Proposal: instead of returning null during missing ActorRef lookups, return Nobody instead

[Aaronontheweb]

And pipe all messages directly to DeadLetters - Akka returns a reference to a static ActorRef.NoSender instance and this is the same idea. That way, rather than throw an exception, messages just get piped into the undeliverables pile.

Thoughts?

[rogeralsing]

In what context? during ResolveActorRef ? ActorSelection?

[Aaronontheweb]

I'm thinking

Context.Child and Context.ActorSelection

[rogeralsing]

Yes, I checked the impl for getSingleChild on actorref, actorcell and actorselection, they all point to this method:

  override def getSingleChild(name: String): InternalActorRef =
    if (name.indexOf('#') == -1) {
      // optimization for the non-uid case
      getChildByName(name) match {
        case Some(crs: ChildRestartStats) ⇒ crs.child.asInstanceOf[InternalActorRef]
        case _                            ⇒ Nobody

So you are correct :)
ActorCell.Child(...) in pigeon needs to be refactored to behave (and renamed) according to the scala code

[rogeralsing]

I made ActorCell.Child(string name) use the extension to resolve Nobody, so we don't get null refs back from this.
In Akka, there are multiple methods for this, "Child(string name)" in their case, returns "some/none" FP style.. while getSingleChild returns Nobody if not found. ¨
Not sure if we need to make a distinction on this here?

[Aaronontheweb]

@rogeralsing nah, seems like semantics. This is a good solution for the time being.

One thing we should consider adding (saw this in Akka) is an EmptyLocalAftorRef for this scenario - subclasses from LocalActorRef and just redirects all messages directly to DeadLetters. Seems like a good solution for being able to help debug scenarios where a Pigeon user is sending messages to a child that doesn't actually exist.