13 files changed, 1190 insertions, 0 deletions
diff --git a/phpBB/includes/cron/manager.php b/phpBB/includes/cron/manager.php
new file mode 100644
index 0000000000..21dcb91695
--- /dev/null
+++ b/phpBB/includes/cron/manager.php
@@ -0,0 +1,251 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2010 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Cron manager class.
+*
+* Finds installed cron tasks, stores task objects, provides task selection.
+*
+* @package phpBB3
+*/
+class phpbb_cron_manager
+{
+	/**
+	* Set of phpbb_cron_task_wrapper objects.
+	* Array holding all tasks that have been found.
+	*
+	* @var array
+	*/
+	protected $tasks = array();
+
+	/**
+	* Path to the root of directory tree with tasks.
+	* For bundled phpBB tasks, this is the path to includes/cron/tasks
+	* under phpBB root.
+	* @var string
+	*/
+	protected $task_path;
+
+	/**
+	* PHP file extension
+	* @var string
+	*/
+	protected $phpEx;
+
+	/**
+	* Cache driver
+	* @var phpbb_cache_driver_interface
+	*/
+	protected $cache;
+
+	/**
+	* Constructor. Loads all available tasks.
+	*
+	* Tasks will be looked up in directory tree rooted at $task_path.
+	* Task classes will be autoloaded and must be named according to
+	* autoloading naming conventions. To load cron tasks shipped with
+	* phpbb, pass $phpbb_root_path . 'includes/cron/task' as $task_path.
+	*
+	* If $cache is given, names of found cron tasks will be cached in it
+	* for one hour. Note that the cron task names are stored without
+	* namespacing; if two different phbb_cron_manager instances are
+	* constructed with different $task_path arguments but the same $cache,
+	* the second instance will use task names found by the first instance.
+	*
+	* @param string $task_path                   Directory containing cron tasks
+	* @param string $phpEx                       PHP file extension
+	* @param phpbb_cache_driver_interface $cache Cache for task names (optional)
+	* @return void
+	*/
+	public function __construct($task_path, $phpEx, phpbb_cache_driver_interface $cache = null)
+	{
+		$this->task_path = $task_path;
+		$this->phpEx = $phpEx;
+		$this->cache = $cache;
+
+		$task_names = $this->find_cron_task_names();
+		$this->load_tasks($task_names);
+	}
+
+	/**
+	* Finds cron task names.
+	*
+	* A cron task file must follow the naming convention:
+	* includes/cron/task/$mod/$name.php.
+	* $mod is core for tasks that are part of phpbb.
+	* Modifications should use their name as $mod.
+	* $name is the name of the cron task.
+	* Cron task is expected to be a class named phpbb_cron_task_${mod}_${name}.
+	*
+	* @return array		List of task names
+	*/
+	public function find_cron_task_names()
+	{
+		if ($this->cache)
+		{
+			$task_names = $this->cache->get('_cron_tasks');
+
+			if ($task_names !== false)
+			{
+				return $task_names;
+			}
+		}
+
+		$task_names = array();
+		$ext = '.' . $this->phpEx;
+		$ext_length = strlen($ext);
+
+		$iterator = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($this->task_path));
+
+		foreach ($iterator as $fileinfo)
+		{
+			$file = preg_replace('#^' . preg_quote($this->task_path, '#') . '#', '', $fileinfo->getPathname());
+
+			// skip directories and files direclty in the task root path
+			if ($fileinfo->isFile() && strpos($file, '/') !== false)
+			{
+				$task_name = str_replace('/', '_', substr($file, 0, -$ext_length));
+				if (substr($file, -$ext_length) == $ext && $this->is_valid_name($task_name))
+				{
+					$task_names[] = 'phpbb_cron_task_' . $task_name;
+				}
+			}
+		}
+
+		if ($this->cache)
+		{
+			$this->cache->put('_cron_tasks', $task_names, 3600);
+		}
+
+		return $task_names;
+	}
+
+	/**
+	* Checks whether $name is a valid identifier, and
+	* therefore part of valid cron task class name.
+	*
+	* @param string $name		Name to check
+	*
+	* @return bool
+	*/
+	public function is_valid_name($name)
+	{
+		return (bool) preg_match('/^[a-zA-Z][a-zA-Z0-9_]*$/', $name);
+	}
+
+	/**
+	* Loads tasks given by name, wraps them
+	* and puts them into $this->tasks.
