README.md

Simplified TwoLevels

This backend is based on the concept of Zend_Cache's TwoLevels backend except it is only intended to use the fast backend for actual cache record storage and the slow backend for tagging support. The slow backend stores only empty records.

modman

TwoLevels.php                          app/code/local/Zend/Cache/Backend/TwoLevels.php

TwoLevels.php

<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Cache
 * @subpackage Zend_Cache_Backend
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: TwoLevels.php 17741 2009-08-22 02:58:33Z yoshida@zend.co.jp $
 */


/**
 * @see Zend_Cache_Backend_ExtendedInterface
 */
#require_once 'Zend/Cache/Backend/ExtendedInterface.php';

/**
 * @see Zend_Cache_Backend
 */
#require_once 'Zend/Cache/Backend.php';


/**
 * @package    Zend_Cache
 * @subpackage Zend_Cache_Backend
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */

class Zend_Cache_Backend_TwoLevels extends Zend_Cache_Backend implements Zend_Cache_Backend_ExtendedInterface
{
    /**
     * Available options
     *
     * =====> (string) slow_backend :
     * - Slow backend name
     * - Must implement the Zend_Cache_Backend_ExtendedInterface
     * - Should provide a big storage
     *
     * =====> (string) fast_backend :
     * - Flow backend name
     * - Must implement the Zend_Cache_Backend_ExtendedInterface
     * - Must be much faster than slow_backend
     *
     * =====> (array) slow_backend_options :
     * - Slow backend options (see corresponding backend)
     *
     * =====> (array) fast_backend_options :
     * - Fast backend options (see corresponding backend)
     *
     * =====> (boolean) slow_backend_custom_naming :
     * =====> (boolean) fast_backend_custom_naming :
     * =====> (boolean) slow_backend_autoload :
     * =====> (boolean) fast_backend_autoload :
     * - See Zend_Cache::factory() method
     *
     * @var array available options
     */
    protected $_options = array(
        'slow_backend' => 'File',
        'fast_backend' => 'Apc',
        'slow_backend_options' => array(),
        'fast_backend_options' => array(),
        'slow_backend_custom_naming' => false,
        'fast_backend_custom_naming' => false,
        'slow_backend_autoload' => false,
        'fast_backend_autoload' => false,
    );

    /**
     * Slow Backend
     *
     * @var Zend_Cache_Backend
     */
    private $_slowBackend;

    /**
     * Fast Backend
     *
     * @var Zend_Cache_Backend
     */
    private $_fastBackend;

    /**
     * Constructor
     *
     * @param  array $options Associative array of options
     * @throws Zend_Cache_Exception
     */
    public function __construct(array $options = array())
    {
        parent::__construct($options);
        if ($this->_options['slow_backend'] === null) {
            Zend_Cache::throwException('slow_backend option has to set');
        }
        if ($this->_options['fast_backend'] === null) {
            Zend_Cache::throwException('fast_backend option has to set');
        }
        $this->_slowBackend = Zend_Cache::_makeBackend($this->_options['slow_backend'], $this->_options['slow_backend_options'], $this->_options['slow_backend_custom_naming'], $this->_options['slow_backend_autoload']);
        $this->_fastBackend = Zend_Cache::_makeBackend($this->_options['fast_backend'], $this->_options['fast_backend_options'], $this->_options['fast_backend_custom_naming'], $this->_options['fast_backend_autoload']);
        if (!in_array('Zend_Cache_Backend_ExtendedInterface', class_implements($this->_slowBackend))) {
            Zend_Cache::throwException('slow_backend must implement the Zend_Cache_Backend_ExtendedInterface interface');
        }
        if (!in_array('Zend_Cache_Backend_ExtendedInterface', class_implements($this->_fastBackend))) {
            Zend_Cache::throwException('fast_backend must implement the Zend_Cache_Backend_ExtendedInterface interface');
        }
        $this->_slowBackend->setDirectives($this->_directives);
        $this->_fastBackend->setDirectives($this->_directives);
    }

