if `p` is `Deferred`, then I expected it to be can...

# coroutines

[vaskir]

if p is Deferred, then I expected it to be cancelled on timeout:

select<Unit> {
    p.onAwait { println("ok") }
    onTimeout(1000) { println("timed out!") }
}

but it's not, it prints "timeout out!", p is not cancelled. What is the best way to cancel a Deferred by timeout?

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

Call p.cancel() from your onTimeout block? Alternatively, if p is a child of the current scope, maybe you have more than one, then you can call scope.coroutineContext.cancelChildren().

[vaskir]

withTimeout(1000) {
    p.await()
}

🙂 This throws

Exception in thread "main" kotlinx.coroutines.TimeoutCancellationException: Timed out waiting for 1000 ms
	at kotlinx.coroutines.TimeoutKt.TimeoutCancellationException(Timeout.kt:158)
	at kotlinx.coroutines.TimeoutCoroutine.run(Timeout.kt:128)
	at kotlinx.coroutines.EventLoopImplBase$DelayedRunnableTask.run(EventLoop.common.kt:497)
	at kotlinx.coroutines.EventLoopImplBase.processNextEvent(EventLoop.common.kt:274)
	at kotlinx.coroutines.DefaultExecutor.run(DefaultExecutor.kt:68)
	at java.base/java.lang.Thread.run(Thread.java:834)

which is what I need.

[vaskir]

IDEA suggested to simplify it, so it become

withTimeout(1000) {
    runCommand("cmd.exe", File("."))
}

🙂

[vaskir]

awesome

[vaskir]

the process is indeed killed 🙂

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

that’s much more readable too imo