Comparing approaches to convert `java.util.concurrent.Future`s to `com.twitter.util.Future`s.

FuturePool'd

import com.twitter.util.{Future => TwitterFuture, FuturePool}
import java.util.concurrent.{Future => JavaFuture}

/**
 * Convert a Java Future to a Twitter Future.
 */
def javaFutureToTwitterFuture[A](javaFuture: JavaFuture[A]): TwitterFuture[A] =
  FuturePool.unboundedPool { javaFuture.get }

polling

import com.twitter.util.{Future => TwitterFuture, _}
import java.util.concurrent.{Future => JavaFuture, TimeUnit}

/**
 * Convert a Java Future to a Twitter Future.
 */
def javaFutureToTwitterFuture[A](
  javaFuture: JavaFuture[A],
  pollingInterval: Duration = Duration(50L, TimeUnit.MILLISECONDS)
): TwitterFuture[A] = {
  val timer = new JavaTimer(isDaemon = false)
  val promise = new Promise[A] {
    timer.schedule(pollingInterval) {
      if (javaFuture.isDone || javaFuture.isCancelled) {
        timer.stop()
        Try(javaFuture.get) match {
          case Return(result) => setValue(result)
          case Throw(t) => setException(t)
        }
      }
    }
  }

  promise.setInterruptHandler { case _ => javaFuture.cancel(true) }

  promise
}