cache.php

<?php
/**
 * Caching for CakePHP.
 *
 *
 * PHP versions 4 and 5
 *
 * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
 * Copyright 2005-2009, Cake Software Foundation, Inc. (http://cakefoundation.org)
 *
 * Licensed under The MIT License
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Copyright 2005-2009, Cake Software Foundation, Inc. (http://cakefoundation.org)
 * @link          http://cakephp.org CakePHP(tm) Project
 * @package       cake
 * @subpackage    cake.cake.libs
 * @since         CakePHP(tm) v 1.2.0.4933
 * @license       MIT License (http://www.opensource.org/licenses/mit-license.php)
 */

/**
 * Caching for CakePHP.
 *
 * @package       cake
 * @subpackage    cake.cake.libs
 */
class Cache extends Object {

/**
 * Cache engine to use
 *
 * @var CacheEngine
 * @access protected
 */
	var $_Engine = null;

/**
 * Cache configuration stack
 *
 * @var array
 * @access private
 */
	var $__config = array();

/**
 * Holds name of the current configuration being used
 *
 * @var array
 * @access private
 */
	var $__name = 'default';

/**
 * whether to reset the settings with the next call to self::set();
 *
 * @var array
 * @access private
 */
	var $__reset = false;

/**
 * Returns a singleton instance
 *
 * @return object
 * @access public
 * @static
 */
	function &getInstance() {
		static $instance = array();
		if (!$instance) {
			$instance[0] =& new Cache();
		}
		return $instance[0];
	}

/**
 * Tries to find and include a file for a cache engine and returns object instance
 *
 * @param $name	Name of the engine (without 'Engine')
 * @return mixed $engine object or null
 * @access private
 */
	function __loadEngine($name) {
		if (!class_exists($name . 'Engine')) {
			require LIBS . DS . 'cache' . DS . strtolower($name) . '.php';
		}
		return true;
	}

/**
 * Set the cache configuration to use
 *
 * @see app/config/core.php for configuration settings
 * @param string $name Name of the configuration
 * @param array $settings Optional associative array of settings passed to the engine
 * @return array(engine, settings) on success, false on failure
 * @access public
 * @static
 */
	function config($name = null, $settings = array()) {
		$_this =& Cache::getInstance();
		if (is_array($name)) {
			$settings = $name;
		}

		if ($name === null || !is_string($name)) {
			$name = $_this->__name;
		}

		$current = array();
		if (isset($_this->__config[$name])) {
			$current = $_this->__config[$name];
		}

		if (!empty($settings)) {
			$_this->__name = null;
			$_this->__config[$name] = array_merge($current, $settings);
		}

		if (empty($_this->__config[$name]['engine'])) {
			return false;
		}

		$_this->__name = $name;
		$engine = $_this->__config[$name]['engine'];

		if (!$_this->isInitialized($engine)) {
			if ($_this->engine($engine, $_this->__config[$name]) === false) {
				return false;
			}
			$settings = $_this->__config[$name] = $_this->settings($engine);
		} else if ($settings = $_this->set($_this->__config[$name])) {
			$_this->__config[$name] = $settings;
		}
		return compact('engine', 'settings');
	}

/**
 * Set the cache engine to use or modify settings for one instance
 *
 * @param string $name Name of the engine (without 'Engine')
 * @param array $settings Optional associative array of settings passed to the engine
 * @return boolean True on success, false on failure
 * @access public
 * @static
 */
	function engine($name = 'File', $settings = array()) {
		$cacheClass = $name . 'Engine';
		$_this =& Cache::getInstance();
		if (!isset($_this->_Engine[$name])) {
			if ($_this->__loadEngine($name) === false) {
				return false;
			}
			$_this->_Engine[$name] =& new $cacheClass();
		}

		if ($_this->_Engine[$name]->init($settings)) {
			if (time() % $_this->_Engine[$name]->settings['probability'] === 0) {
				$_this->_Engine[$name]->gc();
			}
			return true;
		}
		$_this->_Engine[$name] = null;
		return false;
	}

/**
 * Temporarily change settings to current config options. if no params are passed, resets settings if needed
 * Cache::write() will reset the configuration changes made
 *
 * @param mixed $settings Optional string for simple name-value pair or array
 * @param string $value Optional for a simple name-value pair
 * @return array of settings
 * @access public
 * @static
 */
	function set($settings = array(), $value = null) {
		$_this =& Cache::getInstance();
		if (!isset($_this->__config[$_this->__name])) {
			return false;
		}

