what s easiest way to force a suspension point without using kotlinlang #coroutines

what's easiest way to "force" a suspension point without using delay function? I would like to force a suspension point but also not delay by any amount of time.

octylFractal

06/11/2020, 6:19 PM

yield()

Rechee Jozil

06/11/2020, 6:23 PM

Ah. Yes should work indeed! I just checked docs and it doesn't run if your dispatcher is unconfined and my case it is. Maybe I have to rethink what I'm doing. Thanks though! i didn't even think about yield haha

Dominaezzz

06/11/2020, 6:29 PM

Are you using this forced suspension to "lift" a coroutine from the current thread. By "lift" I mean to stop it from running immediately in the current coroutine.

Rechee Jozil

06/11/2020, 6:32 PM

@Dominaezzz I just need something that forces the current coroutine to suspend. If I have to switch to another thread to do so, then so be it.

But if I could somehow force a suspend (with Dispatchers.Unconfined) on the same thread that'd be great.

private suspend fun testSuspendFunction() =
    withContext(Executors.newSingleThreadExecutor().asCoroutineDispatcher()) {
        Unit
    }

I'll probably end up going with this for my use case^

06/11/2020, 6:41 PM

FYI yield will not force suspension on some dispatchers

Rechee Jozil

06/11/2020, 6:42 PM

* If the coroutine dispatcher is [Unconfined][Dispatchers.Unconfined], this
* functions suspends only when there are other unconfined coroutines working and forming an event-loop.
* For other dispatchers, this function calls [CoroutineDispatcher.dispatch] and
* always suspends to be resumed later regardless of the result of [CoroutineDispatcher.isDispatchNeeded].
* If there is no [CoroutineDispatcher] in the context, it does not suspend.

06/11/2020, 6:42 PM

Here's what Retrofit does: https://github.com/square/retrofit/blob/9e597f2525d6ff0c06b2e836869a0328a2e0b388/retrofit/src/main/java/retrofit2/KotlinExtensions.kt#L103-L119 See also the discussion in the link in those docs

Rechee Jozil

06/11/2020, 6:44 PM

@jw Thanks a lot! I actually need something almost exactly like that. I'd like to force suspend and then throw. My purposes are for unit testing some lower level coroutine code I wrote

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