Hey everyone, I’m having some issues finding some way to do something similar to DispatchQueue in Swift What I want to do is launch one coroutine off the main thread with the first queue element and when it’s done, launch the next in queue. I could implement something with async and all that, but I was wondering if there’s anything that already exists to support this behaviour?

Nothing in the core coroutines libraries that i know of. There’s been some talk about potentially including some sort of worker pool abstraction in the future, which is similar to this i think, but nothing yet

That’s really nice, I didn’t know about Channel, thanks for the help!

I mean, if you are talking about doing work sequentially from items in a queue, you can do something such as:

fun main() {
  scope.launch(Dispatchers.Main) {
    dataList().forEach { item ->
      withContext(Dispatchers.Default) {
        doWorkWith(item)
      }
    }
  }
}

Yes, but if that list isn’t thread safe you could have issues. Channels are effectively blocking queues and thread safe

If that is a concern, making the list a

flow

and doing the work on an

onEach

block is essentially the same as using a Channel.

if you subscribe early enough, and by

flow

you mean

MutableSharedFlow

, then yes

I just realized that

DispatchQueue

is conceptually a

Channel

in iOS. I was thinking it was already a cold list of items, which is why I mentioned using flow with it. 😅 For those following along, if you have a cold list of items to run, you can do something such as

list.asFlow().onEach { withContext(<http://Dispatchers.IO|Dispatchers.IO>) { /*.. do work ..*/ } }.launchIn(scope)

to do work sequentially on another thread . You could also use

MutableSharedFlow

to send items to a flow and have them run sequentially, and can be multi-cast. Just be aware of the back pressure strategy you use.