Hey everyone, I need help with putting something t...

# coroutines

[mng]

Hey everyone, I need help with putting something together but I’m not too sure how to do so.

• I want to make 2 API calls in parallel (Call A and Call B)
• If Call A finishes first and is Successful, cancel Call B then return result of Call A
• If Call B finishes first and is Successful, cancel Call A then return result of Call B
I currently have something like this:

val callA = async { the call }
val callB = async { the call }

if (callA.await().isSuccess) {
     callB.cancel()
     return callA.await()
}else {
     callA.cancel()
     return callB.await()
}

However, it doesn’t quite get the behavior I want because I’m essentially only waiting for Call A to complete first before I even check on Call B. Can anyone offer some advice, please?

[Adam Powell]

use select {} and Deferred.onAwait {}

[jw]

see also https://github.com/Kotlin/kotlinx.coroutines/issues/2867#issuecomment-998553524

[Nick Allen]

I find Flow simpler for this:

merge(::suspendMethod1.asFlow(), ::suspendMethod2.asFlow()).first()

[Adam Powell]

Roman's example from that issue thread is a good shape for something like this

[mng]

Thank you everyone for the advice!