Handle impending sinval queue overflow by means of a separate signal
(SIGUSR1, which we have not been using recently) instead of piggybacking on SIGUSR2-driven NOTIFY processing. This has several good results: the processing needed to drain the sinval queue is a lot less than the processing needed to answer a NOTIFY; there's less contention since we don't have a bunch of backends all trying to acquire exclusive lock on pg_listener; backends that are sitting inside a transaction block can still drain the queue, whereas NOTIFY processing can't run if there's an open transaction block. (This last is a fairly serious issue that I don't think we ever recognized before --- with clients like JDBC that tend to sit with open transaction blocks, the sinval queue draining mechanism never really worked as intended, probably resulting in a lot of useless cache-reset overhead.) This is the last of several proposed changes in response to Philip Warner's recent report of sinval-induced performance problems.
This commit is contained in:
Tom Lane
parent
4d86ae4260
commit
ebfc56d3fb
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/commands/async.c,v 1.110 2004/05/22 21:58:24 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/commands/async.c,v 1.111 2004/05/23 03:50:45 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -86,6 +86,7 @@
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#include "libpq/pqformat.h"
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#include "miscadmin.h"
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#include "storage/ipc.h"
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#include "storage/sinval.h"
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#include "tcop/tcopprot.h"
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#include "utils/fmgroids.h"
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#include "utils/ps_status.h"
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@ -607,7 +608,7 @@ AtAbort_Notify(void)
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/*
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*--------------------------------------------------------------
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* Async_NotifyHandler
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* NotifyInterruptHandler
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*
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* This is the signal handler for SIGUSR2.
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*
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@ -623,7 +624,7 @@ AtAbort_Notify(void)
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*--------------------------------------------------------------
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*/
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void
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Async_NotifyHandler(SIGNAL_ARGS)
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NotifyInterruptHandler(SIGNAL_ARGS)
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{
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int save_errno = errno;
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@ -669,12 +670,12 @@ Async_NotifyHandler(SIGNAL_ARGS)
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{
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/* Here, it is finally safe to do stuff. */
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if (Trace_notify)
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elog(DEBUG1, "Async_NotifyHandler: perform async notify");
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elog(DEBUG1, "NotifyInterruptHandler: perform async notify");
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ProcessIncomingNotify();
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if (Trace_notify)
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elog(DEBUG1, "Async_NotifyHandler: done");
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elog(DEBUG1, "NotifyInterruptHandler: done");
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}
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}
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@ -766,12 +767,20 @@ EnableNotifyInterrupt(void)
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* This is called by the PostgresMain main loop just after receiving
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* a frontend command. Signal handler execution of inbound notifies
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* is disabled until the next EnableNotifyInterrupt call.
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*
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* The SIGUSR1 signal handler also needs to call this, so as to
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* prevent conflicts if one signal interrupts the other. So we
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* must return the previous state of the flag.
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* --------------------------------------------------------------
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*/
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void
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bool
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DisableNotifyInterrupt(void)
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{
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bool result = (notifyInterruptEnabled != 0);
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notifyInterruptEnabled = 0;
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return result;
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}
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/*
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@ -785,10 +794,6 @@ DisableNotifyInterrupt(void)
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* and clear the notification field in pg_listener until next time.
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*
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* NOTE: since we are outside any transaction, we must create our own.
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*
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* Results:
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* XXX
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*
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* --------------------------------------------------------------
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*/
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static void
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@ -803,11 +808,15 @@ ProcessIncomingNotify(void)
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Datum value[Natts_pg_listener];
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char repl[Natts_pg_listener],
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nulls[Natts_pg_listener];
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bool catchup_enabled;
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/* Must prevent SIGUSR1 interrupt while I am running */
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catchup_enabled = DisableCatchupInterrupt();
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if (Trace_notify)
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elog(DEBUG1, "ProcessIncomingNotify");
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set_ps_display("async_notify");
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set_ps_display("notify interrupt");
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notifyInterruptOccurred = 0;
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@ -883,6 +892,9 @@ ProcessIncomingNotify(void)
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if (Trace_notify)
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elog(DEBUG1, "ProcessIncomingNotify: done");
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if (catchup_enabled)
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EnableCatchupInterrupt();
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}
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/*
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@ -37,7 +37,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.393 2004/05/21 05:07:57 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.394 2004/05/23 03:50:45 tgl Exp $
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*
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* NOTES
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*
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@ -2861,11 +2861,11 @@ sigusr1_handler(SIGNAL_ARGS)
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if (CheckPostmasterSignal(PMSIGNAL_WAKEN_CHILDREN))
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{
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/*
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* Send SIGUSR2 to all children (triggers AsyncNotifyHandler). See
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* storage/ipc/sinvaladt.c for the use of this.
