Controllable Futures

ControllableFutures.worksheet.sc

// How to Write Controllable Futures in Scala | Rock the JVM
// https://www.youtube.com/watch?v=72kurKY7fX8

import scala.concurrent.Future
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.Promise

val aFuture = Future {
   42
}

// an asyncronous service
object Service {
   def produceValue(v: Int): String = "The meaning of life is " + v

   // shitty executor
   def submitTask[A](arg: A)(task: A => Unit): Unit = {
      task(arg)
   }
}

def getAValue(arg: Int): Future[String] = {
   val p = Promise[String]()

   Service.submitTask(arg) { (v: Int) =>
      val result = Service.produceValue(v)
      p.success(result)
   }

   p.future
}

val aValue = getAValue(42).map(_ + "!!!")

// Promises

val p = Promise[String]()

val f = p.future

def asyncCall(p: Promise[String]) = {
   p.success("Hello")
}

asyncCall(p)

// use the future
val f2 = f.map { x => x + "!!!" }