在 Scala 中的套接字关闭上拦截 Akka HTTP WebSocket 事件

Question

我正在使用带有Akka HTTP的Scala。

我有一个基于 Akka HTTP 的服务器后端应用程序。传入的 WebSocket 消息使用以下handleWebSocketMessages进行处理：

/**
* Route for WebSocket request
*/
private val webSocketRoute: Route = pathSuffix(Constants.WSPROXY_WEBSOCKET_PATH_SUFFIX) {
LOGGER.debug("() Web socket route")
handleWebSocketMessages(wsRouteImpl)
}
/**
* This method calls all registered handlers.
*
* @return flow for handleWebSocketMessages method
*/
private def wsRouteImpl: Flow[Message, Message, Any] = {
LOGGER.debug("() wsRouteHandling")
numOfClients += 1
LOGGER.info(s"Client has connected, current number of clients: $numOfClients")
var flow = Flow[Message].mapConcat {
// Call specific handlers depending on message type
...
}

我的 WebSocket 客户端与保持活动状态建立双向通信连接。

绑定完成：

val binding = Http().bindAndHandle(webSocketRoute, config.host, config.port)

问题是我需要为关闭的套接字注入回调(例如，如果客户端已断开连接(并减少当前客户端的数量，但我找不到任何入口点。

是否可以在套接字关闭时捕获某种事件？

Answer 1

使用watchTermination：

val numOfClients = new java.util.concurrent.atomic.AtomicInteger(0)
private val webSocketRoute: Route = pathSuffix(Constants.WSPROXY_WEBSOCKET_PATH_SUFFIX) {
LOGGER.debug("() Web socket route")
val wsFlow: Flow[Message, Message, Any] =
wsRouteImpl.watchTermination() { (_, fut) =>
numOfClients.incrementAndGet()
LOGGER.info(s"Client has connected. Current number of clients: $numOfClients")
fut onComplete {
case Success(_) =>
numOfClients.decrementAndGet()
LOGGER.info(s"Client has disconnected. Current number of clients: $numOfClients")
case Failure(ex) =>
numOfClients.decrementAndGet()
LOGGER.error(s"Disconnection failure (number of clients: $numOfClients): $ex")
}
}
handleWebSocketMessages(wsFlow)
}
private def wsRouteImpl: Flow[Message, Message, Any] = ???