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Fix (some of the) breakage introduced into query-cancel processing by HS.

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It is absolutely not okay to throw an ereport(ERROR) in any random place in
the code just because DoingCommandRead is set; interrupting, say, OpenSSL
in the midst of its activities is guaranteed to result in heartache.

Instead of that, undo the original optimizations that threw away
QueryCancelPending anytime we were starting or finishing a command read, and
instead discard the cancel request within ProcessInterrupts if we find that
there is no HS reason for forcing a cancel and we are DoingCommandRead.

In passing, may I once again condemn the practice of changing the code
and not fixing the adjacent comment that you just turned into a lie?
This commit is contained in:
Tom Lane 2010-01-07 16:29:58 +00:00
parent 6fb791199d
commit 82170c747b
1 changed files with 60 additions and 37 deletions
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55
src/backend/tcop/postgres.c
View file

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.580 2010/01/02 16:57:52 momjian Exp $
* $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.581 2010/01/07 16:29:58 tgl Exp $
*
* NOTES
* this is the "main" module of the postgres backend and
@ -476,11 +476,10 @@ prepare_for_client_read(void)
EnableNotifyInterrupt();
EnableCatchupInterrupt();
/* Allow "die" interrupt to be processed while waiting */
/* Allow cancel/die interrupts to be processed while waiting */
ImmediateInterruptOK = true;
/* And don't forget to detect one that already arrived */
QueryCancelPending = false;
CHECK_FOR_INTERRUPTS();
}
}
@ -494,7 +493,6 @@ client_read_ended(void)
if (DoingCommandRead)
{
ImmediateInterruptOK = false;
QueryCancelPending = false; /* forget any CANCEL signal */
DisableNotifyInterrupt();
DisableCatchupInterrupt();
@ -2640,12 +2638,11 @@ StatementCancelHandler(SIGNAL_ARGS)
QueryCancelPending = true;
/*
* If it's safe to interrupt, and we're waiting for a lock, service
* the interrupt immediately. No point in interrupting if we're
* waiting for input, however.
* If it's safe to interrupt, and we're waiting for input or a lock,
* service the interrupt immediately
*/
if (InterruptHoldoffCount == 0 && CritSectionCount == 0 &&
(DoingCommandRead || ImmediateInterruptOK))
if (ImmediateInterruptOK && InterruptHoldoffCount == 0 &&
CritSectionCount == 0)
{
/* bump holdoff count to make ProcessInterrupts() a no-op */
/* until we are done getting ready for it */
@ -2717,25 +2714,36 @@ ProcessInterrupts(void)
if (QueryCancelPending)
{
QueryCancelPending = false;
if (ClientAuthInProgress)
{
ImmediateInterruptOK = false; /* not idle anymore */
DisableNotifyInterrupt();
DisableCatchupInterrupt();
/* As in quickdie, don't risk sending to client during auth */
if (ClientAuthInProgress && whereToSendOutput == DestRemote)
if (whereToSendOutput == DestRemote)
whereToSendOutput = DestNone;
if (ClientAuthInProgress)
ereport(ERROR,
(errcode(ERRCODE_QUERY_CANCELED),
errmsg("canceling authentication due to timeout")));
else if (cancel_from_timeout)
}
if (cancel_from_timeout)
{
ImmediateInterruptOK = false; /* not idle anymore */
DisableNotifyInterrupt();
DisableCatchupInterrupt();
ereport(ERROR,
(errcode(ERRCODE_QUERY_CANCELED),
errmsg("canceling statement due to statement timeout")));
else if (IsAutoVacuumWorkerProcess())
}
if (IsAutoVacuumWorkerProcess())
{
ImmediateInterruptOK = false; /* not idle anymore */
DisableNotifyInterrupt();
DisableCatchupInterrupt();
ereport(ERROR,
(errcode(ERRCODE_QUERY_CANCELED),
errmsg("canceling autovacuum task")));
else
}
{
int cancelMode = MyProc->recoveryConflictMode;
@ -2756,6 +2764,9 @@ ProcessInterrupts(void)
switch (cancelMode)
{
case CONFLICT_MODE_FATAL:
ImmediateInterruptOK = false; /* not idle anymore */
DisableNotifyInterrupt();
DisableCatchupInterrupt();
Assert(RecoveryInProgress());
ereport(FATAL,
(errcode(ERRCODE_QUERY_CANCELED),
@ -2772,18 +2783,31 @@ ProcessInterrupts(void)
* transaction tree and cancel just enough
* subxacts to remove locks? Doubt it.
*/
ImmediateInterruptOK = false; /* not idle anymore */
DisableNotifyInterrupt();
DisableCatchupInterrupt();
Assert(RecoveryInProgress());
AbortOutOfAnyTransaction();
ereport(ERROR,
(errcode(ERRCODE_QUERY_CANCELED),
errmsg("canceling statement due to conflict with recovery")));
return;
default:
/* No conflict pending, so fall through */
break;
}
}
/*
* If we are reading a command from the client, just ignore the
* cancel request --- sending an extra error message won't
* accomplish anything. Otherwise, go ahead and throw the error.
*/
if (!DoingCommandRead)
{
ImmediateInterruptOK = false; /* not idle anymore */
DisableNotifyInterrupt();
DisableCatchupInterrupt();
ereport(ERROR,
(errcode(ERRCODE_QUERY_CANCELED),
errmsg("canceling statement due to user request")));
@ -3626,7 +3650,6 @@ PostgresMain(int argc, char *argv[], const char *username)
* conditional since we don't want, say, reads on behalf of COPY FROM
* STDIN doing the same thing.)
*/
QueryCancelPending = false; /* forget any earlier CANCEL signal */
DoingCommandRead = true;
/*