手写rpc框架

文章目录

• 手写rpc框架
• rpc概念
• rpc是什么
• 为什么要用rpc
• rpc核心概念术语
• rpc的流程
• 开发rpc框架
• 设计客户端
• 代理对象生成
• 发现者
• 协议层
• 网络层
• 实现客户端
• 代理对象生成
• 发现者
• 协议层
• 网络层
• 设计服务端
• RPCServer
• RequestHandler
• ServiceRegister
• 实现服务端
• RPCServer
• RequestHandler
• ServiceRegister
• 实现高并发 RPC 框架的要素

手写rpc框架

rpc概念

rpc是什么

远程过程调用（Remote Procedure Call，缩写为 RPC）是一个计算机通信协议。该协议允许运行于一台计算机的程序调用另一台计算机的子程序，而程序员无需额外地为这个交互作用编程。如果涉及的软件采用面向对象编程，那么远程过程调用亦可称作远程调用或远程方法调用。

为什么要用rpc

RPC框架介于传输层和应用中间，它会帮助处理：

• 服务化
• 可重用
• 系统间交互调用

rpc核心概念术语

• Client、Server、calls、replies、service、programs、procedures、version、marshalling（编组）、unmarshalling（解组）
• 一个网络服务由一个或多个远程程序集构成
• 一个远程程序实现一个或多个远程过程
• 过程、过程的参数、结果在程序协议说明书中定义说明
• 为兼容程序协议变更，一个服务端可能支持多个版本的远程程序

rpc的流程

1. 客户端处理过程中调用Client Stub（就像调用本地方法一样），传递参数；

2. Client Stub 将参数编组为消息，然后通过系统调用向服务端发送消息；

3. 客户端本地操作系统将消息从客户端机器发送到服务端机器；

4. 服务端操作系统将接收到的数据包传递给Server Stub；

5. Server Stub解组消息为参数；

6. Server Stub再调用服务端的过程，过程执行结果以反方向的相同步骤响应给客户端。

开发rpc框架

用户使用rpc框架的步骤如下：

1. 定义过程定义接口

2. 服务端实现过程

3. 客户端使用生成的stub代理对象

所以在开发rpc框架中，需实现客户端和服务端。

设计客户端

代理对象生成

首先考虑客户端如何生成过程接口的代理对象。在设计中，设计客户端代理工厂，用JDK动态代理即可生成接口的代理对象。类图如下图所示。

发现者

设计客户端的时候，在ClientStubInvocationHandler中需要完成的两件事为编组消息和发送网络请求，而将请求的内容编组为消息这件事就交由客户端的stub代理，它除了消息协议和网络层的事务以外，可能还存在一个服务信息发现。此外消息协议可能也是会存在变化的，我们也需要去支持多种协议。此时我们需要得知某服务用的是什么协议，所以我们需要引入一个服务发现者。

协议层

想要做到支持多种协议，类该如何设计（面向接口，策略模式，组合）。

此时又存在一些问题，单纯依靠编组和解组的方法是不够的，编组和解组的操作对象是请求、响应，但是它们的内容是不同的，此时我们又需要定义框架标准的请求、响应类。

此时协议层扩展为4个方法。将消息协议独立为一层，因为客户端和服务端都需要使用。

网络层

网络层的工作主要是发送请求和获得响应，此时我们如果需要发起网络请求必定先要知道服务地址，此时我们利用下图中serviceInfo对象作为必须依赖，setRequest()方法里面会存在发送数据，还有发送给谁。

实现客户端

按照之前的类图设计，进行填码。

代理对象生成

public class ClientStubProxyFactory {

	private ServiceInfoDiscoverer sid;

	private Map<String, MessageProtocol> supportMessageProtocols;

	private NetClient netClient;

	private Map<Class<?>, Object> objectCache = new HashMap<>();

	public <T> T getProxy(Class<T> interf) {
		T obj = (T) this.objectCache.get(interf);
		if (obj == null) {
			obj = (T) Proxy.newProxyInstance(interf.getClassLoader(), new Class<?>[] { interf },
					new ClientStubInvocationHandler(interf));
			this.objectCache.put(interf, obj);
		}