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* Send SIGUSR1 to all children (triggers CatchupInterruptHandler).
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* See storage/ipc/sinval[adt].c for the use of this.
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*/
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if (Shutdown == NoShutdown)
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SignalChildren(SIGUSR2);
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SignalChildren(SIGUSR1);
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}
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PG_SETMASK(&UnBlockSig);
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@ -8,20 +8,46 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/storage/ipc/sinval.c,v 1.62 2003/11/29 19:51:56 pgsql Exp $
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* $PostgreSQL: pgsql/src/backend/storage/ipc/sinval.c,v 1.63 2004/05/23 03:50:45 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include <signal.h>
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#include "commands/async.h"
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#include "storage/ipc.h"
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#include "storage/proc.h"
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#include "storage/sinval.h"
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#include "storage/sinvaladt.h"
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#include "utils/inval.h"
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#include "utils/tqual.h"
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#include "miscadmin.h"
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/*
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* Because backends sitting idle will not be reading sinval events, we
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* need a way to give an idle backend a swift kick in the rear and make
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* it catch up before the sinval queue overflows and forces everyone
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* through a cache reset exercise. This is done by broadcasting SIGUSR1
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* to all backends when the queue is threatening to become full.
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*
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* State for catchup events consists of two flags: one saying whether
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* the signal handler is currently allowed to call ProcessCatchupEvent
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* directly, and one saying whether the signal has occurred but the handler
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* was not allowed to call ProcessCatchupEvent at the time.
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*
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* NB: the "volatile" on these declarations is critical! If your compiler
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* does not grok "volatile", you'd be best advised to compile this file
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* with all optimization turned off.
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*/
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static volatile int catchupInterruptEnabled = 0;
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static volatile int catchupInterruptOccurred = 0;
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static void ProcessCatchupEvent(void);
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/****************************************************************************/
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/* CreateSharedInvalidationState() Initialize SI buffer */
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/* */
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@ -91,6 +117,12 @@ ReceiveSharedInvalidMessages(
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for (;;)
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{
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/*
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* We can discard any pending catchup event, since we will not exit
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* this loop until we're fully caught up.
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*/
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catchupInterruptOccurred = 0;
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/*
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* We can run SIGetDataEntry in parallel with other backends
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* running SIGetDataEntry for themselves, since each instance will
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@ -137,6 +169,203 @@ ReceiveSharedInvalidMessages(
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}
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/*
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* CatchupInterruptHandler
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*
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* This is the signal handler for SIGUSR1.
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*
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* If we are idle (catchupInterruptEnabled is set), we can safely
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* invoke ProcessCatchupEvent directly. Otherwise, just set a flag
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* to do it later. (Note that it's quite possible for normal processing
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* of the current transaction to cause ReceiveSharedInvalidMessages()
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* to be run later on; in that case the flag will get cleared again,
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* since there's no longer any reason to do anything.)
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*/
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void
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CatchupInterruptHandler(SIGNAL_ARGS)
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{
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int save_errno = errno;
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/*
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* Note: this is a SIGNAL HANDLER. You must be very wary what you do
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* here.
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*/
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/* Don't joggle the elbow of proc_exit */
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if (proc_exit_inprogress)
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return;
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if (catchupInterruptEnabled)
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{
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bool save_ImmediateInterruptOK = ImmediateInterruptOK;
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/*
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* We may be called while ImmediateInterruptOK is true; turn it
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* off while messing with the catchup state. (We would have to
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* save and restore it anyway, because PGSemaphore operations
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* inside ProcessCatchupEvent() might reset it.)
