INTERNAL API

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 the onFailureMessage will be invoked and its result 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) function 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) function 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 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 Future of That[T] containing all the collected elements. That[T] is limited to the limitations of the CanBuildFrom associated with it. For example, Seq is limited to Int.MaxValue elements. See [The Architecture of Scala 2.13's Collections](https://docs.scala-lang.org/overviews/core/architecture-of-scala-213-collections.html) for more info. This Sink will cancel the stream after having received that many elements.

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

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

Combine two sinks with fan-out strategy like Broadcast or Balance and returns Sink with 2 outlets.

A Sink that counts all incoming elements until upstream terminates.

Since upstream may be unbounded, consider using Flow[T].take or the stricter Flow[T].limit (and their variants) to ensure boundedness. The sink materializes into a Future of Long containing the total count of elements that passed through.

Completes when upstream completes

Backpressures when never (counting is a lightweight operation)

Cancels when never

A Sink that will test the given predicate p for every received element and

1. completes and returns scala.concurrent.Future of true if the predicate is true for any element; 2. completes and returns scala.concurrent.Future of false if the stream is empty (i.e. completes before signalling any elements); 3. completes and returns scala.concurrent.Future of false if the predicate is false for all elements.

The materialized value scala.concurrent.Future will be completed with the value true or false when the input stream ends, or completed with Failure if there is a failure signaled in the stream.

Adheres to the ActorAttributes.SupervisionStrategy attribute.

Completes when upstream completes or the predicate p returns true

Backpressures when the invocation of predicate p has not yet completed

Cancels when predicate p returns true

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 scala.concurrent.Future 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.

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 scala.concurrent.Future 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.

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 scala.concurrent.Future will be completed with value of the final function evaluation when the input stream ends, predicate p returns false, or completed with Failure if there is a failure signaled in the stream.

A Sink that will test the given predicate p for every received element and

1. completes and returns scala.concurrent.Future of true if the predicate is true for all elements; 2. completes and returns scala.concurrent.Future of true if the stream is empty (i.e. completes before signalling any elements); 3. completes and returns scala.concurrent.Future of false if the predicate is false for any element.

The materialized value scala.concurrent.Future will be completed with the value true or false when the input stream ends, or completed with Failure if there is a failure signaled in the stream.

Adheres to the ActorAttributes.SupervisionStrategy attribute.

Completes when upstream completes or the predicate p returns false

Backpressures when the invocation of predicate p has not yet completed

Cancels when predicate p returns false

A Sink that will invoke the given procedure for each received element. The sink is materialized into a scala.concurrent.Future 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 scala.concurrent.Future 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.

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

See also headOption.

A Sink that materializes into a Future of the optional first value received. If the stream completes before signaling at least a single element, the value of the Future will be scala.None. If the stream signals an error errors before signaling at least a single element, the Future will be failed with the streams exception.

See also head.

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

See also lastOption, takeLast.

A Sink that materializes into a Future of the optional last value received. If the stream completes before signaling at least a single element, the value of the Future will be scala.None. If the stream signals an error, the Future will be failed with the stream's exception.

See also last, 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 pekko.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 pekko.stream.NeverMaterializedException.

A Sink that will test the given predicate p for every received element and

1. completes and returns scala.concurrent.Future of true if the predicate is false for all elements; 2. completes and returns scala.concurrent.Future of true if the stream is empty (i.e. completes before signalling any elements); 3. completes and returns scala.concurrent.Future of false if the predicate is true for any element.

The materialized value scala.concurrent.Future will be completed with the value true or false when the input stream ends, or completed with Failure if there is a failure signaled in the stream.

Adheres to the ActorAttributes.SupervisionStrategy attribute.

Completes when upstream completes or the predicate p returns true

Backpressures when the invocation of predicate p has not yet completed

Cancels when predicate p returns true

Creates a Sink that is materialized as an pekko.stream.scaladsl.SinkQueueWithCancel. pekko.stream.scaladsl.SinkQueueWithCancel.pull method is pulling element from the stream and returns Future[Option[T]]. Future completes when element is available.

Before calling pull method second time you need to wait until previous Future 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 pekko.stream.scaladsl.SinkQueueWithCancel including last None as completion marker

See also pekko.stream.scaladsl.SinkQueueWithCancel

Creates a Sink that is materialized as an pekko.stream.scaladsl.SinkQueueWithCancel. pekko.stream.scaladsl.SinkQueueWithCancel.pull method is pulling element from the stream and returns Future[Option[T]. Future 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 pekko.stream.scaladsl.SinkQueueWithCancel including last None as completion marker

See also pekko.stream.scaladsl.SinkQueueWithCancel

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 scala.concurrent.Future 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.

Adheres to the ActorAttributes.SupervisionStrategy attribute.

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 Future of Seq[T] containing all the collected elements. Seq is limited to Int.MaxValue 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 this Sink itself as a Source. The returned Source is a "live view" onto the Sink and only supports a single Subscriber.

Use BroadcastHub#sink if you need a Source that allows multiple subscribers.

Note: even if the Source is directly connected to the Sink, there is still an asynchronous boundary between them; performance may be improved in the future.

A Sink that materializes into a Future of immutable.Seq[T] containing the last n collected elements.

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