Get notified if node disconnects/shuts down about ractor

[xunafay]

I'd love to try to implement this but I'm still a bit of a rusty novice. So if I open a PR for this feel free to give it a healthy dose of criticism

[slawlor]

This might be worth adding some "Node events" channel on the NodeServer actor. Such that you could subscribe to node change events.

[xunafay]

I've identified that

ractor/ractor_cluster/src/node/mod.rs

Line 434 in d79ea28

Entry::Occupied(o) => {

would be the place to emit an event

I was just wondering what you thought would be the best channel/method to notify any listeners to these events? @slawlor

[slawlor]

You could use something like an output port, but their syntax still isn't ideal to me (it's the least "clean" aspect of ractor imho right now). Otherwise I'd say a "broadcast" actor would make sense. It's message structure might look like

enum BroadcastMessage<TMessage, F> 
// this function is what actually sends the message to the subscribing actor
where F: Fn(ActorCell, TMessage) -> () + 'static, 
{
  Subscribe(ActorCell, F),
  SendMessage(TMessage),
}

There's probably some weird lifetime stuff, but I "think" this would work?