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Fix the change-counter increment for WAL pages so that it works even when

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invoked from xStress.  Ticket [5d863f876ee9561b95e2].

FossilOrigin-Name: 228e7c34c64114670fe015747d47fdaa3b7e1270
This commit is contained in:
drh
2011-01-15 18:11:12 +00:00
parent 104a7bba8c
commit 54a7347aa1
3 changed files with 42 additions and 29 deletions
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51
src/pager.c
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@@ -2915,8 +2915,28 @@ static int pagerRollbackWal(Pager *pPager){
return rc;
}
/* Forward declaration */
static int pager_incr_changecounter(Pager*,int);
/*
** Update the value of the change-counter at offsets 24 and 92 in
** the header and the sqlite version number at offset 96.
**
** This is an unconditional update. See also the pager_incr_changecounter()
** routine which only updates the change-counter if the update is actually
** needed, as determined by the pPager->changeCountDone state variable.
*/
static void pager_write_changecounter(PgHdr *pPg){
u32 change_counter;
/* Increment the value just read and write it back to byte 24. */
change_counter = sqlite3Get4byte((u8*)pPg->pPager->dbFileVers)+1;
put32bits(((char*)pPg->pData)+24, change_counter);
/* Also store the SQLite version number in bytes 96..99 and in
** bytes 92..95 store the change counter for which the version number
** is valid. */
put32bits(((char*)pPg->pData)+92, change_counter);
put32bits(((char*)pPg->pData)+96, SQLITE_VERSION_NUMBER);
}
/*
** This function is a wrapper around sqlite3WalFrames(). As well as logging
@@ -2947,11 +2967,7 @@ static int pagerWalFrames(
}
#endif
if( pList->pgno==1 ){
pPager->changeCountDone = 0;
pager_incr_changecounter(pPager,0);
pPager->changeCountDone = 0;
}
if( pList->pgno==1 ) pager_write_changecounter(pList);
rc = sqlite3WalFrames(pPager->pWal,
pPager->pageSize, pList, nTruncate, isCommit, syncFlags
);
@@ -5509,7 +5525,13 @@ void sqlite3PagerDontWrite(PgHdr *pPg){
/*
** This routine is called to increment the value of the database file
** change-counter, stored as a 4-byte big-endian integer starting at
** byte offset 24 of the pager file.
** byte offset 24 of the pager file. The secondary change counter at
** 92 is also updated, as is the SQLite version number at offset 96.
**
** But this only happens if the pPager->changeCountDone flag is false.
** To avoid excess churning of page 1, the update only happens once.
** See also the pager_write_changecounter() routine that does an
** unconditional update of the change counters.
**
** If the isDirectMode flag is zero, then this is done by calling
** sqlite3PagerWrite() on page 1, then modifying the contents of the
@@ -5550,7 +5572,6 @@ static int pager_incr_changecounter(Pager *pPager, int isDirectMode){
if( !pPager->changeCountDone && pPager->dbSize>0 ){
PgHdr *pPgHdr; /* Reference to page 1 */
u32 change_counter; /* Initial value of change-counter field */
assert( !pPager->tempFile && isOpen(pPager->fd) );
@@ -5568,16 +5589,8 @@ static int pager_incr_changecounter(Pager *pPager, int isDirectMode){
}
if( rc==SQLITE_OK ){
/* Increment the value just read and write it back to byte 24. */
change_counter = sqlite3Get4byte((u8*)pPager->dbFileVers);
change_counter++;
put32bits(((char*)pPgHdr->pData)+24, change_counter);
/* Also store the SQLite version number in bytes 96..99 and in
** bytes 92..95 store the change counter for which the version number
** is valid. */
put32bits(((char*)pPgHdr->pData)+92, change_counter);
put32bits(((char*)pPgHdr->pData)+96, SQLITE_VERSION_NUMBER);
/* Actually do the update of the change counter */
pager_write_changecounter(pPgHdr);
/* If running in direct mode, write the contents of page 1 to the file. */
if( DIRECT_MODE ){