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<?php
/**
* DbSession class file.
*
* @link http://www.yiiframework.com/
* @copyright Copyright &copy; 2008 Yii Software LLC
* @license http://www.yiiframework.com/license/
*/
namespace yii\web;
/**
* CacheSession implements a session component using cache as storage medium.
*
* The cache being used can be any cache application component implementing {@link ICache} interface.
* The ID of the cache application component is specified via {@link cacheID}, which defaults to 'cache'.
*
* Beware, by definition cache storage are volatile, which means the data stored on them
* may be swapped out and get lost. Therefore, you must make sure the cache used by this component
* is NOT volatile. If you want to use {@link CDbCache} as storage medium, use {@link CDbHttpSession}
* is a better choice.
*
* @property boolean $useCustomStorage Whether to use custom storage.
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @package system.web
* @since 1.0
*/
class CacheSession extends Session
{
/**
* Prefix to the keys for storing cached data
*/
const CACHE_KEY_PREFIX = 'Yii.CacheSession.';
/**
* @var string the ID of the cache application component. Defaults to 'cache' (the primary cache application component.)
*/
public $cacheID = 'cache';
/**
* @var ICache the cache component
*/
private $_cache;
/**
* Initializes the application component.
* This method overrides the parent implementation by checking if cache is available.
*/
public function init()
{
$this->_cache = Yii::app()->getComponent($this->cacheID);
if (!($this->_cache instanceof ICache)) {
throw new CException(Yii::t('yii', 'CacheSession.cacheID is invalid. Please make sure "{id}" refers to a valid cache application component.',
array('{id}' => $this->cacheID)));
}
parent::init();
}
/**
* Returns a value indicating whether to use custom session storage.
* This method overrides the parent implementation and always returns true.
* @return boolean whether to use custom storage.
*/
public function getUseCustomStorage()
{
return true;
}
/**
* Session read handler.
* Do not call this method directly.
* @param string $id session ID
* @return string the session data
*/
public function readSession($id)
{
$data = $this->_cache->get($this->calculateKey($id));
return $data === false ? '' : $data;
}
/**
* Session write handler.
* Do not call this method directly.
* @param string $id session ID
* @param string $data session data
* @return boolean whether session write is successful
*/
public function writeSession($id, $data)
{
return $this->_cache->set($this->calculateKey($id), $data, $this->getTimeout());
}
/**
* Session destroy handler.
* Do not call this method directly.
* @param string $id session ID
* @return boolean whether session is destroyed successfully
*/
public function destroySession($id)
{
return $this->_cache->delete($this->calculateKey($id));
}
/**
* Generates a unique key used for storing session data in cache.
* @param string $id session variable name
* @return string a safe cache key associated with the session variable name
*/
protected function calculateKey($id)
{
return self::CACHE_KEY_PREFIX . $id;
}
}