reactor.core.publisher.FluxSink Maven / Gradle / Ivy
/*
* Copyright (c) 2011-2017 Pivotal Software Inc, All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package reactor.core.publisher;
import java.util.function.Function;
import java.util.function.LongConsumer;
import org.reactivestreams.Subscriber;
import reactor.core.CoreSubscriber;
import reactor.core.Disposable;
import reactor.util.context.Context;
/**
* Wrapper API around a downstream Subscriber for emitting any number of
* next signals followed by zero or one onError/onComplete.
*
* @param the value type
*/
public interface FluxSink {
/**
* @see Subscriber#onComplete()
*/
void complete();
/**
* Return the current subscriber {@link Context}.
*
* {@link Context} can be enriched via {@link Flux#subscriberContext(Function)}
* operator or directly by a child subscriber overriding
* {@link CoreSubscriber#currentContext()}
*
* @return the current subscriber {@link Context}.
*/
Context currentContext();
/**
* @see Subscriber#onError(Throwable)
* @param e the exception to signal, not null
*/
void error(Throwable e);
/**
* Try emitting, might throw an unchecked exception.
* @see Subscriber#onNext(Object)
* @param t the value to emit, not null
*/
FluxSink next(T t);
/**
* The current outstanding request amount.
* @return the current outstanding request amount
*/
long requestedFromDownstream();
/**
* Returns true if the downstream cancelled the sequence.
* @return true if the downstream cancelled the sequence
*/
boolean isCancelled();
/**
* Attaches a {@link LongConsumer} to this {@link FluxSink} that will be notified of
* any request to this sink.
*
* For push/pull sinks created using {@link Flux#create(java.util.function.Consumer)}
* or {@link Flux#create(java.util.function.Consumer, FluxSink.OverflowStrategy)},
* the consumer
* is invoked for every request to enable a hybrid backpressure-enabled push/pull model.
* When bridging with asynchronous listener-based APIs, the {@code onRequest} callback
* may be used to request more data from source if required and to manage backpressure
* by delivering data to sink only when requests are pending.
*
* For push-only sinks created using {@link Flux#push(java.util.function.Consumer)}
* or {@link Flux#push(java.util.function.Consumer, FluxSink.OverflowStrategy)},
* the consumer is invoked with an initial request of {@code Long.MAX_VALUE} when this method
* is invoked.
*
* @param consumer the consumer to invoke on each request
* @return {@link FluxSink} with a consumer that is notified of requests
*/
FluxSink onRequest(LongConsumer consumer);
/**
* Associates a disposable resource with this FluxSink
* that will be disposed in case the downstream cancels the sequence
* via {@link org.reactivestreams.Subscription#cancel()}.
* @param d the disposable callback to use
* @return the {@link FluxSink} with resource to be disposed on cancel signal
*/
FluxSink onCancel(Disposable d);
/**
* Associates a disposable resource with this FluxSink
* that will be disposed on the first terminate signal which may be
* a cancel, complete or error signal.
* @param d the disposable callback to use
* @return the {@link FluxSink} with resource to be disposed on first terminate signal
*/
FluxSink onDispose(Disposable d);
/**
* Enumeration for backpressure handling.
*/
enum OverflowStrategy {
/**
* Completely ignore downstream backpressure requests.
*
* This may yield {@link IllegalStateException} when queues get full downstream.
*/
IGNORE,
/**
* Signal an {@link IllegalStateException} when the downstream can't keep up
*/
ERROR,
/**
* Drop the incoming signal if the downstream is not ready to receive it.
*/
DROP,
/**
* Downstream will get only the latest signals from upstream.
*/
LATEST,
/**
* Buffer all signals if the downstream can't keep up.
*
* Warning! This does unbounded buffering and may lead to {@link OutOfMemoryError}.
*/
BUFFER
}
}