		$engine = $_this->__config[$_this->__name]['engine'];
		if (!empty($settings)) {
			$_this->__reset = true;
		}

		if ($_this->__reset === true) {
			if (empty($settings)) {
				$_this->__reset = false;
				$settings = $_this->__config[$_this->__name];
			} else {
				if (is_string($settings) && $value !== null) {
					$settings = array($settings => $value);
				}
				$settings = array_merge($_this->__config[$_this->__name], $settings);
			}
			$_this->engine($engine, $settings);
		}

		return $_this->settings($engine);
	}

/**
 * Garbage collection
 *
 * Permanently remove all expired and deleted data
 *
 * @return void
 * @access public
 * @static
 */
	function gc() {
		$_this =& Cache::getInstance();
		$config = $_this->config();
		$_this->_Engine[$config['engine']]->gc();
	}

/**
 * Write data for key into cache
 *
 * @param string $key Identifier for the data
 * @param mixed $value Data to be cached - anything except a resource
 * @param string $config Optional - string configuration name
 * @return boolean True if the data was successfully cached, false on failure
 * @access public
 * @static
 */
	function write($key, $value, $config = null) {
		$_this =& Cache::getInstance();

		if (is_array($config)) {
			extract($config);
		} else if ($config && (is_numeric($config) || is_numeric($config[0]) || (isset($config[1]) && is_numeric($config[1])))) {
			$config = null;
		}

		if ($config && isset($_this->__config[$config])) {
			$settings = $_this->set($_this->__config[$config]);
		} else {
			$settings = $_this->settings();
		}

		if (empty($settings)) {
			return null;
		}
		extract($settings);

		if (!$_this->isInitialized($engine)) {
			return false;
		}

		if (!$key = $_this->_Engine[$engine]->key($key)) {
			return false;
		}

		if (is_resource($value)) {
			return false;
		}

		if ($duration < 1) {
			return false;
		}

		$success = $_this->_Engine[$engine]->write($settings['prefix'] . $key, $value, $duration);
		$settings = $_this->set();
		return $success;
	}

/**
 * Read a key from the cache
 *
 * @param string $key Identifier for the data
 * @param string $config name of the configuration to use
 * @return mixed The cached data, or false if the data doesn't exist, has expired, or if there was an error fetching it
 * @access public
 * @static
 */
	function read($key, $config = null) {
		$_this =& Cache::getInstance();

		if (isset($_this->__config[$config])) {
			$settings = $_this->set($_this->__config[$config]);
		} else {
			$settings = $_this->settings();
		}

		if (empty($settings)) {
			return null;
		}
		extract($settings);

		if (!$_this->isInitialized($engine)) {
			return false;
		}
		if (!$key = $_this->_Engine[$engine]->key($key)) {
			return false;
		}
		$success = $_this->_Engine[$engine]->read($settings['prefix'] . $key);

		if ($config !== null && $config !== $_this->__name) {
			$settings = $_this->set();
		}
		return $success;
	}

/**
 * Delete a key from the cache
 *
 * @param string $key Identifier for the data
 * @param string $config name of the configuration to use
 * @return boolean True if the value was succesfully deleted, false if it didn't exist or couldn't be removed
 * @access public
 * @static
 */
	function delete($key, $config = null) {
		$_this =& Cache::getInstance();
		if (isset($_this->__config[$config])) {
			$settings = $_this->set($_this->__config[$config]);
		} else {
			$settings = $_this->settings();
		}

		if (empty($settings)) {
			return null;
		}
		extract($settings);

		if (!$_this->isInitialized($engine)) {
			return false;
		}

		if (!$key = $_this->_Engine[$engine]->key($key)) {
			return false;
		}

		$success = $_this->_Engine[$engine]->delete($settings['prefix'] . $key);
		$settings = $_this->set();
		return $success;
	}