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*/
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ImmediateInterruptOK = false;
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/*
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* I'm not sure whether some flavors of Unix might allow another
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* SIGUSR1 occurrence to recursively interrupt this routine. To
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* cope with the possibility, we do the same sort of dance that
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* EnableCatchupInterrupt must do --- see that routine for
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* comments.
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*/
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catchupInterruptEnabled = 0; /* disable any recursive signal */
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catchupInterruptOccurred = 1; /* do at least one iteration */
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for (;;)
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{
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catchupInterruptEnabled = 1;
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if (!catchupInterruptOccurred)
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break;
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catchupInterruptEnabled = 0;
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if (catchupInterruptOccurred)
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{
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/* Here, it is finally safe to do stuff. */
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ProcessCatchupEvent();
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}
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}
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/*
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* Restore ImmediateInterruptOK, and check for interrupts if
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* needed.
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*/
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ImmediateInterruptOK = save_ImmediateInterruptOK;
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if (save_ImmediateInterruptOK)
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CHECK_FOR_INTERRUPTS();
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}
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else
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{
|
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/*
|
||||
* In this path it is NOT SAFE to do much of anything, except
|
||||
* this:
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*/
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||||
catchupInterruptOccurred = 1;
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}
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errno = save_errno;
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||||
}
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||||
/*
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||||
* EnableCatchupInterrupt
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*
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||||
* This is called by the PostgresMain main loop just before waiting
|
||||
* for a frontend command. We process any pending catchup events,
|
||||
* and enable the signal handler to process future events directly.
|
||||
*
|
||||
* NOTE: the signal handler starts out disabled, and stays so until
|
||||
* PostgresMain calls this the first time.
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||||
*/
|
||||
void
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||||
EnableCatchupInterrupt(void)
|
||||
{
|
||||
/*
|
||||
* This code is tricky because we are communicating with a signal
|
||||
* handler that could interrupt us at any point. If we just checked
|
||||
* catchupInterruptOccurred and then set catchupInterruptEnabled, we
|
||||
* could fail to respond promptly to a signal that happens in between
|
||||
* those two steps. (A very small time window, perhaps, but Murphy's
|
||||
* Law says you can hit it...) Instead, we first set the enable flag,
|
||||
* then test the occurred flag. If we see an unserviced interrupt has
|
||||
* occurred, we re-clear the enable flag before going off to do the
|
||||
* service work. (That prevents re-entrant invocation of
|
||||
* ProcessCatchupEvent() if another interrupt occurs.) If an
|
||||
* interrupt comes in between the setting and clearing of
|
||||
* catchupInterruptEnabled, then it will have done the service work and
|
||||
* left catchupInterruptOccurred zero, so we have to check again after
|
||||
* clearing enable. The whole thing has to be in a loop in case
|
||||
* another interrupt occurs while we're servicing the first. Once we
|
||||
* get out of the loop, enable is set and we know there is no
|
||||
* unserviced interrupt.
|
||||
*
|
||||
* NB: an overenthusiastic optimizing compiler could easily break this
|
||||
* code. Hopefully, they all understand what "volatile" means these
|
||||
* days.
|
||||
*/
|
||||
for (;;)
|
||||
{
|
||||
catchupInterruptEnabled = 1;
|
||||
if (!catchupInterruptOccurred)
|
||||
break;
|
||||
catchupInterruptEnabled = 0;
|
||||
if (catchupInterruptOccurred)
|
||||
{
|
||||
ProcessCatchupEvent();
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* DisableCatchupInterrupt
|
||||
*
|
||||
* This is called by the PostgresMain main loop just after receiving
|
||||
* a frontend command. Signal handler execution of catchup events
|
||||
* is disabled until the next EnableCatchupInterrupt call.
|
||||
*
|
||||
* The SIGUSR2 signal handler also needs to call this, so as to
|
||||
* prevent conflicts if one signal interrupts the other. So we
|
||||
* must return the previous state of the flag.
