Class Sink<In,​Mat>

  • All Implemented Interfaces:
    Graph<SinkShape<In>,​Mat>

    public final class Sink<In,​Mat>
    extends java.lang.Object
    implements Graph<SinkShape<In>,​Mat>
    Java API

    A Sink is a set of stream processing steps that has one open input. Can be used as a Subscriber

    • Constructor Summary

      Constructors 
      Constructor Description
      Sink​(Sink<In,​Mat> delegate)  
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      static <In> Sink<In,​NotUsed> actorRef​(ActorRef ref, java.lang.Object onCompleteMessage)
      Sends the elements of the stream to the given ActorRef.
      static <In> Sink<In,​NotUsed> actorRefWithAck​(ActorRef ref, java.lang.Object onInitMessage, java.lang.Object ackMessage, java.lang.Object onCompleteMessage, Function<java.lang.Throwable,​java.lang.Object> onFailureMessage)
      Sends the elements of the stream to the given ActorRef that sends back back-pressure signal.
      static <T> Sink<T,​ActorRef> actorSubscriber​(Props props)
      Deprecated.
      Use akka.stream.stage.GraphStage and fromGraph instead, it allows for all operations an Actor would and is more type-safe as well as guaranteed to be ReactiveStreams compliant.
      Sink<In,​Mat> addAttributes​(Attributes attr)
      Add the given attributes to this Sink.
      static <T> Sink<T,​org.reactivestreams.Publisher<T>> asPublisher​(AsPublisher fanout)
      A Sink that materializes into a Publisher.
      Sink<In,​Mat> asScala()
      Converts this Sink to its Scala DSL counterpart.
      Sink<In,​Mat> async()
      Put an asynchronous boundary around this Sink
      Sink<In,​Mat> async​(java.lang.String dispatcher)
      Put an asynchronous boundary around this Sink
      Sink<In,​Mat> async​(java.lang.String dispatcher, int inputBufferSize)
      Put an asynchronous boundary around this Sink
      static <T> Sink<T,​NotUsed> cancelled()
      A Sink that immediately cancels its upstream after materialization.
      static <T,​U>
      Sink<T,​NotUsed>
      combine​(Sink<U,​?> output1, Sink<U,​?> output2, java.util.List<Sink<U,​?>> rest, Function<java.lang.Integer,​Graph<UniformFanOutShape<T,​U>,​NotUsed>> strategy)
      Combine several sinks with fan-out strategy like Broadcast or Balance and returns Sink.
      <In2> Sink<In2,​Mat> contramap​(Function<In2,​In> f)
      Transform this Sink by applying a function to each *incoming* upstream element before it is passed to the Sink
      static <U,​In>
      Sink<In,​java.util.concurrent.CompletionStage<U>>
      fold​(U zero, Function2<U,​In,​U> f)
      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.
      static <U,​In>
      Sink<In,​java.util.concurrent.CompletionStage<U>>
      foldAsync​(U zero, Function2<U,​In,​java.util.concurrent.CompletionStage<U>> f)
      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.
      static <T> Sink<T,​java.util.concurrent.CompletionStage<Done>> foreach​(Procedure<T> f)
      A Sink that will invoke the given procedure for each received element.
      static <T> Sink<T,​java.util.concurrent.CompletionStage<Done>> foreachAsync​(int parallelism, Function<T,​java.util.concurrent.CompletionStage<java.lang.Void>> f)
      A Sink that will invoke the given procedure asynchronously for each received element.
      static <T> Sink<T,​java.util.concurrent.CompletionStage<Done>> foreachParallel​(int parallel, Procedure<T> f, scala.concurrent.ExecutionContext ec)
      Deprecated.
      Use `foreachAsync` instead, it allows you to choose how to run the procedure, by calling some other API returning a CompletionStage or using CompletableFuture.supplyAsync.
