sofa-bolt源码阅读(4)-Protocol

其他 2020-03-06 08:34:11 阅读次数: 0

5. Protocol

5.1 序列化

SerializerManager负责管理序列化类，默认起作用的是HessianSerializer

HessianSerializer实现了序列化接口Serializer，有两个方法

  1. 序列化

    byte[] serialize(final Object obj) throws CodecException;

  2. 反序列化

    <T> T deserialize(final byte[] data, String classOfT) throws CodecException;

直接看实现

public class HessianSerializer implements Serializer {

        private SerializerFactory serializerFactory = new SerializerFactory();

    /** 
     * @see com.alipay.remoting.serialization.Serializer#serialize(java.lang.Object)
     */
    @Override
    public byte[] serialize(Object obj) throws CodecException {
        ByteArrayOutputStream byteArray = new ByteArrayOutputStream();
        Hessian2Output output = new Hessian2Output(byteArray);
        output.setSerializerFactory(serializerFactory);
        try {
            output.writeObject(obj);
            output.close();
        } catch (IOException e) {
            throw new CodecException("IOException occurred when Hessian serializer encode!", e);
        }

        return byteArray.toByteArray();
    }

    /**
     * 
     * @see com.alipay.remoting.serialization.Serializer#deserialize(byte[], java.lang.String)
     */
    @SuppressWarnings("unchecked")
    @Override
    public <T> T deserialize(byte[] data, String classOfT) throws CodecException {
        Hessian2Input input = new Hessian2Input(new ByteArrayInputStream(data));
        input.setSerializerFactory(serializerFactory);
        Object resultObject;
        try {
            resultObject = input.readObject();
            input.close();
        } catch (IOException e) {
            throw new CodecException("IOException occurred when Hessian serializer decode!", e);
        }
        return (T) resultObject;
    }

}

Hessian的文档 http://hessian.caucho.com/doc/hessian-serialization.html

例如

对象RequestBody

序列化结果为

5.2 编码

Bolt的编码处理器是ProtocolCodeBasedEncoder，当发送数据时，会调用encode方法

protected void encode(ChannelHandlerContext ctx, Serializable msg, ByteBuf out)
                                                                               throws Exception {
    Attribute<ProtocolCode> att = ctx.channel().attr(Connection.PROTOCOL);
    ProtocolCode protocolCode;
    if (att == null || att.get() == null) {
        protocolCode = this.defaultProtocolCode;
    } else {
        protocolCode = att.get();
    }
    Protocol protocol = ProtocolManager.getProtocol(protocolCode);
    protocol.getEncoder().encode(ctx, msg, out);
}

该编码器并没有对数据进行直接处理，而是交给Protocol类处理

Protocol有两个实现类，可以在配置项或者连接的URL中指定协议的版本号。上面两个实现类的protocolCode分别是1和2。协议可以创建编码器和解码器。默认的协议号是1，因此默认的编码器是RpcCommandEncoder。

编码的代码如下：

public void encode(ChannelHandlerContext ctx, Serializable msg, ByteBuf out) throws Exception {
    try {
        if (msg instanceof RpcCommand) {
            /*
             * ver: version for protocol
             * type: request/response/request oneway
             * cmdcode: code for remoting command
             * ver2:version for remoting command
             * requestId: id of request
             * codec: code for codec
             * (req)timeout: request timeout.
             * (resp)respStatus: response status
             * classLen: length of request or response class name
             * headerLen: length of header
             * cotentLen: length of content
             * className
             * header
             * content
             */
            RpcCommand cmd = (RpcCommand) msg;
            out.writeByte(RpcProtocol.PROTOCOL_CODE);
            out.writeByte(cmd.getType());
            out.writeShort(((RpcCommand) msg).getCmdCode().value());
            out.writeByte(cmd.getVersion());
            out.writeInt(cmd.getId());
            out.writeByte(cmd.getSerializer());
            if (cmd instanceof RequestCommand) {
                //timeout
                out.writeInt(((RequestCommand) cmd).getTimeout());
            }
            if (cmd instanceof ResponseCommand) {
                //response status
                ResponseCommand response = (ResponseCommand) cmd;
                out.writeShort(response.getResponseStatus().getValue());
            }
            out.writeShort(cmd.getClazzLength());
            out.writeShort(cmd.getHeaderLength());
            out.writeInt(cmd.getContentLength());
            if (cmd.getClazzLength() > 0) {
                out.writeBytes(cmd.getClazz());
            }
            if (cmd.getHeaderLength() > 0) {
                out.writeBytes(cmd.getHeader());
            }
            if (cmd.getContentLength() > 0) {
                out.writeBytes(cmd.getContent());
            }
        } else {
            String warnMsg = "msg type [" + msg.getClass() + "] is not subclass of RpcCommand";
            logger.warn(warnMsg);
        }
    } catch (Exception e) {
        logger.error("Exception caught!", e);
        throw e;
    }
}

