Got a flow question for y'all.. It's about .... ```Exception in thread "main" java.lang.IllegalSta...

# coroutines

[taer]

Got a flow question for y'all.. It's about ....

Exception in thread "main" java.lang.IllegalStateException: Flow invariant is violated:
		Emission from another coroutine is detected.
		Child of StandaloneCoroutine{Active}@2b552920, expected child of BlockingCoroutine{Completing}@2758fe70.
		FlowCollector is not thread-safe and concurrent emissions are prohibited.
		To mitigate this restriction please use 'channelFlow' builder instead of 'flow'

[zak.taccardi]

seems like you need to use the channelFlow builder

[taer]

I do.. But.. I was wanting this to be really suspendable instead of multi-thready...

[taer]

I have a example main thing I wrote up to show what I', shooting for

[taer]

the channelFlow worked.. But.. I'm new to flows and rxjava-style code in general..

[taer]

and I was wondering if that was the "correct way"

[taer]

https://gist.github.com/taer/9866ebc832610d941f4e5e54123abf82

[taer]

I stubbed out the asynchttpclient's completablefuture w/ a faked one.

[taer]

Fixed the initial compile issues. I made a second copy of the gist w/ channelFlow and it didn't work out well. 🙂

[taer]

Just checking to see if I'm doing anything just "wrong" here. if I replaced the flow w/ channelFlow(and emit to send), it works perfectly. But... I'm just checking to see if I'm going down the right path

[Paul Woitaschek]

@taer Set the extension of your gist file to .kt so we get syntax highlighting

[bdawg.io]

The problem is you are doing launchIn(scope) which means you'll emit from that new scope. You indeed need to use a channel-based flow to communicate between the contexts.

[taer]

Updated now. It's all now channelFlow based. I think this is probably correct.

[taer]

The thing I was wondering about is .. Is this "best practice"? The 2 subFlows I have are simulated. The real code calls a http service that can wait up to 60 seconds, but returns a nice completableFuture. So, I think this is correct. All the printing seems to indicate this is working like I'd expect.

[taer]

But it doesn't feel like this is 100% idiomatic. I'd love any pointers on how to make this less async'y and more suspend only.