CStatePersister
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
runtime path. You may change the location by setting the
stateFile property.
To retrieve the data from CStatePersister, call
load(). To save the data, call
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
CApplication::getStatePersister().
Public Properties
Property |
Type |
Description |
Defined By |
behaviors | array | the behaviors that should be attached to this component. | CApplicationComponent |
cacheID | string | the ID of the cache application component that is used to cache the state values. | CStatePersister |
isInitialized | boolean | Checks if this application component has been initialized. | CApplicationComponent |
stateFile | string | the file path storing the state data. | CStatePersister |
Protected Methods
Method |
Description |
Defined By |
getContent() | Loads content from file using a shared lock to avoid data corruption when reading | CStatePersister |
Property Details
public string $cacheID;
the ID of the cache application component that is used to cache the state values. Defaults to 'cache' which refers to the primary cache application component. Set this property to false if you want to disable caching state values.
public string $stateFile;
the file path storing the state data. Make sure the directory containing the file exists and is writable by the Web server process. If using relative path, also make sure the path is correct.
Method Details
protected string getContent($filename) |
$filename | | |
{return} | string | file contents |
Source Code: framework/base/CStatePersister.php#111 (
show)
protected function getContent($filename)
{
$file=@fopen($filename,"r");
if($file && flock($file,LOCK_SH))
{
$contents=@file_get_contents($filename);
flock($file,LOCK_UN);
fclose($file);
return $contents;
}
return false;
}
Loads content from file using a shared lock to avoid data corruption when reading the file while it is being written by save()
Source Code: framework/base/CStatePersister.php#61 (
show)
public function init()
{
parent::init();
if($this->stateFile===null)
$this->stateFile=Yii::app()->getRuntimePath().DIRECTORY_SEPARATOR.'state.bin';
$dir=dirname($this->stateFile);
if(!is_dir($dir) || !is_writable($dir))
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}'=>$this->stateFile)));
}
Initializes the component. This method overrides the parent implementation by making sure stateFile contains valid value.
public mixed load() |
{return} | mixed | state data. Null if no state data available. |
Source Code: framework/base/CStatePersister.php#76 (
show)
public function load()
{
$stateFile=$this->stateFile;
if($this->cacheID!==false && ($cache=Yii::app()->getComponent($this->cacheID))!==null)
{
$cacheKey='Yii.CStatePersister.'.$stateFile;
if(($value=$cache->get($cacheKey))!==false)
return unserialize($value);
else
{
if(($content=$this->getContent($stateFile))!==false)
{
$unserialized_content=unserialize($content);
// If it can't be unserialized, don't cache it:
if ($unserialized_content!==false || $content=="")
$cache->set($cacheKey,$content,0,new CFileCacheDependency($stateFile));
return $unserialized_content;
}
else
return null;
}
}
elseif(($content=$this->getContent($stateFile))!==false)
return unserialize($content);
else
return null;
}
Loads state data from persistent storage.
public void save(mixed $state) |
$state | mixed | state data (must be serializable). |
Saves application state in persistent storage.