Play and Akka Streams source queue

PlayAkkaSourceQueue.scala

class Application @Inject() (implicit actorSystem: ActorSystem, exec: ExecutionContext) extends Controller {
   
   implicit val materializer = ActorMaterializer()

   val Tick = "tick"

   class TickActor(queue: SourceQueue[String]) extends Actor {
     def receive = {
       case Tick => queue.offer("tack")
     }
   }

  def queueAction = Action {

    val (queueSource, futureQueue) = peekMatValue(Source.queue[String](10, OverflowStrategy.fail))

    futureQueue.map { queue =>

      val tickActor = actorSystem.actorOf(Props(new TickActor(queue)))
      val tickSchedule =
        actorSystem.scheduler.schedule(0 milliseconds,
          1 second,
          tickActor,
          Tick)

        queue.watchCompletion().map{ done =>
          Logger.debug("Client disconnected")
          tickSchedule.cancel
          Logger.debug("Scheduler canceled")
        }
    }

    Ok.chunked(
     queueSource.map{e => 
       Logger.debug("queue source element : " + e)
        e
      } 
      via EventSource.flow
    )

  }

  def peekMatValue[T, M](src: Source[T, M]): (Source[T, M], Future[M]) = {
    val p = Promise[M]
    val s = src.mapMaterializedValue { m =>
      p.trySuccess(m)
      m
    }
    (s, p.future)
  }

}