From 7580c8ed1151c77f816cb8910ccbfe6549ad7c63 Mon Sep 17 00:00:00 2001
From: Michael Vogel <icarus@dabo.de>
Date: Sat, 23 Jul 2016 22:57:22 +0200
Subject: [PATCH] Processing of high priority processes

---
 include/poller.php | 51 ++++++++++++++++++++++++++++++++++++----------
 1 file changed, 40 insertions(+), 11 deletions(-)

diff --git a/include/poller.php b/include/poller.php
index bf25549b54..3f1c1d3089 100644
--- a/include/poller.php
+++ b/include/poller.php
@@ -39,7 +39,7 @@ function poller_run(&$argv, &$argc){
 		return;
 
 	// Checking the number of workers
-	if (poller_too_much_workers()) {
+	if (poller_too_much_workers($entries, $queues, $maxqueues)) {
 		poller_kill_stale_workers();
 		return;
 	}
@@ -58,13 +58,15 @@ function poller_run(&$argv, &$argc){
 		sleep(4);
 
 	// Checking number of workers
-	if (poller_too_much_workers())
+	if (poller_too_much_workers($entries, $queues, $maxqueues))
 		return;
 
 	$cooldown = Config::get("system", "worker_cooldown", 0);
 
 	$starttime = time();
 
+	$delayed = 0;
+
 	while ($r = q("SELECT * FROM `workerqueue` WHERE `executed` = '0000-00-00 00:00:00' ORDER BY `created` LIMIT 1")) {
 
 		// Constantly check the number of parallel database processes
@@ -76,9 +78,37 @@ function poller_run(&$argv, &$argc){
 			return;
 
 		// Count active workers and compare them with a maximum value that depends on the load
-		if (poller_too_much_workers())
+		if (poller_too_much_workers($entries, $queues, $maxqueues))
 			return;
 
+		$argv = json_decode($r[0]["parameter"]);
+
+		$argc = count($argv);
+
+		$funcname = str_replace(".php", "", basename($argv[0]))."_run";
+
+		// Define the processes that have priority over any other process
+		/// @todo Better check for priority processes
+		$priority = array("delivery_run", "notifier_run", "pubsubpublish_run");
+
+		// Delay other processes if the system has a high load and there are many pending processes.
+		// The "delayed" value is a safety mechanism for the case when there are no high priority processes in the queue.
+		if ((($queues / $maxqueues) <= 0.5) AND (($entries > 100) AND ($delayed < 100)) AND !in_array($funcname, $priority)) {
+			q("UPDATE `workerqueue` SET `created` = '%s' WHERE `id` = %d",
+				dbesc(datetime_convert()),
+				intval($r[0]["id"]));
+
+			// Count the number of delayed processes
+			++$delayed;
+			logger("Delay call to '".$funcname."' for performance reasons (Delay ".$delayed.")", LOGGER_DEBUG);
+			continue;
+		}
+
+		// If we delivered a process that has high priority we reset the delayed counter.
+		// When we reached the limit we will process any entry until we reach a high priority process.
+		if (in_array($funcname, $priority))
+			$delayed = 0;
+
 		q("UPDATE `workerqueue` SET `executed` = '%s', `pid` = %d WHERE `id` = %d AND `executed` = '0000-00-00 00:00:00'",
 			dbesc(datetime_convert()),
 			intval(getmypid()),
@@ -93,10 +123,6 @@ function poller_run(&$argv, &$argc){
 			continue;
 		}
 
-		$argv = json_decode($r[0]["parameter"]);
-
-		$argc = count($argv);
-
 		// Check for existance and validity of the include file
 		$include = $argv[0];
 
@@ -108,8 +134,6 @@ function poller_run(&$argv, &$argc){
 
 		require_once($include);
 
-		$funcname=str_replace(".php", "", basename($argv[0]))."_run";
-
 		if (function_exists($funcname)) {
 			logger("Process ".getmypid()." - ID ".$r[0]["id"].": ".$funcname." ".$r[0]["parameter"]);
 			$funcname($argv, $argc);
@@ -244,13 +268,17 @@ function poller_kill_stale_workers() {
 		}
 }
 
-function poller_too_much_workers() {
+function poller_too_much_workers(&$entries, &$queues, &$maxqueues) {
+
+	$entries = 0;
 
 	$queues = get_config("system", "worker_queues");
 
 	if ($queues == 0)
 		$queues = 4;
 
+	$maxqueues = $queues;
+
 	$active = poller_active_workers();
 
 	// Decrease the number of workers at higher load
@@ -268,8 +296,9 @@ function poller_too_much_workers() {
 		$queues = ceil($slope * pow(max(0, $maxsysload - $load), $exponent));
 
 		$s = q("SELECT COUNT(*) AS `total` FROM `workerqueue` WHERE `executed` = '0000-00-00 00:00:00'");
+		$entries = $s[0]["total"];
 
-		logger("Current load: ".$load." - maximum: ".$maxsysload." - current queues: ".$active."/".$s[0]["total"]." - maximum: ".$queues, LOGGER_DEBUG);
+		logger("Current load: ".$load." - maximum: ".$maxsysload." - current queues: ".$active."/".$entries." - maximum: ".$queues."/".$maxqueues, LOGGER_DEBUG);
 
 	}