From 9b4f1327773717688653e080da89e0e19fc9a26f Mon Sep 17 00:00:00 2001
From: Florian Forster <octo@collectd.org>
Date: Mon, 8 Jun 2015 12:36:04 +0200
Subject: [PATCH] apcups plugin: Implement the "PersistentConnection" option.

If set to false, close the connection after each interval. This lets
users chose this method if persistent connections pose a problem.

Fixes: #617
---
 src/apcups.c          |  8 +++++---
 src/collectd.conf.in  |  1 +
 src/collectd.conf.pod | 12 +++++++++++-
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/apcups.c b/src/apcups.c
index 66fe45e1..dc533f1e 100644
--- a/src/apcups.c
+++ b/src/apcups.c
@@ -74,12 +74,12 @@ static char *conf_node = NULL;
 static char *conf_service = NULL;
 /* Defaults to false for backwards compatibility. */
 static _Bool conf_report_seconds = 0;
+static _Bool conf_persistent_conn = 1;
 
 static int global_sockfd = -1;
 
 static int count_retries = 0;
 static int count_iterations = 0;
-static _Bool close_socket = 0;
 
 static int net_shutdown (int *fd)
 {
@@ -314,7 +314,7 @@ static int apc_query_server (char const *node, char const *service,
 				"first %i iterations. Will close the socket "
 				"in future iterations.",
 				count_retries, count_iterations);
-		close_socket = 1;
+		conf_persistent_conn = 0;
 	}
 
 	while ((n = net_recv (&global_sockfd, recvline, sizeof (recvline) - 1)) > 0)
@@ -367,7 +367,7 @@ static int apc_query_server (char const *node, char const *service,
 	}
 	status = errno; /* save errno, net_shutdown() may re-set it. */
 
-	if (close_socket)
+	if (!conf_persistent_conn)
 		net_shutdown (&global_sockfd);
 
 	if (n < 0)
@@ -395,6 +395,8 @@ static int apcups_config (oconfig_item_t *ci)
 			cf_util_get_service (child, &conf_service);
 		else if (strcasecmp (child->key, "ReportSeconds") == 0)
 			cf_util_get_boolean (child, &conf_report_seconds);
+		else if (strcasecmp (child->key, "PersistentConnection") == 0)
+			cf_util_get_boolean (child, &conf_persistent_conn);
 		else
 			ERROR ("apcups plugin: Unknown config option \"%s\".", child->key);
 	}
diff --git a/src/collectd.conf.in b/src/collectd.conf.in
index 99f879cc..5a4c4674 100644
--- a/src/collectd.conf.in
+++ b/src/collectd.conf.in
@@ -264,6 +264,7 @@
 #	Host "localhost"
 #	Port "3551"
 #	ReportSeconds true
+#	PersistentConnection true
 #</Plugin>
 
 #<Plugin aquaero>
diff --git a/src/collectd.conf.pod b/src/collectd.conf.pod
index 1884914f..16315ade 100644
--- a/src/collectd.conf.pod
+++ b/src/collectd.conf.pod
@@ -802,12 +802,22 @@ B<apcupsd> can handle it.
 
 TCP-Port to connect to. Defaults to B<3551>.
 
-=item B<ReportSeconds> B<true|false>
+=item B<ReportSeconds> B<true>|B<false>
 
 If set to B<true>, the time reported in the C<timeleft> metric will be
 converted to seconds. This is the recommended setting. If set to B<false>, the
 default for backwards compatibility, the time will be reported in minutes.
 
+=item B<PersistentConnection> B<true>|B<false>
+
+By default, the plugin will try to keep the connection to UPS open between
+reads. Since this appears to be somewhat brittle (I<apcupsd> appears to close
+the connection due to inactivity quite quickly), the plugin will try to detect
+this problem and switch to an open-read-close mode in such cases.
+
+You can instruct the plugin to close the connection after each read by setting
+this option to B<false>.
+
 =back
 
 =head2 Plugin C<aquaero>
-- 
2.11.0