Multiple actor invocation from blocking call

Question

This is probably a simple problem to the scala educated mind but I'm still a beginner ;)

I have a base actor who dispatches a task to multiple worker actors and replies it's result to a blocking external call via !?

a = new a

a.start

println(a !? "12345")



class a extends Actor {

def act = {
     loop {
     react {  
     case msg =>
                     val result = worker_actor_1 !? msg
                     result += worker_actor_2 !? msg
                     result += worker_actor_3 !? msg
                     // So I just have multiple workers who should do stuff in parallel and the aggregated result should be returned to the calling function
                     reply(result)
}

Now I don't know how to truly parallelize the worker actors in the blocking call because in the end I have to reply(). The calling entitiy is no actor, just a regular class.

Answer 1

You can create several futures and then spawn a separate actor to wait for their results. Thus your dispatch will be ready for new requests. The snippet of code follows:

case msg =>
   val invoker = sender
   val flist =
       worker_actor_1 !! task1 ::
       worker_actor_2 !! task2 ::
       worker_actor_3 !! task3 :: Nil 
   Scheduler.execute { invoker ! Futures.awaitAll(100, flist).map{ ..sum the results.. } }

Please note awaitAll returns List[Option[Any]], so you can learn if something went wrong and your worker actors did not accomplish the task in time