PortalRun must guard against the possibility that the portal it's
running contains VACUUM or a similar command that will internally start and commit transactions. In such a case, the original caller values of CurrentMemoryContext and CurrentResourceOwner will point to objects that will be destroyed by the internal commit. We must restore these pointers to point to the newly-manufactured transaction context and resource owner, rather than possibly pointing to deleted memory. Also tweak xact.c so that AbortTransaction and AbortSubTransaction forcibly restore a sane value for CurrentResourceOwner, much as they have always done for CurrentMemoryContext. I'm not certain this is necessary but I'm feeling paranoid today. Responds to Sean Chittenden's bug report of 4-Oct.
This commit is contained in:
Tom Lane
parent
ee7de3d662
commit
4c77cbb272
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@ -10,7 +10,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.190 2004/09/16 20:17:16 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.191 2004/10/04 21:52:14 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -205,6 +205,7 @@ static void AssignSubTransactionId(TransactionState s);
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static void AbortTransaction(void);
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static void AtAbort_Memory(void);
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static void AtCleanup_Memory(void);
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static void AtAbort_ResourceOwner(void);
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static void AtCommit_LocalCache(void);
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static void AtCommit_Memory(void);
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static void AtStart_Cache(void);
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@ -229,6 +230,7 @@ static void PopTransaction(void);
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static void AtSubAbort_Memory(void);
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static void AtSubCleanup_Memory(void);
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static void AtSubAbort_ResourceOwner(void);
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static void AtSubCommit_Memory(void);
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static void AtSubStart_Memory(void);
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static void AtSubStart_ResourceOwner(void);
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@ -1103,7 +1105,6 @@ AtAbort_Memory(void)
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MemoryContextSwitchTo(TopMemoryContext);
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}
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/*
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* AtSubAbort_Memory
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*/
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@ -1115,6 +1116,33 @@ AtSubAbort_Memory(void)
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MemoryContextSwitchTo(TopTransactionContext);
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}
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/*
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* AtAbort_ResourceOwner
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*/
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static void
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AtAbort_ResourceOwner(void)
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{
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/*
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* Make sure we have a valid ResourceOwner, if possible (else it
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* will be NULL, which is OK)
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*/
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CurrentResourceOwner = TopTransactionResourceOwner;
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}
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/*
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* AtSubAbort_ResourceOwner
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*/
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static void
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AtSubAbort_ResourceOwner(void)
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{
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TransactionState s = CurrentTransactionState;
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/* Make sure we have a valid ResourceOwner */
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CurrentResourceOwner = s->curTransactionOwner;
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}
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/*
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* AtSubAbort_childXids
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*/
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@ -1598,8 +1626,9 @@ AbortTransaction(void)
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*/
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s->state = TRANS_ABORT;
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/* Make sure we are in a valid memory context */
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/* Make sure we have a valid memory context and resource owner */
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AtAbort_Memory();
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AtAbort_ResourceOwner();
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/*
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* Reset user id which might have been changed transiently. We cannot
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@ -3338,6 +3367,7 @@ AbortSubTransaction(void)
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* do abort processing
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*/
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AtSubAbort_Memory();
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AtSubAbort_ResourceOwner();
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/*
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* We can skip all this stuff if the subxact failed before creating
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.87 2004/09/13 20:07:05 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.88 2004/10/04 21:52:15 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -491,12 +491,14 @@ PortalRun(Portal portal, long count,
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char *completionTag)
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{
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bool result;
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ResourceOwner saveTopTransactionResourceOwner;
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MemoryContext saveTopTransactionContext;
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Portal saveActivePortal;
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Snapshot saveActiveSnapshot;
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ResourceOwner saveResourceOwner;
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MemoryContext savePortalContext;
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MemoryContext saveQueryContext;
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MemoryContext oldContext;
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MemoryContext saveMemoryContext;
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AssertArg(PortalIsValid(portal));
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@ -523,12 +525,26 @@ PortalRun(Portal portal, long count,
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/*
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* Set up global portal context pointers.
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*
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* We have to play a special game here to support utility commands like
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* VACUUM and CLUSTER, which internally start and commit transactions.
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* When we are called to execute such a command, CurrentResourceOwner
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* will be pointing to the TopTransactionResourceOwner --- which will
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* be destroyed and replaced in the course of the internal commit and
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* restart. So we need to be prepared to restore it as pointing to
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* the exit-time TopTransactionResourceOwner. (Ain't that ugly? This
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* idea of internally starting whole new transactions is not good.)
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* CurrentMemoryContext has a similar problem, but the other pointers
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* we save here will be NULL or pointing to longer-lived objects.
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*/
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saveTopTransactionResourceOwner = TopTransactionResourceOwner;
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saveTopTransactionContext = TopTransactionContext;
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saveActivePortal = ActivePortal;
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saveActiveSnapshot = ActiveSnapshot;
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saveResourceOwner = CurrentResourceOwner;
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savePortalContext = PortalContext;
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saveQueryContext = QueryContext;
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saveMemoryContext = CurrentMemoryContext;
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PG_TRY();
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{
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ActivePortal = portal;
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@ -537,7 +553,7 @@ PortalRun(Portal portal, long count,
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PortalContext = PortalGetHeapMemory(portal);
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QueryContext = portal->queryContext;
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oldContext = MemoryContextSwitchTo(PortalContext);
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MemoryContextSwitchTo(PortalContext);
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switch (portal->strategy)
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{
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@ -620,9 +636,16 @@ PortalRun(Portal portal, long count,
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portal->status = PORTAL_FAILED;
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/* Restore global vars and propagate error */
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if (saveMemoryContext == saveTopTransactionContext)
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MemoryContextSwitchTo(TopTransactionContext);
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else
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MemoryContextSwitchTo(saveMemoryContext);
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ActivePortal = saveActivePortal;
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ActiveSnapshot = saveActiveSnapshot;
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CurrentResourceOwner = saveResourceOwner;
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if (saveResourceOwner == saveTopTransactionResourceOwner)
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CurrentResourceOwner = TopTransactionResourceOwner;
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else
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CurrentResourceOwner = saveResourceOwner;
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PortalContext = savePortalContext;
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QueryContext = saveQueryContext;
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@ -630,11 +653,16 @@ PortalRun(Portal portal, long count,
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}
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PG_END_TRY();
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MemoryContextSwitchTo(oldContext);
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if (saveMemoryContext == saveTopTransactionContext)
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MemoryContextSwitchTo(TopTransactionContext);
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else
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MemoryContextSwitchTo(saveMemoryContext);
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ActivePortal = saveActivePortal;
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ActiveSnapshot = saveActiveSnapshot;
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CurrentResourceOwner = saveResourceOwner;
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if (saveResourceOwner == saveTopTransactionResourceOwner)
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CurrentResourceOwner = TopTransactionResourceOwner;
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else
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CurrentResourceOwner = saveResourceOwner;
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PortalContext = savePortalContext;
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QueryContext = saveQueryContext;
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