		return obj;
	}

	public ServiceInfoDiscoverer getSid() {
		return sid;
	}

	public void setSid(ServiceInfoDiscoverer sid) {
		this.sid = sid;
	}

	public Map<String, MessageProtocol> getSupportMessageProtocols() {
		return supportMessageProtocols;
	}

	public void setSupportMessageProtocols(Map<String, MessageProtocol> supportMessageProtocols) {
		this.supportMessageProtocols = supportMessageProtocols;
	}

	public NetClient getNetClient() {
		return netClient;
	}

	public void setNetClient(NetClient netClient) {
		this.netClient = netClient;
	}

	private class ClientStubInvocationHandler implements InvocationHandler {
		private Class<?> interf;

		private Random random = new Random();

		public ClientStubInvocationHandler(Class<?> interf) {
			super();
			this.interf = interf;
		}

		@Override
		public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

			if (method.getName().equals("toString")) {
				return proxy.getClass().toString();
			}

			if (method.getName().equals("hashCode")) {
				return 0;
			}

			// 1、获得服务信息
			String serviceName = this.interf.getName();
			List<ServiceInfo> sinfos = sid.getServiceInfo(serviceName);

			if (sinfos == null || sinfos.size() == 0) {
				throw new Exception("远程服务不存在！");
			}

			// 随机选择一个服务提供者（软负载均衡）
			ServiceInfo sinfo = sinfos.get(random.nextInt(sinfos.size()));

			// 2、构造request对象
			Request req = new Request();
			req.setServiceName(sinfo.getName());
			req.setMethod(method.getName());
			req.setPrameterTypes(method.getParameterTypes());
			req.setParameters(args);

			// 3、协议层编组
			// 获得该方法对应的协议
			MessageProtocol protocol = supportMessageProtocols.get(sinfo.getProtocol());
			// 编组请求
			byte[] data = protocol.marshallingRequest(req);

			// 4、调用网络层发送请求
			byte[] repData = netClient.sendRequest(data, sinfo);

			// 5解组响应消息
			Response rsp = protocol.unmarshallingResponse(repData);

			// 6、结果处理
			if (rsp.getException() != null) {
				throw rsp.getException();
			}

			return rsp.getReturnValue();
		}
	}
}

发现者

public class ServiceInfo {

	private String name;

	private String protocol;

	private String address;

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getProtocol() {
		return protocol;
	}

	public void setProtocol(String protocol) {
		this.protocol = protocol;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

}

public interface ServiceInfoDiscoverer {
	List<ServiceInfo> getServiceInfo(String name);
}

zookeeper的服务发现实现如下：

public class ZookeeperServiceInfoDiscoverer implements ServiceInfoDiscoverer {

	ZkClient client;

	private String centerRootPath = "/Rpc-framework";

	public ZookeeperServiceInfoDiscoverer() {
		String addr = PropertiesUtils.getProperties("zk.address");
		client = new ZkClient(addr);
		client.setZkSerializer(new MyZkSerializer());
	}

	@Override
	public List<ServiceInfo> getServiceInfo(String name) {
		String servicePath = centerRootPath + "/" + name + "/service";
		List<String> children = client.getChildren(servicePath);
		List<ServiceInfo> resources = new ArrayList<ServiceInfo>();
		for (String ch : children) {
			try {
				String deCh = URLDecoder.decode(ch, "UTF-8");
				ServiceInfo r = JSON.parseObject(deCh, ServiceInfo.class);
				resources.add(r);
			} catch (UnsupportedEncodingException e) {
				e.printStackTrace();
			}
		}
		return resources;
	}

}

协议层

public interface MessageProtocol {

	byte[] marshallingRequest(Request req) throws Exception;

	Request unmarshallingRequest(byte[] data) throws Exception;

	byte[] marshallingResponse(Response rsp) throws Exception;

