What is the proper way in a simple suspend function to check

Question

What is the proper way in a simple suspend function to check if it s running inside a job and if that job is cancelled

gildor · Answer

Why do you need this every suspend point automatically checks for Job cancellation

gildor · Answer

You can get job using `coroutineContext Job `

gildor · Answer

but use this to check for cancellation doesn t make a lot of sense Instead you can use isActive or just call any suspend function or if you don t need it you can use `yield ` which is an empty suspend point if job is cancelled you suspend function will never return after `yield ` or other suspend call

Tolriq · Answer

Because this is a small simple function that would require way too much refactoring slightly smiling face it calls another suspending function and if the job is not cancelled it push the result to observers

Tolriq · Answer

Currently using yield but it gives other coroutines priority before pushing result when not cancelled

gildor · Answer

yield just allows other coroutines chance to be disputched

gildor · Answer

I still don t understand why yield or isActive is not work for you

gildor · Answer

Looks like some problem in your code if you rely on coroutine dispatching order

Tolriq · Answer

Nope yield just push other coroutine when contention I prefer the push to be as fast as possible when not cancelled It s not vital and mandatory just better

Tolriq · Answer

And I just missed the coroutineContext Job to get access to the isActive slightly smiling face

Tolriq · Answer

Thanks for the missing part

gildor · Answer

there is top level isActive you don t need `coroutineContext Job ` to access it

Tolriq · Answer

That class already have a isActive val wink

gildor · Answer

I would rename it then Because `isActive` is available in scope of any coroutine

gildor · Answer

But also you can import it with different name

gildor · Answer

```import kotlinx coroutines isActive as isActiveCoroutine```

Tolriq · Answer

This is part of a larger public API I can t rename import does not work I get ```Unresolved reference None of the following candidates is applicable because of receiver type mismatch public val CoroutineContext isActive Boolean defined in kotlinx coroutines public val CoroutineScope isActive Boolean defined in kotlinx coroutines```

gildor · Answer

What do you mean does not work I see in your error message that you use `isActive` not a renamed one

gildor · Answer

Just checked works for me

Tolriq · Answer

It does not work in a class that does not extend a coroutineScope

gildor · Answer

yes correct

gildor · Answer

otherwise you can use coroutineContext isActive

Tolriq · Answer

```import kotlinx coroutines isActive as isActiveCoroutine class Renderer suspend fun checkStatus if isActiveCoroutine ``` for reference disappointed

gildor · Answer

use `coroutineContext isActive` for suspend functions

Tolriq · Answer

What does it check slightly smiling face Current Job ParentJob the context itself I ll stick with coroutineContext Job at least it s clear what it check

gildor · Answer

This is just an alias for `coroutineContext Job isActive == true`

gildor · Answer

Also if you press F1 on this function you can see documentation

gildor · Answer

Tolriq · Answer

Currently having issues with AS not using the source and doc for custom coroutines build disappointed But ok thanks will use that then