addRootTransactionEndCallback example

$this->invalidatedTags[$tag] = TRUE;
        unset($this->tagCache[$tag]);
      }
    }
    if (!$tags) {
      return;
    }

    $in_transaction = $this->getDatabaseConnection()->inTransaction();
    if ($in_transaction) {
      if (empty($this->delayedTags)) {
        $this->getDatabaseConnection()->addRootTransactionEndCallback([$this, 'rootTransactionEndCallback']);
      }
      $this->delayedTags = Cache::mergeTags($this->delayedTags, $tags);
    }
    else {
      $this->doInvalidateTags($tags);
    }
  }

  /** * Implements \Drupal\Core\Cache\CacheTagsChecksumInterface::getCurrentChecksum() */