抓包结果分析

01 --ver

01 --request,表示请求

00 01 -- cmdcode

01 --ver2

00 00 00 01 -- requestId

01 -- codec

00 00 0b b8 -- timeout (=3000)

00 2a -- classLen(=42)

00 00 -- headerLen(=0)

00 00 00 cc -- cotentLen(=204)

63 6f 6d 2e 61 6c 69 70 61 79 2e 72 65 6d 6f 74 69 6e 67 2e

72 70 63 2e 63 6f 6d 6d 6f 6e 2e 52 65 71 75 65 73 74 42 6f

64 79 -- className(com.alipay.remoting.rpc.common.RequestBody)

4f ba ... -- content (序列化的对象)

5.3 解码

Bolt解码处理器是ProtocolCodeBasedDecoder

protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
    in.markReaderIndex();
    //获取协议号ver
    ProtocolCode protocolCode = decodeProtocolCode(in);
    if (null != protocolCode) {
        byte protocolVersion = decodeProtocolVersion(in);
        if (ctx.channel().attr(Connection.PROTOCOL).get() == null) {
            ctx.channel().attr(Connection.PROTOCOL).set(protocolCode);
            if (DEFAULT_ILLEGAL_PROTOCOL_VERSION_LENGTH != protocolVersion) {
                ctx.channel().attr(Connection.VERSION).set(protocolVersion);
            }
        }
        Protocol protocol = ProtocolManager.getProtocol(protocolCode);
        if (null != protocol) {
            in.resetReaderIndex();
            protocol.getDecoder().decode(ctx, in, out);
        } else {
            throw new CodecException("Unknown protocol code: [" + protocolCode
                                     + "] while decode in ProtocolDecoder.");
        }
    }
}

与编码一样交给Protocol来处理

直接看解码的实现类RpcCommandDecoder的decode方法

@Override
public void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
    // the less length between response header and request header
    if (in.readableBytes() >= lessLen) {
        in.markReaderIndex();
        byte protocol = in.readByte();
        in.resetReaderIndex();
        if (protocol == RpcProtocol.PROTOCOL_CODE) {
            /*
             * ver: version for protocol
             * type: request/response/request oneway
             * cmdcode: code for remoting command
             * ver2:version for remoting command
             * requestId: id of request
             * codec: code for codec
             * (req)timeout: request timeout
             * (resp)respStatus: response status
             * classLen: length of request or response class name
             * headerLen: length of header
             * contentLen: length of content
             * className
             * header
             * content
             */
            if (in.readableBytes() > 2) {
                in.markReaderIndex();
                in.readByte(); //version
                byte type = in.readByte(); //type
                if (type == RpcCommandType.REQUEST || type == RpcCommandType.REQUEST_ONEWAY) {
                    //decode request
                    if (in.readableBytes() >= RpcProtocol.getRequestHeaderLength() - 2) {
                        short cmdCode = in.readShort();
                        byte ver2 = in.readByte();
                        int requestId = in.readInt();
                        byte serializer = in.readByte();
                        int timeout = in.readInt();
                        short classLen = in.readShort();
                        short headerLen = in.readShort();
                        int contentLen = in.readInt();
                        byte[] clazz = null;
                        byte[] header = null;
                        byte[] content = null;
                        if (in.readableBytes() >= classLen + headerLen + contentLen) {
                            if (classLen > 0) {
                                clazz = new byte[classLen];
                                in.readBytes(clazz);
                            }
                            if (headerLen > 0) {
                                header = new byte[headerLen];
                                in.readBytes(header);
                            }
                            if (contentLen > 0) {
                                content = new byte[contentLen];
                                in.readBytes(content);
                            }
                        } else {// not enough data
                            in.resetReaderIndex();
                            return;
                        }
                        RequestCommand command;
                        if (cmdCode == CommandCode.HEARTBEAT_VALUE) {
                            command = new HeartbeatCommand();
                        } else {
                            command = createRequestCommand(cmdCode);
                        }
                        command.setType(type);
                        command.setVersion(ver2);
                        command.setId(requestId);
                        command.setSerializer(serializer);
                        command.setTimeout(timeout);
                        command.setClazz(clazz);
                        command.setHeader(header);
                        command.setContent(content);
                        out.add(command);