      static <T,​M>
      Sink<T,​M>
      fromGraph​(Graph<SinkShape<T>,​M> g)
      A graph with the shape of a sink logically is a sink, this method makes it so also in type.
      static <In> Sink<In,​NotUsed> fromSubscriber​(org.reactivestreams.Subscriber<In> subs)
      Helper to create Sink from Subscriber.
      static <In> Sink<In,​java.util.concurrent.CompletionStage<In>> head()
      A Sink that materializes into a CompletionStage of the first value received.
      static <In> Sink<In,​java.util.concurrent.CompletionStage<java.util.Optional<In>>> headOption()
      A Sink that materializes into a CompletionStage of the optional first value received.
      static <T> Sink<T,​java.util.concurrent.CompletionStage<Done>> ignore()
      A Sink that will consume the stream and discard the elements.
      static <In> Sink<In,​java.util.concurrent.CompletionStage<In>> last()
      A Sink that materializes into a CompletionStage of the last value received.
      static <In> Sink<In,​java.util.concurrent.CompletionStage<java.util.Optional<In>>> lastOption()
      A Sink that materializes into a CompletionStage of the optional last value received.
      static <T,​M>
      Sink<T,​java.util.concurrent.CompletionStage<M>>
      lazyInit​(Function<T,​java.util.concurrent.CompletionStage<Sink<T,​M>>> sinkFactory, Creator<M> fallback)
      Deprecated.
      Use lazyInitAsync instead.
      static <T,​M>
      Sink<T,​java.util.concurrent.CompletionStage<java.util.Optional<M>>>
      lazyInitAsync​(Creator<java.util.concurrent.CompletionStage<Sink<T,​M>>> sinkFactory)
      Creates a real Sink upon receiving the first element.
      <Mat2> Sink<In,​Mat2> mapMaterializedValue​(Function<Mat,​Mat2> f)
      Transform only the materialized value of this Sink, leaving all other properties as they were.
      Sink<In,​Mat> named​(java.lang.String name)
      Add a name attribute to this Sink.
      static <In> Sink<In,​NotUsed> onComplete​(Procedure<scala.util.Try<Done>> callback)
      A Sink that when the flow is completed, either through a failure or normal completion, apply the provided function with Success or Failure.
      Pair<Mat,​Sink<In,​NotUsed>> preMaterialize​(Materializer materializer)
      Materializes this Sink, immediately returning (1) its materialized value, and (2) a new Sink that can be consume elements 'into' the pre-materialized one.
      static <T> Sink<T,​SinkQueueWithCancel<T>> queue()
      Creates a Sink that is materialized as an SinkQueue.
      static <In> Sink<In,​java.util.concurrent.CompletionStage<In>> reduce​(Function2<In,​In,​In> f)
      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.
      <M> M runWith​(Graph<SourceShape<In>,​M> source, Materializer materializer)
      Connect this Sink to a Source and run it.
      static <In> Sink<In,​java.util.concurrent.CompletionStage<java.util.List<In>>> seq()
      A Sink that keeps on collecting incoming elements until upstream terminates.
      SinkShape<In> shape()
      The shape of a graph is all that is externally visible: its inlets and outlets.
      static <In> Sink<In,​java.util.concurrent.CompletionStage<java.util.List<In>>> takeLast​(int n)
      A Sink that materializes into a a CompletionStage of List containing the last n collected elements.
      java.lang.String toString()  
      LinearTraversalBuilder traversalBuilder()
      INTERNAL API.
      Sink<In,​Mat> withAttributes​(Attributes attr)
      Replace the attributes of this Sink with the given ones.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
    • Constructor Detail

