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101 lines
3.1 KiB
101 lines
3.1 KiB
<?php |
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/** |
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* @link http://www.yiiframework.com/ |
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* @copyright Copyright (c) 2008 Yii Software LLC |
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* @license http://www.yiiframework.com/license/ |
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*/ |
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namespace yii\caching; |
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/** |
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* Dependency is the base class for cache dependency classes. |
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* |
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* Child classes should override its [[generateDependencyData()]] for generating |
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* the actual dependency data. |
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* |
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* @property boolean $hasChanged Whether the dependency has changed. |
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* |
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* @author Qiang Xue <qiang.xue@gmail.com> |
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* @since 2.0 |
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*/ |
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abstract class Dependency extends \yii\base\Object |
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{ |
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/** |
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* @var mixed the dependency data that is saved in cache and later is compared with the |
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* latest dependency data. |
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*/ |
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public $data; |
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/** |
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* @var boolean whether this dependency is reusable or not. True value means that dependent |
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* data for this cache dependency will be generated only once per request. This allows you |
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* to use the same cache dependency for multiple separate cache calls while generating the same |
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* page without an overhead of re-evaluating dependency data each time. Defaults to false. |
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*/ |
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public $reusable = false; |
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/** |
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* @var array static storage of cached data for reusable dependencies. |
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*/ |
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private static $_reusableData = array(); |
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/** |
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* @var string a unique hash value for this cache dependency. |
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*/ |
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private $_hash; |
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/** |
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* Evaluates the dependency by generating and saving the data related with dependency. |
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* This method is invoked by cache before writing data into it. |
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* @param Cache $cache the cache component that is currently evaluating this dependency |
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*/ |
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public function evaluateDependency($cache) |
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{ |
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if (!$this->reusable) { |
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$this->data = $this->generateDependencyData($cache); |
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} else { |
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if ($this->_hash === null) { |
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$this->_hash = sha1(serialize($this)); |
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} |
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if (!array_key_exists($this->_hash, self::$_reusableData)) { |
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self::$_reusableData[$this->_hash] = $this->generateDependencyData($cache); |
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} |
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$this->data = self::$_reusableData[$this->_hash]; |
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} |
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} |
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/** |
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* Returns a value indicating whether the dependency has changed. |
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* @param Cache $cache the cache component that is currently evaluating this dependency |
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* @return boolean whether the dependency has changed. |
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*/ |
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public function getHasChanged($cache) |
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{ |
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if (!$this->reusable) { |
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return $this->generateDependencyData($cache) !== $this->data; |
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} else { |
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if ($this->_hash === null) { |
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$this->_hash = sha1(serialize($this)); |
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} |
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if (!array_key_exists($this->_hash, self::$_reusableData)) { |
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self::$_reusableData[$this->_hash] = $this->generateDependencyData($cache); |
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} |
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return self::$_reusableData[$this->_hash] !== $this->data; |
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} |
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} |
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/** |
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* Resets all cached data for reusable dependencies. |
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*/ |
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public static function resetReusableData() |
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{ |
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self::$_reusableData = array(); |
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} |
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/** |
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* Generates the data needed to determine if dependency has been changed. |
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* Derived classes should override this method to generate the actual dependency data. |
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* @param Cache $cache the cache component that is currently evaluating this dependency |
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* @return mixed the data needed to determine if dependency has been changed. |
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*/ |
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abstract protected function generateDependencyData($cache); |
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}
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