Is there some way to get job from `CoroutineContext` by key and cancel it?

# coroutines

[genovich]

Is there some way to get job from CoroutineContext by key and cancel it?

[streetsofboston]

someCoroutineContext[Job]?.cancel()

[genovich]

what if I want to retrieve concrete child job from context?

[streetsofboston]

A CoroutineContext has (at most) one Job. To examine child-jobs, get the main/parent Job (like in my example) and access the children property on it.

[genovich]

I want to associate each started Job with some key to find and cancel them later. What is better: to have Map<Any, Job>, or to add new Element to CoroutineContext?

[genovich]

Or there may be any better solution?

[streetsofboston]

In my opinion, cache each Job (Deferred) returned by launch/async in a Map, like your first suggestion.

An Element in CoroutineContext is not like a map. It is a Unique Type Set, ie you can have only one value of an Element-type in a CoroutineContext. This means, for example, you can't store 2 Jobs in a CoroutineContext.

[genovich]

I see

[genovich]

@elizarov, what is Your suggestion from the creator’s point of view?

[elizarov]

What exactly are you trying to achieve? What's the context of the stuff you are doing?

[genovich]

I want to cancel concrete Jobs in CoroutineScope that have been launched earlier.
You can treat it as a system that can emit signals like start Job or stop Job by token.
I can explain this better in DM, if You want.

[elizarov]

If you want to cancel them from "outside", from some control coroutine that is launching them, then the simplest way is to store somewhere the result of the launch { .. } function that returns a Job that you can call cancel() on.

[genovich]

So I did =)

[genovich]

Thank you both for answers