      • Sink

        public Sink​(Sink<In,​Mat> delegate)
    • Method Detail

      • fold

        public static <U,​In> Sink<In,​java.util.concurrent.CompletionStage<U>> fold​(U zero,
                                                                                               Function2<U,​In,​U> f)
        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 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.
        Parameters:
        zero - (undocumented)
        f - (undocumented)
        Returns:
        (undocumented)
      • foldAsync

        public static <U,​In> Sink<In,​java.util.concurrent.CompletionStage<U>> foldAsync​(U zero,
                                                                                                    Function2<U,​In,​java.util.concurrent.CompletionStage<U>> f)
        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 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.
        Parameters:
        zero - (undocumented)
        f - (undocumented)
        Returns:
        (undocumented)
      • reduce

        public static <In> Sink<In,​java.util.concurrent.CompletionStage<In>> reduce​(Function2<In,​In,​In> f)
        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 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.

        Parameters:
        f - (undocumented)
        Returns:
        (undocumented)
      • fromSubscriber

        public static <In> Sink<In,​NotUsed> fromSubscriber​(org.reactivestreams.Subscriber<In> subs)
        Helper to create Sink from Subscriber.
        Parameters:
        subs - (undocumented)
        Returns:
        (undocumented)
      • cancelled

        public static <T> Sink<T,​NotUsed> cancelled()
        A Sink that immediately cancels its upstream after materialization.
        Returns:
        (undocumented)
      • ignore

        public static <T> Sink<T,​java.util.concurrent.CompletionStage<Done>> ignore()
        A Sink that will consume the stream and discard the elements.
        Returns:
        (undocumented)
      • asPublisher

        public static <T> Sink<T,​org.reactivestreams.Publisher<T>> asPublisher​(AsPublisher fanout)
        A Sink that materializes into a 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 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.

        Parameters:
        fanout - (undocumented)
        Returns:
        (undocumented)
      • foreach

        public static <T> Sink<T,​java.util.concurrent.CompletionStage<Done>> foreach​(Procedure<T> f)
        A Sink that will invoke the given procedure for each received element. The sink is materialized into a 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.
        Parameters:
        f - (undocumented)
        Returns:
        (undocumented)
      • foreachAsync

        public static <T> Sink<T,​java.util.concurrent.CompletionStage<Done>> foreachAsync​(int parallelism,
                                                                                                Function<T,​java.util.concurrent.CompletionStage<java.lang.Void>> f)
        A Sink that will invoke the given procedure asynchronously for each received element. The sink is materialized into a 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.
        Parameters:
        parallelism - (undocumented)
        f - (undocumented)
        Returns:
        (undocumented)
      • foreachParallel

        public static <T> Sink<T,​java.util.concurrent.CompletionStage<Done>> foreachParallel​(int parallel,
                                                                                                   Procedure<T> f,
                                                                                                   scala.concurrent.ExecutionContext ec)
        Deprecated.
        Use `foreachAsync` instead, it allows you to choose how to run the procedure, by calling some other API returning a CompletionStage or using CompletableFuture.supplyAsync. Since 2.5.17.
        A Sink that will invoke the given procedure for each received element in parallel. The sink is materialized into a 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.

        Parameters:
        parallel - (undocumented)
        f - (undocumented)
        ec - (undocumented)
        Returns:
        (undocumented)
      • onComplete

        public static <In> Sink<In,​NotUsed> onComplete​(Procedure<scala.util.Try<Done>> callback)
        A Sink that when the flow is completed, either through a failure or normal completion, apply the provided function with Success or Failure.
        Parameters:
        callback - (undocumented)
        Returns:
        (undocumented)
      • head

        public static <In> Sink<In,​java.util.concurrent.CompletionStage<In>> head()
        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 <In>headOption().

        Returns:
        (undocumented)
      • headOption

        public static <In> Sink<In,​java.util.concurrent.CompletionStage<java.util.Optional<In>>> 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 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 <In>head().

        Returns:
        (undocumented)
      • last

        public static <In> Sink<In,​java.util.concurrent.CompletionStage<In>> last()
        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 <In>lastOption(), <In>takeLast(int).

        Returns:
        (undocumented)
      • lastOption

        public static <In> Sink<In,​java.util.concurrent.CompletionStage<java.util.Optional<In>>> lastOption()
        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 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 <In>head(), <In>takeLast(int).

        Returns:
        (undocumented)
      • takeLast

        public static <In> Sink<In,​java.util.concurrent.CompletionStage<java.util.List<In>>> takeLast​(int n)
        A Sink that materializes into a a CompletionStage of List 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.

