*result_xmax = new_xmax;
}
+/*
+ * Subroutine for heap_lock_updated_tuple_rec.
+ *
+ * Given an hypothetical multixact status held by the transaction identified
+ * with the given xid, does the current transaction need to wait, fail, or can
+ * it continue if it wanted to acquire a lock of the given mode? "needwait"
+ * is set to true if waiting is necessary; if it can continue, then
+ * HeapTupleMayBeUpdated is returned. In case of a conflict, a different
+ * HeapTupleSatisfiesUpdate return code is returned.
+ *
+ * The held status is said to be hypothetical because it might correspond to a
+ * lock held by a single Xid, i.e. not a real MultiXactId; we express it this
+ * way for simplicity of API.
+ */
+static HTSU_Result
+test_lockmode_for_conflict(MultiXactStatus status, TransactionId xid,
+ LockTupleMode mode, bool *needwait)
+{
+ MultiXactStatus wantedstatus;
+
+ *needwait = false;
+ wantedstatus = get_mxact_status_for_lock(mode, false);
+
+ /*
+ * Note: we *must* check TransactionIdIsInProgress before
+ * TransactionIdDidAbort/Commit; see comment at top of tqual.c for an
+ * explanation.
+ */
+ if (TransactionIdIsCurrentTransactionId(xid))
+ {
+ /*
+ * Updated by our own transaction? Just return failure. This shouldn't
+ * normally happen.
+ */
+ return HeapTupleSelfUpdated;
+ }
+ else if (TransactionIdIsInProgress(xid))
+ {
+ /*
+ * If the locking transaction is running, what we do depends on whether
+ * the lock modes conflict: if they do, then we must wait for it to
+ * finish; otherwise we can fall through to lock this tuple version
+ * without waiting.
+ */
+ if (DoLockModesConflict(LOCKMODE_from_mxstatus(status),
+ LOCKMODE_from_mxstatus(wantedstatus)))
+ {
+ *needwait = true;
+ }
+
+ /*
+ * If we set needwait above, then this value doesn't matter; otherwise,
+ * this value signals to caller that it's okay to proceed.
+ */
+ return HeapTupleMayBeUpdated;
+ }
+ else if (TransactionIdDidAbort(xid))
+ return HeapTupleMayBeUpdated;
+ else if (TransactionIdDidCommit(xid))
+ {
+ /*
+ * If the updating transaction committed, what we do depends on whether
+ * the lock modes conflict: if they do, then we must report error to
+ * caller. But if they don't, we can fall through to lock it.
+ */
+ if (DoLockModesConflict(LOCKMODE_from_mxstatus(status),
+ LOCKMODE_from_mxstatus(wantedstatus)))
+ /* bummer */
+ return HeapTupleUpdated;
+
+ return HeapTupleMayBeUpdated;
+ }
+
+ /* Not in progress, not aborted, not committed -- must have crashed */
+ return HeapTupleMayBeUpdated;
+}
+
/*
* Recursive part of heap_lock_updated_tuple
Buffer buf;
uint16 new_infomask,
new_infomask2,
- old_infomask;
+ old_infomask,
+ old_infomask2;
TransactionId xmax,
new_xmax;
TransactionId priorXmax = InvalidTransactionId;
}
old_infomask = mytup.t_data->t_infomask;
+ old_infomask2 = mytup.t_data->t_infomask2;
xmax = HeapTupleHeaderGetRawXmax(mytup.t_data);
/*
- * If this tuple is updated and the key has been modified (or
- * deleted), what we do depends on the status of the updating
- * transaction: if it's live, we sleep until it finishes; if it has
- * committed, we have to fail (i.e. return HeapTupleUpdated); if it
- * aborted, we ignore it. For updates that didn't touch the key, we
- * can just plough ahead.
+ * If this tuple version has been updated or locked by some concurrent
+ * transaction(s), what we do depends on whether our lock mode
+ * conflicts with what those other transactions hold, and also on the
+ * status of them.
