backoff.php

<?php

/**
 * Assume that we're using a message bus which is able to
 * retry failed messages with a custom retry delay.
 */
class FetchCarMessageHandler
{
  public function handle(Message $msg)
  {
    try {
      $id = (int)$msg->getContent();
      $cars = $client->get('/car/'.$id);
  
      return Result::success($cars);
    } catch (TimeoutException $e) {

      $lastBackoff = $msg->getLastBackoff();
      // The infrastructure layer will automagically retry the message after XYZ seconds
      return Result::retryAfter($lastBackoff * 2, $msg);
    }
  }
}