Hello, quick question about suspend and cancellation, what would be the best way to cancel early a s...

# coroutines

[nitrog42]

Hello, quick question about suspend and cancellation, what would be the best way to cancel early a suspend method that iterate on a list (using map operator) ?

suspend fun mappingFunction(dataToMap: List<String>) {
        val mappedData = dataToMap.map { 
            
        }
        
        // run suspendable work with mappedData
    }

[gildor]

return@mappingFunction

[nitrog42]

I’m sorry I meant, if the coroutine is cancelled, the map will still run until we go to the suspendable work here, which will check if the coroutine is active and then cancel itself right ? So is there anyway to make the map cancel itself ?

[nitrog42]

using a sequence or a flow maybe ?

[gildor]

actually you can just use return, no need to use label in this case

[gildor]

Ahhh, I got what you mean. Depends on what is inside of your map if you call any other suspend function it will be cancelled, if you do not call any suspend functions, so don’t have any cancellation points, you can call yield() which creates empty suspend (and cancellation) point

[gildor]

But if this map is very fast, I actually think that would be faster just allow it finish work and cancel later than check on every iteration

[nitrog42]

i have 4 sequentials map actually (4 lists), but calling yield between is a good idea

[gildor]

4 maps in one chain?

[nitrog42]

20 days later => no, I have 4 differents lists (of different objects) and needed to do operation on each, which can take time