    /**
     * Test if a cache is available or not (for the given id)
     *
     * @param  string $id cache id
     * @return mixed|false (a cache is not available) or "last modified" timestamp (int) of the available cache record
     */
    public function test($id)
    {
        return $this->_fastBackend->test($id);
    }

    /**
     * Save some string datas into a cache record
     *
     * Note : $data is always "string" (serialization is done by the
     * core not by the backend)
     *
     * @param  string $data            Datas to cache
     * @param  string $id              Cache id
     * @param  array $tags             Array of strings, the cache record will be tagged by each string entry
     * @param bool|int $specificLifetime If != false, set a specific lifetime for this cache record (null => infinite lifetime)
     * @return boolean true if no problem
     */
    public function save($data, $id, $tags = array(), $specificLifetime = false)
    {
        $lifetime = $this->getLifetime($specificLifetime);
        $boolFast = $this->_fastBackend->save($data, $id, array(), $lifetime);
        $boolSlow = $this->_slowBackend->save('', $id, $tags, $lifetime);
        return ($boolFast && $boolSlow);
    }

    /**
     * Test if a cache is available for the given id and (if yes) return it (false else)
     *
     * Note : return value is always "string" (unserialization is done by the core not by the backend)
     *
     * @param  string  $id                     Cache id
     * @param  boolean $doNotTestCacheValidity If set to true, the cache validity won't be tested
     * @return string|false cached datas
     */
    public function load($id, $doNotTestCacheValidity = false)
    {
        return $this->_fastBackend->load($id, $doNotTestCacheValidity);
    }

    /**
     * Remove a cache record
     *
     * @param  string $id Cache id
     * @return boolean True if no problem
     */
    public function remove($id)
    {
        $boolFast = $this->_fastBackend->remove($id);
        $boolSlow = $this->_slowBackend->remove($id);
        return $boolFast && $boolSlow;
    }

    /**
     * Clean some cache records
     *
     * Available modes are :
     * Zend_Cache::CLEANING_MODE_ALL (default)    => remove all cache entries ($tags is not used)
     * Zend_Cache::CLEANING_MODE_OLD              => remove too old cache entries ($tags is not used)
     * Zend_Cache::CLEANING_MODE_MATCHING_TAG     => remove cache entries matching all given tags
     *                                               ($tags can be an array of strings or a single string)
     * Zend_Cache::CLEANING_MODE_NOT_MATCHING_TAG => remove cache entries not {matching one of the given tags}
     *                                               ($tags can be an array of strings or a single string)
     * Zend_Cache::CLEANING_MODE_MATCHING_ANY_TAG => remove cache entries matching any given tags
     *                                               ($tags can be an array of strings or a single string)
     *
     * @param  string $mode Clean mode
     * @param  array  $tags Array of tags
     * @throws Zend_Cache_Exception
     * @return boolean true if no problem
     */
    public function clean($mode = Zend_Cache::CLEANING_MODE_ALL, $tags = array())
    {
        switch($mode) {
            case Zend_Cache::CLEANING_MODE_ALL:
                $boolFast = $this->_fastBackend->clean(Zend_Cache::CLEANING_MODE_ALL);
                $boolSlow = $this->_slowBackend->clean(Zend_Cache::CLEANING_MODE_ALL);
                return $boolFast && $boolSlow;
            case Zend_Cache::CLEANING_MODE_OLD:
                $boolFast = $this->_fastBackend->clean(Zend_Cache::CLEANING_MODE_OLD);
                $boolSlow = $this->_slowBackend->clean(Zend_Cache::CLEANING_MODE_OLD);
                return $boolFast && $boolSlow;
            case Zend_Cache::CLEANING_MODE_MATCHING_TAG:
                $ids = $this->_slowBackend->getIdsMatchingTags($tags);
                break;
            case Zend_Cache::CLEANING_MODE_NOT_MATCHING_TAG:
                $ids = $this->_slowBackend->getIdsNotMatchingTags($tags);
                break;
            case Zend_Cache::CLEANING_MODE_MATCHING_ANY_TAG:
                $ids = $this->_slowBackend->getIdsMatchingAnyTags($tags);
                break;
            default:
                Zend_Cache::throwException('Invalid mode for clean() method');
                break;
        }
        foreach ($ids as $id) {
            $this->_fastBackend->remove($id);
        }
        return $this->_slowBackend->clean($mode, $tags);
    }

