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<?php
/**
* TCachePageStatePersister class file
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @link https://github.com/pradosoft/prado
* @copyright Copyright © 2005-2016 The PRADO Group
* @license https://github.com/pradosoft/prado/blob/master/COPYRIGHT
* @package System.Web.UI
*/
/**
* TCachePageStatePersister class
*
* TCachePageStatePersister implements a page state persistent method based on cache.
* Page state are stored in cache (e.g. memcache, DB cache, etc.), and only a small token
* is passed to the client side to identify the state. This greatly reduces the size of
* the page state that needs to be transmitted between the server and the client. Of course,
* this is at the cost of using server side resource.
*
* A cache module has to be loaded in order to use TCachePageStatePersister.
* By default, TCachePageStatePersister will use the primary cache module.
* A non-primary cache module can be used by setting {@link setCacheModuleID CacheModuleID}.
* Any cache module, as long as it implements the interface {@link ICache}, may be used.
* For example, one can use {@link TDbCache}, {@link TMemCache}, {@link TAPCCache}, etc.
*
* TCachePageStatePersister uses {@link setCacheTimeout CacheTimeout} to limit the data
* that stores in cache.
*
* Since server resource is often limited, be cautious if you plan to use TCachePageStatePersister
* for high-traffic Web pages. You may consider using a small {@link setCacheTimeout CacheTimeout}.
*
* There are a couple of ways to use TCachePageStatePersister.
* One can override the page's {@link TPage::getStatePersister()} method and
* create a TCachePageStatePersister instance there.
* Or one can configure the pages to use TCachePageStatePersister in page configurations
* as follows,
* <code>
* <pages StatePersisterClass="System.Web.UI.TCachePageStatePersister"
* StatePersister.CacheModuleID="mycache"
* StatePersister.CacheTimeout="3600" />
* </code>
* Note in the above, we use StatePersister.CacheModuleID to configure the cache module ID
* for the TCachePageStatePersister instance.
*
* The above configuration will affect the pages under the directory containing
* this configuration and all its subdirectories.
* To configure individual pages to use TCachePageStatePersister, use
* <code>
* <pages>
* <page id="PageID" StatePersisterClass="System.Web.UI.TCachePageStatePersister" />
* </pages>
* </code>
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @package System.Web.UI
* @since 3.1.1
*/
class TCachePageStatePersister extends TComponent implements IPageStatePersister
{
private $_prefix='statepersister';
private $_page;
private $_cache=null;
private $_cacheModuleID='';
private $_timeout=1800;
/**
* @param TPage the page that this persister works for
*/
public function getPage()
{
return $this->_page;
}
/**
* @param TPage the page that this persister works for.
*/
public function setPage(TPage $page)
{
$this->_page=$page;
}
/**
* @return string the ID of the cache module.
*/
public function getCacheModuleID()
{
return $this->_cacheModuleID;
}
/**
* @param string the ID of the cache module. If not set, the primary cache module will be used.
*/
public function setCacheModuleID($value)
{
$this->_cacheModuleID=$value;
}
/**
* @return ICache the cache module being used for data storage
*/
public function getCache()
{
if($this->_cache===null)
{
if($this->_cacheModuleID!=='')
$cache=Prado::getApplication()->getModule($this->_cacheModuleID);
else
$cache=Prado::getApplication()->getCache();
if($cache===null || !($cache instanceof ICache))
{
if($this->_cacheModuleID!=='')
throw new TConfigurationException('cachepagestatepersister_cachemoduleid_invalid',$this->_cacheModuleID);
else
throw new TConfigurationException('cachepagestatepersister_cache_required');
}
$this->_cache=$cache;
}
return $this->_cache;
}
/**
* @return integer the number of seconds in which the cached state will expire. Defaults to 1800.
*/
public function getCacheTimeout()
{
return $this->_timeout;
}
/**
* @param integer the number of seconds in which the cached state will expire. 0 means never expire.
* @throws TInvalidDataValueException if the number is smaller than 0.
*/
public function setCacheTimeout($value)
{
if(($value=TPropertyValue::ensureInteger($value))>=0)
$this->_timeout=$value;
else
throw new TInvalidDataValueException('cachepagestatepersister_timeout_invalid');
}
/**
* @return string prefix of cache variable name to avoid conflict with other cache data. Defaults to 'statepersister'.
*/
public function getKeyPrefix()
{
return $this->_prefix;
}
/**
* @param string prefix of cache variable name to avoid conflict with other cache data
*/
public function setKeyPrefix($value)
{
$this->_prefix=$value;
}
/**
* @param string micro timestamp when saving state occurs
* @return string a key that is unique per user request
*/
protected function calculateKey($timestamp)
{
return $this->getKeyPrefix().':'
. $this->_page->getRequest()->getUserHostAddress()
. $this->_page->getPagePath()
. $timestamp;
}
/**
* Saves state in cache.
* @param mixed state to be stored
*/
public function save($data)
{
$timestamp=(string)microtime(true);
$key=$this->calculateKey($timestamp);
$this->getCache()->add($key,$data,$this->_timeout);
$this->_page->setClientState(TPageStateFormatter::serialize($this->_page,$timestamp));
}
/**
* Loads page state from cache.
* @return mixed the restored state
* @throws THttpException if page state is corrupted
*/
public function load()
{
if(($timestamp=TPageStateFormatter::unserialize($this->_page,$this->_page->getRequestClientState()))!==null)
{
$key=$this->calculateKey($timestamp);
if(($data=$this->getCache()->get($key))!==false)
return $data;
}
throw new THttpException(400,'cachepagestatepersister_pagestate_corrupted');
}
}
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