期货/成功竞赛

问题描述

我正在学习期货，我想创建一个方法，将两个期货作为参数
（ f 和 g ）并返回成功完成的第一个未来，否则返回 f 或 g 。

I'm learning futures, and I'm trying to create a method that, take two futures as parameter(f and g) and return the first future that was successfully completed, otherwise it returns f or g.

一些用例来说明我的方法的行为是：

Some use cases to illustrate the behaviour of my method are :

Future 1        | Future 2         | Result
Success First     Success Second     Future 1
Success First     Failure Second     Future 1
Success Second    Success First      Future 2
Success Second    Failure First      Future 1
Failure First     Failure Second     Future 2 (because we had a failure on Future 1, so try to see what is the result Future 2)

所以我创建了这个方法：

So I created this method :

def successRace(f: Future[T], g: Future[T]): Future[T] = {
        val p1 = Promise[T]()
        val p2 = Promise[T]()
        val p3 = Promise[T]()
        p1.completeWith(f)
        p2.completeWith(g)
        p3. ????
        p3.future
}

现在，完成第一？

推荐答案

您要使用 tryCompleteWith 方法。

def successRace(f: Future[T], g: Future[T]): Future[T] = {
  val p = Promise[T]()
  p.tryCompleteWith(f)
  p.tryCompleteWith(g)
  p.future
}

这篇关于期货/成功竞赛的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！