mirror of
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122 lines
4.1 KiB
PHP
122 lines
4.1 KiB
PHP
<?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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* For more details and usage information on Cache, see the [guide article on caching](guide:caching-overview).
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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\BaseObject
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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 bool 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 = [];
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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 CacheInterface $cache the cache component that is currently evaluating this dependency
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*/
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public function evaluateDependency($cache)
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{
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if ($this->reusable) {
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$hash = $this->generateReusableHash();
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if (!array_key_exists($hash, self::$_reusableData)) {
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self::$_reusableData[$hash] = $this->generateDependencyData($cache);
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}
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$this->data = self::$_reusableData[$hash];
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} else {
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$this->data = $this->generateDependencyData($cache);
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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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* @deprecated since version 2.0.11. Will be removed in version 2.1. Use [[isChanged()]] instead.
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* @param CacheInterface $cache the cache component that is currently evaluating this dependency
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* @return bool whether the dependency has changed.
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*/
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public function getHasChanged($cache)
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{
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return $this->isChanged($cache);
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}
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/**
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* Checks whether the dependency is changed.
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* @param CacheInterface $cache the cache component that is currently evaluating this dependency
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* @return bool whether the dependency has changed.
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* @since 2.0.11
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*/
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public function isChanged($cache)
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{
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if ($this->reusable) {
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$hash = $this->generateReusableHash();
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if (!array_key_exists($hash, self::$_reusableData)) {
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self::$_reusableData[$hash] = $this->generateDependencyData($cache);
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}
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$data = self::$_reusableData[$hash];
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} else {
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$data = $this->generateDependencyData($cache);
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}
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return $data !== $this->data;
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}
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/**
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* Resets all cached data for reusable dependencies.
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*/
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public static function resetReusableData()
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{
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self::$_reusableData = [];
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}
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/**
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* Generates a unique hash that can be used for retrieving reusable dependency data.
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* @return string a unique hash value for this cache dependency.
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* @see reusable
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*/
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protected function generateReusableHash()
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{
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$data = $this->data;
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$this->data = null; // https://github.com/yiisoft/yii2/issues/3052
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$key = sha1(serialize($this));
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$this->data = $data;
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return $key;
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}
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/**
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* Generates the data needed to determine if dependency is changed.
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* Derived classes should override this method to generate the actual dependency data.
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* @param CacheInterface $cache the cache component that is currently evaluating this dependency
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* @return mixed the data needed to determine if dependency has been changed.
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*/
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abstract protected function generateDependencyData($cache);
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}
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