Question

I’m sure this is a very simple question, but embarrassed to say I can’t get my head around it:

I have a list of values in Scala.
I would like to use use actors to make some (external) calls with each value, in parallel.

I would like to wait until all values have been processed, and then proceed.

There’s no shared values being modified.

Could anyone advise?

Thanks

Answer 1

There’s an actor-using class in Scala that’s made precisely for this kind of problem: Futures. This problem would be solved like this:

// This assigns futures that will execute in parallel
// In the example, the computation is performed by the "process" function
val tasks = list map (value => scala.actors.Futures.future { process(value) })

// The result of a future may be extracted with the apply() method, which
// will block if the result is not ready.
// Since we do want to block until all results are ready, we can call apply()
// directly instead of using a method such as Futures.awaitAll()
val results = tasks map (future => future.apply())

There you go. Just that.