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Minor refinements to the pager. (CVS 844)

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FossilOrigin-Name: 19221dee5fee4c8800cbae309f009964c8d646a2
This commit is contained in:
drh
2003-01-22 01:26:44 +00:00
parent 4764f161ab
commit 2554f8b0c0
3 changed files with 78 additions and 34 deletions
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98
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 1.69 2003/01/21 02:39:37 drh Exp $
** @(#) $Id: pager.c,v 1.70 2003/01/22 01:26:44 drh Exp $
*/
#include "os.h" /* Must be first to enable large file support */
#include "sqliteInt.h"
@@ -99,6 +99,7 @@ struct PgHdr {
u8 dirty; /* TRUE if we need to write back changes */
u8 needSync; /* Sync journal before writing this page */
u8 alwaysRollback; /* Disable dont_rollback() for this page */
PgHdr *pDirty; /* Dirty pages sorted by PgHdr.pgno */
/* SQLITE_PAGE_SIZE bytes of page data follow this header */
/* Pager.nExtra bytes of local data follow the page data */
};
@@ -268,6 +269,24 @@ static int write32bits(OsFile *fd, u32 val){
return sqliteOsWrite(fd, ac, 4);
}
/*
** Write a 32-bit integer into a page header right before the
** page data. This will overwrite the PgHdr.pDirty pointer.
*/
static void storePageNumber(PgHdr *p){
u32 val = p->pgno;
unsigned char *ac;
ac = &((char*)PGHDR_TO_DATA(p))[-4];
if( pager_old_format ){
memcpy(ac, &val, 4);
}else{
ac[0] = (val>>24) & 0xff;
ac[1] = (val>>16) & 0xff;
ac[2] = (val>>8) & 0xff;
ac[3] = val & 0xff;
}
}
/*
** Convert the bits in the pPager->errMask into an approprate
@@ -930,12 +949,49 @@ static int syncAllPages(Pager *pPager){
assert( pPager->pFirstSynced==pPager->pFirst );
}
#endif
return rc;
}
/*
** Given a list of pages (connected by the PgHdr.pDirty pointer) write
** every one of those pages out to the database file and mark them all
** as clean.
*/
static int pager_write_pagelist(PgHdr *pList){
Pager *pPager;
int rc;
if( pList==0 ) return SQLITE_OK;
pPager = pList->pPager;
while( pList ){
assert( pList->dirty );
sqliteOsSeek(&pPager->fd, (pList->pgno-1)*(off_t)SQLITE_PAGE_SIZE);
rc = sqliteOsWrite(&pPager->fd, PGHDR_TO_DATA(pList), SQLITE_PAGE_SIZE);
if( rc ) return rc;
pList->dirty = 0;
pList = pList->pDirty;
}
return SQLITE_OK;
}
/*
** Collect every dirty page into a dirty list and
** return a pointer to the head of that list. All pages are
** collected even if they are still in use.
*/
static PgHdr *pager_get_all_dirty_pages(Pager *pPager){
PgHdr *p, *pList;
pList = 0;
for(p=pPager->pAll; p; p=p->pNextAll){
if( p->dirty ){
p->pDirty = pList;
pList = p;
}
}
return pList;
}
/*
** Acquire a page.
**
@@ -1078,15 +1134,13 @@ int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage){
*/
if( pPg->dirty ){
assert( pPg->needSync==0 );
TRACE2("SAVE %d\n", pPg->pgno);
sqliteOsSeek(&pPager->fd, (pPg->pgno-1)*(off_t)SQLITE_PAGE_SIZE);
rc = sqliteOsWrite(&pPager->fd, PGHDR_TO_DATA(pPg), SQLITE_PAGE_SIZE);
pPg->pDirty = 0;
rc = pager_write_pagelist( pPg );
if( rc!=SQLITE_OK ){
sqlitepager_rollback(pPager);
*ppPage = 0;
return SQLITE_IOERR;
}
pPg->dirty = 0;
}
assert( pPg->dirty==0 );
@@ -1435,10 +1489,8 @@ int sqlitepager_write(void *pData){
*/
if( !pPg->inJournal && pPager->useJournal ){
if( (int)pPg->pgno <= pPager->origDbSize ){
rc = write32bits(&pPager->jfd, pPg->pgno);
if( rc==SQLITE_OK ){
rc = sqliteOsWrite(&pPager->jfd, pData, SQLITE_PAGE_SIZE);
}
storePageNumber(pPg);
rc = sqliteOsWrite(&pPager->jfd, &((char*)pData)[-4], SQLITE_PAGE_SIZE+4);
if( rc!=SQLITE_OK ){
sqlitepager_rollback(pPager);
pPager->errMask |= PAGER_ERR_FULL;
@@ -1467,10 +1519,8 @@ int sqlitepager_write(void *pData){
*/
if( pPager->ckptInUse && !pPg->inCkpt && (int)pPg->pgno<=pPager->ckptSize ){
assert( pPg->inJournal || (int)pPg->pgno>pPager->origDbSize );
rc = write32bits(&pPager->cpfd, pPg->pgno);
if( rc==SQLITE_OK ){
rc = sqliteOsWrite(&pPager->cpfd, pData, SQLITE_PAGE_SIZE);
}
storePageNumber(pPg);
rc = sqliteOsWrite(&pPager->cpfd, &((char*)pData)[-4], SQLITE_PAGE_SIZE+4);
if( rc!=SQLITE_OK ){
sqlitepager_rollback(pPager);
pPager->errMask |= PAGER_ERR_FULL;
@@ -1586,7 +1636,6 @@ void sqlitepager_dont_rollback(void *pData){
int sqlitepager_commit(Pager *pPager){
int rc;
PgHdr *pPg;
int dbChanged;
if( pPager->errMask==PAGER_ERR_FULL ){
rc = sqlitepager_rollback(pPager);
@@ -1615,17 +1664,12 @@ int sqlitepager_commit(Pager *pPager){
if( pPager->needSync && sqliteOsSync(&pPager->jfd)!=SQLITE_OK ){
goto commit_abort;
}
dbChanged = 0;
for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
if( pPg->dirty==0 ) continue;
TRACE2("COMMIT-PAGE %d\n", pPg->pgno);
sqliteOsSeek(&pPager->fd, (pPg->pgno-1)*(off_t)SQLITE_PAGE_SIZE);
rc = sqliteOsWrite(&pPager->fd, PGHDR_TO_DATA(pPg), SQLITE_PAGE_SIZE);
if( rc!=SQLITE_OK ) goto commit_abort;
dbChanged = 1;
}
if( dbChanged && !pPager->noSync && sqliteOsSync(&pPager->fd)!=SQLITE_OK ){
goto commit_abort;
pPg = pager_get_all_dirty_pages(pPager);
if( pPg ){
rc = pager_write_pagelist(pPg);
if( rc || (!pPager->noSync && sqliteOsSync(&pPager->fd)!=SQLITE_OK) ){
goto commit_abort;
}
}
rc = pager_unwritelock(pPager);
pPager->dbSize = -1;