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113 lines
3.3 KiB
PHP
113 lines
3.3 KiB
PHP
<?php
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/**
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* CacheDependency class file.
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*
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* @link http://www.yiiframework.com/
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* @copyright Copyright © 2008-2012 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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* CacheDependency is the base class for cache dependency classes.
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*
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* CacheDependency implements the {@link ICacheDependency} interface.
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* Child classes should override its {@link generateDependentData} for
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* actual dependency checking.
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*
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* @property boolean $hasChanged Whether the dependency has changed.
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* @property mixed $dependentData The data used to determine if dependency has been changed.
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* This data is available after {@link evaluateDependency} is called.
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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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class CacheDependency extends \yii\base\Object
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{
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/**
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* @var boolean Whether this dependency is reusable or not.
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* If set to true, dependent data for this cache dependency will only be generated once per request.
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* You can then use the same cache dependency for multiple separate cache calls on the same page
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* without the overhead of re-evaluating the dependency each time.
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* Defaults to false;
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* @since 1.1.11
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*/
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public $reuseDependentData = false;
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/**
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* @var array cached data for reusable dependencies.
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* @since 1.1.11
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*/
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private static $_reusableData = array();
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private $_hash;
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private $_data;
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/**
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* Evaluates the dependency by generating and saving the data related with dependency.
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* This method is invoked by cache before writing data into it.
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*/
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public function evaluateDependency()
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{
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if ($this->reuseDependentData) {
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$hash = $this->getHash();
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if (!isset(self::$_reusableData[$hash]['dependentData'])) {
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self::$_reusableData[$hash]['dependentData'] = $this->generateDependentData();
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}
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$this->_data = self::$_reusableData[$hash]['dependentData'];
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} else {
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$this->_data = $this->generateDependentData();
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}
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}
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/**
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* @return boolean whether the dependency has changed.
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*/
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public function getHasChanged()
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{
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if ($this->reuseDependentData) {
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$hash = $this->getHash();
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if (!isset(self::$_reusableData[$hash]['hasChanged'])) {
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if (!isset(self::$_reusableData[$hash]['dependentData'])) {
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self::$_reusableData[$hash]['dependentData'] = $this->generateDependentData();
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}
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self::$_reusableData[$hash]['hasChanged'] = self::$_reusableData[$hash]['dependentData'] != $this->_data;
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}
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return self::$_reusableData[$hash]['hasChanged'];
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} else {
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return $this->generateDependentData() != $this->_data;
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}
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}
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/**
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* @return mixed the data used to determine if dependency has been changed.
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* This data is available after {@link evaluateDependency} is called.
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*/
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public function getDependentData()
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{
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return $this->_data;
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}
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/**
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* Generates the data needed to determine if dependency has been changed.
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* Derived classes should override this method to generate actual dependent data.
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* @return mixed the data needed to determine if dependency has been changed.
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*/
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protected function generateDependentData()
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{
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return null;
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}
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/**
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* Generates a unique hash that identifies this cache dependency.
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* @return string the hash for this cache dependency
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*/
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private function getHash()
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{
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if ($this->_hash === null) {
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$this->_hash = sha1(serialize($this));
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}
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return $this->_hash;
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}
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} |