private function backOff()
  {
    $delay = $this->getDelay();

    $this->client->getLogger()->debug(
        'Retrying task with backoff',
        array(
            'request' => $this->name,
            'retry' => $this->attempts,
            'backoff_seconds' => $delay
        )
    );

    usleep($delay * 1000000);
  }