/*
** Playback savepoint pSavepoint. Or, if pSavepoint==NULL, then playback
** the entire master journal file. The case pSavepoint==NULL occurs when
** a ROLLBACK TO command is invoked on a SAVEPOINT that is a transaction
** savepoint.
**
** When pSavepoint is not NULL (meaning a non-transaction savepoint is
** being rolled back), then the rollback consists of up to three stages,
** performed in the order specified:
**
** * Pages are played back from the main journal starting at byte
** offset PagerSavepoint.iOffset and continuing to
** PagerSavepoint.iHdrOffset, or to the end of the main journal
** file if PagerSavepoint.iHdrOffset is zero.
**
** * If PagerSavepoint.iHdrOffset is not zero, then pages are played
** back starting from the journal header immediately following
** PagerSavepoint.iHdrOffset to the end of the main journal file.
**
** * Pages are then played back from the sub-journal file, starting
** with the PagerSavepoint.iSubRec and continuing to the end of
** the journal file.
**
** Throughout the rollback process, each time a page is rolled back, the
** corresponding bit is set in a bitvec structure (variable pDone in the
** implementation below). This is used to ensure that a page is only
** rolled back the first time it is encountered in either journal.
**
** If pSavepoint is NULL, then pages are only played back from the main
** journal file. There is no need for a bitvec in this case.
**
** In either case, before playback commences the Pager.dbSize variable
** is reset to the value that it held at the start of the savepoint
** (or transaction). No page with a page-number greater than this value
** is played back. If one is encountered it is simply skipped.
*/
static int pagerPlaybackSavepoint( Pager pPager, PagerSavepoint pSavepoint )
{
i64 szJ; /* Effective size of the main journal */
i64 iHdrOff; /* End of first segment of main-journal records */
int rc = SQLITE_OK; /* Return code */
Bitvec pDone = null; /* Bitvec to ensure pages played back only once */
Debug.Assert( pPager.state >= PAGER_SHARED );
/* Allocate a bitvec to use to store the set of pages rolled back */
if ( pSavepoint != null )
{
pDone = sqlite3BitvecCreate( pSavepoint.nOrig );
if ( null == pDone )
{
return SQLITE_NOMEM;
}
}
/* Set the database size back to the value it was before the savepoint
** being reverted was opened.
*/
pPager.dbSize = pSavepoint != null ? pSavepoint.nOrig : pPager.dbOrigSize;
/* Use pPager.journalOff as the effective size of the main rollback
** journal. The actual file might be larger than this in
** PAGER_JOURNALMODE_TRUNCATE or PAGER_JOURNALMODE_PERSIST. But anything
** past pPager.journalOff is off-limits to us.
*/
szJ = pPager.journalOff;
/* Begin by rolling back records from the main journal starting at
** PagerSavepoint.iOffset and continuing to the next journal header.
** There might be records in the main journal that have a page number
** greater than the current database size (pPager.dbSize) but those
** will be skipped automatically. Pages are added to pDone as they
** are played back.
*/
if ( pSavepoint != null )
{
iHdrOff = pSavepoint.iHdrOffset != 0 ? pSavepoint.iHdrOffset : szJ;
pPager.journalOff = pSavepoint.iOffset;
while ( rc == SQLITE_OK && pPager.journalOff < iHdrOff )
{
rc = pager_playback_one_page( pPager, 1, 0, ref pPager.journalOff, 1, pDone );
}
Debug.Assert( rc != SQLITE_DONE );
}
else
{
pPager.journalOff = 0;
}
/* Continue rolling back records out of the main journal starting at
** the first journal header seen and continuing until the effective end
** of the main journal file. Continue to skip out-of-range pages and
** continue adding pages rolled back to pDone.
*/
while ( rc == SQLITE_OK && pPager.journalOff < szJ )
{
u32 ii; /* Loop counter */
u32 nJRec = 0; /* Number of Journal Records */
u32 dummy = 0;
rc = readJournalHdr( pPager, 0, (int)szJ, ref nJRec, ref dummy );
Debug.Assert( rc != SQLITE_DONE );
/*
** The "pPager.journalHdr+JOURNAL_HDR_SZ(pPager)==pPager.journalOff"
** test is related to ticket #2565. See the discussion in the
** pager_playback() function for additional information.
*/
if ( nJRec == 0
&& pPager.journalHdr + JOURNAL_HDR_SZ( pPager ) == pPager.journalOff
)
{
nJRec = (u32)( ( szJ - pPager.journalOff ) / JOURNAL_PG_SZ( pPager ) );
}
for ( ii = 0; rc == SQLITE_OK && ii < nJRec && pPager.journalOff < szJ; ii++ )
{
rc = pager_playback_one_page( pPager, 1, 0, ref pPager.journalOff, 1, pDone );
}
Debug.Assert( rc != SQLITE_DONE );
}
Debug.Assert( rc != SQLITE_OK || pPager.journalOff == szJ );
/* Finally, rollback pages from the sub-journal. Page that were
** previously rolled back out of the main journal (and are hence in pDone)
** will be skipped. Out-of-range pages are also skipped.
*/
if ( pSavepoint != null )
{
u32 ii; /* Loop counter */
i64 offset = pSavepoint.iSubRec * ( 4 + pPager.pageSize );
for ( ii = pSavepoint.iSubRec; rc == SQLITE_OK && ii < pPager.nSubRec; ii++ )
{
Debug.Assert( offset == ii * ( 4 + pPager.pageSize ) );
rc = pager_playback_one_page( pPager, 0, 0, ref offset, 1, pDone );
}
Debug.Assert( rc != SQLITE_DONE );
}
sqlite3BitvecDestroy( ref pDone );
if ( rc == SQLITE_OK )
{
pPager.journalOff = (int)szJ;
}
return rc;
