When working with Java

Future

or

CompletableFuture

in JVM > 8 within

suspendCoroutine

what's the suggested pattern for interaction. From what I can tell, the

suspendCoroutine

is designed for an asynchronous callback but from what I can tell JDK 11, 12, 13 and 14 don't have a way to implement a CompletionStage interface.

There's already built-in integration modules in kotlinx.coroutines for these.

@louiscad I'm assuming your referring to this: https://github.com/Kotlin/kotlinx.coroutines/blob/22087ef122b5ac677fd14941a18b6aef[…]7393d2/integration/kotlinx-coroutines-jdk8/src/future/Future.kt This is only available on CompletionStage and not

Future

For Future itself, that's a poor primitive, and I think the best you can do is wrap the call to

get

in

<http://Dispatchers.IO|Dispatchers.IO> { }

.

Launching on an IO thread doesn't continue the scope, this is more or less what I was thinking:

suspend fun <T> Future<T>.await(): T = coroutineScope {
    // If coroutine is cancelled, cancel the future as well
    val cancelJob = launch {
        suspendCancellableCoroutine { cont ->
            cont.invokeOnCancellation {
                this@await.cancel(true)
            }
        }
    }
    while (!isDone) {
        delay(1)
    }
    cancelJob.cancel()
    this@await.get()
}

But obviously that's still sub-optimal.

It's not so bad I think.

You can wrap it with a callbackflow