Compose futures by Scala Async

Question

There are futures f1, f2 and f3. If we need wait till both f1 and f2 complete or f3 does, i.e. the condition looks like completed(f1) & completed(f2) | completed(f3), how can we use Scala Async to compose it fluently?

Answer 1

I don't know async, but you could probably find a solution using Future.firstCompletedOf and promises. There's already a post on SO about this.

If you don't care about cancelling the futures, you can simply do something like :

val f1 = Future { /*...*/ }
val f2 = Future { /*...*/ }
val f3 = Future { /*...*/ }

Future.firstCompletedOf(Seq(f1.flatMap(f2), f3))