/*
* Copyright 2016-2017 the original author or authors.
*
* 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 org.springframework.integration.endpoint;
import java.util.function.Consumer;
import org.reactivestreams.Publisher;
import org.reactivestreams.Subscriber;
import org.reactivestreams.Subscription;
import org.springframework.context.Lifecycle;
import org.springframework.integration.channel.MessageChannelReactiveUtils;
import org.springframework.integration.channel.MessagePublishingErrorHandler;
import org.springframework.integration.core.MessageProducer;
import org.springframework.integration.router.MessageRouter;
import org.springframework.integration.support.channel.BeanFactoryChannelResolver;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageChannel;
import org.springframework.messaging.MessageHandler;
import org.springframework.util.Assert;
import org.springframework.util.ErrorHandler;
import reactor.core.Disposable;
import reactor.core.publisher.BaseSubscriber;
/**
* @author Artem Bilan
* @since 5.0
*/
public class ReactiveStreamsConsumer extends AbstractEndpoint implements IntegrationConsumer {
private final MessageChannel inputChannel;
private final MessageHandler messageHandler;
private final Publisher<Message<Object>> publisher;
private final Subscriber<Message<?>> subscriber;
private final Lifecycle lifecycleDelegate;
private ErrorHandler errorHandler;
private volatile Subscription subscription;
@SuppressWarnings("unchecked")
public ReactiveStreamsConsumer(MessageChannel inputChannel, MessageHandler messageHandler) {
this(inputChannel,
messageHandler instanceof Subscriber
? (Subscriber<Message<?>>) messageHandler
: new MessageHandlerSubscriber(messageHandler));
}
public ReactiveStreamsConsumer(MessageChannel inputChannel, final Subscriber<Message<?>> subscriber) {
this.inputChannel = inputChannel;
Assert.notNull(inputChannel, "'inputChannel' must not be null");
Assert.notNull(subscriber, "'subscriber' must not be null");
this.publisher = MessageChannelReactiveUtils.toPublisher(inputChannel);
this.subscriber = subscriber;
this.lifecycleDelegate = subscriber instanceof Lifecycle ? (Lifecycle) subscriber : null;
if (subscriber instanceof MessageHandlerSubscriber) {
this.messageHandler = ((MessageHandlerSubscriber) subscriber).messageHandler;
}
else {
this.messageHandler = this.subscriber::onNext;
}
}
public void setErrorHandler(ErrorHandler errorHandler) {
this.errorHandler = errorHandler;
}
@Override
public MessageChannel getInputChannel() {
return this.inputChannel;
}
@Override
public MessageChannel getOutputChannel() {
if (this.messageHandler instanceof MessageProducer) {
return ((MessageProducer) this.messageHandler).getOutputChannel();
}
else if (this.messageHandler instanceof MessageRouter) {
return ((MessageRouter) this.messageHandler).getDefaultOutputChannel();
}
else {
return null;
}
}
@Override
public MessageHandler getHandler() {
return this.messageHandler;
}
@Override
protected void onInit() throws Exception {
super.onInit();
if (this.errorHandler == null) {
Assert.notNull(getBeanFactory(), "BeanFactory is required");
this.errorHandler = new MessagePublishingErrorHandler(new BeanFactoryChannelResolver(getBeanFactory()));
}
}
@Override
protected void doStart() {
if (this.lifecycleDelegate != null) {
this.lifecycleDelegate.start();
}
this.publisher.subscribe(new BaseSubscriber<Message<?>>() {
private final Subscriber<Message<?>> delegate = ReactiveStreamsConsumer.this.subscriber;
public void hookOnSubscribe(Subscription s) {
this.delegate.onSubscribe(s);
ReactiveStreamsConsumer.this.subscription = s;
}
public void hookOnNext(Message<?> message) {
try {
this.delegate.onNext(message);
}
catch (Exception e) {
ReactiveStreamsConsumer.this.errorHandler.handleError(e);
hookOnError(e);
}
}
public void hookOnError(Throwable t) {
this.delegate.onError(t);
}
public void hookOnComplete() {
this.delegate.onComplete();
}
});
}
@Override
protected void doStop() {
if (this.subscription != null) {
this.subscription.cancel();
}
if (this.lifecycleDelegate != null) {
this.lifecycleDelegate.stop();
}
}
private static final class MessageHandlerSubscriber
implements Subscriber<Message<?>>, Disposable, Lifecycle {
private final Consumer<Message<?>> consumer;
private Subscription subscription;
private MessageHandler messageHandler;
MessageHandlerSubscriber(MessageHandler messageHandler) {
Assert.notNull(messageHandler, "'messageHandler' must not be null");
this.messageHandler = messageHandler;
this.consumer = this.messageHandler::handleMessage;
}
@Override
public void onSubscribe(Subscription s) {
this.subscription = s;
s.request(Long.MAX_VALUE);
}
@Override
public void onNext(Message<?> message) {
this.consumer.accept(message);
}
@Override
public void onError(Throwable t) {
}
@Override
public void onComplete() {
dispose();
}
@Override
public void dispose() {
Subscription s = this.subscription;
if (s != null) {
this.subscription = null;
s.cancel();
}
}
@Override
public boolean isDisposed() {
return this.subscription == null;
}
@Override
public void start() {
if (this.messageHandler instanceof Lifecycle) {
((Lifecycle) this.messageHandler).start();
}
}
@Override
public void stop() {
if (this.messageHandler instanceof Lifecycle) {
((Lifecycle) this.messageHandler).stop();
}
}
@Override
public boolean isRunning() {
return !(this.messageHandler instanceof Lifecycle) || ((Lifecycle) this.messageHandler).isRunning();
}
}
}