I've got a list of objects that have Deferred properties which produce some kind of reult, afteer re...

# coroutines

[altavir]

I've got a list of objects that have Deferred properties which produce some kind of reult, afteer result is produced, the Deferred is replaced by another (Completable)Deferred.
Now I want to create a listener which will perform some action when any future is completed. I am trying to do so using select clause this way:

val job = launch {
            while (true) {
                select<Unit> {
                    stateHolder.forEach { state ->
                        state.future.onAwait {
                                // do something
                        }
                    }
                }
            }
        }

But it does not seem to enter the select clause even once. What am I doing wrong?

[gildor]

Did you try to debug?

[altavir]

Of course. I found it to be a some bizarre synchronization problem, which i did not expect to encounter in coroutines. Everything works fine if I introduce blocking sleep between state changes which are done from outside of coronations. Probably should use Mutex locks.
In fact, I keep thinking that it should be simpler. All I need is to create an observable mutable state with coroutine based subscribers.

[altavir]

It seems that I really need BroadcastChannel. I missed it previously.

[gildor]

Coroutines do not solve syncronous problems if you have shared mutable states between threads, bit with coroutines you can use actors or other patterns to handle this

[altavir]

I do not have problems with concurrent state changes, the problem was with notifications. I finally solved it with BroadcastChannel. Everything seems to be working fin now.