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For `suspendCancellableCoroutine`, does the `invokeOnCancellation` get called when I call `resume` normally, or should I clean up there as well?

I'm not sure, but I'm curious to find out. I think a good supplementary question is when do we need to use _both_ `invokeOnCancellation` and the cancelation handler provided in `resume`?

I'm not quite sure what you mean, but
`invokeOnCancellation` callback gets invoked when the continuation is cancelled
`resume.onCancellation` callback gets invoked when you try to `resume` after cancellation
it's possible for only 1 to happen, or 1 then 2 to happen

Oh, right. I see. I typed that message when I was still pre-coffee :sweat_smile: makes perfect sense.

Weird, I've had 2 happen without 1 somehow, aka the callback should have been unregistered, but wasn't

<https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/-cancellable-continuation/invoke-on-cancellation.html> should answer this.
&gt;  *synchronously* invoked on <https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/-cancellable-continuation/cancel.html|cancellation> (regular or exceptional) of this continuation
&gt; This handler is also called when this continuation <https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.coroutines/index.html|resumes> normally (with a value) and then is cancelled while waiting to be dispatched. More generally speaking, this handler is called whenever the caller of <https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/suspend-cancellable-coroutine.html|suspendCancellableCoroutine> is getting a <https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/-cancellation-exception/index.html|CancellationException>.
So, after a normal `resume`, the handler can only be called if cancellation happened anyway.