ByteBuf 引用计数问题

netty框架使用过程中关于ByteBuf 的处理
SImpleChannelInbound 会release ByteBuf，ChannelInboundHandlerAdapter 不会影响ByteBuf的引用计数

• 采用尾回收自动释放
• 手动释放

下面是使用EmbeddedChannel来演示ByteBuf引用计数回收的示例

采用尾回收自动释放

EmbeddedChannel embeddedChannel = new EmbeddedChannel();
embeddedChannel.pipeline().addLast(new MyInBound());
ByteBuf buf = Unpooled.buffer();
buf.writeBytes("hello world!".getBytes(StandardCharsets.UTF_8));
embeddedChannel.writeInbound(buf);
System.out.println("The buf refCnt is " + buf.refCnt());
try {
    Thread.sleep(10 * 1000);
} catch (InterruptedException e) {
    e.printStackTrace();
}

public class MyInBound extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        System.out.println("my inbound===");
        ByteBuf byteBuf = (ByteBuf) msg;
        System.out.println(byteBuf.slice().toString(CharsetUtil.UTF_8));
        ctx.fireChannelRead(byteBuf);//must pass Bytebuf 才能出发尾引用计数回收
    }
}

手动释放

public class MyInBound extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        System.out.println("my inbound===");
        ByteBuf byteBuf = (ByteBuf) msg;
        System.out.println(byteBuf.slice().toString(CharsetUtil.UTF_8));
        byteBuf.release();
...
    }
}

netty自带的编码器处理了ByteBuf的引用释放问题 例如：StringDecoder.class