HelloFuturesScala.scala

object HelloFuturesScala extends App {
import scala.concurrent._
import scala.concurrent.duration._
import ExecutionContext.Implicits.global

  def identityFunction(number:Int) = {
    Thread.sleep(3000)
    number
  }  
  println("Hello Futures Scala")
  
  def run(number:() => Int) = {
    val startTime = System.currentTimeMillis
    val value = number();
    val elapsedTime = ((System.currentTimeMillis - startTime) / 1000.0)
    println("------------------------------")
  	println("Value is " + value + " calculated in " + elapsedTime + " seconds")
  	println("------------------------------")
  }  
  println("Blocking version")
  run(()=>{
    val number1 = identityFunction(1)
    val number2 = identityFunction(2)
    val number3 = identityFunction(3)
    number1 + number2 + number3
  })
  
  println("Non-Blocking version")
  run(()=>{
    val number1 = future { identityFunction(1) }
    val number2 = future { identityFunction(2) }
    val number3 = future { identityFunction(3) }
    val sum = for{
      x <- number1
      y <- number2
      z <- number3
    } yield (x + y + z)
    Await.result(sum,Duration.Inf)
  })  
}