Future with Timeout in Scala

Question

Suppose I have a function, which invokes a blocking interruptible operation. I would like to run it asynchronously with a timeout. That is, I would like to interrupt the function when the timeout is expired.

So I am trying to do something like that:

import scala.util.Try
import scala.concurrent.Future

def launch(f: () => Unit, timeout: Int): Future[Try[Unit]] = {

  val aref = new java.util.concurrent.atomic.AtomicReference[Thread]() 

  import ExecutionContext.Implicits.global
  Future {Thread.sleep(timeout); aref.get().interrupt} // 1
  Future {aref.set(Thread.currentThread); Try(f())}    // 2
}

The problem is that aref in (1) can be null because (2) has not set it to the current thread yet. In this case I would like to wait until aref is set. What is the best way to do that ?

Answer 1

You can go for a slightly easier approach using Await. The Await.result method takes timeout duration as a second parameter and throws a TimeoutException on timeout.

try {
  import scala.concurrent.duration._
  Await.result(aref, 10 seconds);
} catch {
    case e: TimeoutException => // whatever you want to do.
}