Poller: Check the number of used database connections

include/items.php

@@ -509,6 +509,16 @@ function item_store($arr,$force_parent = false, $notify = false, $dontcache = fa
 	$arr['inform']        = ((x($arr,'inform'))        ? trim($arr['inform'])                : '');
 	$arr['file']          = ((x($arr,'file'))          ? trim($arr['file'])                  : '');
 
+
+	if (($arr['author-link'] == "") AND ($arr['owner-link'] == "")) {
+		$trace = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 5);
+		foreach ($trace AS $func)
+		        $function[] = $func["function"];
+
+		$function = implode(", ", $function);
+		logger("Both author-link and owner-link are empty. Called by: ".$function, LOGGER_DEBUG);
+	}
+
 	if ($arr['plink'] == "") {
 		$a = get_app();
 		$arr['plink'] = $a->get_baseurl().'/display/'.urlencode($arr['guid']);

include/poller.php

@@ -26,6 +26,9 @@ function poller_run(&$argv, &$argc){
 		unset($db_host, $db_user, $db_pass, $db_data);
 	};
 
+	if (poller_max_connections_reached())
+		return;
+
 	$load = current_load();
 	if($load) {
 		$maxsysload = intval(get_config('system','maxloadavg'));
@@ -117,6 +120,40 @@ function poller_run(&$argv, &$argc){
 
 }
 
+/**
+ * @brief Checks if the number of database connections has reached a critical limit.
+ *
+ * @return bool Are more than 3/4 of the maximum connections used?
+ */
+function poller_max_connections_reached() {
+	$r = q("SHOW VARIABLES WHERE `variable_name` = 'max_connections'");
+	if (!$r)
+		return false;
+
+	$max = intval($r[0]["Value"]);
+	if ($max == 0)
+		return false;
+
+	$r = q("SHOW STATUS WHERE `variable_name` = 'Threads_connected'");
+	if (!$r)
+		return false;
+
+	$connected = intval($r[0]["Value"]);
+	if ($connected == 0)
+		return false;
+
+	$level = $connected / $max;
+
+	logger("Connection usage: ".$connected."/".$max, LOGGER_DEBUG);
+
+	if ($level < (3/4))
+		return false;
+
+	logger("Maximum level (3/4) of connections reached: ".$connected."/".$max);
+	return true;
+
+}
+
 /**
  * @brief fix the queue entry if the worker process died
  *