Hi <@UHAJKUSTU>, with the latest changes in kotlin...

# reaktive

[Mina Eweida]

Hi @Arkadii Ivanov, with the latest changes in kotlin 1.4 with Ktor, I can see we are able to run it in background on native if we run from MainScope already tested that on my project, so would it make sense if this is provided in Reaktive through coroutine-interop?

[Arkadii Ivanov]

Hi, sorry but I don't get. What change in Reaktive would you like?
AFAIK starting from Kotlin 1.4. Ktor uses native-mt coroutines. So you can just use the -nmtc version of Reaktive coroutines-interop module.

[Mina Eweida]

yes but you can’t do singleFromCoroutine because you cannot specify dispatcher. It’s always Dispatcher.Unconfined but maybe there could be some flexibility there

[Arkadii Ivanov]

What are you trying to achieve? Why do you need a dispatcher there?
What if you write:

singleFromCoroutine {}
    .subscribeOn(ioScheduler)

[Arkadii Ivanov]

And why do you want to run Ktor on a particular Dispatcher?

[Mina Eweida]

I have to run Ktor on Coroutines’ MainScope. Even if I use a dispatcher to run in background, I cannot run it unless I launch it through MainScope.
So using singleFromCoroutine won’t work in this case. So I figured for interoperability with coroutines we could have some singleFromCoroutine that will launch the call in MainScope and allow providing a dispatcher to run it on.

[Mina Eweida]

This way we can do calls to Ktor with a reaktive stream.

[Mina Eweida]

It’s not a high priority thing but when upgrading to 1.4 we faced this issue since part of the reaktive stream was calling Ktor so we had to change this.

[Arkadii Ivanov]

I would like to understand the case completely. 🙂 What was the exact issue?

[Mina Eweida]

Let me write down something more clear. Sorry for the confusion 😅

[Mina Eweida]

I am traveling now. I will send it once I am at my laptop.

[Arkadii Ivanov]

Thanks!
My thoughts are as follows. Ktor switches dispatchers under the hood. There should be no need to manually switch dispatchers for Ktor. The only thing that was not possible before 1.4 is switching threads before/after Ktor for data processing. Now it is possible.

singleFromCoroutine { /* Call Ktor, does not matter what is the dispatcher/thread here */ }
    .observeOn(computationScheduler)
    .map { /* parse the response on background thread /* } 
    .observeOn(mainScheduler)
    .susbcribe(isThreadLocal = true) { /* Update the UI on main thread /* }