1 files changed, 71 insertions, 0 deletions
diff --git a/phpBB/includes/cron_lock.php b/phpBB/includes/cron_lock.php
new file mode 100644
index 0000000000..2a09590772
--- /dev/null
+++ b/phpBB/includes/cron_lock.php
@@ -0,0 +1,71 @@
+<?php
+/**
+*
+* @package phpBB3
+* @version $Id$
+* @copyright (c) 2010 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Cron lock class
+* @package phpBB3
+*/
+class cron_lock
+{
+	function lock() {
+		global $config, $db;
+		
+		if (!isset($config['cron_lock']))
+		{
+			set_config('cron_lock', '0', true);
+		}
+
+		// make sure cron doesn't run multiple times in parallel
+		if ($config['cron_lock'])
+		{
+			// if the other process is running more than an hour already we have to assume it
+			// aborted without cleaning the lock
+			$time = explode(' ', $config['cron_lock']);
+			$time = $time[0];
+
+			if ($time + 3600 >= time())
+			{
+				return false;
+			}
+		}
+
+		define('CRON_ID', time() . ' ' . unique_id());
+
+		$sql = 'UPDATE ' . CONFIG_TABLE . "
+			SET config_value = '" . $db->sql_escape(CRON_ID) . "'
+			WHERE config_name = 'cron_lock' AND config_value = '" . $db->sql_escape($config['cron_lock']) . "'";
+		$db->sql_query($sql);
+
+		// another cron process altered the table between script start and UPDATE query so exit
+		if ($db->sql_affectedrows() != 1)
+		{
+			return false;
+		}
+		
+		return true;
+	}
+	
+	function unlock() {
+		global $db;
+
+		$sql = 'UPDATE ' . CONFIG_TABLE . "
+			SET config_value = '0'
+			WHERE config_name = 'cron_lock' AND config_value = '" . $db->sql_escape(CRON_ID) . "'";
+		$db->sql_query($sql);
+	}
+}