Play Framework/Scala example source code file (FPromiseHelper.scala)

This example Play Framework source code file (FPromiseHelper.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Play Framework (and Scala) source code examples by using tags.

All credit for the original source code belongs to Play Framework; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Play Framework tags/keywords

a, api, b, callable, concurrent, executioncontext, future, lib, library, long, play, play framework, promise, t, timertask, timeunit

The FPromiseHelper.scala Play Framework example source code

/*
 * Copyright (C) 2009-2013 Typesafe Inc. <http://www.typesafe.com>
 */
package play.core.j

import java.lang.{ Iterable => JIterable }
import java.util.{ List => JList, Timer, TimerTask }
import java.util.concurrent.{ Callable, TimeoutException, TimeUnit }
import play.api.libs.concurrent.{ Promise => DeprecatedPlayPromise }
import play.api.libs.iteratee.Execution
import play.libs.F
import scala.collection.JavaConverters
import scala.concurrent.{ Await, ExecutionContext, Future, Promise }
import scala.concurrent.duration.{ Duration, MILLISECONDS }
import scala.util.{ Failure, Success, Try }

import play.core.Execution.internalContext

/**
 * Support code for the play.libs.F.Promise class. All public methods of this
 * object are used by F.Promise to implement its methods.
 */
private[play] object FPromiseHelper {

  private val timer = new Timer()

  def pure[A](a: A): F.Promise[A] = F.Promise.wrap(Future.successful(a))

  def throwing[A](t: Throwable): F.Promise[A] = F.Promise.wrap(Future.failed(t))

  // For deprecated method in play.libs.Akka
  def promise[A](callable: Callable[A], ec: ExecutionContext): F.Promise[A] =
    F.Promise.wrap(Future(callable.call())(ec.prepare()))

  def promise[A](function: F.Function0[A], ec: ExecutionContext): F.Promise[A] =
    F.Promise.wrap(Future(function.apply())(ec.prepare()))

  private def delayedWith[A](f: => A, delay: Long, unit: TimeUnit, ec: ExecutionContext): F.Promise[A] = {
    val pec = ec.prepare()
    val p = Promise[A]()
    timer.schedule(new TimerTask {
      def run() { p.completeWith(Future(f)(pec)) }
    }, unit.toMillis(delay))
    F.Promise.wrap[A](p.future)
  }

  def delayed[A](callable: Callable[A], duration: Long, unit: TimeUnit, ec: ExecutionContext): F.Promise[A] =
    delayedWith(callable.call(), duration, unit, ec)

  def delayed[A](function: F.Function0[A], duration: Long, unit: TimeUnit, ec: ExecutionContext): F.Promise[A] =
    delayedWith(function.apply(), duration, unit, ec)

  def get[A](promise: F.Promise[A], timeout: Long, unit: TimeUnit): A = {
    try {
      Await.result(promise.wrapped(), Duration(timeout, unit))
    } catch {
      case ex: TimeoutException => throw new F.PromiseTimeoutException(ex.getMessage, ex)
    }
  }

  def or[A, B](left: F.Promise[A], right: F.Promise[B]): F.Promise[F.Either[A, B]] = {
    import Execution.Implicits.trampoline
    val p = Promise[F.Either[A, B]]
    left.wrapped.onComplete {
      case tryA => p.tryComplete(tryA.map(F.Either.Left[A, B](_)))
    }
    right.wrapped.onComplete {
      case tryB => p.tryComplete(tryB.map(F.Either.Right[A, B](_)))
    }
    F.Promise.wrap(p.future)
  }

  def zip[A, B](pa: F.Promise[A], pb: F.Promise[B]): F.Promise[F.Tuple[A, B]] = {
    import Execution.Implicits.trampoline
    val future = pa.wrapped.zip(pb.wrapped).map { case (a, b) => new F.Tuple(a, b) }
    F.Promise.wrap(future)
  }

