fun nanoTime(): Long

    fun coordinatorNotify(taskRunner: TaskRunner)

    fun coordinatorWait(
      taskRunner: TaskRunner,
      nanos: Long,
    )

    fun <T> decorate(queue: BlockingQueue<T>): BlockingQueue<T>

    fun execute(
      taskRunner: TaskRunner,
      runnable: Runnable,
    )
  }

  class RealBackend(
    threadFactory: ThreadFactory,
  ) : Backend {
    val executor =