* @link http://www.yiiframework.com/
* @copyright Copyright © 2008 Yii Software LLC
* @license http://www.yiiframework.com/license/
*/
/**
* CStatePersister implements a file-based persistent data storage.
*
* It can be used to keep data available through multiple requests and sessions.
*
* By default, CStatePersister stores data in a file named 'state.bin' that is located
* under the application {@link CApplication::getRuntimePath runtime path}.
* You may change the location by setting the {@link setStateFile stateFile} property.
*
* To retrieve the data from CStatePersister, call {@link load()}. To save the data,
* call {@link save()}.
*
* Comparison among state persister, session and cache is as follows:
*
* - session: data persisting within a single user session.
* - state persister: data persisting through all requests/sessions (e.g. hit counter).
* - cache: volatile and fast storage. It may be used as storage medium for session or state persister.
*
*
* Since server resource is often limited, be cautious if you plan to use CStatePersister
* to store large amount of data. You should also consider using database-based persister
* to improve the throughput.
*
* CStatePersister is a core application component used to store global application state.
* It may be accessed via {@link CApplication::getStatePersister)}.
* page state persistent method based on cache.
*
* @author Qiang Xue
* @version $Id$
* @package system.core
* @since 1.0
*/
class CStatePersister extends CApplicationComponent implements IStatePersister
{
private $_stateFile;
/**
* @return string the absolute file path storing the state data
*/
public function getStateFile()
{
if($this->_stateFile!==null)
return $this->_stateFile;
else
return $this->_stateFile=Yii::app()->getRuntimePath().DIRECTORY_SEPARATOR.'state.bin';
}
/**
* @param string the file path storing the state data. Make sure the directory containing
* the file exists and is writable by the Web server process. If using relative path, also
* make sure the path is correct.
*/
public function setStateFile($value)
{
if(($path=realpath(dirname($value)))===false || !is_dir($path) || !is_writable($path))
throw new CException(Yii::t('yii#Unable to create application state file "{file}". Make sure the directory containing the file exists and is writable by the Web server process.',
array('{file}'=>$value)));
$this->_stateFile=$path.DIRECTORY_SEPARATOR.basename($value);
}
/**
* Loads state data from persistent storage.
* @return mixed state data. Null if no state data available.
*/
public function load()
{
$stateFile=$this->getStateFile();
if(($cache=Yii::app()->getCache())!==null)
{
$cacheKey='file:'.$stateFile;
if(($value=$cache->get($cacheKey))!==false)
return unserialize($value);
else if(($content=@file_get_contents($stateFile))!==false)
{
$cache->set($cacheKey,$content,0,new CFileCacheDependency($stateFile));
return unserialize($content);
}
else
return null;
}
else if(($content=@file_get_contents($stateFile))!==false)
return unserialize($content);
else
return null;
}
/**
* Saves application state in persistent storage.
* @param mixed state data (must be serializable).
*/
public function save($state)
{
file_put_contents($this->getStateFile(),serialize($state),LOCK_EX);
}
}