    /**
     * Return an array of stored cache ids
     *
     * @return array array of stored cache ids (string)
     */
    public function getIds()
    {
        return $this->_slowBackend->getIds();
    }

    /**
     * Return an array of stored tags
     *
     * @return array array of stored tags (string)
     */
    public function getTags()
    {
        return $this->_slowBackend->getTags();
    }

    /**
     * Return an array of stored cache ids which match given tags
     *
     * In case of multiple tags, a logical AND is made between tags
     *
     * @param array $tags array of tags
     * @return array array of matching cache ids (string)
     */
    public function getIdsMatchingTags($tags = array())
    {
        return $this->_slowBackend->getIdsMatchingTags($tags);
    }

    /**
     * Return an array of stored cache ids which don't match given tags
     *
     * In case of multiple tags, a logical OR is made between tags
     *
     * @param array $tags array of tags
     * @return array array of not matching cache ids (string)
     */
    public function getIdsNotMatchingTags($tags = array())
    {
        return $this->_slowBackend->getIdsNotMatchingTags($tags);
    }

    /**
     * Return an array of stored cache ids which match any given tags
     *
     * In case of multiple tags, a logical AND is made between tags
     *
     * @param array $tags array of tags
     * @return array array of any matching cache ids (string)
     */
    public function getIdsMatchingAnyTags($tags = array())
    {
        return $this->_slowBackend->getIdsMatchingAnyTags($tags);
    }


    /**
     * Return the filling percentage of the backend storage
     *
     * @return int integer between 0 and 100
     */
    public function getFillingPercentage()
    {
        return $this->_slowBackend->getFillingPercentage();
    }

    /**
     * Return an array of metadatas for the given cache id
     *
     * The array must include these keys :
     * - expire : the expire timestamp
     * - tags : a string array of tags
     * - mtime : timestamp of last modification time
     *
     * @param string $id cache id
     * @return array array of metadatas (false if the cache id is not found)
     */
    public function getMetadatas($id)
    {
        return $this->_slowBackend->getMetadatas($id);
    }

    /**
     * Give (if possible) an extra lifetime to the given cache id
     *
     * @param string $id cache id
     * @param int $extraLifetime
     * @return boolean true if ok
     */
    public function touch($id, $extraLifetime)
    {
        return (
            $this->_fastBackend->touch($id, $extraLifetime) &&
            $this->_slowBackend->touch($id, $extraLifetime)
        );
    }

    /**
     * Return an associative array of capabilities (booleans) of the backend
     *
     * The array must include these keys :
     * - automatic_cleaning (is automating cleaning necessary)
     * - tags (are tags supported)
     * - expired_read (is it possible to read expired cache records
     *                 (for doNotTestCacheValidity option for example))
     * - priority does the backend deal with priority when saving
     * - infinite_lifetime (is infinite lifetime can work with this backend)
     * - get_list (is it possible to get the list of cache ids and the complete list of tags)
     *
     * @return array associative of with capabilities
     */
    public function getCapabilities()
    {
        $fastBackendCapabilities = $this->_fastBackend->getCapabilities();
        $slowBackendCapabilities = $this->_slowBackend->getCapabilities();
        return array(
            'automatic_cleaning' => $slowBackendCapabilities['automatic_cleaning'] || $fastBackendCapabilities['automatic_cleaning'],
            'tags' => $slowBackendCapabilities['tags'],
            'expired_read' => $fastBackendCapabilities['expired_read'],
            'priority' => false,
            'infinite_lifetime' => $slowBackendCapabilities['infinite_lifetime'] && $fastBackendCapabilities['infinite_lifetime'],
            'get_list' => $slowBackendCapabilities['get_list']
        );
    }

    /**
     * PUBLIC METHOD FOR UNIT TESTING ONLY !
     *
     * Force a cache record to expire
     *
     * @param string $id cache id
     */
    public function ___expire($id)
    {
        $this->_fastBackend->remove($id);
        $this->_slowBackend->___expire($id);
    }

}