将Scala未来转化为Twitter未来

Question

我使用Finagle作为web服务器，我想从我的应用程序逻辑中返回服务器。当然，如何以非阻塞的方式将scala.concurrent.Future转换为com.twitter.util.Future？

Answer 1

没有足够的环境来测试这一点，但是下面是我为"com.twitter" %% "finagle-http" % "6.25.0"编写的

import com.twitter.{util => twitter}
import scala.concurrent.{ExecutionContext, Promise, Future}
import scala.util.{Failure, Success, Try}
import language.implicitConversions

object TwitterConverters {
  implicit def scalaToTwitterTry[T](t: Try[T]): twitter.Try[T] = t match {
    case Success(r) => twitter.Return(r)
    case Failure(ex) => twitter.Throw(ex)
  }

  implicit def twitterToScalaTry[T](t: twitter.Try[T]): Try[T] = t match {
    case twitter.Return(r) => Success(r)
    case twitter.Throw(ex) => Failure(ex)
  }

  implicit def scalaToTwitterFuture[T](f: Future[T])(implicit ec: ExecutionContext): twitter.Future[T] = {
    val promise = twitter.Promise[T]()
    f.onComplete(promise update _)
    promise
  }

  implicit def twitterToScalaFuture[T](f: twitter.Future[T]): Future[T] = {
    val promise = Promise[T]()
    f.respond(promise complete _)
    promise.future
  }
}

Answer 2

还可以使用Twitter双射库：https://github.com/twitter/bijection

即com.twitter.bijection.twitter_util.UtilBijections (util/UtilBijections.scala)

这个库处理重要的细节，例如，如果您前后转换对象，它只是打开原始对象。

Answer 3

下面是一个使用twitter双射库的示例：

import scala.concurrent.{Future => ScalaFuture}
import com.twitter.util.{Future => TwitterFuture}

// extend values by adding the conversion method "as"
import com.twitter.bijection.Conversion.asMethod

// pull in various implicit converters that "as" expects, 
// including twitter2ScalaFuture:
import com.twitter.bijection.twitter_util.UtilBijections._

def doSomething: ScalaFuture[T] = {
    val response: TwitterFuture[T] = ???
    response.as[ScalaFuture[T]]
}