malcolm.HttpProxyBackendHandler.java Source code

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Here is the source code for malcolm.HttpProxyBackendHandler.java

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/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you 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 malcolm;

import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.codec.http.HttpContent;
import io.netty.handler.codec.http.HttpObject;
import io.netty.handler.codec.http.HttpResponse;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class HttpProxyBackendHandler extends ChannelInboundHandlerAdapter {

    private static final Logger logger = LoggerFactory.getLogger(HttpProxyBackendHandler.class);

    private final Channel frontendChannel;

    public HttpProxyBackendHandler(final Channel frontendChannel) {
        this.frontendChannel = frontendChannel;
    }

    @Override
    public void channelActive(final ChannelHandlerContext ctx) {
        // TODO what does this to?
        ctx.read();
        ctx.write(Unpooled.EMPTY_BUFFER);
    }

    @Override
    public void channelRead(final ChannelHandlerContext ctx, final Object msg) {
        if (msg instanceof HttpResponse) {
            channelReadHttpResponse(ctx, (HttpResponse) msg);
        }
        if (msg instanceof HttpContent) {
            channelReadHttpContent(ctx, (HttpContent) msg);
        }
    }

    private void writeHttpMessage(final ChannelHandlerContext ctx, final HttpObject obj) {
        frontendChannel.writeAndFlush(obj).addListener(f -> {
            if (f.isSuccess()) {
                ctx.channel().read();
            } else {
                logger.debug("write response failed");
                ctx.channel().close();
            }
        });
    }

    private void channelReadHttpResponse(final ChannelHandlerContext ctx, final HttpResponse response) {
        writeHttpMessage(ctx, response);
    }

    private void channelReadHttpContent(final ChannelHandlerContext ctx, final HttpContent content) {
        writeHttpMessage(ctx, content);
    }

    @Override
    public void channelInactive(final ChannelHandlerContext ctx) {
        closeOnFlush(frontendChannel);
    }

    @Override
    public void exceptionCaught(final ChannelHandlerContext ctx, final Throwable cause) {
        logger.info("Error processing backend request", cause);
        closeOnFlush(ctx.channel());
    }

    private static void closeOnFlush(final Channel ch) {
        if (ch.isActive()) {
            ch.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
        }
    }
}