final def ready[T](awaitable: Awaitable[T],
                     atMost: Duration): awaitable.type = {
    if (blockingNotNeeded(awaitable, atMost)) {
      awaitable.ready(atMost)(AwaitPermission)
    } else {
      blocking(awaitable.ready(atMost)(AwaitPermission))
    }
  }

  private def blockingNotNeeded(awaitable: Awaitable[_],
                                atMost: Duration): Boolean = {
    (awaitable.isInstanceOf[Future[_]] &&
    awaitable.asInstanceOf[Future[_]].isCompleted) ||
    (atMost match {
      case duration: FiniteDuration => duration.length <= 0
      // this returns true in case of Duration.Undefined
      case _ => !(atMost.toUnit(null) > 0.0)
    })
  }