}
/*
** Check that there are at least nSavepoint savepoints open. If there are
** currently less than nSavepoints open, then open one or more savepoints
** to make up the difference. If the number of savepoints is already
** equal to nSavepoint, then this function is a no-op.
**
** If a memory allocation fails, SQLITE_NOMEM is returned. If an error
** occurs while opening the sub-journal file, then an IO error code is
** returned. Otherwise, SQLITE_OK.
*/
static int sqlite3PagerOpenSavepoint( Pager pPager, int nSavepoint )
{
int rc = SQLITE_OK; /* Return code */
int nCurrent = pPager.nSavepoint; /* Current number of savepoints */
if ( nSavepoint > nCurrent && pPager.useJournal != 0 )
{
int ii; /* Iterator variable */
PagerSavepoint[] aNew; /* New Pager.aSavepoint array */
/* Either there is no active journal or the sub-journal is open or
** the journal is always stored in memory */
Debug.Assert( pPager.nSavepoint == 0 || isOpen( pPager.sjfd ) ||
pPager.journalMode == PAGER_JOURNALMODE_MEMORY );
/* Grow the Pager.aSavepoint array using realloc(). Return SQLITE_NOMEM
** if the allocation fails. Otherwise, zero the new portion in case a
** malloc failure occurs while populating it in the for(...) loop below.
*/
//aNew = (PagerSavepoint *)sqlite3Realloc(
// pPager->aSavepoint, sizeof(PagerSavepoint)*nSavepoint
//);
Array.Resize( ref pPager.aSavepoint, nSavepoint );
aNew = pPager.aSavepoint;
//if( null==aNew ){
// return SQLITE_NOMEM;
//}
// memset(&aNew[nCurrent], 0, (nSavepoint-nCurrent) * sizeof(PagerSavepoint));
// pPager.aSavepoint = aNew;
pPager.nSavepoint = nSavepoint;
/* Populate the PagerSavepoint structures just allocated. */
for ( ii = nCurrent; ii < nSavepoint; ii++ )
{
Debug.Assert( pPager.dbSizeValid );
aNew[ii] = new PagerSavepoint();
aNew[ii].nOrig = pPager.dbSize;
if ( isOpen( pPager.jfd ) && ALWAYS( pPager.journalOff > 0 ) )
{
aNew[ii].iOffset = pPager.journalOff;
}
else
{
aNew[ii].iOffset = (int)JOURNAL_HDR_SZ( pPager );
}
aNew[ii].iSubRec = pPager.nSubRec;
aNew[ii].pInSavepoint = sqlite3BitvecCreate( pPager.dbSize );
if ( null == aNew[ii].pInSavepoint )
{
return SQLITE_NOMEM;
}
}
/* Open the sub-journal, if it is not already opened. */
rc = openSubJournal( pPager );
assertTruncateConstraint( pPager );
}
return rc;
}
/*
** Check that there are at least nSavepoint savepoints open. If there are
** currently less than nSavepoints open, then open one or more savepoints
** to make up the difference. If the number of savepoints is already
** equal to nSavepoint, then this function is a no-op.
**
** If a memory allocation fails, SQLITE_NOMEM is returned. If an error
** occurs while opening the sub-journal file, then an IO error code is
** returned. Otherwise, SQLITE_OK.
*/
static int sqlite3PagerOpenSavepoint( Pager pPager, int nSavepoint )
{
int rc = SQLITE_OK; /* Return code */
int nCurrent = pPager.nSavepoint; /* Current number of savepoints */
Debug.Assert( pPager.eState >= PAGER_WRITER_LOCKED );
Debug.Assert( assert_pager_state( pPager ) );
if ( nSavepoint > nCurrent && pPager.useJournal != 0 )
{
int ii; /* Iterator variable */
PagerSavepoint[] aNew; /* New Pager.aSavepoint array */
/* Grow the Pager.aSavepoint array using realloc(). Return SQLITE_NOMEM
** if the allocation fails. Otherwise, zero the new portion in case a
** malloc failure occurs while populating it in the for(...) loop below.
*/
//aNew = (PagerSavepoint *)sqlite3Realloc(
// pPager.aSavepoint, sizeof(PagerSavepoint)*nSavepoint
//);
Array.Resize( ref pPager.aSavepoint, nSavepoint );
aNew = pPager.aSavepoint;
//if( null==aNew ){
// return SQLITE_NOMEM;
//}
// memset(&aNew[nCurrent], 0, (nSavepoint-nCurrent) * sizeof(PagerSavepoint));
// pPager.aSavepoint = aNew;
/* Populate the PagerSavepoint structures just allocated. */
for ( ii = nCurrent; ii < nSavepoint; ii++ )
{
aNew[ii] = new PagerSavepoint();
aNew[ii].nOrig = pPager.dbSize;
if ( isOpen( pPager.jfd ) && pPager.journalOff > 0 )
{
aNew[ii].iOffset = pPager.journalOff;
}
else
{
aNew[ii].iOffset = (int)JOURNAL_HDR_SZ( pPager );
}
aNew[ii].iSubRec = pPager.nSubRec;
aNew[ii].pInSavepoint = sqlite3BitvecCreate( pPager.dbSize );
if ( null == aNew[ii].pInSavepoint )
{
return SQLITE_NOMEM;
}
if ( pagerUseWal( pPager ) )
{
sqlite3WalSavepoint( pPager.pWal, aNew[ii].aWalData );
}
pPager.nSavepoint = ii + 1;
}
Debug.Assert( pPager.nSavepoint == nSavepoint );
assertTruncateConstraint( pPager );
}
return rc;
}
