Google 3.0 in Scala

SearchBackend.scala

import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.{Await, Future}
import scala.concurrent.duration._
import scala.util.Random

// go original from here: https://github.com/golang/talks/blob/master/content/2012/concurrency/support/google3.0.go

object SearchBackend extends App {
  type Query  = String
  type Result = String
  type Search = Query => Future[Result]

  val webBackends = List(
    fakeSearch("web1"),
    fakeSearch("web2")
  )
  val imageBackends = List(
    fakeSearch("image1"),
    fakeSearch("image2")
  )
  val videoBackends = List(
    fakeSearch("video1"),
    fakeSearch("video2")
  )

  def search(query: Query): Future[List[Result]] = {
    val results = List(
      firstResult(query, webBackends),
      firstResult(query, imageBackends),
      firstResult(query, videoBackends)
    )

    Future.sequence(results)
  }

  private def firstResult(query: Query, backendReplicas: List[Search]): Future[Result] = {
    val timeoutFuture = Future { Thread.sleep(80); "timeout" } // or use akka.pattern.after, monix.execution.FutureUtils, etc.
    val searches: List[Future[Result]] = backendReplicas.map(r => r(query))

    Future.firstCompletedOf(timeoutFuture :: searches)
  }

  private def fakeSearch(kind: String): Search =
    { query =>
      Future {
        Thread.sleep(Random.nextInt(100).toLong)
        s"$kind result for '$query'"
      }
    }

  // using it
  Await.result(search("cute cats"), 5.seconds).foreach(println)
}