[writing-async-app-in-scala-part-2] RPC with caching 2

RpcCaching2.scala

val handlers: List[HttpRequest => Future[Option[Int]]] = List(
  handleFromMemcached,
  handleFromCdn,
  r => handleFromHadoop(r).map(Some.apply)
)

def handle(r: HttpRequest): Future[Int] = {
  executeLazily(handlers.map(handler => () => handler(r)))
    .map(_.getOrElse(throw new IllegalStateException("Hadoop should always return Some!")))
}

def executeLazily(list: List[() => Future[Option[Int]]]): Future[Option[Int]]