useDirective1.scala

def timeRequest(request: HttpRequest): Try[RouteResult] => Unit = {
  val start = System.currentTimeMillis()

  {
    case Success(Complete(resp)) => 
      val d = System.currentTimeMillis() - start
      logger.info(s"[${resp.status.intValue()}] ${request.method.name} " +
        s"${request.uri} took: ${d}ms")
    case Success(Rejected(_)) => 
    case Failure(_)           => 
  }
}

val routes: Route = 
  aroundRequest(timeRequest) {
    path("...") { 
      ... 
    } 
  }