+	*
+	* @param array $task_names		Array of strings
+	*
+	* @return void
+	*/
+	public function load_tasks(array $task_names)
+	{
+		foreach ($task_names as $task_name)
+		{
+			$task = new $task_name();
+			$wrapper = new phpbb_cron_task_wrapper($task);
+			$this->tasks[] = $wrapper;
+		}
+	}
+
+	/**
+	* Finds a task that is ready to run.
+	*
+	* If several tasks are ready, any one of them could be returned.
+	*
+	* If no tasks are ready, null is returned.
+	*
+	* @return phpbb_cron_task_wrapper|null
+	*/
+	public function find_one_ready_task()
+	{
+		foreach ($this->tasks as $task)
+		{
+			if ($task->is_ready())
+			{
+				return $task;
+			}
+		}
+		return null;
+	}
+
+	/**
+	* Finds all tasks that are ready to run.
+	*
+	* @return array		List of tasks which are ready to run (wrapped in phpbb_cron_task_wrapper).
+	*/
+	public function find_all_ready_tasks()
+	{
+		$tasks = array();
+		foreach ($this->tasks as $task)
+		{
+			if ($task->is_ready())
+			{
+				$tasks[] = $task;
+			}
+		}
+		return $tasks;
+	}
+
+	/**
+	* Finds a task by name.
+	*
+	* If there is no task with the specified name, null is returned.
+	*
+	* Web runner uses this method to resolve names to tasks.
+	*
+	* @param string				$name Name of the task to look up.
+	* @return phpbb_cron_task	A task corresponding to the given name, or null.
+	*/
+	public function find_task($name)
+	{
+		foreach ($this->tasks as $task)
+		{
+			if ($task->get_name() == $name)
+			{
+				return $task;
+			}
+		}
+		return null;
+	}
+
+	/**
+	* Creates an instance of parametrized cron task $name with args $args.
+	* The constructed task is wrapped with cron task wrapper before being returned.
+	*
+	* @param string $name		The task name, which is the same as cron task class name.
+	* @param array $args		Will be passed to the task class's constructor.
+	*
+	* @return phpbb_cron_task_wrapper|null
+	*/
+	public function instantiate_task($name, array $args)
+	{
+		$task = $this->find_task($name);
+		if ($task)
+		{
+			// task here is actually an instance of cron task wrapper
+			$class = $task->get_name();
+			$task = new $class($args);
+			// need to wrap the new task too
+			$task = new phpbb_cron_task_wrapper($task);
+		}
+		return $task;
+	}
+}
diff --git a/phpBB/includes/cron/task/base.php b/phpBB/includes/cron/task/base.php
new file mode 100644
index 0000000000..38c0b844d9
--- /dev/null
+++ b/phpBB/includes/cron/task/base.php
@@ -0,0 +1,73 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2010 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Cron task base class. Provides sensible defaults for cron tasks
+* and partially implements cron task interface, making writing cron tasks easier.
+*
+* At a minimum, subclasses must override the run() method.
+*
+* Cron tasks need not inherit from this base class. If desired,
+* they may implement cron task interface directly.
+*
+* @package phpBB3
+*/
+abstract class phpbb_cron_task_base implements phpbb_cron_task
+{
+	/**
+	* Returns whether this cron task can run, given current board configuration.
+	*
+	* For example, a cron task that prunes forums can only run when
+	* forum pruning is enabled.
+	*
+	* @return bool
+	*/
+	public function is_runnable()
+	{
+		return true;
+	}
+
+	/**
+	* Returns whether this cron task should run now, because enough time
+	* has passed since it was last run.
+	*
+	* @return bool
+	*/
+	public function should_run()
+	{
+		return true;
+	}
+
+	/**
+	* Returns whether this cron task can be run in shutdown function.
+	*
+	* By the time shutdown sequence invokes a particular piece of code,
+	* resources that that code requires may already be released.
+	* If so, a particular cron task may be marked shutdown function-
+	* unsafe, and it will be executed in normal program flow.
+	*
+	* Generally speaking cron tasks should start off as shutdown function-
+	* safe, and only be marked shutdown function-unsafe if a problem
+	* is discovered.
+	*
+	* @return bool		Whether the cron task is shutdown function-safe.
