add multiprocess update daemon

update_daemon2.php

@@ -0,0 +1,55 @@
+#!/usr/bin/php
+<?php
+	// This is an experimental multiprocess update daemon
+	// It consists of the master server (this file) and
+	// client batch script (update_daemon2_client.php) which
+	// should only be run by the server process
+
+	declare(ticks = 1);
+
+	require "config.php";
+
+	define('MAX_JOBS', 2);
+	define('CLIENT_PROCESS', './update_daemon2_client.php SRV_RUN_OK');
+	define('SPAWN_INTERVAL', DAEMON_SLEEP_INTERVAL);
+
+	$running_jobs = 0;
+	$last_checkpoint = -1;
+
+	function sigchld_handler($signal) {
+		global $running_jobs;
+		if ($running_jobs > 0) $running_jobs--;
+		print posix_getpid() . ": SIGCHLD received, jobs left: $running_jobs\n";
+		pcntl_waitpid(-1, $status, WNOHANG);
+	}
+
+	pcntl_signal(SIGCHLD, 'sigchld_handler');
+
+	while (true) {
+
+		$next_spawn = $last_checkpoint + SPAWN_INTERVAL - time();
+
+		print "[MASTER] active jobs: $running_jobs, next spawn at $next_spawn sec\n";
+
+		if ($last_checkpoint + SPAWN_INTERVAL < time()) {
+
+			for ($j = $running_jobs; $j < MAX_JOBS; $j++) {
+				print "[MASTER] spawning client $j...";
+				$pid = pcntl_fork();
+				if ($pid == -1) {
+					die("fork failed!\n");
+				} else if ($pid) {
+					$running_jobs++;
+					print "OK [$running_jobs]\n";
+				} else {
+					pcntl_signal(SIGCHLD, SIG_IGN);
+					passthru(CLIENT_PROCESS);
+					exit(0);
+				}
+			}
+			$last_checkpoint = time();
+		}
+		sleep(1);
+	}
+
+?>