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vendor/yiisoft/yii2/caching/Dependency.php 3.58 KB
abf1649b   andryeyev   Чистая установка ...
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  <?php
  /**
   * @link http://www.yiiframework.com/
   * @copyright Copyright (c) 2008 Yii Software LLC
   * @license http://www.yiiframework.com/license/
   */
  
  namespace yii\caching;
  
  /**
   * Dependency is the base class for cache dependency classes.
   *
   * Child classes should override its [[generateDependencyData()]] for generating
   * the actual dependency data.
   *
   * @author Qiang Xue <qiang.xue@gmail.com>
   * @since 2.0
   */
  abstract class Dependency extends \yii\base\Object
  {
      /**
       * @var mixed the dependency data that is saved in cache and later is compared with the
       * latest dependency data.
       */
      public $data;
      /**
       * @var boolean whether this dependency is reusable or not. True value means that dependent
       * data for this cache dependency will be generated only once per request. This allows you
       * to use the same cache dependency for multiple separate cache calls while generating the same
       * page without an overhead of re-evaluating dependency data each time. Defaults to false.
       */
      public $reusable = false;
  
      /**
       * @var array static storage of cached data for reusable dependencies.
       */
      private static $_reusableData = [];
  
  
      /**
       * Evaluates the dependency by generating and saving the data related with dependency.
       * This method is invoked by cache before writing data into it.
       * @param Cache $cache the cache component that is currently evaluating this dependency
       */
      public function evaluateDependency($cache)
      {
          if ($this->reusable) {
              $hash = $this->generateReusableHash();
              if (!array_key_exists($hash, self::$_reusableData)) {
                  self::$_reusableData[$hash] = $this->generateDependencyData($cache);
              }
              $this->data = self::$_reusableData[$hash];
          } else {
              $this->data = $this->generateDependencyData($cache);
          }
      }
  
      /**
       * Returns a value indicating whether the dependency has changed.
       * @param Cache $cache the cache component that is currently evaluating this dependency
       * @return boolean whether the dependency has changed.
       */
      public function getHasChanged($cache)
      {
          if ($this->reusable) {
              $hash = $this->generateReusableHash();
              if (!array_key_exists($hash, self::$_reusableData)) {
                  self::$_reusableData[$hash] = $this->generateDependencyData($cache);
              }
              $data = self::$_reusableData[$hash];
          } else {
              $data = $this->generateDependencyData($cache);
          }
          return $data !== $this->data;
      }
  
      /**
       * Resets all cached data for reusable dependencies.
       */
      public static function resetReusableData()
      {
          self::$_reusableData = [];
      }
  
      /**
       * Generates a unique hash that can be used for retrieving reusable dependency data.
       * @return string a unique hash value for this cache dependency.
       * @see reusable
       */
      protected function generateReusableHash()
      {
          $data = $this->data;
          $this->data = null;  // https://github.com/yiisoft/yii2/issues/3052
          $key = sha1(serialize($this));
          $this->data = $data;
          return $key;
      }
  
      /**
       * Generates the data needed to determine if dependency has been changed.
       * Derived classes should override this method to generate the actual dependency data.
       * @param Cache $cache the cache component that is currently evaluating this dependency
       * @return mixed the data needed to determine if dependency has been changed.
       */
      abstract protected function generateDependencyData($cache);
  }