Bumping this - what are the best practices about using anonymous actors to
modify shared state?
Thanks
Jeff
On Wednesday, December 27, 2017 at 4:51:04 PM UTC-8, Jeff wrote:
>
> I have a class that is read heavy with low contention on writes. I'd like
> to be able to access a piece of shared mutable state outside of Actors. The
> state itself (AnnouncementRegistry) is immutable. Since it is a single
> writer, having a shared @volatile var between the actor and the class seems
> to be a good approach, however it also has a code smell to it since I am
> closing over external mutable state and using an anonymous actor. Is there
> a better approach to what I have below?
>
> class DiscoveryClient(config: DiscoveryConfig, singleRequest: HttpRequest =>
> Future[HttpResponse])
> (implicit system: ActorSystem, m: Materializer) {
>
> @volatile
> private[this] var _registry = AnnouncementRegistry.empty
>
> def registry = _registry
>
> private[this] val client = system.actorOf(Props(new Actor with ActorLogging
> {
> import DiscoveryClient._
>
> private[this] var subscribers = HashSet.empty[ActorRef]
>
> private[this] val killswitch =
> ChangeWatcher(config.seeds, singleRequest).to(Sink.foreach(self !
> RegistryUpdate(_))).run()
>
> def receive: Receive = uninitialized
>
> private[this] def uninitialized: Receive = {
> case Subscribe =>
> subscribers += sender
> context.watch(sender)
>
> case Terminated(ref) =>
> subscribers -= ref
>
> case m @ RegistryUpdate(newRegistry) =>
> _registry = newRegistry
> context.become(initialized)
> subscribers.foreach(_ ! m)
> }
>
> private[this] def initialized: Receive = {
> case Subscribe =>
> subscribers += sender
> context.watch(sender)
> sender ! RegistryUpdate(_registry)
>
> case Terminated(ref) =>
> subscribers -= ref
>
> case m @ RegistryUpdate(newRegistry) =>
> _registry = newRegistry
> subscribers.foreach(_ ! m)
> }
>
> override def postStop(): Unit = killswitch.shutdown()
> }), "discovery-client")
> }
>
>
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