<?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) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 * @version    $Id$

 */

/**

 * @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) 2005-2015 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)

     *

     * =====> (int) stats_update_factor :

     * - Disable / Tune the computation of the fast backend filling percentage

     * - When saving a record into cache :

     *     1               => systematic computation of the fast backend filling percentage

     *     x (integer) > 1 => computation of the fast backend filling percentage randomly 1 times on x cache write

     *

     * =====> (boolean) slow_backend_custom_naming :

     * =====> (boolean) fast_backend_custom_naming :

     * =====> (boolean) slow_backend_autoload :

     * =====> (boolean) fast_backend_autoload :

     * - See Zend_Cache::factory() method

     *

     * =====> (boolean) auto_fill_fast_cache

     * - If true, automatically fill the fast cache when a cache record was not found in fast cache, but did

     *   exist in slow cache. This can be usefull when a non-persistent cache like APC or Memcached got

     *   purged for whatever reason.

     * 

     * =====> (boolean) auto_refresh_fast_cache

     * - If true, auto refresh the fast cache when a cache record is hit

     *

     * @var array available options

     */

    protected $_options = array(

        'slow_backend' => 'File',

        'fast_backend' => 'Apc',

        'slow_backend_options' => array(),

        'fast_backend_options' => array(),

        'stats_update_factor' => 10,

        'slow_backend_custom_naming' => false,

        'fast_backend_custom_naming' => false,

        'slow_backend_autoload' => false,

        'fast_backend_autoload' => false,

        'auto_fill_fast_cache' => true,

        'auto_refresh_fast_cache' => true

    );

    /**

     * Slow Backend

     *

     * @var Zend_Cache_Backend_ExtendedInterface

     */

    protected $_slowBackend;

    /**

     * Fast Backend

     *

     * @var Zend_Cache_Backend_ExtendedInterface

     */

    protected $_fastBackend;

    /**

     * Cache for the fast backend filling percentage

     *

     * @var int

     */

    protected $_fastBackendFillingPercentage = null;

    /**

     * Constructor

     *

     * @param  array $options Associative array of options

     * @throws Zend_Cache_Exception

     * @return void

     */

    public function __construct(array $options = array())

    {

        parent::__construct($options);

        if ($this->_options['slow_backend'] === null) {

            Zend_Cache::throwException('slow_backend option has to set');

        } elseif ($this->_options['slow_backend'] instanceof Zend_Cache_Backend_ExtendedInterface) {

            $this->_slowBackend = $this->_options['slow_backend'];

        } else {

            $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']

            );

            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 ($this->_options['fast_backend'] === null) {

            Zend_Cache::throwException('fast_backend option has to set');

        } elseif ($this->_options['fast_backend'] instanceof Zend_Cache_Backend_ExtendedInterface) {

            $this->_fastBackend = $this->_options['fast_backend'];

        } else {

            $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->_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)

    {

        $fastTest = $this->_fastBackend->test($id);

        if ($fastTest) {

            return $fastTest;

        } else {

            return $this->_slowBackend->test($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  int   $specificLifetime If != false, set a specific lifetime for this cache record (null => infinite lifetime)

     * @param  int   $priority         integer between 0 (very low priority) and 10 (maximum priority) used by some particular backends

     * @return boolean true if no problem

     */

    public function save($data, $id, $tags = array(), $specificLifetime = false, $priority = 8)

    {

        $usage = $this->_getFastFillingPercentage('saving');

        $boolFast = true;

        $lifetime = $this->getLifetime($specificLifetime);

        $preparedData = $this->_prepareData($data, $lifetime, $priority);

        if (($priority > 0) && (10 * $priority >= $usage)) {

            $fastLifetime = $this->_getFastLifetime($lifetime, $priority);

            $boolFast = $this->_fastBackend->save($preparedData, $id, array(), $fastLifetime);

            $boolSlow = $this->_slowBackend->save($preparedData, $id, $tags, $lifetime);

        } else {

            $boolSlow = $this->_slowBackend->save($preparedData, $id, $tags, $lifetime);

            if ($boolSlow === true) {

                $boolFast = $this->_fastBackend->remove($id);

                if (!$boolFast && !$this->_fastBackend->test($id)) {

                    // some backends return false on remove() even if the key never existed. (and it won't if fast is full)

                    // all we care about is that the key doesn't exist now

                    $boolFast = true;

                }

            }

        }

        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)

    {

        $resultFast = $this->_fastBackend->load($id, $doNotTestCacheValidity);

        if ($resultFast === false) {

            $resultSlow = $this->_slowBackend->load($id, $doNotTestCacheValidity);

            if ($resultSlow === false) {

                // there is no cache at all for this id

                return false;

            }

        }

        $array = $resultFast !== false ? unserialize($resultFast) : unserialize($resultSlow);

        //In case no cache entry was found in the FastCache and auto-filling is enabled, copy data to FastCache

        if ($resultFast === false && $this->_options['auto_fill_fast_cache']) {

            $preparedData = $this->_prepareData($array['data'], $array['lifetime'], $array['priority']);

            $this->_fastBackend->save($preparedData, $id, array(), $array['lifetime']);

        }

        // maybe, we have to refresh the fast cache ?

        elseif ($this->_options['auto_refresh_fast_cache']) {

            if ($array['priority'] == 10) {

                // no need to refresh the fast cache with priority = 10

                return $array['data'];

            }

            $newFastLifetime = $this->_getFastLifetime($array['lifetime'], $array['priority'], time() - $array['expire']);

            // we have the time to refresh the fast cache

            $usage = $this->_getFastFillingPercentage('loading');

            if (($array['priority'] > 0) && (10 * $array['priority'] >= $usage)) {

                // we can refresh the fast cache

                $preparedData = $this->_prepareData($array['data'], $array['lifetime'], $array['priority']);

                $this->_fastBackend->save($preparedData, $id, array(), $newFastLifetime);

            }

        }

        return $array['data'];

    }

    /**

     * 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;

                break;

            case Zend_Cache::CLEANING_MODE_OLD:

                return $this->_slowBackend->clean(Zend_Cache::CLEANING_MODE_OLD);

            case Zend_Cache::CLEANING_MODE_MATCHING_TAG:

                $ids = $this->_slowBackend->getIdsMatchingTags($tags);

                $res = true;

                foreach ($ids as $id) {

                    $bool = $this->remove($id);

                    $res = $res && $bool;

                }

                return $res;

                break;

            case Zend_Cache::CLEANING_MODE_NOT_MATCHING_TAG:

                $ids = $this->_slowBackend->getIdsNotMatchingTags($tags);

                $res = true;

                foreach ($ids as $id) {

                    $bool = $this->remove($id);

                    $res = $res && $bool;

                }

                return $res;

                break;

            case Zend_Cache::CLEANING_MODE_MATCHING_ANY_TAG:

                $ids = $this->_slowBackend->getIdsMatchingAnyTags($tags);

                $res = true;

                foreach ($ids as $id) {

                    $bool = $this->remove($id);

                    $res = $res && $bool;

                }

                return $res;

                break;

            default:

                Zend_Cache::throwException('Invalid mode for clean() method');

                break;

        }

    }

    /**

     * 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 $this->_slowBackend->touch($id, $extraLifetime);

    }

    /**