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/*-------------------------------------------------------------------------
*
* interrupt.c
* Interrupt handling routines.
*
* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/postmaster/interrupt.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <unistd.h>
#include "miscadmin.h"
#include "postmaster/interrupt.h"
#include "storage/ipc.h"
#include "storage/latch.h"
#include "storage/procsignal.h"
#include "utils/guc.h"
volatile sig_atomic_t ConfigReloadPending = false;
volatile sig_atomic_t ShutdownRequestPending = false;
/*
* Simple interrupt handler for main loops of background processes.
*/
void
HandleMainLoopInterrupts(void)
{
if (ProcSignalBarrierPending)
ProcessProcSignalBarrier();
if (ConfigReloadPending)
{
ConfigReloadPending = false;
ProcessConfigFile(PGC_SIGHUP);
}
if (ShutdownRequestPending)
proc_exit(0);
}
/*
* Simple signal handler for triggering a configuration reload.
*
* Normally, this handler would be used for SIGHUP. The idea is that code
* which uses it would arrange to check the ConfigReloadPending flag at
* convenient places inside main loops, or else call HandleMainLoopInterrupts.
*/
void
SignalHandlerForConfigReload(SIGNAL_ARGS)
{
int save_errno = errno;
ConfigReloadPending = true;
SetLatch(MyLatch);
errno = save_errno;
}
/*
* Simple signal handler for exiting quickly as if due to a crash.
*
* Normally, this would be used for handling SIGQUIT.
*/
void
SignalHandlerForCrashExit(SIGNAL_ARGS)
{
/*
* We DO NOT want to run proc_exit() or atexit() callbacks -- we're here
* because shared memory may be corrupted, so we don't want to try to
* clean up our transaction. Just nail the windows shut and get out of
* town. The callbacks wouldn't be safe to run from a signal handler,
* anyway.
*
* Note we do _exit(2) not _exit(0). This is to force the postmaster into
* a system reset cycle if someone sends a manual SIGQUIT to a random
* backend. This is necessary precisely because we don't clean up our
* shared memory state. (The "dead man switch" mechanism in pmsignal.c
* should ensure the postmaster sees this as a crash, too, but no harm in
* being doubly sure.)
*/
_exit(2);
}
/*
* Simple signal handler for triggering a long-running background process to
* shut down and exit.
*
* Typically, this handler would be used for SIGTERM, but some processes use
* other signals. In particular, the checkpointer exits on SIGUSR2, the
* stats collector on SIGQUIT, and the WAL writer exits on either SIGINT
* or SIGTERM.
*
* ShutdownRequestPending should be checked at a convenient place within the
* main loop, or else the main loop should call HandleMainLoopInterrupts.
*/
void
SignalHandlerForShutdownRequest(SIGNAL_ARGS)
{
int save_errno = errno;
ShutdownRequestPending = true;
SetLatch(MyLatch);
errno = save_errno;
}
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