14 files changed, 950 insertions, 163 deletions
diff --git a/phpBB/includes/cron/cron_lock.php b/phpBB/includes/cron/cron_lock.php
new file mode 100644
index 0000000000..1046d62da4
--- /dev/null
+++ b/phpBB/includes/cron/cron_lock.php
@@ -0,0 +1,75 @@
+<?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
+{
+	private $cron_id;
+
+	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;
+			}
+		}
+
+		$this->cron_id = time() . ' ' . unique_id();
+
+		$sql = 'UPDATE ' . CONFIG_TABLE . "
+			SET config_value = '" . $db->sql_escape($this->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 = '" . $db->sql_escape($this->cron_id) . "'";
+		$db->sql_query($sql);
+	}
+}
diff --git a/phpBB/includes/cron/cron_manager.php b/phpBB/includes/cron/cron_manager.php
new file mode 100644
index 0000000000..5ee06ac102
--- /dev/null
+++ b/phpBB/includes/cron/cron_manager.php
@@ -0,0 +1,175 @@
+<?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 manager class.
+*
+* Finds installed cron tasks, stores task objects, provides task selection.
+*
+* @package phpBB3
+*/
+class cron_manager
+{
+	private $tasks = array();
+
+	public function __construct()
+	{
+		$task_files = $this->find_cron_task_files();
+		$this->load_tasks($task_files);
+	}
+
+	/**
+	* Finds cron task files.
+	*
+	* A cron task file must follow the naming convention:
+	* includes/cron/tasks/$mod/$name.php.
+	* $mod is core for tasks that are part of phpbb.
+	* Modifications should use their name as $mod.
+	* $name is the name of the cron task.
+	* Cron task is expected to be a class named cron_task_${mod}_${name}.
+	*
+	* Todo: consider caching found task file list in global cache.
+	*/
+	public function find_cron_task_files()
+	{
+		global $phpbb_root_path, $phpEx;
+
+		$tasks_root_path = $phpbb_root_path . 'includes/cron/tasks';
+		$dir = opendir($tasks_root_path);
+		$task_dirs = array();
+		while (($entry = readdir($dir)) !== false)
+		{
+			// ignore ., .. and dot directories
+			// todo: change is_dir to account for symlinks
+			if ($entry[0] == '.' || !is_dir($entry))
+			{
+				continue;
+			}
+			$task_dirs[] = $entry;
+		}
+		closedir($dir);
+
+		$ext = '.' . $phpEx;
+		$ext_length = strlen($ext);
+		$task_files = array();
+		foreach ($task_dirs as $task_dir)
+		{
+			$path = $phpbb_root_path . 'includes/cron/tasks/' . $task_dir;
+			$dir = opendir($path);
+			while (($entry = readdir($dir)) !== false && substr($entry, -$ext_length) == $ext)
+			{
+				$task_file = substr($entry, 0, -$ext_length);
+				$task_files[] = array($task_dir, $task_file);
+			}
+			closedir($dir);
+		}
+		return $task_files;
+	}
+
+	/**
+	* Checks whether $name is a valid identifier, and therefore part of valid cron task class name.
+	*/
+	public function is_valid_name($name)
+	{
+		return preg_match('/^[a-zA-Z][a-zA-Z0-9_]*$/', $name);
+	}
+
+	public function load_tasks($task_files)
+	{
+		global $phpbb_root_path, $phpEx;
+
+		foreach ($task_files as $task_file)
+		{
+			list($mod, $filename) = $task_file;
+			if ($this->is_valid_name($mod) && $this->is_valid_name($filename))
+			{
+				include_once($phpbb_root_path . "includes/cron/$mod/$filename.$phpEx");
+				$class = "cron_task_${mod}_${filename}";
+				$object = new $class;
+				$this->tasks[] = $object;
+			}
+		}
+	}
+
+	/**
+	* Finds a task that is ready to run.
+	*
+	* If several tasks are ready, any one of them could be returned.
+	*/
+	function find_one_ready_task()
+	{
+		foreach ($this->tasks as $task)
+		{
+			if ($task->is_ready())
+			{
+				return $task;
+			}
+		}
+		return null;
+	}
+
+	/**
+	* Finds all tasks that are ready to run.
