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 from the given actor which means that it is ready to process elements. It also requires an ack message after each stream element to make backpressure work. This variant will consider any message as ack message.

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.

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.

Creates a sink which materializes into a CompletionStage which will be completed with a result of the Java Collector transformation and reduction operations. This allows usage of Java streams transformations for reactive streams. The Collector will trigger demand downstream. Elements emitted through the stream will be accumulated into a mutable result container, optionally transformed into a final representation after all input elements have been processed. The Collector can also do reduction at the end. Reduction processing is performed sequentially.

Combine several sinks with fan-out strategy like Broadcast or Balance and returns Sink. The fanoutGraph's outlets size must match the provides sinks'.

Turn a Future[Sink] into a Sink that will consume the values of the source when the future completes successfully. If the Future is completed with a failure the stream is failed.

The materialized future value is completed with the materialized value of the future sink or failed with a NeverMaterializedException if upstream fails or downstream cancels before the future has completed.

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.

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

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.

Defers invoking the create function to create a future sink until there is a first element passed from upstream.

The materialized future value is completed with the materialized value of the created sink when that has successfully been materialized.

If the create function throws or returns a future that is failed, or the stream fails to materialize, in this case the materialized future value is failed with a akka.stream.NeverMaterializedException.

Defers invoking the create function to create a sink until there is a first element passed from upstream.

The materialized future value is completed with the materialized value of the created sink when that has successfully been materialized.

If the create function throws or returns or the stream fails to materialize, in this case the materialized future value is failed with a akka.stream.NeverMaterializedException.

Creates a Sink that is materialized as an akka.stream.javadsl.SinkQueueWithCancel. akka.stream.javadsl.SinkQueueWithCancel.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.SinkQueueWithCancel including last None as completion marker

Creates a Sink that is materialized as an akka.stream.javadsl.SinkQueueWithCancel. akka.stream.javadsl.SinkQueueWithCancel.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 ensure that number of pending pulls is less then maxConcurrentPulls or wait until some of the previous Futures completes. Pull returns Failed future with IllegalStateException if there will be more then maxConcurrentPulls number of pending pulls.

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.SinkQueueWithCancel 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

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.

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 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.

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.

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.