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<?php
/**
* COutputCache class file.
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @link http://www.yiiframework.com/
* @copyright Copyright &copy; 2008-2009 Yii Software LLC
* @license http://www.yiiframework.com/license/
*/
/**
* COutputCache enables caching the output generated by an action or a view fragment.
*
* If the output to be displayed is found valid in cache, the cached
* version will be displayed instead, which saves the time for generating
* the original output.
*
* Since COutputCache extends from {@link CFilterWidget}, it can be used
* as either a filter (for action caching) or a widget (for fragment caching).
* For the latter, the shortcuts {@link CBaseController::beginCache()} and {@link CBaseController::endCache()}
* are often used instead, like the following in a view file:
* <pre>
* if($this->beginCache('cacheName',array('property1'=>'value1',...))
* {
* // ... display the content to be cached here
* $this->endCache();
* }
* </pre>
*
* COutputCache must work with a cache application component specified via {@link cacheID}.
* If the cache application component is not available, COutputCache will be disabled.
*
* The validity of the cached content is determined based on two factors:
* the {@link duration} and the cache {@link dependency}.
* The former specifies the number of seconds that the data can remain
* valid in cache (defaults to 60s), while the latter specifies conditions
* that the cached data depends on. If a dependency changes,
* (e.g. relevant data in DB are updated), the cached data will be invalidated.
* For more details about cache dependency, see {@link CCacheDependency}.
*
* Sometimes, it is necessary to turn off output caching only for certain request types.
* For exapmle, we only want to cache a form when it is initially requested;
* any subsequent display of the form should not be cached because it contains user input.
* We can set {@link requestTypes} to be <code>array('GET')</code> to accomplish this task.
*
* The content fetched from cache may be variated with respect to
* some parameters. COutputCache supports two kinds of variations:
* <ul>
* <li>{@link varyByRoute}: this specifies whether the cached content
* should be varied with the requested route (controller and action)</li>
* <li>{@link varyByParam}: this specifies a list of GET parameter names
* and uses the corresponding values to determine the version of the cached content.</li>
* <li>{@link varyBySession}: this specifies whether the cached content
* should be varied with the user session.</li>
* <li>{@link varyByExpression}: this specifies whether the cached content
* should be varied with the result of the specified PHP expression.</li>
* </ul>
* For more advanced variation, override {@link getBaseCacheKey()} method.
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @version $Id$
* @package system.web.widgets
* @since 1.0
*/
class COutputCache extends CFilterWidget
{
/**
* Prefix to the keys for storing cached data
*/
const CACHE_KEY_PREFIX='Yii.COutputCache.';
/**
* @var integer number of seconds that the data can remain in cache. Defaults to 60 seconds.
* If 0 or negative, it means the cache is disabled. Note, if cache dependency changes or cache space is limited,
* the data may be purged out of cache earlier.
*/
public $duration=60;
/**
* @var boolean whether the content being cached should be differentiated according to route.
* A route consists of the requested controller ID and action ID.
* Defaults to true.
*/
public $varyByRoute=true;
/**
* @var boolean whether the content being cached should be differentiated according to user sessions. Defaults to false.
*/
public $varyBySession=false;
/**
* @var array list of GET parameters that should participate in cache key calculation.
* By setting this property, the output cache will use different cached data
* for each different set of GET parameter values.
*/
public $varyByParam;
/**
* @var string a PHP expression whose result is used in the cache key calculation.
* By setting this property, the output cache will use different cached data
* for each different expression result.
* @since 1.0.4
*/
public $varyByExpression;
/**
* @var array list of request types (e.g. GET, POST) for which the cache should be enabled only.
* Defaults to null, meaning all request types.
*/
public $requestTypes;
/**
* @var string the ID of the cache application component. Defaults to 'cache' (the primary cache application component.)
*/
public $cacheID='cache';
/**
* @var mixed the dependency that the cached content depends on.
* This can be either an object implementing {@link ICacheDependency} interface or an array
* specifying the configuration of the dependency object. For example,
* <pre>
* array(
* 'class'=>'CDbCacheDependency',
* 'sql'=>'SELECT MAX(lastModified) FROM Post',
* )
* </pre>
* would make the output cache depends on the last modified time of all posts.
* If any post has its modification time changed, the cached content would be invalidated.
*/
public $dependency;
private $_key;
private $_cache;
private $_contentCached;
private $_content;
private $_actions;
/**
* Performs filtering before the action is executed.
* This method is meant to be overridden by child classes if begin-filtering is needed.
* @return boolean whether the filtering process should stop after this filter. Defaults to false.
*/
public function filter($filterChain)
{
$this->init();
if(!$this->getIsContentCached())
$filterChain->run();
$this->run();
}
/**
* Marks the start of content to be cached.