        Parameters:
        n - (undocumented)
        Returns:
        (undocumented)
      • seq

        public static <In> Sink<In,​java.util.concurrent.CompletionStage<java.util.List<In>>> seq()
        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

        Returns:
        (undocumented)
      • actorRef

        public static <In> Sink<In,​NotUsed> actorRef​(ActorRef ref,
                                                           java.lang.Object onCompleteMessage)
        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 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.

        Parameters:
        ref - (undocumented)
        onCompleteMessage - (undocumented)
        Returns:
        (undocumented)
      • actorRefWithAck

        public static <In> Sink<In,​NotUsed> actorRefWithAck​(ActorRef ref,
                                                                  java.lang.Object onInitMessage,
                                                                  java.lang.Object ackMessage,
                                                                  java.lang.Object onCompleteMessage,
                                                                  Function<java.lang.Throwable,​java.lang.Object> onFailureMessage)
        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.

        Parameters:
        ref - (undocumented)
        onInitMessage - (undocumented)
        ackMessage - (undocumented)
        onCompleteMessage - (undocumented)
        onFailureMessage - (undocumented)
        Returns:
        (undocumented)
      • actorSubscriber

        public static <T> Sink<T,​ActorRef> actorSubscriber​(Props props)
        Deprecated.
        Use akka.stream.stage.GraphStage and fromGraph instead, it allows for all operations an Actor would and is more type-safe as well as guaranteed to be ReactiveStreams compliant.
        Creates a Sink that is materialized to an ActorRef which points to an Actor created according to the passed in Props. Actor created by the props should be ActorSubscriber.

        Parameters:
        props - (undocumented)
        Returns:
        (undocumented)
      • fromGraph

        public static <T,​M> Sink<T,​M> fromGraph​(Graph<SinkShape<T>,​M> g)
        A graph with the shape of a sink logically is a sink, this method makes it so also in type.
        Parameters:
        g - (undocumented)
        Returns:
        (undocumented)
      • combine

        public static <T,​U> Sink<T,​NotUsed> combine​(Sink<U,​?> output1,
                                                                Sink<U,​?> output2,
                                                                java.util.List<Sink<U,​?>> rest,
                                                                Function<java.lang.Integer,​Graph<UniformFanOutShape<T,​U>,​NotUsed>> strategy)
        Combine several sinks with fan-out strategy like Broadcast or Balance and returns Sink.
        Parameters:
        output1 - (undocumented)
        output2 - (undocumented)
        rest - (undocumented)
        strategy - (undocumented)
        Returns:
        (undocumented)
      • queue

        public static <T> Sink<T,​SinkQueueWithCancel<T>> queue()
        Creates a Sink that is materialized as an 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 SinkQueue including last None as completion marker

        Returns:
        (undocumented)
        See Also:
        SinkQueueWithCancel
      • lazyInit

        public static <T,​M> Sink<T,​java.util.concurrent.CompletionStage<M>> lazyInit​(Function<T,​java.util.concurrent.CompletionStage<Sink<T,​M>>> sinkFactory,
                                                                                                 Creator<M> fallback)
        Deprecated.
        Use lazyInitAsync instead. (lazyInitAsync no more needs a fallback function and the materialized value more clearly indicates if the internal sink was materialized or not.). Since 2.5.11.
        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.

        Parameters:
        sinkFactory - (undocumented)
        fallback - (undocumented)
        Returns:
        (undocumented)
      • lazyInitAsync

        public static <T,​M> Sink<T,​java.util.concurrent.CompletionStage<java.util.Optional<M>>> lazyInitAsync​(Creator<java.util.concurrent.CompletionStage<Sink<T,​M>>> sinkFactory)
        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.

