+str - #17662 - Changes Sink.ignore to return a Future[Unit]

akka-docs-dev/rst/scala/code/docs/stream/TwitterStreamQuickstartDocSpec.scala

@@ -106,8 +106,8 @@ class TwitterStreamQuickstartDocSpec extends AkkaSpec {
   }
 
   "simple broadcast" in {
-    val writeAuthors: Sink[Author, Unit] = Sink.ignore
-    val writeHashtags: Sink[Hashtag, Unit] = Sink.ignore
+    val writeAuthors: Sink[Author, Future[Unit]] = Sink.ignore
+    val writeHashtags: Sink[Hashtag, Future[Unit]] = Sink.ignore
 
     // format: OFF
     //#flow-graph-broadcast

akka-stream-tck/src/test/scala/akka/stream/tck/BlackholeSubscriberTest.scala

@@ -4,12 +4,13 @@
 package akka.stream.tck
 
 import akka.stream.impl.BlackholeSubscriber
+import scala.concurrent.Promise
 import org.reactivestreams.Publisher
 import org.reactivestreams.Subscriber
 
 class BlackholeSubscriberTest extends AkkaSubscriberBlackboxVerification[Int] {
 
-  override def createSubscriber(): Subscriber[Int] = new BlackholeSubscriber[Int](2)
+  override def createSubscriber(): Subscriber[Int] = new BlackholeSubscriber[Int](2, Promise[Unit]())
 
   override def createElement(element: Int): Int = element
 }

akka-stream/src/main/scala/akka/stream/impl/BlackholeSubscriber.scala

@@ -4,14 +4,14 @@
 package akka.stream.impl
 
 import java.util.concurrent.atomic.AtomicReference
-
+import scala.concurrent.Promise
 import org.reactivestreams.{ Subscriber, Subscription }
 
 /**
  * INTERNAL API
  */
 
-private[akka] class BlackholeSubscriber[T](highWatermark: Int) extends Subscriber[T] {
+private[akka] class BlackholeSubscriber[T](highWatermark: Int, onComplete: Promise[Unit]) extends Subscriber[T] {
 
   private val lowWatermark = Math.max(1, highWatermark / 2)
   private var requested = 0L
@@ -26,10 +26,11 @@ private[akka] class BlackholeSubscriber[T](highWatermark: Int) extends Subscribe
 
   override def onError(cause: Throwable): Unit = {
     ReactiveStreamsCompliance.requireNonNullException(cause)
+    onComplete.tryFailure(cause)
     ()
   }
 
-  override def onComplete(): Unit = ()
+  override def onComplete(): Unit = onComplete.trySuccess(())
 
   override def onNext(element: T): Unit = {
     ReactiveStreamsCompliance.requireNonNullElement(element)

akka-stream/src/main/scala/akka/stream/impl/Sinks.scala

@@ -150,15 +150,15 @@ private[akka] class HeadSink[In](val attributes: OperationAttributes, shape: Sin
  * Attaches a subscriber to this stream which will just discard all received
  * elements.
  */
-private[akka] final class BlackholeSink(val attributes: OperationAttributes, shape: SinkShape[Any]) extends SinkModule[Any, Unit](shape) {
+private[akka] final class BlackholeSink(val attributes: OperationAttributes, shape: SinkShape[Any]) extends SinkModule[Any, Future[Unit]](shape) {
 
   override def create(context: MaterializationContext) = {
-    val effectiveSettings = ActorFlowMaterializer.downcast(context.materializer)
-      .effectiveSettings(context.effectiveAttributes)
-    (new BlackholeSubscriber[Any](effectiveSettings.maxInputBufferSize), ())
+    val effectiveSettings = ActorFlowMaterializer.downcast(context.materializer).effectiveSettings(context.effectiveAttributes)
+    val p = Promise[Unit]()
+    (new BlackholeSubscriber[Any](effectiveSettings.maxInputBufferSize, p), p.future)
   }
 
-  override protected def newInstance(shape: SinkShape[Any]): SinkModule[Any, Unit] = new BlackholeSink(attributes, shape)
+  override protected def newInstance(shape: SinkShape[Any]): SinkModule[Any, Future[Unit]] = new BlackholeSink(attributes, shape)
   override def withAttributes(attr: OperationAttributes): Module = new BlackholeSink(attr, amendShape(attr))
 }
 

akka-stream/src/main/scala/akka/stream/javadsl/Sink.scala

@@ -47,7 +47,7 @@ object Sink {
   /**
    * A `Sink` that will consume the stream and discard the elements.
    */
-  def ignore[T](): Sink[T, Unit] =
+  def ignore[T](): Sink[T, Future[Unit]] =
     new Sink(scaladsl.Sink.ignore)
 
   /**

akka-stream/src/main/scala/akka/stream/scaladsl/Sink.scala

@@ -95,7 +95,7 @@ object Sink extends SinkApply {
   /**
    * A `Sink` that will consume the stream and discard the elements.
    */
-  def ignore: Sink[Any, Unit] =
+  def ignore: Sink[Any, Future[Unit]] =
     new Sink(new BlackholeSink(DefaultAttributes.ignoreSink, shape("BlackholeSink")))
 
   /**