threading in scala with futures

Threading.scala

import scala.util.{Success, Failure}
import scala.concurrent._
import ExecutionContext.Implicits.global
import duration._

class Thing {
  private var _a = 0

  def a = {
    Thread.sleep(500L)
    _a
    // uncomment the following line to see other behavior
    // throw new RuntimeException("um, something happened")
  }

  def a_=(v: Int) = _a = v
}

object Threading1 {
  def main(args: Array[String]) {
    val t = new Thing()
    val f: Future[Int] = future {
      t.a // reference to something outside this future. cool!
    }
    t.a = 1
    f onComplete {
      case Success(value) => println("I have a thing: " + value)
      case Failure(e: RuntimeException) => t.a = 0 // Await.result rethrows exceptions thrown
      case Failure(e) => println("something really weird happened")
    }
    println("doing something else now")
    t.a = 2
    // the state of this object kind of scares me
    // uncomment the following line to see what I mean
    // Await.ready(f, 60.seconds)
    t.a = 3
    val result = Await.result(f, 60.seconds)
    println("doing more stuff right now because I have a thing: " + result)
  }
}

object Threading2 {
  def main(args: Array[String]) {
    val tasks: Seq[Future[Int]] = for (i <- 1 to 100) yield future {
      println("Executing task " + i)
      Thread.sleep(1000L) // Doing work
      i * i
    }

    val aggregated: Future[Seq[Int]] = Future.sequence(tasks)

    val squares: Seq[Int] = Await.result(aggregated, 15.seconds)
    println("Squares: " + squares)
  }
}