watchTermination没有在阿卡-HTTP流量触发

Question

目前我正在试图建立一个阿卡-HTTP WebSocket连接，可以：

• 广播到所有连接的客户端
• 回答客户的某些请求

这是我创造我的流量至今：

// keeps a list of all actors so I can broadcast to them
var actors: List[ActorRef] = Nil

private def wsFlow(implicit materializer: ActorMaterializer): Flow[ws.Message, ws.Message, NotUsed] = {
    val (actor, source) = Source.actorRef[String](10, akka.stream.OverflowStrategy.dropTail)
      .toMat(BroadcastHub.sink[String])(Keep.both)
      .run()

    // this never triggers
    source.watchTermination() { (m, f) =>
      f.onComplete(r => println("TERMINATION: " + r.toString))
      actors = actors diff actor :: Nil
      m
    }

    actors = actor :: actors

    val wsHandler: Flow[ws.Message, ws.Message, NotUsed] =
      Flow[ws.Message]
        .merge(source)
        .map {
          case TextMessage.Strict(tm) => handleMessage(actor, tm)
          case _ => TextMessage.Strict("Ignored message!")
        }
    wsHandler
  }

  def broadcast(msg: String): Unit = {
    actors.foreach(_ ! TextMessage.Strict(msg))
  }

本 - 希望 - 我遇到了最后一个问题是，watchTermination回调从来没有触发（我从来没有得到一个“终止：......”我的控制台上的消息）。这是为什么？而且怎么可能当客户端离开（这样我就可以从我的actors列表中删除他）来检测？

Answer 1

我想出如何做到这一点：

val wsHandler: Flow[ws.Message, ws.Message, NotUsed] = Flow[ws.Message]
  .watchTermination() { (m, f) =>
    f.onComplete(r => {
      println("Client left: " + r.toString)
      actors = actors diff actor :: Nil
      }
    )
    m
  }
  .merge(source)
  .map {
    case TextMessage.Strict(tm) => handleMessage(actor, tm)
    case _ => TextMessage.Strict("Ignored message!")
  }