+	*/
+	function find_all_ready_tasks()
+	{
+		$tasks = array();
+		foreach ($this->tasks as $task)
+		{
+			if ($task->is_ready())
+			{
+				$tasks[] = $task;
+			}
+		}
+		return $tasks;
+	}
+
+	/**
+	* Finds a task by name.
+	*
+	* Web runner uses this method to resolve names to tasks.
+	*/
+	function find_task($name)
+	{
+		foreach ($this->tasks as $task)
+		{
+			if ($task->get_name() == $name)
+			{
+				return $task;
+			}
+		}
+		return null;
+	}
+
+	function instantiate_task($name, $args)
+	{
+		$task = $this->find_task($name);
+		if ($task)
+		{
+			$class = get_class($task);
+			$task = new $class($args);
+		}
+		return $task;
+	}
+
+	function generate_generic_task_code($cron_type)
+	{
+		global $phpbb_root_path, $phpEx;
+		return '<img src="' . $url . '" width="1" height="1" alt="cron" />';
+	}
+}
diff --git a/phpBB/includes/cron/cron_task.php b/phpBB/includes/cron/cron_task.php
new file mode 100644
index 0000000000..8b9ffacae6
--- /dev/null
+++ b/phpBB/includes/cron/cron_task.php
@@ -0,0 +1,60 @@
+<?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 task interface
+* @package phpBB3
+*/
+interface cron_task
+{
+	/**
+	* Runs this cron task.
+	*/
+	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.
+	*/
+	public function is_runnable();
+
+	/**
+	* Returns whether this cron task should run now, because enough time
+	* has passed since it was last run.
+	*/
+	public function should_run();
+
+	/**
+	* Returns whether this cron task can be run in shutdown function.
+	*/
+	public function is_shutdown_function_safe();
+}
+
+/**
+* Parametrized cron task interface
+* @package phpBB3
+*/
+interface parametrized_cron_task extends cron_task
+{
+	/**
+	* Returns parameters of this cron task as a query string.
+	*/
+	public function get_url_query_string();
+}
diff --git a/phpBB/includes/cron/cron_task_base.php b/phpBB/includes/cron/cron_task_base.php
new file mode 100644
index 0000000000..f66894e7b2
--- /dev/null
+++ b/phpBB/includes/cron/cron_task_base.php
@@ -0,0 +1,64 @@
+<?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 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 cron_task_base
+{
+	/**
+	* Runs this cron task.
+	*/
+	abstract 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.
+	*/
+	public function is_runnable()
+	{
+		return true;
+	}
+
+	/**
+	* Returns whether this cron task should run now, because enough time
+	* has passed since it was last run.
+	*/
+	public function should_run()
+	{
+		return true;
+	}
+
+	/**
+	* Returns whether this cron task can be run in shutdown function.
+	*/
+	public function is_shutdown_function_safe()
+	{
+		return true;
+	}
+}
diff --git a/phpBB/includes/cron/cron_task_wrapper.php b/phpBB/includes/cron/cron_task_wrapper.php
new file mode 100644
index 0000000000..3919e4f049
--- /dev/null
+++ b/phpBB/includes/cron/cron_task_wrapper.php
@@ -0,0 +1,68 @@
+<?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 task wrapper class.
+* Enhances cron tasks with convenience methods that work identically for all tasks.
+*
+* @package phpBB3
+*/
+class cron_task_wrapper
+{
+	public function __construct($task)
+	{
+		$this->task = $task;
+	}
+
+	/**
+	* 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.
+	*/
+	public function is_ready()
+	{
+		return $this->task->is_runnable() && $this->task->should_run();
+	}
+
+	/**
+	* Returns the name of wrapped task.
+	*/
+	public function get_name()
+	{
+		$class = get_class($this->task);
+		return preg_replace('/^cron_task_/', '', $class);
+	}
+
+	public function get_url()
+	{
+		global $phpbb_root_path, $phpEx;
+
+		$name = $this->get_name();
+		$url = append_sid($phpbb_root_path . 'cron.' . $phpEx, 'cron_type=' . $name);
+		return $url;
+	}
+
+	/**
+	* Forwards all other method calls to the wrapped task implementation.
