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Fix bugs in WAL mode rollback.

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FossilOrigin-Name: 31215969f59be536fe87431bb9fbfa7d13027e35
This commit is contained in:
dan
2010-04-24 18:44:05 +00:00
parent 9de7943783
commit 74d6cd887f
6 changed files with 141 additions and 26 deletions
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62
src/pager.c
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@@ -2235,16 +2235,44 @@ static int readDbPage(PgHdr *pPg){
}
/*
** This function is called when a transaction on a WAL database is rolled
** back. For each dirty page in the cache, do one of the following:
** This function is invoked once for each page that has already been
** written into the log file when a WAL transaction is rolled back.
** Parameter iPg is the page number of said page. The pCtx argument
** is actually a pointer to the Pager structure.
**
** * If the page has no outstanding references, simply discard it.
** * Otherwise, if the page has one or more outstanding references,
** reload the original content from the database (or log file).
** If page iPg is present in the cache, and has no outstanding references,
** it is discarded. Otherwise, if there are one or more outstanding
** references, the page content is reloaded from the database. If the
** attempt to reload content from the database is required and fails,
** return an SQLite error code. Otherwise, SQLITE_OK.
*/
static int pagerUndoCallback(void *pCtx, Pgno iPg){
int rc = SQLITE_OK;
Pager *pPager = (Pager *)pCtx;
PgHdr *pPg;
pPg = sqlite3PagerLookup(pPager, iPg);
if( pPg ){
if( sqlite3PcachePageRefcount(pPg)==1 ){
sqlite3PcacheDrop(pPg);
}else{
rc = readDbPage(pPg);
if( rc==SQLITE_OK ){
pPager->xReiniter(pPg);
}
sqlite3PagerUnref(pPg);
}
}
return rc;
}
/*
** This function is called to rollback a transaction on a WAL database.
*/
static int pagerRollbackLog(Pager *pPager){
int rc = SQLITE_OK;
PgHdr *pList = sqlite3PcacheDirtyList(pPager->pPCache);
int rc; /* Return Code */
PgHdr *pList; /* List of dirty pages to revert */
/* Normally, if a transaction is rolled back, any backup processes are
** updated as data is copied out of the rollback journal and into the
@@ -2258,20 +2286,22 @@ static int pagerRollbackLog(Pager *pPager){
sqlite3BackupRestart(pPager->pBackup);
}
/* For all pages in the cache that are currently dirty or have already
** been written (but not committed) to the log file, do one of the
** following:
**
** + Discard the cached page (if refcount==0), or
** + Reload page content from the database (if refcount>0).
*/
pPager->dbSize = pPager->dbOrigSize;
rc = sqlite3LogUndo(pPager->pLog, pagerUndoCallback, (void *)pPager);
pList = sqlite3PcacheDirtyList(pPager->pPCache);
while( pList && rc==SQLITE_OK ){
PgHdr *pNext = pList->pDirty;
if( sqlite3PcachePageRefcount(pList)==0 ){
sqlite3PagerLookup(pPager, pList->pgno);
sqlite3PcacheDrop(pList);
}else{
rc = readDbPage(pList);
if( rc==SQLITE_OK ){
pPager->xReiniter(pList);
}
}
rc = pagerUndoCallback((void *)pPager, pList->pgno);
pList = pNext;
}
return rc;
}