How can I avoid the ClosedByInterruptException fro...

# coroutines

[Exerosis]

How can I avoid the ClosedByInterruptException from being throw up when doing something like this:

val test = withTimeoutOrNull(3.seconds) {
    runInterruptible {
        channel.receive(ByteBuffer.allocateDirect(10))
    }
}

I would have expected null to be returned. Catching the exception results in a value being returned instead of null.

[Joffrey]

Why do you use runInterruptible here? channel.receive is suspending, so I don't see a reason

[Joffrey]

The point of runInterruptible is to convert cancellations from calling code into thread interruption for the wrapped blocking code. If the code is already coroutine-based and supports coroutine cancellation, you shouldn't use runInterruptible

[simon.vergauwen]

Looking at the code, it looks like he's using java.nio.channels 🤔 KotlinX Coroutines Channels doesn't have such an API with ByteBuffer, does it?

[simon.vergauwen]

java.nio.channels don't work with InterruptedException it seems, like runInterruptible relies on.

[uli]

Well, ClosedByInterruptException is not an InterruptedException . That’s the issue.
In more depth: runInterruptible works by catching InterruptedException and rethrowing it as CancellationException.
The issue is here, that channel.receive (did you mean channel.read?) catches the `InterruptedException`and rethrows it as ClosedByInterruptException which is unknown to runInterruptible and breaks everything.

[uli]

Not nice, but you could do:

val test = withTimeoutOrNull(3.seconds) {
    runInterruptible {
        try {
            channel.receive(ByteBuffer.allocateDirect(10))
        }  catch (e: ClosedByInterruptException) {
            throw CancellationException("Blocking call was interrupted due to parent cancellation").initCause(e)
        }
    }
}