	Response unmarshallingResponse(byte[] data) throws Exception;
}

public class JavaSerializeMessageProtocol implements MessageProtocol {

	private byte[] serialize(Object obj) throws Exception {
		ByteArrayOutputStream bout = new ByteArrayOutputStream();
		ObjectOutputStream out = new ObjectOutputStream(bout);
		out.writeObject(obj);

		return bout.toByteArray();
	}

	@Override
	public byte[] marshallingRequest(Request req) throws Exception {

		return this.serialize(req);
	}

	@Override
	public Request unmarshallingRequest(byte[] data) throws Exception {
		ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(data));
		return (Request) in.readObject();
	}

	@Override
	public byte[] marshallingResponse(Response rsp) throws Exception {
		return this.serialize(rsp);
	}

	@Override
	public Response unmarshallingResponse(byte[] data) throws Exception {
		ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(data));
		return (Response) in.readObject();
	}

}

public class Request implements Serializable {

	/**
	 * 
	 */
	private static final long serialVersionUID = -5200571424236772650L;

	private String serviceName;

	private String method;

	private Map<String, String> headers = new HashMap<String, String>();

	private Class<?>[] prameterTypes;

	private Object[] parameters;

	public String getServiceName() {
		return serviceName;
	}

	public void setServiceName(String serviceName) {
		this.serviceName = serviceName;
	}

	public String getMethod() {
		return method;
	}

	public void setMethod(String method) {
		this.method = method;
	}

	public Map<String, String> getHeaders() {
		return headers;
	}

	public void setHeaders(Map<String, String> headers) {
		this.headers = headers;
	}

	public Class<?>[] getPrameterTypes() {
		return prameterTypes;
	}

	public void setPrameterTypes(Class<?>[] prameterTypes) {
		this.prameterTypes = prameterTypes;
	}

	public void setParameters(Object[] prameters) {
		this.parameters = prameters;
	}

	public String getHeader(String name) {
		return this.headers == null ? null : this.headers.get(name);
	}

	public Object[] getParameters() {
		return this.parameters;
	}

}

public class Response implements Serializable {

	/**
	 * 
	 */
	private static final long serialVersionUID = -4317845782629589997L;

	private Status status;

	private Map<String, String> headers = new HashMap<>();

	private Object returnValue;

	private Exception exception;

	public Response() {
	};

	public Response(Status status) {
		this.status = status;
	}

	public void setStatus(Status status) {
		this.status = status;
	}

	public void setHeaders(Map<String, String> headers) {
		this.headers = headers;
	}

	public void setReturnValue(Object returnValue) {
		this.returnValue = returnValue;
	}

	public void setException(Exception exception) {
		this.exception = exception;
	}

	public Status getStatus() {
		return status;
	}

	public Map<String, String> getHeaders() {
		return headers;
	}

	public Object getReturnValue() {
		return returnValue;
	}

	public Exception getException() {
		return exception;
	}

	public String getHeader(String name) {
		return this.headers == null ? null : this.headers.get(name);
	}

	public void setHaader(String name, String value) {
		this.headers.put(name, value);

	}
}

public enum Status {
	SUCCESS(200, "SUCCESS"), ERROR(500, "ERROR"), NOT_FOUND(404, "NOT FOUND");

	private int code;

	private String message;

	private Status(int code, String message) {
		this.code = code;
		this.message = message;
	}

	public int getCode() {
		return code;
	}

	public String getMessage() {
		return message;
	}
}

网络层

public interface NetClient {
	byte[] sendRequest(byte[] data, ServiceInfo sinfo) throws Throwable;
}

public class NettyNetClient implements NetClient {

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

	@Override
	public byte[] sendRequest(byte[] data, ServiceInfo sinfo) throws Throwable {

		String[] addInfoArray = sinfo.getAddress().split(":");

		SendHandler sendHandler = new SendHandler(data);
		byte[] respData = null;
		// 配置客户端
		EventLoopGroup group = new NioEventLoopGroup();
		try {
			Bootstrap b = new Bootstrap();

			b.group(group).channel(NioSocketChannel.class).option(ChannelOption.TCP_NODELAY, true)
					.handler(new ChannelInitializer<SocketChannel>() {
						@Override
						public void initChannel(SocketChannel ch) throws Exception {
							ChannelPipeline p = ch.pipeline();
							p.addLast(sendHandler);
						}
					});

