Scala_MultiThreading

import scala.concurrent.{Await, ExecutionContext, Future}
import scala.concurrent.duration._

// No @volatile or `synchronized`
class Foo {
  private var _id: Option[String] = None

  def set(id: String): Unit = {
    _id = Option(id)
  }
  def unset(): Unit = {
    _id = None
  }
  def get: Option[String] = {
    _id
  }
}

object Test {
  val arr = Array[Foo](new Foo, new Foo)
  implicit val ex: ExecutionContext = scala.concurrent.ExecutionContext.Implicits.global

  def main(args: Array[String]): Unit = {
    val f = Future {
      println(s"Thread[${Thread.currentThread.getId}]: set to 0")
      arr(0).set("0")
    }
    .map { _ =>
      val p = arr(0).get
      println(s"Thread[${Thread.currentThread.getId}]: get ${p}")
    }
    .map { _ =>
      println(s"Thread[${Thread.currentThread.getId}]: unset")
      arr(0).unset
    }

    val res = Await.result(f, 100.seconds)
    println(res)
  }
}