poller: An optional lockfile is used to check if the poller is already running

htconfig.php

@@ -83,5 +83,8 @@ $a->config['system']['no_regfullname'] = true;
 // If set to true the priority settings of ostatus contacts are used
 $a->config['system']['ostatus_use_priority'] = false;
 
-// If enabled all items are cached in the given directory
+// If enabled, all items are cached in the given directory
 $a->config['system']['itemcache'] = "";
+
+// If enabled, the lockpath is used for a lockfile to check if the poller is running
+$a->config['system']['lockpath'] = "";

include/poller.php

@@ -25,10 +25,20 @@ function poller_run($argv, $argc){
 	require_once('include/Contact.php');
 	require_once('include/email.php');
 	require_once('include/socgraph.php');
+	require_once('include/pidfile.php');
 
 	load_config('config');
 	load_config('system');
 
+	$lockpath = get_config('system','lockpath');
+	if ($lockpath != '') {
+		$pidfile = new pidfile($lockpath, 'poller.lck');
+		if($pidfile->is_already_running()) {
+			logger("poller: Already running");
+			exit;
+		}
+	}
+
 	$a->set_baseurl(get_config('system','url'));
 
 	load_hooks();