        Parameters:
        sinkFactory - (undocumented)
        Returns:
        (undocumented)
      • shape

        public SinkShape<In> shape()
        Description copied from interface: Graph
        The shape of a graph is all that is externally visible: its inlets and outlets.
        Specified by:
        shape in interface Graph<In,​Mat>
        Returns:
        (undocumented)
      • traversalBuilder

        public LinearTraversalBuilder traversalBuilder()
        Description copied from interface: Graph
        INTERNAL API.

        Every materializable element must be backed by a stream layout module

        Specified by:
        traversalBuilder in interface Graph<In,​Mat>
        Returns:
        (undocumented)
      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object
      • asScala

        public Sink<In,​Mat> asScala()
        Converts this Sink to its Scala DSL counterpart.
        Returns:
        (undocumented)
      • runWith

        public <M> M runWith​(Graph<SourceShape<In>,​M> source,
                             Materializer materializer)
        Connect this Sink to a Source and run it.
        Parameters:
        source - (undocumented)
        materializer - (undocumented)
        Returns:
        (undocumented)
      • contramap

        public <In2> Sink<In2,​Mat> contramap​(Function<In2,​In> f)
        Transform this Sink by applying a function to each *incoming* upstream element before it is passed to the Sink

        '''Backpressures when''' original Sink backpressures

        '''Cancels when''' original Sink backpressures

        Parameters:
        f - (undocumented)
        Returns:
        (undocumented)
      • mapMaterializedValue

        public <Mat2> Sink<In,​Mat2> mapMaterializedValue​(Function<Mat,​Mat2> f)
        Transform only the materialized value of this Sink, leaving all other properties as they were.
        Parameters:
        f - (undocumented)
        Returns:
        (undocumented)
      • preMaterialize

        public Pair<Mat,​Sink<In,​NotUsed>> preMaterialize​(Materializer materializer)
        Materializes this Sink, immediately returning (1) its materialized value, and (2) a new Sink that can be consume elements 'into' the pre-materialized one.

        Useful for when you need a materialized value of a Sink when handing it out to someone to materialize it for you.

        Parameters:
        materializer - (undocumented)
        Returns:
        (undocumented)
      • withAttributes

        public Sink<In,​Mat> withAttributes​(Attributes attr)
        Replace the attributes of this Sink with the given ones. If this Sink is a composite of multiple graphs, new attributes on the composite will be less specific than attributes set directly on the individual graphs of the composite.
        Specified by:
        withAttributes in interface Graph<In,​Mat>
        Parameters:
        attr - (undocumented)
        Returns:
        (undocumented)
      • addAttributes

        public Sink<In,​Mat> addAttributes​(Attributes attr)
        Add the given attributes to this Sink. If the specific attribute was already present on this graph this means the added attribute will be more specific than the existing one. If this Sink is a composite of multiple graphs, new attributes on the composite will be less specific than attributes set directly on the individual graphs of the composite.
        Specified by:
        addAttributes in interface Graph<In,​Mat>
        Parameters:
        attr - (undocumented)
        Returns:
        (undocumented)
      • named

        public Sink<In,​Mat> named​(java.lang.String name)
        Add a name attribute to this Sink.
        Specified by:
        named in interface Graph<In,​Mat>
        Parameters:
        name - (undocumented)
        Returns:
        (undocumented)
      • async

        public Sink<In,​Mat> async()
        Put an asynchronous boundary around this Sink
        Specified by:
        async in interface Graph<In,​Mat>
        Returns:
        (undocumented)
      • async

        public Sink<In,​Mat> async​(java.lang.String dispatcher)
        Put an asynchronous boundary around this Sink

        Specified by:
        async in interface Graph<In,​Mat>
        Parameters:
        dispatcher - Run the graph on this dispatcher
        Returns:
        (undocumented)
      • async

        public Sink<In,​Mat> async​(java.lang.String dispatcher,
                                        int inputBufferSize)
        Put an asynchronous boundary around this Sink

        Specified by:
        async in interface Graph<In,​Mat>
        Parameters:
        dispatcher - Run the graph on this dispatcher
        inputBufferSize - Set the input buffer to this size for the graph
        Returns:
        (undocumented)