Akka 演员总是超时等待未来

Question

我有下面定义的以下演员，意在 "login" 一个用户。

object AuthenticationActor {
  def props = Props[AuthenticationActor]

  case class LoginUser(id: UUID)
}

class AuthenticationActor @Inject()(cache: CacheApi, userService: UserService) extends Actor{
  import AuthenticationActor._

  def receive = {
    case LoginEmployee(id: UUID) => {
      userService.getUserById(id).foreach {
        case Some(e) => {
          println("Logged user in")
          val sessionId = UUID.randomUUID()
          cache.set(sessionId.toString, e)
          sender() ! Some(e, sessionId)
        }
        case None => println("No user was found")
      }
    }
  }
}

注：userService.getUserByIdreturns一个Future[Option[User]]

下面是非常简单的 API cal

class EmployeeController @Inject()(@Named("authentication-actor") authActor: ActorRef)(implicit ec: ExecutionContext) extends Controller {

  override implicit val timeout: Timeout = 5.seconds

  def login(id: UUID) = Action.async { implicit request =>
    (authActor ? LoginUser(id)).mapTo[Option[(User, UUID)]].map {
      case Some(authInfo) =>   Ok("Authenticated").withSession(request.session + ("auth" -> authInfo._2.toString))
      case None => Forbidden("Not Authenticated")
    }
  }
}

两个 println 调用都会执行，但是 login 调用总是会失败，表示请求已超时。有什么建议吗？

Answer 1

当你做这样的事情时（在 Futures 回调中访问发件人）你需要在收到请求时将 sender 存储在外部范围的 val 中，因为它很可能在 Future 完成之前更改。

def receive = {
    case LoginEmployee(id: UUID) => {
      val recipient = sender

      userService.getUserById(id).foreach {
        case Some(e) => {
          ...
          recipient ! Some(e, sessionId)
        }
        ...
      }
    }
  }

当找不到用户时，您也永远不会发送结果。

你实际上应该在这里做的是将 Future 结果传递给 sender

def receive = {
  case LoginEmployee(id: UUID) => {
    userService.getUserById(id) map { _.map { e =>
        val sessionId = UUID.randomUUID()
        cache.set(sessionId.toString, e)
        (e, sessionId)
      }
    } pipeTo sender
  }
}

或打印

def receive = {
  case LoginEmployee(id: UUID) => {
    userService.getUserById(id) map { 
      case Some(e) =>
        println("logged user in")
        val sessionId = UUID.randomUUID()
        cache.set(sessionId.toString, e)
        Some(e, sessionId)
      case None =>
        println("user not found")
        None
    } pipeTo sender
  }
}

Akka 演员总是超时等待未来

Akka actors always times out waiting for future

scala

actor

akka