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 <?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);
     }
 
     /**
      * 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()
     {
         $slowBackendCapabilities = $this->_slowBackend->getCapabilities();
         return array(
             'automatic_cleaning' => $slowBackendCapabilities['automatic_cleaning'],
             'tags' => $slowBackendCapabilities['tags'],
             'expired_read' => $slowBackendCapabilities['expired_read'],
             'priority' => $slowBackendCapabilities['priority'],
             'infinite_lifetime' => $slowBackendCapabilities['infinite_lifetime'],
             'get_list' => $slowBackendCapabilities['get_list']
         );
     }
 
     /**
      * Prepare a serialized array to store datas and metadatas informations
      *
      * @param string $data data to store
      * @param int $lifetime original lifetime
      * @param int $priority priority
      * @return string serialize array to store into cache
      */
     private function _prepareData($data, $lifetime, $priority)
     {
         $lt = $lifetime;
         if ($lt === null) {
             $lt = 9999999999;
         }
         return serialize(array(
             'data' => $data,
             'lifetime' => $lifetime,
             'expire' => time() + $lt,
             'priority' => $priority
         ));
     }
 
     /**
      * Compute and return the lifetime for the fast backend
      *
      * @param int $lifetime original lifetime
      * @param int $priority priority
      * @param int $maxLifetime maximum lifetime
      * @return int lifetime for the fast backend
      */
     private function _getFastLifetime($lifetime, $priority, $maxLifetime = null)
     {
         if ($lifetime <= 0) {
             // if no lifetime, we have an infinite lifetime
             // we need to use arbitrary lifetimes
             $fastLifetime = (int) (2592000 / (11 - $priority));
         } else {
             // prevent computed infinite lifetime (0) by ceil
             $fastLifetime = (int) ceil($lifetime / (11 - $priority));
         }
 
         if ($maxLifetime >= 0 && $fastLifetime > $maxLifetime) {
             return $maxLifetime;
         }
 
         return $fastLifetime;
     }
 
     /**
      * 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);
     }
 
     private function _getFastFillingPercentage($mode)
     {
 
         if ($mode == 'saving') {
             // mode saving
             if ($this->_fastBackendFillingPercentage === null) {
                 $this->_fastBackendFillingPercentage = $this->_fastBackend->getFillingPercentage();
             } else {
                 $rand = rand(1, $this->_options['stats_update_factor']);
                 if ($rand == 1) {
                     // we force a refresh
                     $this->_fastBackendFillingPercentage = $this->_fastBackend->getFillingPercentage();
                 }
             }
         } else {
             // mode loading
             // we compute the percentage only if it's not available in cache
             if ($this->_fastBackendFillingPercentage === null) {
                 $this->_fastBackendFillingPercentage = $this->_fastBackend->getFillingPercentage();
             }
         }
         return $this->_fastBackendFillingPercentage;
     }
 
 }