io.micronaut.http.server.netty.async.ContextCompletionAwareSubscriber Maven / Gradle / Ivy

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/*
 * Copyright 2017-2020 original 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
 *
 * https://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 io.micronaut.http.server.netty.async;

import io.micronaut.core.annotation.Internal;
import io.micronaut.core.async.subscriber.CompletionAwareSubscriber;
import io.micronaut.http.netty.reactive.HandlerPublisher;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPipeline;
import org.reactivestreams.Subscription;

/**
 * A subscriber that subscribes to a single result with special handling for the {@link ChannelHandlerContext}.
 *
 * @param  The type of data being published
 * @author James Kleeh
 * @since 1.0
 */
@Internal
public abstract class ContextCompletionAwareSubscriber extends CompletionAwareSubscriber {

    private final ChannelHandlerContext context;
    private Subscription s;
    private Object message;

    /**
     * @param context The channel handler context
     */
    protected ContextCompletionAwareSubscriber(ChannelHandlerContext context) {
        this.context = context;
    }

    @Override
    protected void doOnSubscribe(Subscription subscription) {
        this.s = subscription;
        this.s.request(1);
    }

    @Override
    protected void doOnNext(T message) {
        this.message = message;
    }

    @Override
    protected void doOnError(Throwable t) {
        s.cancel();

        ChannelPipeline pipeline = context.pipeline();
        // remove the subscriber
        HandlerPublisher handlerPublisher = pipeline.get(HandlerPublisher.class);
        if (handlerPublisher != null) {
            pipeline.remove(handlerPublisher);
        }
        // fire the exception
        pipeline.fireExceptionCaught(t);
    }

    @Override
    protected void doOnComplete() {
        onComplete((T) message);
    }

    /**
     * @param message The message
     */
    protected abstract void onComplete(T message);
}