|
||||
*/
|
||||
bool
|
||||
DisableCatchupInterrupt(void)
|
||||
{
|
||||
bool result = (catchupInterruptEnabled != 0);
|
||||
|
||||
catchupInterruptEnabled = 0;
|
||||
|
||||
return result;
|
||||
}
|
||||
|
||||
/*
|
||||
* ProcessCatchupEvent
|
||||
*
|
||||
* Respond to a catchup event (SIGUSR1) from another backend.
|
||||
*
|
||||
* This is called either directly from the SIGUSR1 signal handler,
|
||||
* or the next time control reaches the outer idle loop (assuming
|
||||
* there's still anything to do by then).
|
||||
*/
|
||||
static void
|
||||
ProcessCatchupEvent(void)
|
||||
{
|
||||
bool notify_enabled;
|
||||
|
||||
/* Must prevent SIGUSR2 interrupt while I am running */
|
||||
notify_enabled = DisableNotifyInterrupt();
|
||||
|
||||
/*
|
||||
* What we need to do here is cause ReceiveSharedInvalidMessages()
|
||||
* to run, which will do the necessary work and also reset the
|
||||
* catchupInterruptOccurred flag. If we are inside a transaction
|
||||
* we can just call AcceptInvalidationMessages() to do this. If we
|
||||
* aren't, we start and immediately end a transaction; the call to
|
||||
* AcceptInvalidationMessages() happens down inside transaction start.
|
||||
*
|
||||
* It is awfully tempting to just call AcceptInvalidationMessages()
|
||||
* without the rest of the xact start/stop overhead, and I think that
|
||||
* would actually work in the normal case; but I am not sure that things
|
||||
* would clean up nicely if we got an error partway through.
|
||||
*/
|
||||
if (IsTransactionOrTransactionBlock())
|
||||
{
|
||||
elog(DEBUG4, "ProcessCatchupEvent inside transaction");
|
||||
AcceptInvalidationMessages();
|
||||
}
|
||||
else
|
||||
{
|
||||
elog(DEBUG4, "ProcessCatchupEvent outside transaction");
|
||||
StartTransactionCommand();
|
||||
CommitTransactionCommand();
|
||||
}
|
||||
|
||||
if (notify_enabled)
|
||||
EnableNotifyInterrupt();
|
||||
}
|
||||
|
||||
|
||||
/****************************************************************************/
|
||||
/* Functions that need to scan the PGPROC structures of all running backends. */
|
||||
/* It's a bit strange to keep these in sinval.c, since they don't have any */
|
||||
|
|
|
|||
|
|
@ -8,7 +8,7 @@
|
|||
*
|
||||
*
|
||||
* IDENTIFICATION
|
||||
* $PostgreSQL: pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.54 2003/12/20 17:31:21 momjian Exp $
|
||||
* $PostgreSQL: pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.55 2004/05/23 03:50:45 tgl Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
|
|
@ -215,16 +215,12 @@ SIInsertDataEntry(SISeg *segP, SharedInvalidationMessage *data)
|
|||
/*
|
||||
* Try to prevent table overflow. When the table is 70% full send a
|
||||
* WAKEN_CHILDREN request to the postmaster. The postmaster will send
|
||||
* a SIGUSR2 signal (ordinarily a NOTIFY signal) to all the backends.
|
||||
* This will force idle backends to execute a transaction to look
|
||||
* through pg_listener for NOTIFY messages, and as a byproduct of the
|
||||
* transaction start they will read SI entries.
|
||||
* a SIGUSR1 signal to all the backends, which will cause sinval.c
|
||||
* to read any pending SI entries.
|
||||
*
|
||||
* This should never happen if all the backends are actively executing
|
||||
* queries, but if a backend is sitting idle then it won't be starting
|
||||
* transactions and so won't be reading SI entries.
