Serial Futures (Healthy Ping).scala

def run() = {
    import scala.concurrent.{ blocking, ExecutionContext, Future }
    implicit val ec = ExecutionContext.fromExecutor(java.util.concurrent.Executors.newFixedThreadPool(1))

    val startTime = System.nanoTime()
    def event(name: String) =
        Console.println(s"t=${(System.nanoTime - startTime) / 1000000000}s | $name")

    event("REPORT request RCVD")
    val candidates = 1 to 10
    val calculations = candidates.foldLeft(Future.successful(List.empty[Int]))((pf, c) => pf.flatMap(p => Future {
        Thread.sleep(1000)
        event("REPORT processing")
        p ::: List(c * c)
    }))
    calculations.map { calcs =>
        event("REPORT response SENT")
    }

    event("PING request RCVD")
    Future {
        event("PING response SENT")
    }
}
run()