			// 启动客户端连接
			b.connect(addInfoArray[0], Integer.valueOf(addInfoArray[1])).sync();
			respData = (byte[]) sendHandler.rspData();
			logger.info("sendRequest get reply: " + respData);

		} finally {
			// 释放线程组资源
			group.shutdownGracefully();
		}

		return respData;
	}

	private class SendHandler extends ChannelInboundHandlerAdapter {

		private CountDownLatch cdl = null;
		private Object readMsg = null;
		private byte[] data;

		public SendHandler(byte[] data) {
			cdl = new CountDownLatch(1);
			this.data = data;
		}

		@Override
		public void channelActive(ChannelHandlerContext ctx) throws Exception {
			logger.info("连接服务端成功：" + ctx);
			ByteBuf reqBuf = Unpooled.buffer(data.length);
			reqBuf.writeBytes(data);
			logger.info("客户端发送消息：" + reqBuf);
			ctx.writeAndFlush(reqBuf);
		}

		public Object rspData() {

			try {
				cdl.await();
			} catch (InterruptedException e) {
				e.printStackTrace();
			}

			return readMsg;
		}

		@Override
		public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
			logger.info("client read msg: " + msg);
			ByteBuf msgBuf = (ByteBuf) msg;
			byte[] resp = new byte[msgBuf.readableBytes()];
			msgBuf.readBytes(resp);
			readMsg = resp;
			cdl.countDown();
		}

		@Override
		public void channelReadComplete(ChannelHandlerContext ctx) {
			ctx.flush();
		}

		@Override
		public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
			// Close the connection when an exception is raised.
			cause.printStackTrace();
			logger.error("发生异常：" + cause.getMessage());
			ctx.close();
		}
	}
}

设计服务端

RPCServer

客户端请求过来了，服务端首先通过RPCServer接收请求。在RPCServer中需开启网络服务。

RequestHandler

RPCServer接收到请求以后，将请求交给RequestHandler处理，RequestHandler调用协议层来解组请求消息为Request对象，然后调用过程。消息协议层是复用客户端设计的。

ServiceRegister

ServiceRegister模块实现服务注册、发布。

实现服务端

RPCServer

public abstract class RpcServer {

	protected int port;

	protected String protocol;

	protected RequestHandler handler;

	public RpcServer(int port, String protocol, RequestHandler handler) {
		super();
		this.port = port;
		this.protocol = protocol;
		this.handler = handler;
	}

	/**
	 * 开启服务
	 */
	public abstract void start();

	/**
	 * 停止服务
	 */
	public abstract void stop();

	public int getPort() {
		return port;
	}

	public void setPort(int port) {
		this.port = port;
	}

	public String getProtocol() {
		return protocol;
	}

	public void setProtocol(String protocol) {
		this.protocol = protocol;
	}

	public RequestHandler getHandler() {
		return handler;
	}

	public void setHandler(RequestHandler handler) {
		this.handler = handler;
	}

}

public class NettyRpcServer extends RpcServer {
	private static Logger logger = LoggerFactory.getLogger(NettyRpcServer.class);

	private Channel channel;

	public NettyRpcServer(int port, String protocol, RequestHandler handler) {
		super(port, protocol, handler);
	}

	@Override
	public void start() {
		// 配置服务器
		EventLoopGroup bossGroup = new NioEventLoopGroup(1);
		EventLoopGroup workerGroup = new NioEventLoopGroup();
		try {
			ServerBootstrap b = new ServerBootstrap();
			b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class).option(ChannelOption.SO_BACKLOG, 100)
					.handler(new LoggingHandler(LogLevel.INFO)).childHandler(new ChannelInitializer<SocketChannel>() {
						@Override
						public void initChannel(SocketChannel ch) throws Exception {
							ChannelPipeline p = ch.pipeline();
							p.addLast(new ChannelRequestHandler());
						}
					});

			// 启动服务
			ChannelFuture f = b.bind(port).sync();
			logger.info("完成服务端端口绑定与启动");
			channel = f.channel();
			// 等待服务通道关闭
			f.channel().closeFuture().sync();
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			// 释放线程组资源
			bossGroup.shutdownGracefully();
			workerGroup.shutdownGracefully();
		}
	}