+	*/
+	public function __call($name, $args)
+	{
+		return call_user_func_array(array($this->task, $name), $args);
+	}
+}
diff --git a/phpBB/includes/cron/standard.php b/phpBB/includes/cron/standard.php
deleted file mode 100644
index 1cb8738f17..0000000000
--- a/phpBB/includes/cron/standard.php
+++ /dev/null
@@ -1,163 +0,0 @@
-<?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;
-}
-
-/**
-* Standard cron tasks
-* @package phpBB3
-*/
-class cron_tasks_standard
-{
-	var $tasks = array(
-		// key: cron type
-		// values: config name for enable/disable flag,
-		//         whether to check condition function to determine if the task can/should be run,
-		//         config name for interval,
-		//         config name for last run time,
-		//         whether task should be considered in phpbb cron mode,
-		//         whether task should be considered in system cron mode,
-		//         whether task requires special code generation
-		'prune_all_forums' => array(
-			'custom_condition' => true,
-			'run_from_system' => true,
-		),
-		'prune_forum' => array(
-			'custom_condition' => true,
-			'custom_code' => true,
-		),
-		'queue' => array(
-			'custom_condition' => true,
-			'interval_config' => 'queue_interval_config',
-			'last_run_config' => 'last_queue_run',
-			'run_from_phpbb' => true,
-			'run_from_system' => true,
-			'shutdown_function_condition' => true,
-		),
-		'tidy_cache' => array(
-			'custom_condition' => true,
-			'interval_config' => 'cache_gc',
-			'last_run_config' => 'cache_last_gc',
-			'run_from_phpbb' => true,
-			'run_from_system' => true,
-		),
-		'tidy_database' => array(
-			'interval_config' => 'database_gc',
-			'last_run_config' => 'database_last_gc',
-			'run_from_phpbb' => true,
-			'run_from_system' => true,
-		),
-		'tidy_search' => array(
-			'interval_config' => 'search_gc',
-			'last_run_config' => 'search_last_gc',
-			'run_from_phpbb' => true,
-			'run_from_system' => true,
-		),
-		'tidy_sessions' => array(
-			'interval_config' => 'session_gc',
-			'last_run_config' => 'session_last_gc',
-			'run_from_phpbb' => true,
-			'run_from_system' => true,
-		),
-		'tidy_warnings' => array(
-			'enable_config' => 'warnings_expire_days',
-			'interval_config' => 'warnings_gc',
-			'last_run_config' => 'warnings_last_gc',
-			'run_from_phpbb' => true,
-			'run_from_system' => true,
-		),
-	);
-	
-	function prune_forum_condition($forum_data) {
-		return $forum_data['enable_prune'] && $forum_data['prune_next'] < time();
-	}
-	
-	function prune_forum_code($forum_id) {
-		global $phpbb_root_path, $phpEx;
-		return '<img src="' . append_sid($phpbb_root_path . 'cron.' . $phpEx, 'cron_type=prune_forum&amp;f=' . $forum_id) . '" alt="cron" width="1" height="1" />';
-	}
-	
-	function run_prune_forum() {
-	}
-	
-	function queue_condition() {
-		global $phpbb_root_path, $phpEx;
-		return file_exists($phpbb_root_path . 'cache/queue.' . $phpEx);
-	}
-	
-	function queue_shutdown_function_condition() {
-		global $config;
-		return !$config['smtp_delivery'];
-	}
-	
-	function run_queue() {
-		global $phpbb_root_path, $phpEx;
-		include_once($phpbb_root_path . 'includes/functions_messenger.' . $phpEx);
-		$queue = new queue();
-		$queue->process();
-	}
-	
-	function tidy_cache_condition() {
-		global $cache;
-		return method_exists($cache, 'tidy');
-	}
-	
-	function run_tidy_cache() {
-		global $cache;
-		$cache->tidy();
-	}
-	
-	function run_tidy_database() {
-		include_once($phpbb_root_path . 'includes/functions_admin.' . $phpEx);
-		tidy_database();
-	}
-	
-	function tidy_search_condition() {
-		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);
-	}
-	
-	function run_tidy_search() {
-		global $phpbb_root_path, $phpEx, $config, $error;
-		
-		// Select the search method
-		$search_type = basename($config['search_type']);
-		
-		include_once("{$phpbb_root_path}includes/search/$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();
-		}
-	}
-	
-	function run_tidy_sessions() {
-		global $user;
-		$user->session_gc();
-	}
-	
-	function run_tidy_warnings() {
-		include_once($phpbb_root_path . 'includes/functions_admin.' . $phpEx);
-		tidy_warnings();
-	}
-}
diff --git a/phpBB/includes/cron/tasks/core/prune_all_forums.php b/phpBB/includes/cron/tasks/core/prune_all_forums.php
new file mode 100644
index 0000000000..13286de2b0
--- /dev/null
+++ b/phpBB/includes/cron/tasks/core/prune_all_forums.php
@@ -0,0 +1,63 @@
+<?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;
+}
+
+/**
+* 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 cron_task_core_prune_all_forums extends cron_task_base
+{
+	/**
+	* Runs this cron task.
