Here’s a very naive totally unsafe example of how ...

# coroutines

[Marc Knaup]

Here’s a very naive totally unsafe example of how it should work.
send(…) will block untill all flows have processed the sent element.

Is there something like that already?

[Dominaezzz]

You could maintain a list of rendezvous channels (protected by Mutex), then return consumeAsFlow() in receiveAsFlow().

[Dominaezzz]

What should happen if a consumer calls receiveAsFlow calls when send is suspended?

[Marc Knaup]

receiveAsFlow merely creates a new Flow. It’s not even suspending.

[Marc Knaup]

I’ve opened a new issue for this feature with new approach 🙂

https://github.com/Kotlin/kotlinx.coroutines/issues/1901

[Marc Knaup]

Channels can’t solve this issue. Channels never wait for for a value to be processed by the consumer. They only wait for retrieval.

[Dominaezzz]

Flows cannot solve this either. You probably want a custom actor or something along those lines.

[Dominaezzz]

Especially since "processed" will have to be concretely defined between the sender and receiver.

[Marc Knaup]

A regular Flow already has exactly that behavior: emit() suspends until the value collection is completed downstream.

It just doesn’t work for broadcasts.

[Dominaezzz]

Ah. I guess you want some version of https://github.com/Kotlin/kotlinx.coroutines/issues/1261 or https://github.com/Kotlin/kotlinx.coroutines/issues/1086 .

[Marc Knaup]

Very interesting, thank you!