+	*/
+	public function is_shutdown_function_safe()
+	{
+		return true;
+	}
+}
diff --git a/phpBB/includes/cron/task/core/prune_all_forums.php b/phpBB/includes/cron/task/core/prune_all_forums.php
new file mode 100644
index 0000000000..39b5765229
--- /dev/null
+++ b/phpBB/includes/cron/task/core/prune_all_forums.php
@@ -0,0 +1,75 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2010 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Prune all forums cron task.
+*
+* It is intended to be invoked from system cron.
+* This task will find all forums for which pruning is enabled, and will
+* prune all forums as necessary.
+*
+* @package phpBB3
+*/
+class phpbb_cron_task_core_prune_all_forums extends phpbb_cron_task_base
+{
+	/**
+	* Runs this cron task.
+	*
+	* @return void
+	*/
+	public function run()
+	{
+		global $phpbb_root_path, $phpEx, $db;
+
+		if (!function_exists('auto_prune'))
+		{
+			include($phpbb_root_path . 'includes/functions_admin.' . $phpEx);
+		}
+
+		$sql = 'SELECT forum_id, prune_next, enable_prune, prune_days, prune_viewed, forum_flags, prune_freq
+			FROM ' . FORUMS_TABLE . "
+			WHERE enable_prune = 1 
+				AND prune_next < " . time();
+		$result = $db->sql_query($sql);
+		while ($row = $db->sql_fetchrow($result))
+		{
+			if ($row['prune_days'])
+			{
+				auto_prune($row['forum_id'], 'posted', $row['forum_flags'], $row['prune_days'], $row['prune_freq']);
+			}
+
+			if ($row['prune_viewed'])
+			{
+				auto_prune($row['forum_id'], 'viewed', $row['forum_flags'], $row['prune_viewed'], $row['prune_freq']);
+			}
+		}
+		$db->sql_freeresult($result);
+	}
+
+	/**
+	* Returns whether this cron task can run, given current board configuration.
+	*
+	* This cron task will only run when system cron is utilised.
+	*
+	* @return bool
+	*/
+	public function is_runnable()
+	{
+		global $config;
+		return (bool) $config['use_system_cron'];
+	}
+}
diff --git a/phpBB/includes/cron/task/core/prune_forum.php b/phpBB/includes/cron/task/core/prune_forum.php
new file mode 100644
index 0000000000..55b1c58cd4
--- /dev/null
+++ b/phpBB/includes/cron/task/core/prune_forum.php
@@ -0,0 +1,153 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2010 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Prune one forum cron task.
+*
+* It is intended to be used when cron is invoked via web.
+* This task can decide whether it should be run using data obtained by viewforum
+* code, without making additional database queries.
+*
+* @package phpBB3
+*/
+class phpbb_cron_task_core_prune_forum extends phpbb_cron_task_base implements phpbb_cron_task_parametrized
+{
+	private $forum_data;
+
+	/**
+	* Constructor.
+	*
+	* If $forum_data is given, it is assumed to contain necessary information
+	* about a single forum that is to be pruned.
+	*
+	* If $forum_data is not given, forum id will be retrieved via request_var
+	* and a database query will be performed to load the necessary information
+	* about the forum.
+	*
+	* @param array $forum_data Information about a forum to be pruned.
+	*/
+	public function __construct($forum_data = null)
+	{
+		global $db;
+		if ($forum_data)
+		{
+			$this->forum_data = $forum_data;
+		}
+		else
+		{
+			$this->forum_data = null;
+		}
+	}
+
+	/**
+	* Runs this cron task.
+	*
+	* @return void
+	*/
+	public function run()
+	{
+		global $phpbb_root_path, $phpEx;
+		if (!function_exists('auto_prune'))
+		{
+			include($phpbb_root_path . 'includes/functions_admin.' . $phpEx);
+		}
+
+		if ($this->forum_data['prune_days'])
+		{
+			auto_prune($this->forum_data['forum_id'], 'posted', $this->forum_data['forum_flags'], $this->forum_data['prune_days'], $this->forum_data['prune_freq']);
+		}
+
+		if ($this->forum_data['prune_viewed'])
+		{
+			auto_prune($this->forum_data['forum_id'], 'viewed', $this->forum_data['forum_flags'], $this->forum_data['prune_viewed'], $this->forum_data['prune_freq']);
+		}
+	}
+
+	/**
+	* Returns whether this cron task can run, given current board configuration.
