database/sqlite
1
0
Fork 0
mirror of https://github.com/sqlite/sqlite.git synced 2025-08-08 14:02:16 +03:00
Code Activity

In the pager, cache a pointer to the first page on the freelist that does not

Browse Source 
need to be synced.  This makes a fetch of a page that is not in cache go a
lot faster when the cache is full.  This check-in also adds some performance
instrumentation to the OS layer. (CVS 842)

FossilOrigin-Name: 00f08fc0b5b6b9c5efbf15a62f9a1cc1cfa71283
This commit is contained in:
drh
2003-01-21 02:39:36 +00:00
parent e78e8284ad
commit 341eae8d35
4 changed files with 75 additions and 24 deletions
Download Patch File Download Diff File Expand all files Collapse all files

48
src/pager.c
View File

@@ -18,7 +18,7 @@
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.68 2003/01/16 13:42:43 drh Exp $
** @(#) $Id: pager.c,v 1.69 2003/01/21 02:39:37 drh Exp $
*/
#include "os.h" /* Must be first to enable large file support */
#include "sqliteInt.h"
@@ -162,6 +162,7 @@ struct Pager {
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 *pFirstSynced; /* First free page with PgHdr.needSync==0 */
PgHdr *pAll; /* List of all pages */
PgHdr *pCkpt; /* List of pages in the checkpoint journal */
PgHdr *aHash[N_PG_HASH]; /* Hash table to map page number of PgHdr */
@@ -346,6 +347,7 @@ static void pager_reset(Pager *pPager){
sqliteFree(pPg);
}
pPager->pFirst = 0;
pPager->pFirstSynced = 0;
pPager->pLast = 0;
pPager->pAll = 0;
memset(pPager->aHash, 0, sizeof(pPager->aHash));
@@ -737,6 +739,7 @@ int sqlitepager_open(
pPager->needSync = 0;
pPager->noSync = pPager->tempFile || !useJournal;
pPager->pFirst = 0;
pPager->pFirstSynced = 0;
pPager->pLast = 0;
pPager->nExtra = nExtra;
memset(pPager->aHash, 0, sizeof(pPager->aHash));
@@ -837,6 +840,11 @@ Pgno sqlitepager_pagenumber(void *pData){
static void _page_ref(PgHdr *pPg){
if( pPg->nRef==0 ){
/* The page is currently on the freelist. Remove it. */
if( pPg==pPg->pPager->pFirstSynced ){
PgHdr *p = pPg->pNextFree;
while( p && p->needSync ){ p = p->pNextFree; }
pPg->pPager->pFirstSynced = p;
}
if( pPg->pPrevFree ){
pPg->pPrevFree->pNextFree = pPg->pNextFree;
}else{
@@ -901,13 +909,29 @@ static int syncAllPages(Pager *pPager){
pPager->journalStarted = 1;
}
pPager->needSync = 0;
/* Erase the needSync flag from every page.
*/
for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
pPg->needSync = 0;
}
pPager->pFirstSynced = pPager->pFirst;
}
/* Erase the needSync flag from every page.
#ifndef NDEBUG
/* If the Pager.needSync flag is clear then the PgHdr.needSync
** flag must also be clear for all pages. Verify that this
** invariant is true.
*/
for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
pPg->needSync = 0;
else{
for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
assert( pPg->needSync==0 );
}
assert( pPager->pFirstSynced==pPager->pFirst );
}
#endif
return rc;
}
@@ -1032,10 +1056,7 @@ int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage){
/* Find a page to recycle. Try to locate a page that does not
** require us to do an fsync() on the journal.
*/
pPg = pPager->pFirst;
while( pPg && pPg->needSync ){
pPg = pPg->pNextFree;
}
pPg = pPager->pFirstSynced;
/* If we could not find a page that does not require an fsync()
** on the journal file then fsync the journal file. This is a
@@ -1083,6 +1104,11 @@ int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage){
/* Unlink the old page from the free list and the hash table
*/
if( pPg==pPager->pFirstSynced ){
PgHdr *p = pPg->pNextFree;
while( p && p->needSync ){ p = p->pNextFree; }
pPager->pFirstSynced = p;
}
if( pPg->pPrevFree ){
pPg->pPrevFree->pNextFree = pPg->pNextFree;
}else{
@@ -1226,6 +1252,9 @@ int sqlitepager_unref(void *pData){
}else{
pPager->pFirst = pPg;
}
if( pPg->needSync==0 && pPager->pFirstSynced==0 ){
pPager->pFirstSynced = pPg;
}
if( pPager->xDestructor ){
pPager->xDestructor(pData);
}
@@ -1577,13 +1606,12 @@ int sqlitepager_commit(Pager *pPager){
if( pPager->dirtyFile==0 ){
/* Exit early (without doing the time-consuming sqliteOsSync() calls)
** if there have been no changes to the database file. */
assert( pPager->needSync==0 );
rc = pager_unwritelock(pPager);
pPager->dbSize = -1;
return rc;
}
assert( pPager->journalOpen );
if( !pPager->journalStarted && !pPager->noSync ) pPager->needSync = 1;
assert( pPager->dirtyFile || !pPager->needSync );
if( pPager->needSync && sqliteOsSync(&pPager->jfd)!=SQLITE_OK ){
goto commit_abort;
}