spray-routingをベースしたControllerの書き方

Spray.scala

import akka.actor._
import akka.io.IO
import spray.can.Http
import spray.routing.{Directives, HttpService, RequestContext, Route}

trait Action {

  def apply(request: RequestContext): Unit

}

object Action {

  def apply(block: RequestContext => Unit) = new Action {
    override def apply(ctx: RequestContext): Unit = block(ctx)
  }
}

trait ControllerSupport extends Directives {

  protected def getQueryParam(key: String)(implicit ctx: RequestContext): Option[String] =
    ctx.request.uri.query.get(key)

}

// ほんとはこのアプリケーションサービス内でドメインモデルとファクトリ、リポジトリが登場するが、サンプルなので省略している。
case class FactApplicationService {

  def fact(n: Seq[Long]): Seq[Future[Long]] = {
    Future.traversal(n) { n =>
      fact(n)
    }
  }

  private def fact(n: Long): Long = {
    def fact0(result: Long, n: Long): Long =
      n match {
        case 0 => result
        case _ => fact0(n * result, n - 1)
      }
    fact(1, n)
  }

}

case class FactController(factApplicationService: FactApplicationService) extends ControllerSupport {

  def fact = Action { implicit ctx =>
    val values: Seq[Int] = getQueryParam("values")
      .map(s => s.split(",")
      .map(_.toInt).toSeq)
      .getOrElse((1 to 10).toSeq)
    val future: Future[Seq[Int]] = 
      Future.sequence(factApplicationService.fact(values))
    val results: Seq[Int] = Await.result(future, Duration.Inf)
    ctx.complete(s"results = $results")
  }

}

trait Routes extends HttpService with ControllerSupport {

  val factController = FactController()

  protected val routes: Route = {
    get {
      path("fact") { ctx =>
        factController.fact(ctx)
      }
    }
  }

}

class ServiceActor extends Actor with Routes {

  def actorRefFactory = context

  def receive = runRoute(routes)

}

object Main extends App {

  implicit val system = ActorSystem()

  val handler = system.actorOf(Props[ServiceActor], name = "handler")

  IO(Http) ! Http.Bind(handler, interface = "localhost", port = 8080)

}