1: <?php
  2: /**
  3:  * CCacheHttpSession class
  4:  *
  5:  * @author Qiang Xue <qiang.xue@gmail.com>
  6:  * @link http://www.yiiframework.com/
  7:  * @copyright 2008-2013 Yii Software LLC
  8:  * @license http://www.yiiframework.com/license/
  9:  */
 10: 
 11: 
 12: /**
 13:  * CCacheHttpSession implements a session component using cache as storage medium.
 14:  *
 15:  * The cache being used can be any cache application component implementing {@link ICache} interface.
 16:  * The ID of the cache application component is specified via {@link cacheID}, which defaults to 'cache'.
 17:  *
 18:  * Beware, by definition cache storage are volatile, which means the data stored on them
 19:  * may be swapped out and get lost. Therefore, you must make sure the cache used by this component
 20:  * is NOT volatile. If you want to use {@link CDbCache} as storage medium, use {@link CDbHttpSession}
 21:  * is a better choice.
 22:  *
 23:  * @property boolean $useCustomStorage Whether to use custom storage.
 24:  *
 25:  * @author Qiang Xue <qiang.xue@gmail.com>
 26:  * @package system.web
 27:  * @since 1.0
 28:  */
 29: class CCacheHttpSession extends CHttpSession
 30: {
 31:     /**
 32:      * Prefix to the keys for storing cached data
 33:      */
 34:     const CACHE_KEY_PREFIX='Yii.CCacheHttpSession.';
 35:     /**
 36:      * @var string the ID of the cache application component. Defaults to 'cache' (the primary cache application component.)
 37:      */
 38:     public $cacheID='cache';
 39: 
 40:     /**
 41:      * @var ICache the cache component
 42:      */
 43:     private $_cache;
 44: 
 45:     /**
 46:      * Initializes the application component.
 47:      * This method overrides the parent implementation by checking if cache is available.
 48:      */
 49:     public function init()
 50:     {
 51:         $this->_cache=Yii::app()->getComponent($this->cacheID);
 52:         if(!($this->_cache instanceof ICache))
 53:             throw new CException(Yii::t('yii','CCacheHttpSession.cacheID is invalid. Please make sure "{id}" refers to a valid cache application component.',
 54:                 array('{id}'=>$this->cacheID)));
 55:         parent::init();
 56:     }
 57: 
 58:     /**
 59:      * Returns a value indicating whether to use custom session storage.
 60:      * This method overrides the parent implementation and always returns true.
 61:      * @return boolean whether to use custom storage.
 62:      */
 63:     public function getUseCustomStorage()
 64:     {
 65:         return true;
 66:     }
 67: 
 68:     /**
 69:      * Session read handler.
 70:      * Do not call this method directly.
 71:      * @param string $id session ID
 72:      * @return string the session data
 73:      */
 74:     public function readSession($id)
 75:     {
 76:         $data=$this->_cache->get($this->calculateKey($id));
 77:         return $data===false?'':$data;
 78:     }
 79: 
 80:     /**
 81:      * Session write handler.
 82:      * Do not call this method directly.
 83:      * @param string $id session ID
 84:      * @param string $data session data
 85:      * @return boolean whether session write is successful
 86:      */
 87:     public function writeSession($id,$data)
 88:     {
 89:         return $this->_cache->set($this->calculateKey($id),$data,$this->getTimeout());
 90:     }
 91: 
 92:     /**
 93:      * Session destroy handler.
 94:      * Do not call this method directly.
 95:      * @param string $id session ID
 96:      * @return boolean whether session is destroyed successfully
 97:      */
 98:     public function destroySession($id)
 99:     {
100:         return $this->_cache->delete($this->calculateKey($id));
101:     }
102: 
103:     /**
104:      * Generates a unique key used for storing session data in cache.
105:      * @param string $id session variable name
106:      * @return string a safe cache key associated with the session variable name
107:      */
108:     protected function calculateKey($id)
109:     {
110:         return self::CACHE_KEY_PREFIX.$id;
111:     }
112: }
113: