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Fix a couple of snapshot management bugs in the new ResourceOwner world:

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non-writable large objects need to have their snapshots registered on the
transaction resowner, not the current portal's, because it must persist until
the large object is closed (which the portal does not).  Also, ensure that the
serializable snapshot is recorded by the transaction resource owner too, even
when a subtransaction has changed the current resource owner before
serializable is taken.

Per bug reports from Pavan Deolasee.
This commit is contained in:
Alvaro Herrera
2008-12-04 14:51:02 +00:00
parent 30c52532d2
commit 7b640b0345
7 changed files with 101 additions and 19 deletions
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68
src/backend/utils/time/snapmgr.c
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@ -19,7 +19,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/time/snapmgr.c,v 1.7 2008/11/25 20:28:29 alvherre Exp $
* $PostgreSQL: pgsql/src/backend/utils/time/snapmgr.c,v 1.8 2008/12/04 14:51:02 alvherre Exp $
*
*-------------------------------------------------------------------------
*/
@ -136,7 +136,8 @@ GetTransactionSnapshot(void)
*/
if (IsXactIsoLevelSerializable)
{
CurrentSnapshot = RegisterSnapshot(CurrentSnapshot);
CurrentSnapshot = RegisterSnapshotOnOwner(CurrentSnapshot,
TopTransactionResourceOwner);
registered_serializable = true;
}
@ -345,14 +346,27 @@ ActiveSnapshotSet(void)
/*
* RegisterSnapshot
* Register a snapshot as being in use
* Register a snapshot as being in use by the current resource owner
*
* If InvalidSnapshot is passed, it is not registered.
*/
Snapshot
RegisterSnapshot(Snapshot snapshot)
{
Snapshot snap;
if (snapshot == InvalidSnapshot)
return InvalidSnapshot;
return RegisterSnapshotOnOwner(snapshot, CurrentResourceOwner);
}
/*
* RegisterSnapshotOnOwner
* As above, but use the specified resource owner
*/
Snapshot
RegisterSnapshotOnOwner(Snapshot snapshot, ResourceOwner owner)
{
Snapshot snap;
if (snapshot == InvalidSnapshot)
return InvalidSnapshot;
@ -361,9 +375,9 @@ RegisterSnapshot(Snapshot snapshot)
snap = snapshot->copied ? snapshot : CopySnapshot(snapshot);
/* and tell resowner.c about it */
ResourceOwnerEnlargeSnapshots(CurrentResourceOwner);
ResourceOwnerEnlargeSnapshots(owner);
snap->regd_count++;
ResourceOwnerRememberSnapshot(CurrentResourceOwner, snap);
ResourceOwnerRememberSnapshot(owner, snap);
RegisteredSnapshots++;
@ -379,6 +393,19 @@ RegisterSnapshot(Snapshot snapshot)
*/
void
UnregisterSnapshot(Snapshot snapshot)
{
if (snapshot == NULL)
return;
UnregisterSnapshotFromOwner(snapshot, CurrentResourceOwner);
}
/*
* UnregisterSnapshotFromOwner
* As above, but use the specified resource owner
*/
void
UnregisterSnapshotFromOwner(Snapshot snapshot, ResourceOwner owner)
{
if (snapshot == NULL)
return;
@ -386,7 +413,7 @@ UnregisterSnapshot(Snapshot snapshot)
Assert(snapshot->regd_count > 0);
Assert(RegisteredSnapshots > 0);
ResourceOwnerForgetSnapshot(CurrentResourceOwner, snapshot);
ResourceOwnerForgetSnapshot(owner, snapshot);
RegisteredSnapshots--;
if (--snapshot->regd_count == 0 && snapshot->active_count == 0)
{
@ -463,6 +490,26 @@ AtSubAbort_Snapshot(int level)
SnapshotResetXmin();
}
/*
* AtEarlyCommit_Snapshot
*
* Snapshot manager's cleanup function, to be called on commit, before
* doing resowner.c resource release.
*/
void
AtEarlyCommit_Snapshot(void)
{
/*
* On a serializable transaction we must unregister our private refcount to
* the serializable snapshot.
*/
if (registered_serializable)
UnregisterSnapshotFromOwner(CurrentSnapshot,
TopTransactionResourceOwner);
registered_serializable = false;
}
/*
* AtEOXact_Snapshot
* Snapshot manager's cleanup function for end of transaction
@ -475,13 +522,6 @@ AtEOXact_Snapshot(bool isCommit)
{
ActiveSnapshotElt *active;
/*
* On a serializable snapshot we must first unregister our private
* refcount to the serializable snapshot.
*/
if (registered_serializable)
UnregisterSnapshot(CurrentSnapshot);
if (RegisteredSnapshots != 0)
elog(WARNING, "%d registered snapshots seem to remain after cleanup",
RegisteredSnapshots);