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<?php |
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namespace Yiisoft\Cache\Dependency; |
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use Yiisoft\Cache\CacheInterface; |
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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 {@see 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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abstract class Dependency |
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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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protected $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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protected $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 $reusableData = []; |
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/** |
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* Changes dependecy behavior so dependent data for this cache dependency will be generated only once per request. |
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* This allows you to use the same cache dependency for multiple separate cache calls while generating the same |
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* page without an overhead of re-evaluating dependency data each time. |
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*/ |
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public function markAsReusable(): void |
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{ |
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$this->reusable = true; |
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} |
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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(CacheInterface $cache): void |
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{ |
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if ($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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* 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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*/ |
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public function isChanged(CacheInterface $cache): bool |
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{ |
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if ($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 !== $this->data; |
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} |
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/** |
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* Resets all cached data for reusable dependencies. |
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*/ |
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public static function resetReusableData(): void |
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{ |
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self::$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(): string |
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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(CacheInterface $cache); |
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} |
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