+	*
+	* This cron task will not run when system cron is utilised, as in
+	* such cases prune_all_forums task would run instead.
+	*
+	* Additionally, this task must be given the forum data, either via
+	* the constructor or parse_parameters method.
+	*
+	* @return bool
+	*/
+	public function is_runnable()
+	{
+		global $config;
+		return !$config['use_system_cron'] && $this->forum_data;
+	}
+
+	/**
+	* Returns whether this cron task should run now, because enough time
+	* has passed since it was last run.
+	*
+	* Forum pruning interval is specified in the forum data.
+	*
+	* @return bool
+	*/
+	public function should_run()
+	{
+		return $this->forum_data['enable_prune'] && $this->forum_data['prune_next'] < time();
+	}
+
+	/**
+	* Returns parameters of this cron task as an array.
+	* The array has one key, f, whose value is id of the forum to be pruned.
+	*
+	* @return array
+	*/
+	public function get_parameters()
+	{
+		return array('f' => $this->forum_data['forum_id']);
+	}
+
+	/**
+	* Parses parameters found in $request, which is an instance of
+	* phpbb_request_interface.
+	*
+	* It is expected to have a key f whose value is id of the forum to be pruned.
+	*
+	* @param phpbb_request_interface $request Request object.
+	*
+	* @return void
+	*/
+	public function parse_parameters(phpbb_request_interface $request)
+	{
+		global $db;
+
+		$this->forum_data = null;
+		if ($request->is_set('f'))
+		{
+			$forum_id = $request->variable('f', 0);
+
+			$sql = 'SELECT forum_id, prune_next, enable_prune, prune_days, prune_viewed, forum_flags, prune_freq
+				FROM ' . FORUMS_TABLE . "
+				WHERE forum_id = $forum_id";
+			$result = $db->sql_query($sql);
+			$row = $db->sql_fetchrow($result);
+			$db->sql_freeresult($result);
+
+			if ($row)
+			{
+				$this->forum_data = $row;
+			}
+		}
+	}
+}
diff --git a/phpBB/includes/cron/task/core/queue.php b/phpBB/includes/cron/task/core/queue.php
new file mode 100644
index 0000000000..0e9de05984
--- /dev/null
+++ b/phpBB/includes/cron/task/core/queue.php
@@ -0,0 +1,84 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2010 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Queue cron task. Sends email and jabber messages queued by other scripts.
+*
+* @package phpBB3
+*/
+class phpbb_cron_task_core_queue extends phpbb_cron_task_base
+{
+	/**
+	* Runs this cron task.
+	*
+	* @return void
+	*/
+	public function run()
+	{
+		global $phpbb_root_path, $phpEx;
+		if (!class_exists('queue'))
+		{
+			include($phpbb_root_path . 'includes/functions_messenger.' . $phpEx);
+		}
+		$queue = new queue();
+		$queue->process();
+	}
+
+	/**
+	* Returns whether this cron task can run, given current board configuration.
+	*
+	* Queue task is only run if the email queue (file) exists.
+	*
+	* @return bool
+	*/
+	public function is_runnable()
+	{
+		global $phpbb_root_path, $phpEx;
+		return file_exists($phpbb_root_path . 'cache/queue.' . $phpEx);
+	}
+
+	/**
+	* Returns whether this cron task should run now, because enough time
+	* has passed since it was last run.
+	*
+	* The interval between queue runs is specified in board configuration.
+	*
+	* @return bool
+	*/
+	public function should_run()
+	{
+		global $config;
+		return $config['last_queue_run'] < time() - $config['queue_interval_config'];
+	}
+
+	/**
+	* Returns whether this cron task can be run in shutdown function.
+	*
+	* A user reported that using the mail() function during shutdown
+	* function execution does not work. Therefore if email is delivered
+	* via the mail() function (as opposed to SMTP) queue cron task marks
+	* itself shutdown function-unsafe.
+	*
+	* @return bool
+	*/
+	public function is_shutdown_function_safe()
+	{
+		global $config;
+		// A user reported using the mail() function while using shutdown does not work. We do not want to risk that.