+	*/
+	public function run()
+	{
+		global $db;
+		$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.
+	*/
+	public function is_runnable()
+	{
+		global $config;
+		return !!$config['use_system_cron'];
+	}
+}
diff --git a/phpBB/includes/cron/tasks/core/prune_forum.php b/phpBB/includes/cron/tasks/core/prune_forum.php
new file mode 100644
index 0000000000..4925447162
--- /dev/null
+++ b/phpBB/includes/cron/tasks/core/prune_forum.php
@@ -0,0 +1,112 @@
+<?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;
+}
+
+/**
+* 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 cron_task_core_prune_forum extends cron_task_base implements parametrized_cron_task
+{
+	/**
+	* Constructor.
+	*
+	* If $forum_data is given, it is assumed to contain necessary information
+	* about a single forum that is to be pruned.
+	*
+	* If $forum_data is not given, forum id will be retrieved via request_var
+	* and a database query will be performed to load the necessary information
+	* about the forum.
+	*/
+	public function __construct($forum_data=null)
+	{
+		global $db;
+		if ($forum_data)
+		{
+			$this->forum_data = $forum_data;
+		}
+		else
+		{
+			$forum_id = request_var('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)
+			{
+				// FIXME what to do?
+				break;
+			}
+
+			$this->forum_data = $row;
+		}
+	}
+
+	/**
+	* Runs this cron task.
+	*/
+	public function run()
+	{
+		global $phpbb_root_path, $phpEx;
+		include_once($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.
+	*/
+	public function is_runnable()
+	{
+		global $config;
+		return !$config['use_system_cron'];
+	}
+
+	/**
+	* Returns whether this cron task should run now, because enough time
+	* has passed since it was last run.
+	*/
+	public function should_run()
+	{
+		return $this->forum_data['enable_prune'] && $this->forum_data['prune_next'] < time();
+	}
+
+	/**
+	* Returns parameters of this cron task as a query string.
+	*/
+	public function get_url_query_string()
+	{
+		return 'f=' . $this->forum_data['forum_id'];
+	}
+}
diff --git a/phpBB/includes/cron/tasks/core/queue.php b/phpBB/includes/cron/tasks/core/queue.php
new file mode 100644
index 0000000000..d7dfeb9319
--- /dev/null
+++ b/phpBB/includes/cron/tasks/core/queue.php
@@ -0,0 +1,64 @@
+<?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;
+}
+
+/**
+* Queue cron task. Sends email and jabber messages queued by other scripts.
+*
+* @package phpBB3
+*/
+class cron_task_core_queue extends cron_task_base
+{
+	/**
+	* Runs this cron task.
+	*/
+	public function run()
+	{
+		global $phpbb_root_path, $phpEx;
+		include_once($phpbb_root_path . 'includes/functions_messenger.' . $phpEx);
+		$queue = new queue();
+		$queue->process();
+	}
+
+	/**
+	* Returns whether this cron task can run, given current board configuration.
+	*/
+	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.
+	*/
+	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.
+	*/
+	public function is_shutdown_function_safe()
+	{
+		global $config;
+		return !$config['smtp_delivery'];
+	}
+}
diff --git a/phpBB/includes/cron/tasks/core/tidy_cache.php b/phpBB/includes/cron/tasks/core/tidy_cache.php
new file mode 100644
index 0000000000..69038a8a5a
--- /dev/null
+++ b/phpBB/includes/cron/tasks/core/tidy_cache.php
@@ -0,0 +1,53 @@
+<?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;
+}
+
+/**
+* Tidy cache cron task.
+*
+* @package phpBB3
+*/
+class cron_task_core_tidy_cache extends cron_task_base
+{
+	/**
+	* Runs this cron task.
