package com.example.agvcontroller.met;

import com.example.agvcontroller.protocol.AgvPackage;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.ReferenceCountUtil;

/**
 * netty handler增强器
 * 设计模式: 适配器模式
 * Created by vincent on 2019-04-06
 */
public abstract class AbstractInboundHandler<T> extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object obj) throws Exception {
        @SuppressWarnings("unchecked")
        T t = (T) obj;
        if (channelRead0(ctx, t)) {
            ctx.fireChannelRead(t);
        } else  {
            // 管道中断，fireChannelRead未执行，需要手动释放堆外内存
            if (obj instanceof AgvPackage){
                AgvPackage pac = (AgvPackage) obj;
                if (pac.getSourceBuff().refCnt() > 0) {
                    pac.getSourceBuff().skipBytes(pac.getSourceBuff().readableBytes());
                    ReferenceCountUtil.release(pac.getSourceBuff());
                }
            }
        }
    }

    protected abstract boolean channelRead0(ChannelHandlerContext ctx, T t) throws Exception;

}