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#coroutines
Title
# coroutines
g

Gus

08/19/2020, 9:52 AM
Hey folks. I'm new to Kotlin and coroutines. I have a function that will return a
Flow<Thingy>
and, in some cases, that flow/job should be cancelled if no new
Thingy
has been emitted in the past X seconds (and I'll need to close an underlying connection when the flow is cancelled). Is there any readily-available utility to achieve this? If not, does anyone have any pointers on how to do this in an idiomatic way? If I have to implement it myself, I'm thinking of implementing it as two separate functions:
getThingy(): Flow<Thingy>
and
getThingy(timeoutMillis: Int): Flow<Thingy>
.
getThingy()
would return a cancellable flow, and
getThingy(timeoutMillis)
would use the former function behind the scenes and add the timeout logic. I'm thinking of using
Timer.schedule()
in the timeout logic so I can cancel the timer and start a new one each time a new
Thingy
is emitted, but I wonder whether there's a better way to do this.
p

pedro

08/19/2020, 11:30 AM
I’m not particularly proud, but this does what you want:
Copy code
fun main() {
    val flow = flow {
        emit(1)
        delay(250)
        emit(2)
        delay(250)
        emit(3)
        delay(250)
        emit(4)
        delay(1250)
        emit(5)
    }

    runBlocking {
        launch {
            flow.transformLatest {
                emit(it)
                delay(1000)
                cancel("Timeout")
            }.collect{
                println(it)
            }
        }
    }
}
g

Gus

08/19/2020, 1:01 PM
Thanks Pedro!
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