fix: forward dispatch return value

[ronag]

Refs: #3373
Refs: #3370

[ronag]

Things this doesn't solve.

• async dispatch
• drain event parameters (which you could argue are useless)

[metcoder95]

It has sense; I just feel that this can cause the false sensation of having a fully fledge dispatcher.

It might be possible that we end with max listeners problems.

Shall we tests the events are emitted as we expect?

[ronag]

I feel this is just a hack until we have a better solution.

[ronag]

We would need to have some form of weak event listeners for this to work well.

[ronag]

@benjamingr Do you have any input on how we can have weak event listeners here that when the ComposedDispatcher is gc:d will be freed?

[ronag]

This is still not great though... until GC the event listeners are still registered.

[ronag]

The alternative is that we have some kind of ref/unref API. But that is going to be a constant pain of people doing it wrong.

[benjamingr]

@benjamingr Do you have any input on how we can have weak event listeners here that when the ComposedDispatcher is gc:d will be freed?

We don't currently expose it but you can use kWeakHandler in the version bundled with Node, that lets you pass a listener and an object that the listener's lifetime is bound to - that's EventTarget though.

So we would need to build kWeakHandler (or similar) to EventEmitter and expose that to undici somehow - it has to be baked into the abstraction (EventEmitter) itself - otherwise it leaks the WeakRef itself (as you probably noticed).

[ronag]

@metcoder95 @mcollina wdyt of returning a Proxy?

[metcoder95]

So we would need to build kWeakHandler (or similar) to EventEmitter and expose that to undici somehow

This sounds great, but personally I'm afraid we will be attaching undici to Node internals and userland usage might suffer from a workaround that does not behaves the same.
It would be nice to have something we can use in the form of a public API for that

wdyt of returning a Proxy?

It simplifies a lot certainly, how does the gc behave (out of curiosity mostly)?

[ronag]

how does the gc behave (out of curiosity mostly)?

We cannot say anything definite about gc behavior. It's totally undefined.