From 4455ded935a4856b06a389bb3d32eb08c0b5c980 Mon Sep 17 00:00:00 2001
From: Ian Barwick <ian@2ndquadrant.com>
Date: Mon, 23 Apr 2018 23:51:03 +0900
Subject: [PATCH] repmgrd: prevent standby connection handle from going stale

If monitoring history not in use, there's no activity on the standby's
connection handle, so if e.g. the standby is restarted, PQstatus()
never returns CONNECTION_BAD and repmgrd never notices the connection
is stale. Therefore execute a throw-away statement at "monitor_interval_secs".
---
 dbutils.c          | 15 +++++++++++++++
 dbutils.h          |  1 +
 repmgrd-physical.c |  6 ++++++
 3 files changed, 22 insertions(+)

diff --git a/dbutils.c b/dbutils.c
index c8f27edf..f8c91657 100644
--- a/dbutils.c
+++ b/dbutils.c
@@ -3847,6 +3847,21 @@ is_server_available_params(t_conninfo_param_list *param_list)
 }
 
 
+
+/*
+ * Simple throw-away query to stop a connection handle going stale
+ */
+void
+connection_ping(PGconn *conn)
+{
+	PGresult   *res = PQexec(conn, "SELECT TRUE");
+
+	PQclear(res);
+	return;
+}
+
+
+
 /* ==================== */
 /* monitoring functions */
 /* ==================== */
diff --git a/dbutils.h b/dbutils.h
index 93fbf019..8d78ca71 100644
--- a/dbutils.h
+++ b/dbutils.h
@@ -466,6 +466,7 @@ int			wait_connection_availability(PGconn *conn, long long timeout);
 /* node availability functions */
 bool		is_server_available(const char *conninfo);
 bool		is_server_available_params(t_conninfo_param_list *param_list);
+void		connection_ping(PGconn *conn);
 
 /* monitoring functions  */
 void
diff --git a/repmgrd-physical.c b/repmgrd-physical.c
index a70c8172..e8db03f4 100644
--- a/repmgrd-physical.c
+++ b/repmgrd-physical.c
@@ -1070,7 +1070,13 @@ loop:
 
 
 		if (PQstatus(primary_conn) == CONNECTION_OK && config_file_options.monitoring_history == true)
+		{
 			update_monitoring_history();
+		}
+		else
+		{
+			connection_ping(local_conn);
+		}
 
 		if (got_SIGHUP)
 		{