                    } else {
                        in.resetReaderIndex();
                    }
                } else if (type == RpcCommandType.RESPONSE) {
                    //decode response
                    if (in.readableBytes() >= RpcProtocol.getResponseHeaderLength() - 2) {
                        short cmdCode = in.readShort();
                        byte ver2 = in.readByte();
                        int requestId = in.readInt();
                        byte serializer = in.readByte();
                        short status = in.readShort();
                        short classLen = in.readShort();
                        short headerLen = in.readShort();
                        int contentLen = in.readInt();
                        byte[] clazz = null;
                        byte[] header = null;
                        byte[] content = null;
                        if (in.readableBytes() >= classLen + headerLen + contentLen) {
                            if (classLen > 0) {
                                clazz = new byte[classLen];
                                in.readBytes(clazz);
                            }
                            if (headerLen > 0) {
                                header = new byte[headerLen];
                                in.readBytes(header);
                            }
                            if (contentLen > 0) {
                                content = new byte[contentLen];
                                in.readBytes(content);
                            }
                        } else {// not enough data
                            in.resetReaderIndex();
                            return;
                        }
                        ResponseCommand command;
                        if (cmdCode == CommandCode.HEARTBEAT_VALUE) {

                            command = new HeartbeatAckCommand();
                        } else {
                            command = createResponseCommand(cmdCode);
                        }
                        command.setType(type);
                        command.setVersion(ver2);
                        command.setId(requestId);
                        command.setSerializer(serializer);
                        command.setResponseStatus(ResponseStatus.valueOf(status));
                        command.setClazz(clazz);
                        command.setHeader(header);
                        command.setContent(content);
                        command.setResponseTimeMillis(System.currentTimeMillis());
                        command.setResponseHost((InetSocketAddress) ctx.channel()
                            .remoteAddress());
                        out.add(command);
                    } else {
                        in.resetReaderIndex();
                    }
                } else {
                    String emsg = "Unknown command type: " + type;
                    logger.error(emsg);
                    throw new RuntimeException(emsg);
                }
            }

        } else {
            String emsg = "Unknown protocol: " + protocol;
            logger.error(emsg);
            throw new RuntimeException(emsg);
        }

    }
}

解码时根据type的类型，将字节流分装成RequestCommand或ResponseCommand的对象。

5.4 流程分析

服务器的数据流转过程总结一下:

  1. decoder将字节流解码成RequestCommand或ResponseCommand的对象
  2. idleStateHandler更新read时间
  3. serverIdleHandler未接收到空闲事件，pass
  4. connectionEventHandler,pass
  5. handler根据协议号获取commandHandler
  6. commandHandler根据msg(第1步保证肯定是RpcCommand的实现类)的cmdCode获取具体的命令处理器RemotingProcessor。
    • 心跳 HeartbeatCommand -> RpcHeartBeatProcessor
    • 请求 RpcRequestCommand-> RpcRequestProcessor
    • 响应 RpcResponseCommand -> RpcResponseProcessor
  7. 以请求RpcRequestCommand为例，RpcRequestProcessor根据requestClass获取具体的UserProcessor,处理自定义业务后封装响应为RpcResponseCommand 并写入到channel中
  8. connectionEventHandler,pass
  9. serverIdleHandler未接收到空闲事件，pass
  10. idleStateHandler更新write时间
  11. encoder将对象编码成字节流发送给客户端

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