Sends the elements of the stream to the given ActorRef. If the target actor terminates the stream will be canceled. When the stream is completed successfully the given onCompleteMessage will be sent to the destination actor. When the stream is completed with failure a akka.actor.Status.Failure message will be sent to the destination actor.

It will request at most maxInputBufferSize number of elements from upstream, but there is no back-pressure signal from the destination actor, i.e. if the actor is not consuming the messages fast enough the mailbox of the actor will grow. For potentially slow consumer actors it is recommended to use a bounded mailbox with zero mailbox-push-timeout-time or use a rate limiting operator in front of this Sink.

Sends the elements of the stream to the given ActorRef that sends back back-pressure signal. First element is always onInitMessage, then stream is waiting for acknowledgement message ackMessage from the given actor which means that it is ready to process elements. It also requires ackMessage message after each stream element to make backpressure work.

If the target actor terminates the stream will be canceled. When the stream is completed successfully the given onCompleteMessage will be sent to the destination actor. When the stream is completed with failure - result of onFailureMessage(throwable) message will be sent to the destination actor.

A Sink that materializes into a org.reactivestreams.Publisher.

If fanout is true, the materialized Publisher will support multiple Subscribers and the size of the inputBuffer configured for this operator becomes the maximum number of elements that the fastest org.reactivestreams.Subscriber can be ahead of the slowest one before slowing the processing down due to back pressure.

If fanout is false then the materialized Publisher will only support a single Subscriber and reject any additional Subscribers.

A Sink that will invoke the given function for every received element, giving it its previous output (or the given zero value) and the element as input. The returned java.util.concurrent.CompletionStage will be completed with value of the final function evaluation when the input stream ends, or completed with Failure if there is a failure is signaled in the stream.

A Sink that will invoke the given asynchronous function for every received element, giving it its previous output (or the given zero value) and the element as input. The returned java.util.concurrent.CompletionStage will be completed with value of the final function evaluation when the input stream ends, or completed with Failure if there is a failure is signaled in the stream.

A Sink that will invoke the given procedure for each received element. The sink is materialized into a java.util.concurrent.CompletionStage which will be completed with Success when reaching the normal end of the stream, or completed with Failure if there is a failure signaled in the stream.

A Sink that will invoke the given procedure asynchronously for each received element. The sink is materialized into a java.util.concurrent.CompletionStage which will be completed with Success when reaching the normal end of the stream, or completed with Failure if there is a failure signaled in the stream.

A Sink that materializes into a CompletionStage of the first value received. If the stream completes before signaling at least a single element, the CompletionStage will be failed with a NoSuchElementException. If the stream signals an error before signaling at least a single element, the CompletionStage will be failed with the streams exception.

See also headOption.

A Sink that materializes into a CompletionStage of the optional first value received. If the stream completes before signaling at least a single element, the value of the CompletionStage will be an empty java.util.Optional. If the stream signals an error errors before signaling at least a single element, the CompletionStage will be failed with the streams exception.

See also head.

A Sink that materializes into a CompletionStage of the last value received. If the stream completes before signaling at least a single element, the CompletionStage will be failed with a NoSuchElementException. If the stream signals an error errors before signaling at least a single element, the CompletionStage will be failed with the streams exception.

See also lastOption, takeLast.

A Sink that materializes into a CompletionStage of the optional last value received. If the stream completes before signaling at least a single element, the value of the CompletionStage will be an empty java.util.Optional. If the stream signals an error errors before signaling at least a single element, the CompletionStage will be failed with the streams exception.

See also head, takeLast.

Creates a real Sink upon receiving the first element. Internal Sink will not be created if there are no elements, because of completion or error.

If upstream completes before an element was received then the Future is completed with None. If upstream fails before an element was received, sinkFactory throws an exception, or materialization of the internal sink fails then the Future is completed with the exception. Otherwise the Future is completed with the materialized value of the internal sink.

Creates a Sink that is materialized as an akka.stream.javadsl.SinkQueue. akka.stream.javadsl.SinkQueue.pull method is pulling element from the stream and returns CompletionStage[Option[T]]. CompletionStage completes when element is available.

Before calling pull method second time you need to wait until previous CompletionStage completes. Pull returns Failed future with IllegalStateException if previous future has not yet completed.

Sink will request at most number of elements equal to size of inputBuffer from upstream and then stop back pressure. You can configure size of input buffer by using Sink.withAttributes method.

For stream completion you need to pull all elements from akka.stream.javadsl.SinkQueue including last None as completion marker

A Sink that will invoke the given function for every received element, giving it its previous output (from the second element) and the element as input. The returned java.util.concurrent.CompletionStage will be completed with value of the final function evaluation when the input stream ends, or completed with Failure if there is a failure signaled in the stream.

If the stream is empty (i.e. completes before signalling any elements), the reduce operator will fail its downstream with a NoSuchElementException, which is semantically in-line with that Scala's standard library collections do in such situations.

A Sink that keeps on collecting incoming elements until upstream terminates. As upstream may be unbounded, Flow[T].take or the stricter Flow[T].limit (and their variants) may be used to ensure boundedness. Materializes into a CompletionStage of Seq[T] containing all the collected elements. List is limited to Integer.MAX_VALUE elements, this Sink will cancel the stream after having received that many elements.

See also Flow.limit, Flow.limitWeighted, Flow.take, Flow.takeWithin, Flow.takeWhile

Defers the creation of a Sink until materialization. The factory function exposes ActorMaterializer which is going to be used during materialization and Attributes of the Sink returned by this method.

A Sink that materializes into a a CompletionStage of List<In> containing the last n collected elements.

If the stream completes before signaling at least n elements, the CompletionStage will complete with all elements seen so far. If the stream never completes the CompletionStage will never complete. If there is a failure signaled in the stream the CompletionStage will be completed with failure.

Creates a Sink that is materialized to an akka.actor.ActorRef which points to an Actor created according to the passed in akka.actor.Props. Actor created by the props should be akka.stream.actor.ActorSubscriber.

A Sink that will invoke the given procedure for each received element in parallel. The sink is materialized into a java.util.concurrent.CompletionStage.

If f throws an exception and the supervision decision is akka.stream.Supervision.Stop the CompletionStage will be completed with failure.

If f throws an exception and the supervision decision is akka.stream.Supervision.Resume or akka.stream.Supervision.Restart the element is dropped and the stream continues.

Creates a real Sink upon receiving the first element. Internal Sink will not be created if there are no elements, because of completion or error.

If upstream completes before an element was received then the Future is completed with the value created by fallback. If upstream fails before an element was received, sinkFactory throws an exception, or materialization of the internal sink fails then the Future is completed with the exception. Otherwise the Future is completed with the materialized value of the internal sink.