When returning a Coroutines JDK Future to a Java library, what’s the best way to do this? ```fun re...

# coroutines

[ryan413]

When returning a Coroutines JDK Future to a Java library, what’s the best way to do this?

fun returnFuture(): CompleteableFuture<String> {
  return runBlocking {
    future {
      // blocking code
      "result"
    }
  }
}

or

fun returnFuture(): CompleteableFuture<String> {
    return GlobalScope.future {
      // blocking code
      "result"
    }
  }
}

We have coroutine code further up the chain that then calls GraphQL-java, which in turn is wired with DataFetchers that implement an interface returning a CompleteableFuture. Ideally we want to share the same coroutine context throughout (so we can leverage MDC via MDCContext , etc.)

[sikri]

can you share coroutine context between datafetchers and that code with futures?

[sikri]

afaiu, you have 3 layers, with coroutines on sides and with java futures in a middle
maybe, you can just create object DomainScope : CoroutineScope to at least limit global scope usage

[ryan413]

that’s doable 🤔

[ryan413]

we are able to share the coroutine context between the coroutines on both sides, will look further I suppose. Would still need to use either runBlocking { future {} } or GlobalScope.future {} somewhere in there though

[ryan413]

Oh wait, think I misunderstood:

DomainScope.future { /* ... */ }