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Update the file change counter just before each transaction is committed. (CVS 1582)

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FossilOrigin-Name: 4649abcbfd032836b196b5d690ef66e4aa494c45
This commit is contained in:
danielk1977
2004-06-14 05:10:42 +00:00
parent 59eb676017
commit aa5ccdf5b8
4 changed files with 76 additions and 23 deletions
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77
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 1.124 2004/06/12 01:43:26 danielk1977 Exp $
** @(#) $Id: pager.c,v 1.125 2004/06/14 05:10:43 danielk1977 Exp $
*/
#include "os.h" /* Must be first to enable large file support */
#include "sqliteInt.h"
@@ -71,6 +71,13 @@ static Pager *mainPager = 0;
** threads can be reading or writing while one
** process is writing.
**
** PAGER_SYNCED The pager moves to this state from PAGER_EXCLUSIVE
** after all dirty pages have been written to the
** database file and the file has been synced to
** disk. All that remains to do is to remove the
** journal file and the transaction will be
** committed.
**
** The page cache comes up in PAGER_UNLOCK. The first time a
** sqlite3pager_get() occurs, the state transitions to PAGER_SHARED.
** After all pages have been released using sqlite_page_unref(),
@@ -87,6 +94,7 @@ static Pager *mainPager = 0;
#define PAGER_SHARED 1
#define PAGER_RESERVED 2
#define PAGER_EXCLUSIVE 3
#define PAGER_SYNCED 4
/*
@@ -323,8 +331,8 @@ static int write32bits(OsFile *fd, u32 val){
}
/*
** Write a 32-bit integer into a page header right before the
** page data. This will overwrite the PgHdr.pDirty pointer.
** Write the 32-bit integer 'val' into the page identified by page header
** 'p' at offset 'offset'.
*/
static void store32bits(u32 val, PgHdr *p, int offset){
unsigned char *ac;
@@ -335,6 +343,16 @@ static void store32bits(u32 val, PgHdr *p, int offset){
ac[3] = val & 0xff;
}
/*
** Read a 32-bit integer at offset 'offset' from the page identified by
** page header 'p'.
*/
static u32 retrieve32bits(PgHdr *p, int offset){
unsigned char *ac;
ac = &((unsigned char*)PGHDR_TO_DATA(p))[offset];
return (ac[0]<<24) | (ac[1]<<16) | (ac[2]<<8) | ac[3];
}
/*
** Convert the bits in the pPager->errMask into an approprate
@@ -532,7 +550,7 @@ static int pager_playback_one_page(Pager *pPager, OsFile *jfd, int useCksum){
}
}
assert( pPager->state==PAGER_RESERVED || pPager->state==PAGER_EXCLUSIVE );
assert( pPager->state==PAGER_RESERVED || pPager->state>=PAGER_EXCLUSIVE );
/* If the pager is in RESERVED state, then there must be a copy of this
** page in the pager cache. In this case just update the pager cache,
@@ -546,9 +564,9 @@ static int pager_playback_one_page(Pager *pPager, OsFile *jfd, int useCksum){
** and the main file. The page is then marked not dirty.
*/
pPg = pager_lookup(pPager, pgno);
assert( pPager->state==PAGER_EXCLUSIVE || pPg );
assert( pPager->state>=PAGER_EXCLUSIVE || pPg );
TRACE2("PLAYBACK page %d\n", pgno);
if( pPager->state==PAGER_EXCLUSIVE ){
if( pPager->state>=PAGER_EXCLUSIVE ){
sqlite3OsSeek(&pPager->fd, (pgno-1)*(off_t)SQLITE_PAGE_SIZE);
rc = sqlite3OsWrite(&pPager->fd, aData, SQLITE_PAGE_SIZE);
}
@@ -564,7 +582,7 @@ static int pager_playback_one_page(Pager *pPager, OsFile *jfd, int useCksum){
if( pPager->xDestructor ){ /*** FIX ME: Should this be xReinit? ***/
pPager->xDestructor(pData, pPager->pageSize);
}
if( pPager->state==PAGER_EXCLUSIVE ){
if( pPager->state>=PAGER_EXCLUSIVE ){
pPg->dirty = 0;
pPg->needSync = 0;
}
@@ -1315,6 +1333,7 @@ int sqlite3pager_close(Pager *pPager){
PgHdr *pPg, *pNext;
switch( pPager->state ){
case PAGER_RESERVED:
case PAGER_SYNCED:
case PAGER_EXCLUSIVE: {
sqlite3pager_rollback(pPager);
if( !pPager->memDb ){
@@ -2627,6 +2646,35 @@ void sqlite3pager_set_codec(
pPager->pCodecArg = pCodecArg;
}
/*
** This routine is called to increment the database file change-counter,
** stored at byte 24 of the pager file.
*/
static int pager_incr_changecounter(Pager *pPager){
void *pPage;
PgHdr *pPgHdr;
u32 change_counter;
int rc;
/* Open page 1 of the file for writing. */
rc = sqlite3pager_get(pPager, 1, &pPage);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3pager_write(pPage);
if( rc!=SQLITE_OK ) return rc;
/* Read the current value at byte 24. */
pPgHdr = DATA_TO_PGHDR(pPage);
change_counter = retrieve32bits(pPgHdr, 24);
/* Increment the value just read and write it back to byte 24. */
change_counter++;
store32bits(change_counter, pPgHdr, 24);
/* Release the page reference. */
sqlite3pager_unref(pPage);
return SQLITE_OK;
}
/*
** Sync the database file for the pager pPager. zMaster points to the name
** of a master journal file that should be written into the individual
@@ -2644,13 +2692,16 @@ void sqlite3pager_set_codec(
int sqlite3pager_sync(Pager *pPager, const char *zMaster){
int rc = SQLITE_OK;
/* If this is an in-memory db, or no pages have been written to, this
** function is a no-op.
/* If this is an in-memory db, or no pages have been written to, or this
** function has already been called, it is a no-op.
*/
if( !pPager->memDb && pPager->dirtyCache ){
if( pPager->state!=PAGER_SYNCED && !pPager->memDb && pPager->dirtyCache ){
PgHdr *pPg;
assert( pPager->journalOpen );
rc = pager_incr_changecounter(pPager);
if( rc!=SQLITE_OK ) goto sync_exit;
/* Sync the journal file */
rc = syncJournal(pPager, zMaster);
if( rc!=SQLITE_OK ) goto sync_exit;
@@ -2660,10 +2711,12 @@ int sqlite3pager_sync(Pager *pPager, const char *zMaster){
rc = pager_write_pagelist(pPg);
if( rc!=SQLITE_OK ) goto sync_exit;
/* If any pages were actually written, sync the database file */
if( pPg && !pPager->noSync ){
/* Sync the database file. */
if( !pPager->noSync ){
rc = sqlite3OsSync(&pPager->fd);
}
pPager->state = PAGER_SYNCED;
}
sync_exit: