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=str Make ConcurrentAsyncCallback extends AtomicReference directly. (#31257)

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kerr 2022-04-08 16:57:34 +08:00 • committed by GitHub
parent a394b2cdf7
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1 changed files with 9 additions and 9 deletions
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18
akka-stream/src/main/scala/akka/stream/stage/GraphStage.scala
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@ -9,9 +9,7 @@ import scala.annotation.tailrec
import scala.collection.{ immutable, mutable }
import scala.concurrent.{ Future, Promise }
import scala.concurrent.duration.FiniteDuration
import scala.annotation.nowarn
import akka.{ Done, NotUsed }
import akka.actor._
import akka.annotation.InternalApi
@ -22,6 +20,7 @@ import akka.stream.impl.{ ReactiveStreamsCompliance, TraversalBuilder }
import akka.stream.impl.ActorSubscriberMessage
import akka.stream.impl.fusing.{ GraphInterpreter, GraphStageModule, SubSink, SubSource }
import akka.stream.scaladsl.GenericGraphWithChangedAttributes
import akka.stream.stage.ConcurrentAsyncCallbackState.{ NoPendingEvents, State }
import akka.util.OptionVal
import akka.util.unused
@ -284,7 +283,7 @@ private[akka] object ConcurrentAsyncCallbackState {
// Event with feedback promise
final case class Event[+E](e: E, handlingPromise: Promise[Done])
val NoPendingEvents = Pending[Nothing](Nil)
val NoPendingEvents: Pending[Nothing] = Pending[Nothing](Nil)
}
/**
@ -1186,21 +1185,22 @@ abstract class GraphStageLogic private[stream] (val inCount: Int, val outCount:
* [[onStop]] puts class in `Completed` state
* "Real world" calls of [[invokeWithFeedback]] always return failed promises for `Completed` state
*/
private final class ConcurrentAsyncCallback[T](handler: T => Unit) extends AsyncCallback[T] {
private final class ConcurrentAsyncCallback[T](handler: T => Unit)
extends AtomicReference[State[T]](NoPendingEvents)
with AsyncCallback[T] {
import ConcurrentAsyncCallbackState._
private[this] val currentState = new AtomicReference[State[T]](NoPendingEvents)
// is called from the owning [[GraphStage]]
@tailrec
private[stage] def onStart(): Unit = {
// dispatch callbacks that have been queued before the interpreter was started
(currentState.getAndSet(NoPendingEvents): @unchecked) match {
(getAndSet(NoPendingEvents): @unchecked) match {
case Pending(l) => if (l.nonEmpty) l.reverse.foreach(evt => onAsyncInput(evt.e, evt.handlingPromise))
case s => throw new IllegalStateException(s"Unexpected callback state [$s]")
}
// in the meantime more callbacks might have been queued (we keep queueing them to ensure order)
if (!currentState.compareAndSet(NoPendingEvents, Initialized))
if (!compareAndSet(NoPendingEvents, Initialized))
// state guaranteed to be still Pending
onStart()
}
@ -1236,14 +1236,14 @@ abstract class GraphStageLogic private[stream] (val inCount: Int, val outCount:
@tailrec
private def invokeWithPromise(event: T, promise: Promise[Done]): Unit =
currentState.get() match {
get() match {
case Initialized =>
// started - can just dispatch async message to interpreter
onAsyncInput(event, promise)
case list @ Pending(l: List[Event[T]]) =>
// not started yet
if (!currentState.compareAndSet(list, Pending[T](Event[T](event, promise) :: l)))
if (!compareAndSet(list, Pending[T](Event[T](event, promise) :: l)))
invokeWithPromise(event, promise)
}