```private suspend fun connectAndStartListening() ...

# coroutines

[ursus]

private suspend fun connectAndStartListening() = coroutineScope {
    val webSocketSession = ktorClient.webSocketSession("<ws://10.0.2.2:8765>")

    launch {
        for (frame in webSocketSession.incoming) {
            Log.d("Default", "frame=$frame")
        }
    }
    ... stuff
}

I want to add graceful closing when this coroutine gets cancelled. How do I listen for cancellation of this function?

launch {
   awaitCancellation()
   webSocketSession.close()
}

like this?

[Zach Klippenstein (he/him) [MOD]]

private suspend fun connectAndStartListening() {
    val webSocketSession = ktorClient.webSocketSession("<ws://10.0.2.2:8765>")

    // Assuming the session implements AutoCloseable
    webSocketSession.use {
        coroutineScope {
            launch {
                for (frame in webSocketSession.incoming) {
                    Log.d("Default", "frame=$frame")
                }
            }
            ... stuff
        }
    }
}

[ursus]

public interface WebSocketSession : CoroutineScope

so.. I dont think so?

also now im noticing, close is a suspend function

public suspend fun WebSocketSession.close(reason: CloseReason = CloseReason(CloseReason.Codes.NORMAL, ""))

[Zach Klippenstein (he/him) [MOD]]

then replace use with try/finally

[ursus]

but, which part exactly will throw? I was expecting some sort of callback api

[Zach Klippenstein (he/him) [MOD]]

Presumably whatever suspends? I’m guessing incoming? I don’t know this api so maybe I’m totally wrong

[ursus]

btw if I run a suspend function in finally; doesnt that break the structured concurrency?

[Zach Klippenstein (he/him) [MOD]]

Nope that’s fine

[Zach Klippenstein (he/him) [MOD]]

The coroutine will be in a “canceling” state while finally blocks run and join calls won’t resume until all finally blocks are done.

[ursus]

alrighty, thanks !

[ursus]

private suspend fun listenAndSend(webSocketSession: DefaultClientWebSocketSession) = coroutineScope {
    val channel = Channel<ByteArray>(capacity = Channel.BUFFERED)
    launch {
        while (isActive) {
            val bytes = queryMicrophone()
            channel.send(bytes)
        }
        channel.close()
    }

    for (bytes in channel) { <-------
        webSocketSession.send(bytes)
    }
}

If I may follow up

would you wrap this loop in launch or not?

[Zach Klippenstein (he/him) [MOD]]

No

[ursus]

@Zach Klippenstein (he/him) [MOD] sorry to resurect this but I don't think I understand what you meant.
Running a suspend function in finally seems to do nothing once the coroutine was cancelled? it hits first suspension point, which throws cancellation exception and rest is a no-op then. So basically it doesnt do anything (?)