/**
 * Delete all keys from the cache
 *
 * @param boolean $check if true will check expiration, otherwise delete all
 * @param string $config name of the configuration to use
 * @return boolean True if the cache was succesfully cleared, false otherwise
 * @access public
 * @static
 */
	function clear($check = false, $config = null) {
		$_this =& Cache::getInstance();
		if (isset($_this->__config[$config])) {
			$settings = $_this->set($_this->__config[$config]);
		} else {
			$settings = $_this->settings();
		}

		if (empty($settings)) {
			return null;
		}
		extract($settings);

		if (isset($engine) && !$_this->isInitialized($engine)) {
			return false;
		}
		$success = $_this->_Engine[$engine]->clear($check);
		$settings = $_this->set();
		return $success;
	}

/**
 * Check if Cache has initialized a working storage engine
 *
 * @param string $engine Name of the engine
 * @param string $config Name of the configuration setting
 * @return bool
 * @access public
 * @static
 */
	function isInitialized($engine = null) {
		if (Configure::read('Cache.disable')) {
			return false;
		}
		$_this =& Cache::getInstance();
		if (!$engine && isset($_this->__config[$_this->__name]['engine'])) {
			$engine = $_this->__config[$_this->__name]['engine'];
		}
		return isset($_this->_Engine[$engine]);
	}

/**
 * Return the settings for current cache engine
 *
 * @param string $engine Name of the engine
 * @return array list of settings for this engine
 * @access public
 * @static
 */
	function settings($engine = null) {
		$_this =& Cache::getInstance();
		if (!$engine && isset($_this->__config[$_this->__name]['engine'])) {
			$engine = $_this->__config[$_this->__name]['engine'];
		}

		if (isset($_this->_Engine[$engine]) && !is_null($_this->_Engine[$engine])) {
			return $_this->_Engine[$engine]->settings();
		}
		return array();
	}
}

/**
 * Storage engine for CakePHP caching
 *
 * @package       cake
 * @subpackage    cake.cake.libs
 */
class CacheEngine extends Object {

/**
 * settings of current engine instance
 *
 * @var int
 * @access public
 */
	var $settings = array();

/**
 * Iitialize the cache engine
 *
 * Called automatically by the cache frontend
 *
 * @param array $params Associative array of parameters for the engine
 * @return boolean True if the engine has been succesfully initialized, false if not
 * @access public
 */
	function init($settings = array()) {
		$this->settings = array_merge(array('prefix' => 'cake_', 'duration'=> 3600, 'probability'=> 100), $this->settings, $settings);
		if (!is_numeric($this->settings['duration'])) {
			$this->settings['duration'] = strtotime($this->settings['duration']) - time();
		}
		return true;
	}

/**
 * Garbage collection
 *
 * Permanently remove all expired and deleted data
 *
 * @access public
 */
	function gc() {
	}

/**
 * Write value for a key into cache
 *
 * @param string $key Identifier for the data
 * @param mixed $value Data to be cached
 * @param mixed $duration How long to cache the data, in seconds
 * @return boolean True if the data was succesfully cached, false on failure
 * @access public
 */
	function write($key, &$value, $duration) {
		trigger_error(sprintf(__('Method write() not implemented in %s', true), get_class($this)), E_USER_ERROR);
	}

/**
 * Read a key from the cache
 *
 * @param string $key Identifier for the data
 * @return mixed The cached data, or false if the data doesn't exist, has expired, or if there was an error fetching it
 * @access public
 */
	function read($key) {
		trigger_error(sprintf(__('Method read() not implemented in %s', true), get_class($this)), E_USER_ERROR);
	}

/**
 * Delete a key from the cache
 *
 * @param string $key Identifier for the data
 * @return boolean True if the value was succesfully deleted, false if it didn't exist or couldn't be removed
 * @access public
 */
	function delete($key) {
	}

/**
 * Delete all keys from the cache
 *
 * @param boolean $check if true will check expiration, otherwise delete all
 * @return boolean True if the cache was succesfully cleared, false otherwise
 * @access public
 */
	function clear($check) {
	}

/**
 * Cache Engine settings
 *
 * @return array settings
 * @access public
 */
	function settings() {
		return $this->settings;
	}

/**
 * generates a safe key
 *
 * @param string $key the key passed over
 * @return mixed string $key or false
 * @access public
 */
	function key($key) {
		if (empty($key)) {
			return false;
		}
		$key = Inflector::underscore(str_replace(array(DS, '/', '.'), '_', strval($key)));
		return $key;
	}
}
?>