Unify SIGHUP handling between normal and walsender backends.

Because walsender and normal backends share the same main loop it's
problematic to have two different flag variables, set in signal
handlers, indicating a pending configuration reload.  Only certain
walsender commands reach code paths checking for the
variable (START_[LOGICAL_]REPLICATION, CREATE_REPLICATION_SLOT
... LOGICAL, notably not base backups).

This is a bug present since the introduction of walsender, but has
gotten worse in releases since then which allow walsender to do more.

A later patch, not slated for v10, will similarly unify SIGHUP
handling in other types of processes as well.

Author: Petr Jelinek, Andres Freund
Reviewed-By: Michael Paquier
Discussion: https://postgr.es/m/20170423235941.qosiuoyqprq4nu7v@alap3.anarazel.de
Backpatch: 9.2-, bug is present since 9.0

1 files changed, 7 insertions, 22 deletions

diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 8cd839bda83..6304e2e46c0 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -174,7 +174,6 @@ static bool streamingDoneReceiving;
 static bool WalSndCaughtUp = false;
 
 /* Flags set by signal handlers for later service in main loop */
-static volatile sig_atomic_t got_SIGHUP = false;
 static volatile sig_atomic_t got_SIGUSR2 = false;
 static volatile sig_atomic_t got_STOPPING = false;
 
@@ -190,7 +189,6 @@ static LogicalDecodingContext *logical_decoding_ctx = NULL;
 static XLogRecPtr logical_startptr = InvalidXLogRecPtr;
 
 /* Signal handlers */
-static void WalSndSigHupHandler(SIGNAL_ARGS);
 static void WalSndLastCycleHandler(SIGNAL_ARGS);
 
 /* Prototypes for private functions */
@@ -1104,9 +1102,9 @@ WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
 			exit(1);
 
 		/* Process any requests or signals received recently */
-		if (got_SIGHUP)
+		if (ConfigReloadPending)
 		{
-			got_SIGHUP = false;
+			ConfigReloadPending = false;
 			ProcessConfigFile(PGC_SIGHUP);
 			SyncRepInitConfig();
 		}
@@ -1188,9 +1186,9 @@ WalSndWaitForWal(XLogRecPtr loc)
 			exit(1);
 
 		/* Process any requests or signals received recently */
-		if (got_SIGHUP)
+		if (ConfigReloadPending)
 		{
-			got_SIGHUP = false;
+			ConfigReloadPending = false;
 			ProcessConfigFile(PGC_SIGHUP);
 			SyncRepInitConfig();
 		}
@@ -1843,9 +1841,9 @@ WalSndLoop(WalSndSendDataCallback send_data)
 			exit(1);
 
 		/* Process any requests or signals received recently */
-		if (got_SIGHUP)
+		if (ConfigReloadPending)
 		{
-			got_SIGHUP = false;
+			ConfigReloadPending = false;
 			ProcessConfigFile(PGC_SIGHUP);
 			SyncRepInitConfig();
 		}
@@ -2636,19 +2634,6 @@ HandleWalSndInitStopping(void)
 	}
 }
 
-/* SIGHUP: set flag to re-read config file at next convenient time */
-static void
-WalSndSigHupHandler(SIGNAL_ARGS)
-{
-	int			save_errno = errno;
-
-	got_SIGHUP = true;
-	if (MyWalSnd)
-		SetLatch(&MyWalSnd->latch);
-
-	errno = save_errno;
-}
-
 /*
  * SIGUSR2: set flag to do a last cycle and shut down afterwards. The WAL
  * sender should already have been switched to WALSNDSTATE_STOPPING at
@@ -2670,7 +2655,7 @@ void
 WalSndSignals(void)
 {
 	/* Set up signal handlers */
-	pqsignal(SIGHUP, WalSndSigHupHandler);		/* set flag to read config
+	pqsignal(SIGHUP, PostgresSigHupHandler);	/* set flag to read config
 												 * file */
 	pqsignal(SIGINT, SIG_IGN);	/* not used */
 	pqsignal(SIGTERM, die);		/* request shutdown */