/*
* RecordTransactionCommitPrepared
*
* This is basically the same as RecordTransactionCommit: in particular,
* we must set the inCommit flag to avoid a race condition.
*
* We know the transaction made at least one XLOG entry (its PREPARE),
* so it is never possible to optimize out the commit record.
*/
static void
RecordTransactionCommitPrepared(TransactionId xid,
int nchildren,
TransactionId *children,
int nrels,
RelFileNode *rels)
{
XLogRecData rdata[3];
int lastrdata = 0;
xl_xact_commit_prepared xlrec;
XLogRecPtr recptr;
START_CRIT_SECTION();
/* See notes in RecordTransactionCommit */
MyProc->inCommit = true;
/* Emit the XLOG commit record */
xlrec.xid = xid;
xlrec.crec.xact_time = GetCurrentTimestamp();
xlrec.crec.nrels = nrels;
xlrec.crec.nsubxacts = nchildren;
rdata[0].data = (char *) (&xlrec);
rdata[0].len = MinSizeOfXactCommitPrepared;
rdata[0].buffer = InvalidBuffer;
/* dump rels to delete */
if (nrels > 0)
{
rdata[0].next = &(rdata[1]);
rdata[1].data = (char *) rels;
rdata[1].len = nrels * sizeof(RelFileNode);
rdata[1].buffer = InvalidBuffer;
lastrdata = 1;
}
/* dump committed child Xids */
if (nchildren > 0)
{
rdata[lastrdata].next = &(rdata[2]);
rdata[2].data = (char *) children;
rdata[2].len = nchildren * sizeof(TransactionId);
rdata[2].buffer = InvalidBuffer;
lastrdata = 2;
}
rdata[lastrdata].next = NULL;
recptr = XLogInsert(RM_XACT_ID, XLOG_XACT_COMMIT_PREPARED, rdata);
/*
* We don't currently try to sleep before flush here ... nor is there any
* support for async commit of a prepared xact (the very idea is probably
* a contradiction)
*/
/* Flush XLOG to disk */
XLogFlush(recptr);
/* Mark the transaction committed in pg_clog */
TransactionIdCommitTree(xid, nchildren, children);
/* Checkpoint can proceed now */
MyProc->inCommit = false;
END_CRIT_SECTION();
}
/*
* RecordTransactionCommitPrepared
*
* This is basically the same as RecordTransactionCommit: in particular,
* we must take the CheckpointStartLock to avoid a race condition.
*
* We know the transaction made at least one XLOG entry (its PREPARE),
* so it is never possible to optimize out the commit record.
*/
static void
RecordTransactionCommitPrepared(TransactionId xid,
int nchildren,
TransactionId *children,
int nrels,
RelFileNode *rels)
{
XLogRecData rdata[3];
int lastrdata = 0;
xl_xact_commit_prepared xlrec;
XLogRecPtr recptr;
START_CRIT_SECTION();
/* See notes in RecordTransactionCommit */
LWLockAcquire(CheckpointStartLock, LW_SHARED);
/* Emit the XLOG commit record */
xlrec.xid = xid;
xlrec.crec.xtime = time(NULL);
xlrec.crec.nrels = nrels;
xlrec.crec.nsubxacts = nchildren;
rdata[0].data = (char *) (&xlrec);
rdata[0].len = MinSizeOfXactCommitPrepared;
rdata[0].buffer = InvalidBuffer;
/* dump rels to delete */
if (nrels > 0)
{
rdata[0].next = &(rdata[1]);
rdata[1].data = (char *) rels;
rdata[1].len = nrels * sizeof(RelFileNode);
rdata[1].buffer = InvalidBuffer;
lastrdata = 1;
}
/* dump committed child Xids */
if (nchildren > 0)
{
rdata[lastrdata].next = &(rdata[2]);
rdata[2].data = (char *) children;
rdata[2].len = nchildren * sizeof(TransactionId);
rdata[2].buffer = InvalidBuffer;
lastrdata = 2;
}
rdata[lastrdata].next = NULL;
recptr = XLogInsert(RM_XACT_ID,
XLOG_XACT_COMMIT_PREPARED | XLOG_NO_TRAN,
rdata);
/* we don't currently try to sleep before flush here ... */
/* Flush XLOG to disk */
XLogFlush(recptr);
/* Mark the transaction committed in pg_clog */
TransactionIdCommit(xid);
/* to avoid race conditions, the parent must commit first */
TransactionIdCommitTree(nchildren, children);
/* Checkpoint is allowed again */
LWLockRelease(CheckpointStartLock);
END_CRIT_SECTION();
}