如何将基于时间的观察者添加到Scala Future？

发布时间：2020-12-16 18:31:41 所属栏目：安全来源：网络整理

导读：我想在 Scala Futures中添加一个after(d：FiniteDuration)(callback：= Unit)util,它可以让我这样做： val f = Future(someTask)f.after(30.seconds) { println("f has not completed in 30 seconds!")}f.after(60.seconds) { println("f has not completed

我想在 Scala Futures中添加一个after(d：FiniteDuration)(callback：=> Unit)util,它可以让我这样做：

val f = Future(someTask)

f.after(30.seconds) {
  println("f has not completed in 30 seconds!")
}

f.after(60.seconds) {
  println("f has not completed in 60 seconds!")
}

我怎样才能做到这一点？

解决方法

通常我使用线程池执行器并承诺：

import scala.concurrent.duration._
import java.util.concurrent.{Executors,ScheduledThreadPoolExecutor}
import scala.concurrent.{Future,Promise}

val f: Future[Int] = ???

val executor = new ScheduledThreadPoolExecutor(2,Executors.defaultThreadFactory(),AbortPolicy)

def withDelay[T](operation: ? T)(by: FiniteDuration): Future[T] = {
  val promise = Promise[T]()
  executor.schedule(new Runnable {
    override def run() = {
      promise.complete(Try(operation))
    }
  },by.length,by.unit)
  promise.future
}

Future.firstCompletedOf(Seq(f,withDelay(println("still going"))(30 seconds)))
Future.firstCompletedOf(Seq(f,withDelay(println("still still going"))(60 seconds)))

（编辑：李大同）

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