+		return !$config['smtp_delivery'];
+	}
+}
diff --git a/phpBB/includes/cron/task/core/tidy_cache.php b/phpBB/includes/cron/task/core/tidy_cache.php
new file mode 100644
index 0000000000..793ce746b4
--- /dev/null
+++ b/phpBB/includes/cron/task/core/tidy_cache.php
@@ -0,0 +1,64 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2010 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Tidy cache cron task.
+*
+* @package phpBB3
+*/
+class phpbb_cron_task_core_tidy_cache extends phpbb_cron_task_base
+{
+	/**
+	* Runs this cron task.
+	*
+	* @return void
+	*/
+	public function run()
+	{
+		global $cache;
+		$cache->tidy();
+	}
+
+	/**
+	* Returns whether this cron task can run, given current board configuration.
+	*
+	* Tidy cache cron task runs if the cache implementation in use
+	* supports tidying.
+	*
+	* @return bool
+	*/
+	public function is_runnable()
+	{
+		global $cache;
+		return method_exists($cache, 'tidy');
+	}
+
+	/**
+	* Returns whether this cron task should run now, because enough time
+	* has passed since it was last run.
+	*
+	* The interval between cache tidying is specified in board
+	* configuration.
+	*
+	* @return bool
+	*/
+	public function should_run()
+	{
+		global $config;
+		return $config['cache_last_gc'] < time() - $config['cache_gc'];
+	}
+}
diff --git a/phpBB/includes/cron/task/core/tidy_database.php b/phpBB/includes/cron/task/core/tidy_database.php
new file mode 100644
index 0000000000..fb0e81eaba
--- /dev/null
+++ b/phpBB/includes/cron/task/core/tidy_database.php
@@ -0,0 +1,54 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2010 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Tidy database cron task.
+*
+* @package phpBB3
+*/
+class phpbb_cron_task_core_tidy_database extends phpbb_cron_task_base
+{
+	/**
+	* Runs this cron task.
+	*
+	* @return void
+	*/
+	public function run()
+	{
+		global $phpbb_root_path, $phpEx;
+		if (!function_exists('tidy_database'))
+		{
+			include($phpbb_root_path . 'includes/functions_admin.' . $phpEx);
+		}
+		tidy_database();
+	}
+
+	/**
+	* Returns whether this cron task should run now, because enough time
+	* has passed since it was last run.
+	*
+	* The interval between database tidying is specified in board
+	* configuration.
+	*
+	* @return bool
+	*/
+	public function should_run()
+	{
+		global $config;
+		return $config['database_last_gc'] < time() - $config['database_gc'];
+	}
+}
diff --git a/phpBB/includes/cron/task/core/tidy_search.php b/phpBB/includes/cron/task/core/tidy_search.php
new file mode 100644
index 0000000000..dcc78abbb8
--- /dev/null
+++ b/phpBB/includes/cron/task/core/tidy_search.php
@@ -0,0 +1,87 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2010 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Tidy search cron task.
+*
+* Will only run when the currently selected search backend supports tidying.
+*
+* @package phpBB3
+*/
+class phpbb_cron_task_core_tidy_search extends phpbb_cron_task_base
+{
+	/**
+	* Runs this cron task.
+	*
+	* @return void
+	*/
+	public function run()
+	{
+		global $phpbb_root_path, $phpEx, $config, $error;
+
+		// Select the search method
+		$search_type = basename($config['search_type']);
+
+		if (!class_exists($search_type))
+		{
+			include("{$phpbb_root_path}includes/search/$search_type.$phpEx");
+		}
+
+		// We do some additional checks in the module to ensure it can actually be utilised
+		$error = false;
+		$search = new $search_type($error);
+
+		if (!$error)
+		{
+			$search->tidy();
+		}
+	}
+
+	/**
+	* Returns whether this cron task can run, given current board configuration.
+	*
+	* Search cron task is runnable in all normal use. It may not be
+	* runnable if the search backend implementation selected in board
+	* configuration does not exist.
+	*
+	* @return bool
+	*/
+	public function is_runnable()
+	{
+		global $phpbb_root_path, $phpEx, $config;
+
+		// Select the search method
+		$search_type = basename($config['search_type']);
+
+		return file_exists($phpbb_root_path . 'includes/search/' . $search_type . '.' . $phpEx);
+	}
+
+	/**
+	* Returns whether this cron task should run now, because enough time
+	* has passed since it was last run.
