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Fix a number of places where brittle data structures or overly strong

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Asserts would lead to a server core dump if an error occurred while
trying to abort a failed subtransaction (thereby leading to re-execution
of whatever parts of AbortSubTransaction had already run).  This of course
does not prevent such an error from creating an infinite loop, but at
least we don't make the situation worse.  Responds to an open item on
the subtransactions to-do list.
This commit is contained in:
Tom Lane
2004-09-06 23:33:48 +00:00
parent d55588ea7a
commit 083258e535
4 changed files with 102 additions and 54 deletions
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22
src/backend/commands/async.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/async.c,v 1.115 2004/08/29 05:06:41 momjian Exp $
* $PostgreSQL: pgsql/src/backend/commands/async.c,v 1.116 2004/09/06 23:32:54 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -630,6 +630,9 @@ AtSubStart_Notify(void)
upperPendingNotifies = lcons(pendingNotifies, upperPendingNotifies);
Assert(list_length(upperPendingNotifies) ==
GetCurrentTransactionNestLevel() - 1);
pendingNotifies = NIL;
MemoryContextSwitchTo(old_cxt);
@ -648,6 +651,9 @@ AtSubCommit_Notify(void)
parentPendingNotifies = (List *) linitial(upperPendingNotifies);
upperPendingNotifies = list_delete_first(upperPendingNotifies);
Assert(list_length(upperPendingNotifies) ==
GetCurrentTransactionNestLevel() - 2);
/*
* We could try to eliminate duplicates here, but it seems not
* worthwhile.
@ -661,13 +667,23 @@ AtSubCommit_Notify(void)
void
AtSubAbort_Notify(void)
{
int my_level = GetCurrentTransactionNestLevel();
/*
* All we have to do is pop the stack --- the notifies made in this
* subxact are no longer interesting, and the space will be freed when
* CurTransactionContext is recycled.
*
* This routine could be called more than once at a given nesting level
* if there is trouble during subxact abort. Avoid dumping core by
* using GetCurrentTransactionNestLevel as the indicator of how far
* we need to prune the list.
*/
pendingNotifies = (List *) linitial(upperPendingNotifies);
upperPendingNotifies = list_delete_first(upperPendingNotifies);
while (list_length(upperPendingNotifies) > my_level - 2)
{
pendingNotifies = (List *) linitial(upperPendingNotifies);
upperPendingNotifies = list_delete_first(upperPendingNotifies);
}
}
/*