+	*/
+	public function run()
+	{
+		global $cache;
+		$cache->tidy();
+	}
+
+	/**
+	* Returns whether this cron task can run, given current board configuration.
+	*/
+	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.
+	*/
+	public function should_run()
+	{
+		global $config;
+		return $config['cache_last_gc'] < time() - $config['cache_gc'];
+	}
+}
diff --git a/phpBB/includes/cron/tasks/core/tidy_database.php b/phpBB/includes/cron/tasks/core/tidy_database.php
new file mode 100644
index 0000000000..c6c2a60445
--- /dev/null
+++ b/phpBB/includes/cron/tasks/core/tidy_database.php
@@ -0,0 +1,44 @@
+<?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;
+}
+
+/**
+* Tidy database cron task.
+*
+* @package phpBB3
+*/
+class cron_task_core_tidy_database extends cron_task_base
+{
+	/**
+	* Runs this cron task.
+	*/
+	public function run()
+	{
+		include_once($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.
+	*/
+	public function should_run()
+	{
+		global $config;
+		return $config['database_last_gc'] < time() - $config['database_gc'];
+	}
+}
diff --git a/phpBB/includes/cron/tasks/core/tidy_search.php b/phpBB/includes/cron/tasks/core/tidy_search.php
new file mode 100644
index 0000000000..0f409d114a
--- /dev/null
+++ b/phpBB/includes/cron/tasks/core/tidy_search.php
@@ -0,0 +1,72 @@
+<?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;
+}
+
+/**
+* Tidy search cron task.
+*
+* Will only run when the currently selected search backend supports tidying.
+*
+* @package phpBB3
+*/
+class cron_task_core_tidy_sessions extends cron_task_base
+{
+	/**
+	* Runs this cron task.
+	*/
+	public function run()
+	{
+		global $phpbb_root_path, $phpEx, $config, $error;
+
+		// Select the search method
+		$search_type = basename($config['search_type']);
+
+		include_once("{$phpbb_root_path}includes/search/$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.
+	*/
+	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.
+	*/
+	public function should_run()
+	{
+		global $config;
+		return $config['search_last_gc'] < time() - $config['search_gc'];
+	}
+}
diff --git a/phpBB/includes/cron/tasks/core/tidy_sessions.php b/phpBB/includes/cron/tasks/core/tidy_sessions.php
new file mode 100644
index 0000000000..ea6aa70699
--- /dev/null
+++ b/phpBB/includes/cron/tasks/core/tidy_sessions.php
@@ -0,0 +1,44 @@
+<?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;
+}
+
+/**
+* Tidy sessions cron task.
+*
+* @package phpBB3
+*/
+class cron_task_core_tidy_sessions extends cron_task_base
+{
+	/**
+	* Runs this cron task.
+	*/
+	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.
+	*/
+	public function should_run()
+	{
+		global $config;
+		return $config['session_last_gc'] < time() - $config['session_gc'];
+	}
+}
diff --git a/phpBB/includes/cron/tasks/core/tidy_warnings.php b/phpBB/includes/cron/tasks/core/tidy_warnings.php
new file mode 100644
index 0000000000..c1ab14d788
--- /dev/null
+++ b/phpBB/includes/cron/tasks/core/tidy_warnings.php
@@ -0,0 +1,56 @@
+<?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;
+}
+
+/**
+* Tidy warnings cron task.
+*
+* Will only run when warnings are configured to expire.
+*
+* @package phpBB3
+*/
+class cron_task_core_tidy_warnings extends cron_task_base
+{
+	/**
+	* Runs this cron task.
+	*/
+	public function run()
+	{
+		global $phpbb_root_path, $phpEx;
+		include_once($phpbb_root_path . 'includes/functions_admin.' . $phpEx);
+		tidy_warnings();
+	}
+
+	/**
+	* Returns whether this cron task can run, given current board configuration.
+	*/
+	public function is_runnable()
+	{
+		global $config;
+		return !!$config['warnings_expire_days'];
+	}
+
+	/**
+	* Returns whether this cron task should run now, because enough time
+	* has passed since it was last run.
+	*/
+	public function should_run()
+	{
+		global $config;
+		return $config['warnings_last_gc'] < time() - $config['warnings_gc'];
+	}
+}