=SQLITE_OK ) goto commit_abort;
if( !pPager->noSync && sqliteOsSync(&pPager->fd)!=SQLITE_OK ){
goto commit_abort;
}
rc = pager_unwritelock(pPager);
pPager->dbSize = -1;
return rc;