|
||||
*
|
||||
* dz - 27 Jan 1998
|
||||
*/
|
||||
if (numMsgs == (MAXNUMMESSAGES * 70 / 100) &&
|
||||
IsUnderPostmaster)
|
||||
|
|
|
|||
|
|
@ -8,7 +8,7 @@
|
|||
*
|
||||
*
|
||||
* IDENTIFICATION
|
||||
* $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.413 2004/05/21 05:07:58 tgl Exp $
|
||||
* $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.414 2004/05/23 03:50:45 tgl Exp $
|
||||
*
|
||||
* NOTES
|
||||
* this is the "main" module of the postgres backend and
|
||||
|
|
@ -52,6 +52,7 @@
|
|||
#include "storage/ipc.h"
|
||||
#include "storage/pg_shmem.h"
|
||||
#include "storage/proc.h"
|
||||
#include "storage/sinval.h"
|
||||
#include "tcop/fastpath.h"
|
||||
#include "tcop/pquery.h"
|
||||
#include "tcop/tcopprot.h"
|
||||
|
|
@ -1899,6 +1900,7 @@ die(SIGNAL_ARGS)
|
|||
/* until we are done getting ready for it */
|
||||
InterruptHoldoffCount++;
|
||||
DisableNotifyInterrupt();
|
||||
DisableCatchupInterrupt();
|
||||
/* Make sure CheckDeadLock won't run while shutting down... */
|
||||
LockWaitCancel();
|
||||
InterruptHoldoffCount--;
|
||||
|
|
@ -1955,6 +1957,7 @@ StatementCancelHandler(SIGNAL_ARGS)
|
|||
if (LockWaitCancel())
|
||||
{
|
||||
DisableNotifyInterrupt();
|
||||
DisableCatchupInterrupt();
|
||||
InterruptHoldoffCount--;
|
||||
ProcessInterrupts();
|
||||
}
|
||||
|
|
@ -2006,6 +2009,7 @@ ProcessInterrupts(void)
|
|||
QueryCancelPending = false; /* ProcDie trumps QueryCancel */
|
||||
ImmediateInterruptOK = false; /* not idle anymore */
|
||||
DisableNotifyInterrupt();
|
||||
DisableCatchupInterrupt();
|
||||
ereport(FATAL,
|
||||
(errcode(ERRCODE_ADMIN_SHUTDOWN),
|
||||
errmsg("terminating connection due to administrator command")));
|
||||
|
|
@ -2015,6 +2019,7 @@ ProcessInterrupts(void)
|
|||
QueryCancelPending = false;
|
||||
ImmediateInterruptOK = false; /* not idle anymore */
|
||||
DisableNotifyInterrupt();
|
||||
DisableCatchupInterrupt();
|
||||
ereport(ERROR,
|
||||
(errcode(ERRCODE_QUERY_CANCELED),
|
||||
errmsg("canceling query due to user request")));
|
||||
|
|
@ -2595,9 +2600,8 @@ PostgresMain(int argc, char *argv[], const char *username)
|
|||
* midst of output during who-knows-what operation...
|
||||
*/
|
||||
pqsignal(SIGPIPE, SIG_IGN);
|
||||
pqsignal(SIGUSR1, SIG_IGN); /* this signal available for use */
|
||||
|
||||
pqsignal(SIGUSR2, Async_NotifyHandler); /* flush also sinval cache */
|
||||
pqsignal(SIGUSR1, CatchupInterruptHandler);
|
||||
pqsignal(SIGUSR2, NotifyInterruptHandler);
|
||||
pqsignal(SIGFPE, FloatExceptionHandler);
|
||||
|
||||
/*
|
||||
|
|
@ -2761,6 +2765,7 @@ PostgresMain(int argc, char *argv[], const char *username)
|
|||
disable_sig_alarm(true);
|
||||
QueryCancelPending = false; /* again in case timeout occurred */
|
||||
DisableNotifyInterrupt();
|
||||
DisableCatchupInterrupt();
|
||||
debug_query_string = NULL;
|
||||
|
||||
/*
|
||||
|
|
@ -2879,6 +2884,7 @@ PostgresMain(int argc, char *argv[], const char *username)
|
|||
* signal */
|
||||
|
||||
EnableNotifyInterrupt();
|
||||
EnableCatchupInterrupt();
|
||||
|
||||
/* Allow "die" interrupt to be processed while waiting */
|
||||
ImmediateInterruptOK = true;
|
||||
|
|
@ -2901,6 +2907,7 @@ PostgresMain(int argc, char *argv[], const char *username)
|
|||
QueryCancelPending = false; /* forget any CANCEL signal */
|
||||
|
||||
DisableNotifyInterrupt();
|
||||
DisableCatchupInterrupt();
|
||||
|
||||
/*
|
||||
* (5) check for any other interesting events that happened while
|
||||
|
|
|
|||
|
|
@ -6,7 +6,7 @@
|
|||
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* $PostgreSQL: pgsql/src/include/commands/async.h,v 1.23 2003/11/29 22:40:59 pgsql Exp $
|
||||
* $PostgreSQL: pgsql/src/include/commands/async.h,v 1.24 2004/05/23 03:50:45 tgl Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
|
|
@ -25,15 +25,14 @@ extern void AtCommit_Notify(void);
|
|||
extern void AtAbort_Notify(void);
|
||||
|
||||
/* signal handler for inbound notifies (SIGUSR2) */
|
||||
extern void Async_NotifyHandler(SIGNAL_ARGS);
|
||||
extern void NotifyInterruptHandler(SIGNAL_ARGS);
|
||||
|
||||
/*
|
||||
* enable/disable processing of inbound notifies directly from signal handler.
