Partially deduplicate interrupt handling for background processes.

Where possible, share signal handler code and main loop interrupt
checking. This saves quite a bit of code and should simplify
maintenance, too.

This commit intends not to change the way anything works, even
though that might allow more code to be unified. It does unify
a bunch of individual variables into a ShutdownRequestPending
flag that has is now used by a bunch of different process types,
though.

Patch by me, reviewed by Andres Freund and Daniel Gustafsson.

Discussion: http://postgr.es/m/CA+TgmoZwDk=BguVDVa+qdA6SBKef=PKbaKDQALTC_9qoz1mJqg@mail.gmail.com

1 files changed, 6 insertions, 54 deletions

diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index 9cf91b0d35c..3f35b324c33 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -36,10 +36,7 @@
  */
 #include "postgres.h"
 
-#include <signal.h>
 #include <sys/time.h>
-#include <time.h>
-#include <unistd.h>
 
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
@@ -47,6 +44,7 @@
 #include "miscadmin.h"
 #include "pgstat.h"
 #include "postmaster/bgwriter.h"
+#include "postmaster/interrupt.h"
 #include "replication/syncrep.h"
 #include "storage/bufmgr.h"
 #include "storage/condition_variable.h"
@@ -149,11 +147,6 @@ int			CheckPointWarning = 30;
 double		CheckPointCompletionTarget = 0.5;
 
 /*
- * Flags set by interrupt handlers for later service in the main loop.
- */
-static volatile sig_atomic_t shutdown_requested = false;
-
-/*
  * Private state
  */
 static bool ckpt_active = false;
@@ -176,10 +169,7 @@ static bool CompactCheckpointerRequestQueue(void);
 static void UpdateSharedMemoryConfig(void);
 
 /* Signal handlers */
-
-static void chkpt_quickdie(SIGNAL_ARGS);
 static void ReqCheckpointHandler(SIGNAL_ARGS);
-static void ReqShutdownHandler(SIGNAL_ARGS);
 
 
 /*
@@ -204,14 +194,14 @@ CheckpointerMain(void)
 	 * want to wait for the backends to exit, whereupon the postmaster will
 	 * tell us it's okay to shut down (via SIGUSR2).
 	 */
-	pqsignal(SIGHUP, PostgresSigHupHandler);	/* set flag to read config file */
+	pqsignal(SIGHUP, SignalHandlerForConfigReload);
 	pqsignal(SIGINT, ReqCheckpointHandler); /* request checkpoint */
 	pqsignal(SIGTERM, SIG_IGN); /* ignore SIGTERM */
-	pqsignal(SIGQUIT, chkpt_quickdie);	/* hard crash time */
+	pqsignal(SIGQUIT, SignalHandlerForCrashExit);
 	pqsignal(SIGALRM, SIG_IGN);
 	pqsignal(SIGPIPE, SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
-	pqsignal(SIGUSR2, ReqShutdownHandler);	/* request shutdown */
+	pqsignal(SIGUSR2, SignalHandlerForShutdownRequest);
 
 	/*
 	 * Reset some signals that are accepted by postmaster but not here
@@ -551,7 +541,7 @@ HandleCheckpointerInterrupts(void)
 		 */
 		UpdateSharedMemoryConfig();
 	}
-	if (shutdown_requested)
+	if (ShutdownRequestPending)
 	{
 		/*
 		 * From here on, elog(ERROR) should end with exit(1), not send
@@ -679,7 +669,7 @@ CheckpointWriteDelay(int flags, double progress)
 	 * in which case we just try to catch up as quickly as possible.
 	 */
 	if (!(flags & CHECKPOINT_IMMEDIATE) &&
-		!shutdown_requested &&
+		!ShutdownRequestPending &&
 		!ImmediateCheckpointRequested() &&
 		IsCheckpointOnSchedule(progress))
 	{
@@ -807,32 +797,6 @@ IsCheckpointOnSchedule(double progress)
  * --------------------------------
  */
 
-/*
- * chkpt_quickdie() occurs when signalled SIGQUIT by the postmaster.
- *
- * Some backend has bought the farm,
- * so we need to stop what we're doing and exit.
- */
-static void
-chkpt_quickdie(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);
-}
-
 /* SIGINT: set flag to run a normal checkpoint right away */
 static void
 ReqCheckpointHandler(SIGNAL_ARGS)
@@ -848,18 +812,6 @@ ReqCheckpointHandler(SIGNAL_ARGS)
 	errno = save_errno;
 }
 
-/* SIGUSR2: set flag to run a shutdown checkpoint and exit */
-static void
-ReqShutdownHandler(SIGNAL_ARGS)
-{
-	int			save_errno = errno;
-
-	shutdown_requested = true;
-	SetLatch(MyLatch);
-
-	errno = save_errno;
-}
-
 
 /* --------------------------------
  *		communication with backends