structured concurrency

CoroutineScope

A

B

A

B

class A {
	val coroutineContext: CoroutineContext ...
}

class B {
	fun myFunction(){
		// run with A.coroutineContext?
	}
}

coroutineContext

B

A

CoroutineScope

A

B

class A : CoroutineScope {
    override val coroutineContext: CoroutineContext ...
}

class B(private val a: A) {
    fun myFunction() {
        a.launch { ... }
    }
}

withContext

A

A

A

override val coroutineContext: CoroutineContext = job + Dispatchers.Main

suspend fun foo(){
   withContext(<http://Dispatchers.IO|Dispatchers.IO>){ some work }
}

produce

I can’t use

produce

directly from a suspending function

B

onBindViewHolder

RecyclerView.Adapter

class MyAdapter(coroutineScole: CoroutineScope): RecyclerView.Adapter<...>(), CoroutineScope by coroutineScope {

It's not incorrect, it's just explicit about it's context. IIRC

user.getIdToken()
        .addOnCompleteListener { task ->
            // send my data here, but in other thread
        }

Channel

class B {
    fun CoroutineScope.runMyChannel() = Channel<Boolean>().also { launch { it.send(true) } }

produce

produce

if A’s object scope will be cancelled all invocations deep inside call graph of withContext launch won’t be cancelled (they are non-cancellable by default

a Job which was started by withContext is not cancelled by that

implementing coroutineContext of CoroutineScope without explicit job is unknown behaviour

withContext(this.coroutineScope)

withContext(MyDispatcher)

but the pratice is if you are implementing CoroutineScope interface you should define job object otherwise it won’t be possible to control scope

withContext(this.coroutineContext)

withContext(this.coroutineContext) {
   someSuspendCall()
}

someSuspendCall()

coroutineScope{}

withContext(this.coroutineContext

but also I want somehow to cancel all suspended download() calls in system with another background operation which destroys and cancels downloader