|
||||
* The enable routine first performs processing of any inbound notifies that
|
||||
* have occurred since the last disable. These are meant to be called ONLY
|
||||
* from the appropriate places in PostgresMain().
|
||||
* have occurred since the last disable.
|
||||
*/
|
||||
extern void EnableNotifyInterrupt(void);
|
||||
extern void DisableNotifyInterrupt(void);
|
||||
extern bool DisableNotifyInterrupt(void);
|
||||
|
||||
#endif /* ASYNC_H */
|
||||
|
|
|
|||
|
|
@ -7,7 +7,7 @@
|
|||
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* $PostgreSQL: pgsql/src/include/storage/pmsignal.h,v 1.6 2003/11/29 22:41:13 pgsql Exp $
|
||||
* $PostgreSQL: pgsql/src/include/storage/pmsignal.h,v 1.7 2004/05/23 03:50:45 tgl Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
|
|
@ -24,7 +24,7 @@ typedef enum
|
|||
{
|
||||
PMSIGNAL_DO_CHECKPOINT, /* request to start a checkpoint */
|
||||
PMSIGNAL_PASSWORD_CHANGE, /* pg_pwd file has changed */
|
||||
PMSIGNAL_WAKEN_CHILDREN, /* send a NOTIFY signal to all backends */
|
||||
PMSIGNAL_WAKEN_CHILDREN, /* send a SIGUSR1 signal to all backends */
|
||||
|
||||
NUM_PMSIGNALS /* Must be last value of enum! */
|
||||
} PMSignalReason;
|
||||
|
|
|
|||
|
|
@ -7,7 +7,7 @@
|
|||
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* $PostgreSQL: pgsql/src/include/storage/sinval.h,v 1.33 2004/02/10 01:55:26 tgl Exp $
|
||||
* $PostgreSQL: pgsql/src/include/storage/sinval.h,v 1.34 2004/05/23 03:50:45 tgl Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
|
|
@ -99,10 +99,19 @@ extern bool DatabaseHasActiveBackends(Oid databaseId, bool ignoreMyself);
|
|||
extern bool TransactionIdIsInProgress(TransactionId xid);
|
||||
extern TransactionId GetOldestXmin(bool allDbs);
|
||||
extern int CountActiveBackends(void);
|
||||
|
||||
extern int CountEmptyBackendSlots(void);
|
||||
/* Use "struct PGPROC", not PGPROC, to avoid including proc.h here */
|
||||
extern struct PGPROC *BackendIdGetProc(BackendId procId);
|
||||
|
||||
extern int CountEmptyBackendSlots(void);
|
||||
/* signal handler for catchup events (SIGUSR1) */
|
||||
extern void CatchupInterruptHandler(SIGNAL_ARGS);
|
||||
|
||||
/*
|
||||
* enable/disable processing of catchup events directly from signal handler.
|
||||
* The enable routine first performs processing of any catchup events that
|
||||
* have occurred since the last disable.
|
||||
*/
|
||||
extern void EnableCatchupInterrupt(void);
|
||||
extern bool DisableCatchupInterrupt(void);
|
||||
|
||||
#endif /* SINVAL_H */
|
||||
|
|
|
|||
Loading…
Reference in New Issue