+	*
+	* The interval between search tidying is specified in board
+	* configuration.
+	*
+	* @return bool
+	*/
+	public function should_run()
+	{
+		global $config;
+		return $config['search_last_gc'] < time() - $config['search_gc'];
+	}
+}
diff --git a/phpBB/includes/cron/task/core/tidy_sessions.php b/phpBB/includes/cron/task/core/tidy_sessions.php
new file mode 100644
index 0000000000..81e7e6a147
--- /dev/null
+++ b/phpBB/includes/cron/task/core/tidy_sessions.php
@@ -0,0 +1,50 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2010 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Tidy sessions cron task.
+*
+* @package phpBB3
+*/
+class phpbb_cron_task_core_tidy_sessions extends phpbb_cron_task_base
+{
+	/**
+	* Runs this cron task.
+	*
+	* @return void
+	*/
+	public function run()
+	{
+		global $user;
+		$user->session_gc();
+	}
+
+	/**
+	* Returns whether this cron task should run now, because enough time
+	* has passed since it was last run.
+	*
+	* The interval between session tidying is specified in board
+	* configuration.
+	*
+	* @return bool
+	*/
+	public function should_run()
+	{
+		global $config;
+		return $config['session_last_gc'] < time() - $config['session_gc'];
+	}
+}
diff --git a/phpBB/includes/cron/task/core/tidy_warnings.php b/phpBB/includes/cron/task/core/tidy_warnings.php
new file mode 100644
index 0000000000..e7d4cc9eea
--- /dev/null
+++ b/phpBB/includes/cron/task/core/tidy_warnings.php
@@ -0,0 +1,69 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2010 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Tidy warnings cron task.
+*
+* Will only run when warnings are configured to expire.
+*
+* @package phpBB3
+*/
+class phpbb_cron_task_core_tidy_warnings extends phpbb_cron_task_base
+{
+	/**
+	* Runs this cron task.
+	*
+	* @return void
+	*/
+	public function run()
+	{
+		global $phpbb_root_path, $phpEx;
+		if (!function_exists('tidy_warnings'))
+		{
+			include($phpbb_root_path . 'includes/functions_admin.' . $phpEx);
+		}
+		tidy_warnings();
+	}
+
+	/**
+	* Returns whether this cron task can run, given current board configuration.
+	*
+	* If warnings are set to never expire, this cron task will not run.
+	*
+	* @return bool
+	*/
+	public function is_runnable()
+	{
+		global $config;
+		return (bool) $config['warnings_expire_days'];
+	}
+
+	/**
+	* Returns whether this cron task should run now, because enough time
+	* has passed since it was last run.
+	*
+	* The interval between warnings tidying is specified in board
+	* configuration.
+	*
+	* @return bool
+	*/
+	public function should_run()
+	{
+		global $config;
+		return $config['warnings_last_gc'] < time() - $config['warnings_gc'];
+	}
+}
diff --git a/phpBB/includes/cron/task/parametrized.php b/phpBB/includes/cron/task/parametrized.php
new file mode 100644
index 0000000000..c6c45be0c0
--- /dev/null
+++ b/phpBB/includes/cron/task/parametrized.php
@@ -0,0 +1,52 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2010 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Parametrized cron task interface.
+*
+* Parametrized cron tasks are somewhat of a cross between regular cron tasks and
+* delayed jobs. Whereas regular cron tasks perform some action globally,
+* parametrized cron tasks perform actions on a particular object (or objects).
+* Parametrized cron tasks do not make sense and are not usable without
+* specifying these objects.
+*
+* @package phpBB3
+*/
+interface phpbb_cron_task_parametrized extends phpbb_cron_task
+{
+	/**
+	* Returns parameters of this cron task as an array.
+	*
+	* The array must map string keys to string values.
+	*
+	* @return array
+	*/
+	public function get_parameters();
+
+	/**
+	* Parses parameters found in $request, which is an instance of
+	* phpbb_request_interface.
+	*
+	* $request contains user input and must not be trusted.
+	* Cron task must validate all data before using it.
+	*
+	* @param phpbb_request_interface $request Request object.
