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Fix bogus coding in ExecAppendAsyncEventWait().

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No configured-by-FDW events would result in "return" directly out of a
PG_TRY block, making the exception stack dangling.  Repair.

Oversight in commit 501cfd07d; back-patch to v14, like that commit, but
as we do not have this issue in HEAD (cf. commit 50c67c201), no need to
apply this patch to it.

In passing, improve a comment about the handling of in-process requests
in a postgres_fdw.c function called from this function.

Alexander Pyhalov, with comment adjustment/improvement by me.

Discussion: https://postgr.es/m/425fa29a429b21b0332737c42a4fdc70%40postgrespro.ru
This commit is contained in:
Etsuro Fujita 2024-04-04 17:25:00 +09:00
parent bafad43c37
commit f6f61a4bd9
2 changed files with 25 additions and 24 deletions
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18
contrib/postgres_fdw/postgres_fdw.c
View File

@ -7174,14 +7174,16 @@ postgresForeignAsyncConfigureWait(AsyncRequest *areq)
{
/*
* This is the case when the in-process request was made by another
* Append. Note that it might be useless to process the request,
* because the query might not need tuples from that Append anymore.
* If there are any child subplans of the same parent that are ready
* for new requests, skip the given request. Likewise, if there are
* any configured events other than the postmaster death event, skip
* it. Otherwise, process the in-process request, then begin a fetch
* to configure the event below, because we might otherwise end up
* with no configured events other than the postmaster death event.
* Append. Note that it might be useless to process the request made
* by that Append, because the query might not need tuples from that
* Append anymore; so we avoid processing it to begin a fetch for the
* given request if possible. If there are any child subplans of the
* same parent that are ready for new requests, skip the given
* request. Likewise, if there are any configured events other than
* the postmaster death event, skip it. Otherwise, process the
* in-process request, then begin a fetch to configure the event
* below, because we might otherwise end up with no configured events
* other than the postmaster death event.
*/
if (!bms_is_empty(requestor->as_needrequest))
return;

31
src/backend/executor/nodeAppend.c
View File

@ -1043,26 +1043,25 @@ ExecAppendAsyncEventWait(AppendState *node)
}
/*
* No need for further processing if there are no configured events
* other than the postmaster death event.
* If there are no configured events other than the postmaster death
* event, we don't need to wait or poll.
*/
if (GetNumRegisteredWaitEvents(node->as_eventset) == 1)
noccurred = 0;
else
{
FreeWaitEventSet(node->as_eventset);
node->as_eventset = NULL;
return;
/* Return at most EVENT_BUFFER_SIZE events in one call. */
if (nevents > EVENT_BUFFER_SIZE)
nevents = EVENT_BUFFER_SIZE;
/*
* If the timeout is -1, wait until at least one event occurs. If
* the timeout is 0, poll for events, but do not wait at all.
*/
noccurred = WaitEventSetWait(node->as_eventset, timeout,
occurred_event, nevents,
WAIT_EVENT_APPEND_READY);
}
/* Return at most EVENT_BUFFER_SIZE events in one call. */
if (nevents > EVENT_BUFFER_SIZE)
nevents = EVENT_BUFFER_SIZE;
/*
* If the timeout is -1, wait until at least one event occurs. If the
* timeout is 0, poll for events, but do not wait at all.
*/
noccurred = WaitEventSetWait(node->as_eventset, timeout, occurred_event,
nevents, WAIT_EVENT_APPEND_READY);
}
PG_FINALLY();
{