  def sequence[A](promises: JIterable[F.Promise[A]], ec: ExecutionContext): F.Promise[JList[A]] = {
    val futures = JavaConverters.iterableAsScalaIterableConverter(promises).asScala.toBuffer.map((_: F.Promise[A]).wrapped)
    implicit val pec = ec.prepare() // Easiest to provide implicitly so don't need to provide other implicit arg to sequence method
    F.Promise.wrap(Future.sequence(futures).map(az => JavaConverters.bufferAsJavaListConverter(az).asJava))
  }

  private def timeoutWith[A](result: Try[A], delay: Long, unit: TimeUnit): F.Promise[A] = {
    val p = Promise[A]()
    timer.schedule(new TimerTask {
      def run() { p.complete(result) }
    }, unit.toMillis(delay))
    F.Promise.wrap[A](p.future)
  }

  def timeout[A](message: A, delay: Long, unit: TimeUnit): F.Promise[A] =
    timeoutWith(Success(message), delay, unit)

  def timeout[A](delay: Long, unit: TimeUnit): F.Promise[A] =
    timeoutWith(Failure(new TimeoutException("Timeout in promise")), delay, unit)

  def onRedeem[A](promise: F.Promise[A], action: F.Callback[A], ec: ExecutionContext): Unit =
    promise.wrapped().onSuccess { case a => action.invoke(a) }(ec.prepare())

  def map[A, B, T >: A](promise: F.Promise[A], function: F.Function[T, B], ec: ExecutionContext): F.Promise[B] =
    F.Promise.wrap[B](promise.wrapped().map((a: A) => function.apply(a))(ec.prepare()))

  def flatMap[A, B, T >: A](promise: F.Promise[A], function: F.Function[T, F.Promise[B]], ec: ExecutionContext): F.Promise[B] =
    F.Promise.wrap[B](promise.wrapped().flatMap((a: A) => function.apply(a).wrapped())(ec.prepare()))

  def filter[A, T >: A](promise: F.Promise[A], predicate: F.Predicate[T], ec: ExecutionContext): F.Promise[A] =
    F.Promise.wrap[A](promise.wrapped().filter(predicate.test)(ec.prepare()))

  def recover[A](promise: F.Promise[A], function: F.Function[Throwable, A], ec: ExecutionContext): F.Promise[A] =
    F.Promise.wrap[A](promise.wrapped().recover { case t => function.apply(t) }(ec.prepare()))

  def recoverWith[A](promise: F.Promise[A], function: F.Function[Throwable, F.Promise[A]], ec: ExecutionContext): F.Promise[A] =
    F.Promise.wrap[A](promise.wrapped().recoverWith { case t => function.apply(t).wrapped() }(ec.prepare()))

  def fallbackTo[A](promise: F.Promise[A], fallback: F.Promise[A]): F.Promise[A] =
    F.Promise.wrap[A](promise.wrapped.fallbackTo(fallback.wrapped))

  def onFailure[A](promise: F.Promise[A], action: F.Callback[Throwable], ec: ExecutionContext) {
    promise.wrapped().onFailure { case t => action.invoke(t) }(ec.prepare())
  }

  def transform[A, B, T >: A](promise: F.Promise[A], s: F.Function[T, B], f: F.Function[Throwable, Throwable], ec: ExecutionContext): F.Promise[B] =
    F.Promise.wrap[B](promise.wrapped.transform(s.apply, f.apply)(ec.prepare()))

  def empty[A]() = {
    Promise[A]()
  }

  def getFuture[A](promise: Promise[A]): Future[A] = promise.future

  def completeWith[T](promise: Promise[T], other: Future[T], ec: ExecutionContext): Future[Void] = {
    val p = Promise[Unit]
    other.onComplete { x =>
      p.complete(Try(promise complete x))
    }(ec)
    p.future.map(_ => null)(ec)
  }

  def tryCompleteWith[T](promise: Promise[T], other: Future[T], ec: ExecutionContext): Future[Boolean] = {
    val p = Promise[Boolean]
    other.onComplete { x =>
      p.complete(Try(promise tryComplete x))
    }(ec)
    p.future
  }
}