NettyDecoder.java

/**
 * $Id: NettyDecoder.java 1831 2013-05-16 01:39:51Z shijia.wxr $
 */
package com.alibaba.rocketmq.remoting.netty;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;

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

import com.alibaba.rocketmq.remoting.common.RemotingHelper;
import com.alibaba.rocketmq.remoting.protocol.RemotingCommand;


/**
 * @author vintage.wang@gmail.com shijia.wxr@taobao.com
 * 
 */
public class NettyDecoder extends LengthFieldBasedFrameDecoder {
    private static final Logger log = LoggerFactory.getLogger(RemotingHelper.RemotingLogName);
    private static final int FRAME_MAX_LENGTH = 1024 * 1024 * 8;


    public NettyDecoder() {
        super(FRAME_MAX_LENGTH, 0, 4, 0, 4);
    }


    @Override
    public Object decode(ChannelHandlerContext ctx, ByteBuf in) throws Exception {
        try {
            ByteBuf frame = (ByteBuf) super.decode(ctx, in);
            if (frame == null) {
                return null;
            }

            return RemotingCommand.decode(frame.array());
        }
        catch (Exception e) {
            log.error("decode exception, " + RemotingHelper.parseChannelRemoteAddr(ctx.channel()), e);
            ctx.channel().close();
        }

        return null;
    }
}