Does a suspend function check for the coroutine to be active

Question

Does a suspend function check for the coroutine to be active when the function resume and the coroutine is continued ie say you have a long running io call and during that time the coroutine job is canceled When the io call completes will the coroutine resume or stop I know that the suspend call will check for isActive before running the suspend block but I can t find a definitive answer if it will resume without checking isActive Thanks

octylFractal · Answer

the `suspend` language feature itself does not know about cancellation that s strictly a concept from the coroutines library so it does not check for cancellation many but not all functions provided by the coroutines library do check for cancellation and the docs will say if they do or not

octylFractal · Answer

also to be clear usually a long running IO call is blocking and therefore suspend mechanics do not come in to play at all

Shmuel Rosansky [G] · Answer

yeah correct It s a network call that s being run on the IO context

Shmuel Rosansky [G] · Answer

ok thanks this settles it then

Shmuel Rosansky [G] · Answer

is best practice to check for isActive when resuming after the network code

octylFractal · Answer

as I said some of the coroutines library provided functions already check that `withContext` is one of them <https kotlin github io kotlinx coroutines kotlinx coroutines core kotlinx coroutines with context html>

octylFractal · Answer

gt Note that the result of withContext invocation is dispatched into the original context in a cancellable way which means that if the original coroutineContext in which withContext was invoked is cancelled by the time its dispatcher starts to execute the code it discards the result of withContext and throws CancellationException

Shmuel Rosansky [G] · Answer

right but if by base context is UI then I generally won t be using withContext UI after making an IO call

octylFractal · Answer

right but did you do `withContext IO `

octylFractal · Answer

the paragraph above describes the return path from `withContext` in short `withContext` checks for cancellation before it returns

Shmuel Rosansky [G] · Answer

ah I see

Shmuel Rosansky [G] · Answer

looks like I m using coroutineScope

octylFractal · Answer

that doesn t change contexts though

octylFractal · Answer

regardless <https kotlin github io kotlinx coroutines kotlinx coroutines core kotlinx coroutines coroutine scope html> gt The method may throw a CancellationException if the current job was cancelled externally

Shmuel Rosansky [G] · Answer

Ok thanks I ll dig into this