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fail fast in mapAsync for completed failed future, #21318 (#21322)

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* fail fast in mapAsync for completed failed future, #21318

* the callback was not run until todo == parallelism or the sync
  event limit was reached, and that can be a problem if upstream
  stages are slow (noticed this for a blocking Kafka producer stage)

* skip callback for completed futures

* fix callback allocation
This commit is contained in:
Patrik Nordwall 2016-08-30 19:30:08 +02:00 • committed by GitHub
parent e20d6f5f36
commit a95b2d6746
4 changed files with 100 additions and 43 deletions
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72
akka-stream/src/main/scala/akka/stream/impl/fusing/Ops.scala
View file

@ -942,11 +942,14 @@ final class Expand[In, Out](val extrapolate: In ⇒ Iterator[Out]) extends Graph
*/
private[akka] object MapAsync {
final class Holder[T](var elem: Try[T], val cb: AsyncCallback[Holder[T]]) extends (Try[T] ⇒ Unit) {
override def apply(t: Try[T]): Unit = {
def setElem(t: Try[T]): Unit =
elem = t match {
case Success(null) ⇒ Failure[T](ReactiveStreamsCompliance.elementMustNotBeNullException)
case other ⇒ other
}
override def apply(t: Try[T]): Unit = {
setElem(t)
cb.invoke(this)
}
}
@ -974,12 +977,14 @@ final case class MapAsync[In, Out](parallelism: Int, f: In ⇒ Future[Out])
//FIXME Put Supervision.stoppingDecider as a SupervisionStrategy on DefaultAttributes.mapAsync?
lazy val decider = inheritedAttributes.get[SupervisionStrategy].map(_.decider).getOrElse(Supervision.stoppingDecider)
var buffer: BufferImpl[Holder[Out]] = _
val futureCB =
getAsyncCallback[Holder[Out]](
_.elem match {
case Failure(e) if decider(e) == Supervision.Stop ⇒ failStage(e)
case _ ⇒ if (isAvailable(out)) pushOne()
})
def holderCompleted(h: Holder[Out]): Unit = {
h.elem match {
case Failure(e) if decider(e) == Supervision.Stop ⇒ failStage(e)
case _ ⇒ if (isAvailable(out)) pushOne()
}
}
val futureCB = getAsyncCallback[Holder[Out]](holderCompleted)
private[this] def todo = buffer.used
@ -1007,14 +1012,16 @@ final case class MapAsync[In, Out](parallelism: Int, f: In ⇒ Future[Out])
// #20217 We dispatch the future if it's ready to optimize away
// scheduling it to an execution context
future.value match {
case None ⇒ future.onComplete(holder)(akka.dispatch.ExecutionContexts.sameThreadExecutionContext)
case Some(f) ⇒ holder.apply(f)
case None ⇒ future.onComplete(holder)(akka.dispatch.ExecutionContexts.sameThreadExecutionContext)
case Some(v) ⇒
holder.setElem(v)
holderCompleted(holder)
}
} catch {
case NonFatal(ex) ⇒ if (decider(ex) == Supervision.Stop) failStage(ex)
}
if (todo < parallelism) tryPull(in)
if (todo < parallelism && !hasBeenPulled(in)) tryPull(in)
}
override def onUpstreamFinish(): Unit = if (todo == 0) completeStage()
@ -1049,38 +1056,39 @@ final case class MapAsyncUnordered[In, Out](parallelism: Int, f: In ⇒ Future[O
override def preStart(): Unit = buffer = BufferImpl(parallelism, materializer)
private val futureCB =
getAsyncCallback((result: Try[Out]) ⇒ {
inFlight -= 1
result match {
case Success(elem) if elem != null ⇒
if (isAvailable(out)) {
if (!hasBeenPulled(in)) tryPull(in)
push(out, elem)
} else buffer.enqueue(elem)
case other ⇒
val ex = other match {
case Failure(t) ⇒ t
case Success(s) if s == null ⇒ ReactiveStreamsCompliance.elementMustNotBeNullException
}
if (decider(ex) == Supervision.Stop) failStage(ex)
else if (isClosed(in) && todo == 0) completeStage()
else if (!hasBeenPulled(in)) tryPull(in)
}
}).invoke _
def futureCompleted(result: Try[Out]): Unit = {
inFlight -= 1
result match {
case Success(elem) if elem != null ⇒
if (isAvailable(out)) {
if (!hasBeenPulled(in)) tryPull(in)
push(out, elem)
} else buffer.enqueue(elem)
case other ⇒
val ex = other match {
case Failure(t) ⇒ t
case Success(s) if s == null ⇒ ReactiveStreamsCompliance.elementMustNotBeNullException
}
if (decider(ex) == Supervision.Stop) failStage(ex)
else if (isClosed(in) && todo == 0) completeStage()
else if (!hasBeenPulled(in)) tryPull(in)
}
}
private val futureCB = getAsyncCallback(futureCompleted)
private val invokeFutureCB: Try[Out] ⇒ Unit = futureCB.invoke
override def onPush(): Unit = {
try {
val future = f(grab(in))
inFlight += 1
future.value match {
case None ⇒ future.onComplete(futureCB)(akka.dispatch.ExecutionContexts.sameThreadExecutionContext)
case Some(f) ⇒ futureCB.apply(f)
case None ⇒ future.onComplete(invokeFutureCB)(akka.dispatch.ExecutionContexts.sameThreadExecutionContext)
case Some(v) ⇒ futureCompleted(v)
}
} catch {
case NonFatal(ex) ⇒ if (decider(ex) == Supervision.Stop) failStage(ex)
}
if (todo < parallelism) tryPull(in)
if (todo < parallelism && !hasBeenPulled(in)) tryPull(in)
}
override def onUpstreamFinish(): Unit = {