* Content displayed after this method call and before {@link endCache()}
* will be captured and saved in cache.
* This method does nothing if valid content is already found in cache.
*/
public function init()
{
if($this->getIsContentCached())
$this->replayActions();
else if($this->_cache!==null)
{
$this->getController()->getCachingStack()->push($this);
ob_start();
ob_implicit_flush(false);
}
}
/**
* Marks the end of content to be cached.
* Content displayed before this method call and after {@link init()}
* will be captured and saved in cache.
* This method does nothing if valid content is already found in cache.
*/
public function run()
{
if($this->getIsContentCached())
{
if($this->getController()->isCachingStackEmpty())
echo $this->getController()->processDynamicOutput($this->_content);
else
echo $this->_content;
}
else if($this->_cache!==null)
{
$this->_content=ob_get_clean();
$this->getController()->getCachingStack()->pop();
$data=array($this->_content,$this->_actions);
if(is_array($this->dependency))
$this->dependency=Yii::createComponent($this->dependency);
$this->_cache->set($this->getCacheKey(),$data,$this->duration>0 ? $this->duration : 0,$this->dependency);
if($this->getController()->isCachingStackEmpty())
echo $this->getController()->processDynamicOutput($this->_content);
else
echo $this->_content;
}
}
/**
* @return boolean whether the content can be found from cache
*/
public function getIsContentCached()
{
if($this->_contentCached!==null)
return $this->_contentCached;
else
return $this->_contentCached=$this->checkContentCache();
}
/**
* Looks for content in cache.
* @return boolean whether the content is found in cache.
*/
protected function checkContentCache()
{
if((empty($this->requestTypes) || in_array(Yii::app()->getRequest()->getRequestType(),$this->requestTypes))
&& $this->duration>0 && ($this->_cache=$this->getCache())!==null)
{
if(($data=$this->_cache->get($this->getCacheKey()))!==false)
{
$this->_content=$data[0];
$this->_actions=$data[1];
return true;
}
}
return false;
}
/**
* @return ICache the cache used for caching the content.
*/
protected function getCache()
{
return Yii::app()->getComponent($this->cacheID);
}
/**
* Caclulates the base cache key.
* The calculated key will be further variated in {@link getCacheKey}.
* Derived classes may override this method if more variations are needed.
* @return string basic cache key without variations
*/
protected function getBaseCacheKey()
{
return self::CACHE_KEY_PREFIX.':'.$this->getId().':';
}
/**
* Calculates the cache key.
* The key is calculated based on {@link getBaseCacheKey} and other factors, including
* {@link varyByRoute}, {@link varyByParam} and {@link varyBySession}.
* @return string cache key
*/
protected function getCacheKey()
{
if($this->_key!==null)
return $this->_key;
else
{
$key=$this->getBaseCacheKey().':';
if($this->varyByRoute)
{
$controller=$this->getController();
$key.=$controller->getUniqueId().'/';
if(($action=$controller->getAction())!==null)
$key.=$action->getId();
}
$key.=':';
if($this->varyBySession)
$key.=Yii::app()->getSession()->getSessionID();
$key.=':';
if(is_array($this->varyByParam) && isset($this->varyByParam[0]))
{
$params=array();
foreach($this->varyByParam as $name)
{
if(isset($_GET[$name]))
$params[$name]=$_GET[$name];
else
$params[$name]='';
}
$key.=serialize($params);
}
$key.=':';
if($this->varyByExpression!==null)
$key.=$this->evaluateExpression($this->varyByExpression);
$key.=':';
return $this->_key=$key;
}
}
private function evaluateExpression($expression)
{
return @eval('return '.$expression.';');
}
/**
* Records a method call when this output cache is in effect.
* When the content is served from the output cache, the recorded
* method will be re-invoked.
* @param string a property name of the controller. The property should refer to an object
* whose method is being recorded. If empty it means the controller itself.
* @param string the method name
* @param array parameters passed to the method
*/
public function recordAction($context,$method,$params)
{
$this->_actions[]=array($context,$method,$params);
}
/**
* Replays the recorded method calls.
*/
protected function replayActions()
{
if(empty($this->_actions))
return;
$controller=$this->getController();
$cs=Yii::app()->getClientScript();
foreach($this->_actions as $action)
{
if($action[0]==='clientScript')
$object=$cs;
else if($action[0]==='')
$object=$controller;
else
$object=$controller->{$action[0]};
if(method_exists($object,$action[1]))
call_user_func_array(array($object,$action[1]),$action[2]);
else if($action[0]==='' && function_exists($action[1]))
call_user_func_array($action[1],$action[2]);
else
throw new CException(Yii::t('yii','Unable to replay the action "{object}.{method}". The method does not exist.',
array('object'=>$action[0],
'method'=>$action[1])));
}
}
}
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