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cache.php

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<?php
/* SVN FILE: $Id: cache_8php-source.html 580 2008-07-01 14:45:49Z gwoo $ */
/**
 * Caching for CakePHP.
 *
 *
 * PHP versions 4 and 5
 *
 * CakePHP(tm) :  Rapid Development Framework <http://www.cakephp.org/>
 * Copyright 2005-2008, Cake Software Foundation, Inc.
 *                              1785 E. Sahara Avenue, Suite 490-204
 *                              Las Vegas, Nevada 89104
 *
 * Licensed under The MIT License
 * Redistributions of files must retain the above copyright notice.
 *
 * @filesource
 * @copyright       Copyright 2005-2008, Cake Software Foundation, Inc.
 * @link                http://www.cakefoundation.org/projects/info/cakephp CakePHP(tm) Project
 * @package         cake
 * @subpackage      cake.cake.libs
 * @since           CakePHP(tm) v 1.2.0.4933
 * @version         $Revision: 580 $
 * @modifiedby      $LastChangedBy: gwoo $
 * @lastmodified    $Date: 2008-07-01 09:45:49 -0500 (Tue, 01 Jul 2008) $
 * @license         http://www.opensource.org/licenses/mit-license.php The MIT License
 */
/**
 * Included libraries.
 */
/**
 * Caching for CakePHP.
 *
 * @package     cake
 * @subpackage  cake.cake.libs
 */
class Cache extends Object {
/**
 * Cache engine to use
 *
 * @var object
 * @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';
/**
 * Returns a singleton instance
 *
 * @return object
 * @access public
 */
    function &getInstance() {
        static $instance = array();
        if (!isset($instance[0]) || !$instance[0]) {
            $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')) {
            $fileName = LIBS . DS . 'cache' . DS . strtolower($name) . '.php';
            if (!require($fileName)) {
                return false;
            }
        }
        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 $settings Optional associative array of settings passed to the engine
 * @return array(engine, settings) on success, false on failure
 * @access public
 */
    function config($name = null, $settings = array()) {
        $_this =& Cache::getInstance();
        if (is_array($name)) {
            $settings = $name;
        }

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

        if (!empty($settings)) {
            $_this->__name = null;
            $_this->__config[$name] = $settings;
        } elseif (isset($_this->__config[$name])) {
            $settings = $_this->__config[$name];
        } else {
            return false;
        }

        if (empty($settings['engine'])) {
            return false;
        }

        $engine = $settings['engine'];

        if ($name !== $_this->__name) {
            if ($_this->engine($engine, $settings) === false) {
                return false;
            }
            $_this->__name = $name;

        }
        $settings = $_this->__config[$name] = $_this->settings($engine);
        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 $settings Optional associative array of settings passed to the engine
 * @return boolean True on success, false on failure
 * @access public
 */
    function engine($name = 'File', $settings = array()) {
        if (!$name || Configure::read('Cache.disable')) {
            return false;
        }

        $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;
    }
/**
 * Garbage collection
 *
 * Permanently remove all expired and deleted data
 *
 * @access public
 */
    function gc() {
        $_this =& Cache::getInstance();
        $config = $_this->config();
        extract($config);
        $_this->_Engine[$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 mixed $duration Optional - string configuration name OR how long to cache the data, either in seconds or a
 *          string that can be parsed by the strtotime() function OR array('config' => 'default', 'duration' => '3600')
 * @return boolean True if the data was successfully cached, false on failure
 * @access public
 */
    function write($key, $value, $duration = null) {
        $_this =& Cache::getInstance();
        $config = null;
        if (is_array($duration)) {
            extract($duration);
        } elseif (isset($_this->__config[$duration])) {
            $config = $duration;
            $duration = null;
        }
        $current = $_this->__name;
        $config = $_this->config($config);

        if (!is_array($config)) {
            return null;
        }
        extract($config);

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

        if (!$key = $_this->__key($key)) {
            return false;
        }

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

        if (!$duration) {
            $duration = $settings['duration'];
        }
        $duration = ife(is_numeric($duration), intval($duration), strtotime($duration) - time());

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

        $success = $_this->_Engine[$engine]->write($settings['prefix'] . $key, $value, $duration);
        $_this->config($current);
        return $success;
    }
/**
 * Read a key from the cache
 *
 * @param string $key Identifier for the data
 * @param string $config name of the configuration to use
 * @return mixed The cached data, or false if the data doesn't exist, has expired, or if there was an error fetching it
 * @access public
 */
    function read($key, $config = null) {
        $_this =& Cache::getInstance();
        $current = $_this->__name;

        $config = $_this->config($config);

        if (!is_array($config)) {
            return null;
        }
        extract($config);

        if (!$_this->isInitialized($engine)) {
            return false;
        }
        if (!$key = $_this->__key($key)) {
            return false;
        }
        $success = $_this->_Engine[$engine]->read($settings['prefix'] . $key);
        $_this->config($current);
        return $success;
    }
/**
 * Delete a key from the cache
 *
 * @param string $key Identifier for the data
 * @param string $config name of the configuration to use
 * @return boolean True if the value was succesfully deleted, false if it didn't exist or couldn't be removed
 * @access public
 */
    function delete($key, $config = null) {
        $_this =& Cache::getInstance();
        $current = $_this->__name;
        $config = $_this->config($config);
        extract($config);

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

        if (!$key = $_this->__key($key)) {
            return false;
        }

        $success = $_this->_Engine[$engine]->delete($settings['prefix'] . $key);
        $_this->config($current);
        return $success;
    }
/**
 * Delete all keys from the cache
 *
 * @param boolean $check if true will check expiration, otherwise delete all
 * @param string $config name of the configuration to use
 * @return boolean True if the cache was succesfully cleared, false otherwise
 * @access public
 */
    function clear($check = false, $config = null) {
        $_this =& Cache::getInstance();
        $current = $_this->__name;
        $config = $_this->config($config);
        extract($config);

        if (!$_this->isInitialized($engine)) {
            return false;
        }
        $success = $_this->_Engine[$engine]->clear($check);
        $_this->config($current);
        return $success;
    }
/**
 * Check if Cache has initialized a working storage engine
 *
 * @param string $engine Name of the engine
 * @param string $config Name of the configuration setting
 * @return bool
 * @access public
 */
    function isInitialized($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 $engine Name of the engine
 * @return array list of settings for this engine
 * @access public
 */
    function settings($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();
    }
/**
 * generates a safe key
 *
 * @param string $key the key passed over
 * @return mixed string $key or false
 * @access private
 */
    function __key($key) {
        if (empty($key)) {
            return false;
        }
        $key = str_replace(array(DS, '/', '.'), '_', strval($key));
        return $key;
    }
}
/**
 * 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);
        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;
    }
}
?>

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