Question

我正在尝试使用Scala实现Map条目监听器。

想法：

我需要订阅服务中的地图。
当添加/更新具有特定密钥的条目时，我需要通知所有订户。
我需要从其他服务访问地图以检查条目值。

我无法为此找到解决方案，所以我尝试用Akka实现它：

class TrackingService(system: ActorSystem) extends LazyLogging {
  private val trackingActor = system.actorOf(TrackingActor.props)
  private val duration = Duration(15, TimeUnit.SECONDS)
  private implicit val timeout = Timeout(duration)

  def fireEvent(key: String): Unit = {
    TrackingActor ! EventFired(key)
  }

  def eventHappened(key: String): Future[Boolean] = {
    TrackingActor ? DoesEventHappened(key)).mapTo[Boolean]
  }

  def registerHiddenCardListener(key: String, data: MyData): Unit = {
    TrackingActor ! Subscribe(key, data)
  }
}

case class EventFired(key: String)
case class EventHappened(key: String)
case class EventHappenedResponse(happened: Boolean)

case class Subscribe(key: String, data: Data)
class TrackingActor extends Actor with LazyLogging {
  var eventMap: Map[String, Boolean] = Map.empty[String, Boolean]
  var dataMap: Map[String, List[Data]] = Map.empty[String, List[Data]]

  def receive: Receive = {
    case Subscribe(key, data)       =>
      val currentData: List[Data] = dataMap.getOrElse(key, Nil)
      val newData = data :: currentData
      dataMap = dataMap + (key -> newData)
    case EventHappened(key)         => sender() ! EventHappenedResponse(eventMap.getOrElse(key, false))
    case e@EventFired(key)          =>
      eventMap = eventMap + (key -> true)

      for {
        dataOpt <- dataMap.get(key)
        data <- dataOpt
      } {
        // do callback with data (e.g. send email)
      }
    case x => logger.warn(s"Received unknown message: $x")
  }
}

object TrackingActor {
  def props: Props = Props(classOf[TrackingActor])
}

我不喜欢这个解决方案：我不喜欢问模式，但我需要访问非演员类的条目。另外，我不喜欢有2张地图，但我需要存储一些应该用于回调的数据。

关于如何改进这一点的任何想法？

Answer 1

这是一个想法：

function [fitresult, gof] = createFit_MSSI_Venus(RockerArm, mos)
%CREATEFIT1(ROCKERARM,MOS)
%  Create a fit.
%
%  Data for 'Psychometric curve fitting MSSI-RockeArm 3D mesh' fit:
%      X Input : RockerArm
%      Y Output: mos
%  Output:
%      fitresult : a fit object representing the fit.
%      gof : structure with goodness-of fit info.
%
%  See also FIT, CFIT, SFIT.

%  Auto-generated by MATLAB on 08-Jan-2016 15:40:41


%% Fit: 'Psychometric curve fitting MSSI-RockeArm 3D mesh'.
[xData, yData] = prepareCurveData( RockerArm, mos );

% Set up fittype and options.
ft = fittype( 'erfc((a+b*x)/sqrt(2))/2', 'independent', 'x',  
'dependent', 'y' );

opts = fitoptions( 'Method', 'NonlinearLeastSquares' );
opts.Algorithm = 'Levenberg-Marquardt';
opts.Display = 'Off';
opts.StartPoint = [0.655477890177557 0.171186687811562];

% Fit model to data.
[fitresult, gof] = fit( xData, yData, ft, opts );

% Plot fit with data.
figure( 'Name', 'Psychometric curve fitting MSSI-RockeArm 3D mesh' );
h = plot( fitresult, xData, yData);
set(h, 'Markersize',20);
legend( h, 'mos vs. RockerArm', 'Psychometric curve fitting MSSI-        
RockeArm 3D mesh', 'Location', 'NorthEast' );

% Label axes
xlabel MSSI-RockerArm 3D mesh
ylabel mos
grid on

通过执行此操作，您可以使订阅者保持非case class Subscribe[A, B](f: (A, B, NotifyingMap[A,B]) => Any) case class Event[A, B](key: A, value: B, originator: NotifyingMap[A,B]) case class RegisterObserver(actorRef: ActorRef) /** * Subscribes to events */ class Subscriber[A,B]{ def register(actorSystem: ActorSystem) = { val actor = actorSystem.actorOf(Props(classOf[Observer[A,B]])) actor ! Subscribe(handleEvent) } def handleEvent(key: A, value: B, notifyingMap: NotifyingMap[A, B]) = { println(s"Saw key $key with value $value") } } /** * Observer of events that will call a partial function when * an event comes in. */ class Observer[A, B] extends Actor{ var f: (A,B,NotifyingMap[A,B]) => Any = _ def receive = { case x: Subscribe[A, B] => f = x.f Notifier() ! RegisterObserver(self) case e: Event[A,B] => f(e.key, e.value, e.originator) } } /** * Notifier that sends out the event to all registered observers. */ class Notifier extends Actor { var observers = List[ActorRef]() def receive = { case x: RegisterObserver => observers = x.actorRef :: observers case x: Event[_,_] => observers.foreach(_ ! Event) } } /** * Singleton notifier. */ object Notifier{ var notifier: ActorRef = _ def create(actorSystem: ActorSystem) = actorSystem.actorOf(Props(classOf[Notifier])) def apply(): ActorRef = notifier } /** * Class that sends out an event when an item is put. Also allows for * getting an item based on a key. */ class NotifyingMap[A, B](){ val map: TrieMap[A,B] = TrieMap[A,B]() // Specific business logic here on when you publish the event. def put(key: A, value: B) = { map.put(key, value).foreach(v => Notifier() ! Event(key, v, this)) } def get(key: A) = map.get(key) }类，同时仍允许其对事件做出反应。您也可以在Actor上调用简单的旧方法，因为它只是一个类，而不是NotifyingMap。

我个人喜欢在邮件中存储回调信息。通常，您通过在案例类中使用另一个Actor来看到这一点。在此示例中，我们在案例类中有ActorRef，因此我们知道事件的起源，并可以在那里适当地调用NotifyingMap方法。

完全披露：我没有运行任何此代码。它确实编译。

实现地图条目监听器

1 个答案: