markAsOutdated example

    }

    return $cache;
  }

  /** * {@inheritdoc} */
  public function set($cid, $data, $expire = Cache::PERMANENT, array $tags = []) {
    $this->consistentBackend->set($cid, $data, $expire, $tags);
    $this->markAsOutdated();
    // Don't write the cache tags to the fast backend as any cache tag     // invalidation results in an invalidation of the whole fast backend.     $this->fastBackend->set($cid, $data, $expire);
  }

  /** * {@inheritdoc} */
  public function setMultiple(array $items) {
    $this->consistentBackend->setMultiple($items);
    $this->markAsOutdated();