+	*
+	* @return void
+	*/
+	public function parse_parameters(phpbb_request_interface $request);
+}
diff --git a/phpBB/includes/cron/task/task.php b/phpBB/includes/cron/task/task.php
new file mode 100644
index 0000000000..58c4a96f8e
--- /dev/null
+++ b/phpBB/includes/cron/task/task.php
@@ -0,0 +1,64 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2010 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Cron task interface
+* @package phpBB3
+*/
+interface phpbb_cron_task
+{
+	/**
+	* Runs this cron task.
+	*
+	* @return void
+	*/
+	public function run();
+
+	/**
+	* Returns whether this cron task can run, given current board configuration.
+	*
+	* For example, a cron task that prunes forums can only run when
+	* forum pruning is enabled.
+	*
+	* @return bool
+	*/
+	public function is_runnable();
+
+	/**
+	* Returns whether this cron task should run now, because enough time
+	* has passed since it was last run.
+	*
+	* @return bool
+	*/
+	public function should_run();
+
+	/**
+	* Returns whether this cron task can be run in shutdown function.
+	*
+	* By the time shutdown sequence invokes a particular piece of code,
+	* resources that that code requires may already be released.
+	* If so, a particular cron task may be marked shutdown function-
+	* unsafe, and it will be executed in normal program flow.
+	*
+	* Generally speaking cron tasks should start off as shutdown function-
+	* safe, and only be marked shutdown function-unsafe if a problem
+	* is discovered.
+	*
+	* @return bool
+	*/
+	public function is_shutdown_function_safe();
+}
diff --git a/phpBB/includes/cron/task/wrapper.php b/phpBB/includes/cron/task/wrapper.php
new file mode 100644
index 0000000000..238d97853c
--- /dev/null
+++ b/phpBB/includes/cron/task/wrapper.php
@@ -0,0 +1,114 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2010 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Cron task wrapper class.
+* Enhances cron tasks with convenience methods that work identically for all tasks.
+*
+* @package phpBB3
+*/
+class phpbb_cron_task_wrapper
+{
+	/**
+	* Constructor.
+	*
+	* Wraps a task $task, which must implement cron_task interface.
+	*
+	* @param phpbb_cron_task $task The cron task to wrap.
+	*/
+	public function __construct(phpbb_cron_task $task)
+	{
+		$this->task = $task;
+	}
+
+	/**
+	* Returns whether the wrapped task is parametrised.
+	*
+	* Parametrized tasks accept parameters during initialization and must
+	* normally be scheduled with parameters.
+	*
+	* @return bool		Whether or not this task is parametrized.
+	*/
+	public function is_parametrized()
+	{
+		return $this->task instanceof phpbb_cron_task_parametrized;
+	}
+
+	/**
+	* Returns whether the wrapped task is ready to run.
+	*
+	* A task is ready to run when it is runnable according to current configuration
+	* and enough time has passed since it was last run.
+	*
+	* @return bool		Whether the wrapped task is ready to run.
+	*/
+	public function is_ready()
+	{
+		return $this->task->is_runnable() && $this->task->should_run();
+	}
+
+	/**
+	* Returns the name of wrapped task. It is the same as the wrapped class's class name.
+	*
+	* @return string		Class name of wrapped task.
+	*/
+	public function get_name()
+	{
+		return get_class($this->task);
+	}
+
+	/**
+	* Returns a url through which this task may be invoked via web.
+	*
+	* When system cron is not in use, running a cron task is accomplished
+	* by outputting an image with the url returned by this function as
+	* source.
+	*
+	* @return string		URL through which this task may be invoked.
+	*/
+	public function get_url()
+	{
+		global $phpbb_root_path, $phpEx;
+
+		$name = $this->get_name();
+		if ($this->is_parametrized())
+		{
+			$params = $this->task->get_parameters();
+			$extra = '';
+			foreach ($params as $key => $value)
+			{
+				$extra .= '&amp;' . $key . '=' . urlencode($value);
+			}
+		}
+		else
+		{
+			$extra = '';
+		}
+		$url = append_sid($phpbb_root_path . 'cron.' . $phpEx, 'cron_type=' . $name . $extra);
+		return $url;
+	}
+
+	/**
+	* Forwards all other method calls to the wrapped task implementation.
+	*
+	* @return mixed
+	*/
+	public function __call($name, $args)
+	{
+		return call_user_func_array(array($this->task, $name), $args);
+	}
+}