*/
- if (!(old_infomask & HEAP_XMAX_INVALID) &&
- (mytup.t_data->t_infomask2 & HEAP_KEYS_UPDATED))
+ if (!(old_infomask & HEAP_XMAX_INVALID))
{
- TransactionId update_xid;
+ TransactionId rawxmax;
+ bool needwait;
- /*
- * Note: we *must* check TransactionIdIsInProgress before
- * TransactionIdDidAbort/Commit; see comment at top of tqual.c for
- * an explanation.
- */
- update_xid = HeapTupleHeaderGetUpdateXid(mytup.t_data);
- if (TransactionIdIsCurrentTransactionId(update_xid))
+ rawxmax = HeapTupleHeaderGetRawXmax(mytup.t_data);
+ if (old_infomask & HEAP_XMAX_IS_MULTI)
{
- UnlockReleaseBuffer(buf);
- return HeapTupleSelfUpdated;
- }
- else if (TransactionIdIsInProgress(update_xid))
- {
- LockBuffer(buf, BUFFER_LOCK_UNLOCK);
- /* No LockTupleTuplock here -- see heap_lock_updated_tuple */
- XactLockTableWait(update_xid);
- goto l4;
+ int nmembers;
+ int i;
+ MultiXactMember *members;
+
+ nmembers = GetMultiXactIdMembers(rawxmax, &members, false);
+ for (i = 0; i < nmembers; i++)
+ {
+ HTSU_Result res;
+
+ res = test_lockmode_for_conflict(members[i].status,
+ members[i].xid,
+ mode, &needwait);
+
+ if (needwait)
+ {
+ LockBuffer(buf, BUFFER_LOCK_UNLOCK);
+ XactLockTableWait(members[i].xid);
+ pfree(members);
+ goto l4;
+ }
+ if (res != HeapTupleMayBeUpdated)
+ {
+ UnlockReleaseBuffer(buf);
+ pfree(members);
+ return res;
+ }
+ }
+ if (members)
+ pfree(members);
}
- else if (TransactionIdDidAbort(update_xid))
- ; /* okay to proceed */
- else if (TransactionIdDidCommit(update_xid))
+ else
{
- UnlockReleaseBuffer(buf);
- return HeapTupleUpdated;
+ HTSU_Result res;
+ MultiXactStatus status;
+
+ /*
+ * For a non-multi Xmax, we first need to compute the
+ * corresponding MultiXactStatus by using the infomask bits.
+ */
+ if (HEAP_XMAX_IS_LOCKED_ONLY(old_infomask))
+ {
+ if (HEAP_XMAX_IS_KEYSHR_LOCKED(old_infomask))
+ status = MultiXactStatusForKeyShare;
+ else if (HEAP_XMAX_IS_SHR_LOCKED(old_infomask))
+ status = MultiXactStatusForShare;
+ else if (HEAP_XMAX_IS_EXCL_LOCKED(old_infomask))
+ {
+ if (old_infomask2 & HEAP_KEYS_UPDATED)
+ status = MultiXactStatusForUpdate;
+ else
+ status = MultiXactStatusForNoKeyUpdate;
+ }
+ else
+ {
+ /*
+ * LOCK_ONLY present alone (a pg_upgraded tuple
+ * marked as share-locked in the old cluster) shouldn't
+ * be seen in the middle of an update chain.
+ */
+ elog(ERROR, "invalid lock status in tuple");
+ }
+ }
+ else
+ {
+ /* it's an update, but which kind? */
+ if (old_infomask2 & HEAP_KEYS_UPDATED)
+ status = MultiXactStatusUpdate;
+ else
+ status = MultiXactStatusNoKeyUpdate;
+ }
+
+ res = test_lockmode_for_conflict(status, rawxmax, mode,
+ &needwait);
+ if (needwait)
+ {
+ LockBuffer(buf, BUFFER_LOCK_UNLOCK);
+ XactLockTableWait(rawxmax);
+ goto l4;
+ }
+ if (res != HeapTupleMayBeUpdated)
+ {
+ UnlockReleaseBuffer(buf);
+ return res;
+ }
}
}
projects / postgresql / commitdiff