[task/acm-refactor] Refactor the ACM classes to have a common interface.

They are now refered to as cache drivers rather than ACM classes. The
additional utility functions from the original cache class have been
moved to the cache_service. The class loader is now instantiated without
a cache instance and passed one as soon as it is constructed to allow
autoloading the cache classes.

PHPBB3-9983

phpBB/includes/cache/driver/xcache.php

@@ -0,0 +1,113 @@
+<?php
+/**
+*
+* @package acm
+* @version $Id$
+* @copyright (c) 2005, 2009 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* ACM for XCache
+* @package acm
+*
+* To use this module you need ini_get() enabled and the following INI settings configured as follows:
+* - xcache.var_size > 0
+* - xcache.admin.enable_auth = off (or xcache.admin.user and xcache.admin.password set)
+*
+*/
+class phpbb_cache_driver_xcache extends phpbb_cache_driver_memory
+{
+	var $extension = 'XCache';
+
+	function __construct()
+	{
+		parent::__construct();
+
+		if (!function_exists('ini_get') || (int) ini_get('xcache.var_size') <= 0)
+		{
+			trigger_error('Increase xcache.var_size setting above 0 or enable ini_get() to use this ACM module.', E_USER_ERROR);
+		}
+	}
+
+	/**
+	* Purge cache data
+	*
+	* @return void
+	*/
+	function purge()
+	{
+		// Run before for XCache, if admin functions are disabled it will terminate execution
+		parent::purge();
+
+		// If the admin authentication is enabled but not set up, this will cause a nasty error.
+		// Not much we can do about it though.
+		$n = xcache_count(XC_TYPE_VAR);
+
+		for ($i = 0; $i < $n; $i++)
+		{
+			xcache_clear_cache(XC_TYPE_VAR, $i);
+		}
+	}
+
+	/**
+	* Fetch an item from the cache
+	*
+	* @access protected
+	* @param string $var Cache key
+	* @return mixed Cached data
+	*/
+	function _read($var)
+	{
+		$result = xcache_get($this->key_prefix . $var);
+
+		return ($result !== null) ? $result : false;
+	}
+
+	/**
+	* Store data in the cache
+	*
+	* @access protected
+	* @param string $var Cache key
+	* @param mixed $data Data to store
+	* @param int $ttl Time-to-live of cached data
+	* @return bool True if the operation succeeded
+	*/
+	function _write($var, $data, $ttl = 2592000)
+	{
+		return xcache_set($this->key_prefix . $var, $data, $ttl);
+	}
+
+	/**
+	* Remove an item from the cache
+	*
+	* @access protected
+	* @param string $var Cache key
+	* @return bool True if the operation succeeded
+	*/
+	function _delete($var)
+	{
+		return xcache_unset($this->key_prefix . $var);
+	}
+
+	/**
+	* Check if a cache var exists
+	*
+	* @access protected
+	* @param string $var Cache key
+	* @return bool True if it exists, otherwise false
+	*/
+	function _isset($var)
+	{
+		return xcache_isset($this->key_prefix . $var);
+	}
+}