/**
* Sends a request message to an actor, awaits a response value (but no longer than the given
* timeout) and returns it. This method can be called by any code, even non-actor code. If the
* actor responds with an error message, a {@link RuntimeException} will be thrown by this method.
* <br>
* The message's {@code id} and {@code from} properties may be left unset.
*
* <p>This method should be used as in the following example (assuming a {@code String} return
* value:
*
* <pre>{@code
* String res = call(actor, new MyRequest());
* }</pre>
*
* In the example, {@code MyRequest} extends {@link RequestMessage}. Note how the result of the
* {@link #from() from} method is passed to the request's constructor, but the message ID isn't.
*
* @param <V> the return value's type
* @param actor the actor to which the request is sent
* @param timeout the maximum duration to wait for a response
* @param unit the time unit of the timeout
* @return the value sent by the actor as a response
* @throws RuntimeException if the actor responds with an error message, its contained exception
* will be thrown, possibly wrapped by a {@link RuntimeException}.
* @throws TimeoutException if the timeout expires before a response is received from the actor.
* @throws InterruptedException
*/
public static <V> V call(final ActorRef actor, RequestMessage<V> m, long timeout, TimeUnit unit)
throws TimeoutException, InterruptedException, SuspendExecution {
assert !actor.equals(LocalActor.self()) : "Can't \"call\" self - deadlock guaranteed";
if (m.getFrom() == null) m.setFrom(from());
final Actor currentActor;
if (m.getFrom() instanceof TempActor) currentActor = ((TempActor<?>) m.getFrom()).actor.get();
else currentActor = Actor.currentActor();
assert currentActor != null;
final Object watch = currentActor.watch(actor);
if (m.getId() == null) m.setId(watch);
final Object id = m.getId();
final SelectiveReceiveHelper<Object> helper =
new SelectiveReceiveHelper<Object>(currentActor) {
@Override
protected void handleLifecycleMessage(LifecycleMessage m) {
if (m instanceof ExitMessage) {
final ExitMessage exit = (ExitMessage) m;
if (Objects.equals(exit.getActor(), actor) && exit.getWatch() == watch)
throw Exceptions.rethrow(exit.getCause());
}
super.handleLifecycleMessage(m);
}
};
try {
actor.sendSync(m);
final ResponseMessage response =
(ResponseMessage)
helper.receive(
timeout,
unit,
new MessageProcessor<Object, Object>() {
@Override
public Object process(Object m) throws SuspendExecution, InterruptedException {
return (m instanceof ResponseMessage
&& id.equals(((ResponseMessage) m).getId()))
? m
: null;
}
});
currentActor.unwatch(
actor,
watch); // no need to unwatch in case of receiver death, so not doen in finally block
if (response instanceof ErrorResponseMessage)
throw Exceptions.rethrow(((ErrorResponseMessage) response).getError());
return ((ValueResponseMessage<V>) response).getValue();
} finally {
if (m.getFrom() instanceof TempActor) ((TempActor) m.getFrom()).done();
}
}
@SuppressWarnings("unchecked")
private Pair<ActorRef<? extends WebMessage>, Class<? extends ActorImpl<? extends WebMessage>>>
autoCreateActor(FullHttpRequest req) {
registerActorClasses();
final String uri = req.getUri();
for (final Class<?> c : actorClasses) {
if (WebActorHandler.handlesWithHttp(uri, c) || WebActorHandler.handlesWithWebSocket(uri, c))
return new Pair<
ActorRef<? extends WebMessage>, Class<? extends ActorImpl<? extends WebMessage>>>(
Actor.newActor(
new ActorSpec(
c, actorParams != null ? actorParams.get(c) : EMPTY_OBJECT_ARRAY))
.spawn(),
(Class<? extends ActorImpl<? extends WebMessage>>) c);
}
return null;
}