	@Override
	public void stop() {
		this.channel.close();
	}

	private class ChannelRequestHandler extends ChannelInboundHandlerAdapter {

		@Override
		public void channelActive(ChannelHandlerContext ctx) throws Exception {
			logger.info("激活");
		}

		@Override
		public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
			logger.info("服务端收到消息：" + msg);
			ByteBuf msgBuf = (ByteBuf) msg;
			byte[] req = new byte[msgBuf.readableBytes()];
			msgBuf.readBytes(req);
			byte[] res = handler.handleRequest(req);
			logger.info("发送响应：" + msg);
			ByteBuf respBuf = Unpooled.buffer(res.length);
			respBuf.writeBytes(res);
			ctx.write(respBuf);
		}

		@Override
		public void channelReadComplete(ChannelHandlerContext ctx) {
			ctx.flush();
		}

		@Override
		public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
			// Close the connection when an exception is raised.
			cause.printStackTrace();
			logger.error("发生异常：" + cause.getMessage());
			ctx.close();
		}
	}

}

RequestHandler

public class RequestHandler {
	private MessageProtocol protocol;

	private ServiceRegister serviceRegister;

	public RequestHandler(MessageProtocol protocol, ServiceRegister serviceRegister) {
		super();
		this.protocol = protocol;
		this.serviceRegister = serviceRegister;
	}

	public byte[] handleRequest(byte[] data) throws Exception {
		// 1、解组消息
		Request req = this.protocol.unmarshallingRequest(data);

		// 2、查找服务对象
		ServiceObject so = this.serviceRegister.getServiceObject(req.getServiceName());

		Response rsp = null;

		if (so == null) {
			rsp = new Response(Status.NOT_FOUND);
		} else {
			// 3、反射调用对应的过程方法
			try {
				Method m = so.getInterf().getMethod(req.getMethod(), req.getPrameterTypes());
				Object returnValue = m.invoke(so.getObj(), req.getParameters());
				rsp = new Response(Status.SUCCESS);
				rsp.setReturnValue(returnValue);
			} catch (NoSuchMethodException | SecurityException | IllegalAccessException | IllegalArgumentException
					| InvocationTargetException e) {
				rsp = new Response(Status.ERROR);
				rsp.setException(e);
			}
		}

		// 4、编组响应消息
		return this.protocol.marshallingResponse(rsp);
	}

	public MessageProtocol getProtocol() {
		return protocol;
	}

	public void setProtocol(MessageProtocol protocol) {
		this.protocol = protocol;
	}

	public ServiceRegister getServiceRegister() {
		return serviceRegister;
	}

	public void setServiceRegister(ServiceRegister serviceRegister) {
		this.serviceRegister = serviceRegister;
	}

}

ServiceRegister

public interface ServiceRegister {

	void register(ServiceObject so, String protocol, int port) throws Exception;

	ServiceObject getServiceObject(String name) throws Exception;
}

public class ServiceObject {

	private String name;

	private Class<?> interf;

	private Object obj;

	public ServiceObject(String name, Class<?> interf, Object obj) {
		super();
		this.name = name;
		this.interf = interf;
		this.obj = obj;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public Class<?> getInterf() {
		return interf;
	}

	public void setInterf(Class<?> interf) {
		this.interf = interf;
	}

	public Object getObj() {
		return obj;
	}

	public void setObj(Object obj) {
		this.obj = obj;
	}

}

public class DefaultServiceRegister implements ServiceRegister {

	private Map<String, ServiceObject> serviceMap = new HashMap<>();

	@Override
	public void register(ServiceObject so, String protocolName, int port) throws Exception {
		if (so == null) {
			throw new IllegalArgumentException("参数不能为空");
		}

		this.serviceMap.put(so.getName(), so);
	}

	@Override
	public ServiceObject getServiceObject(String name) {
		return this.serviceMap.get(name);
	}

}

/**
 * Zookeeper方式获取远程服务信息类。
 * 
 * ZookeeperServiceInfoDiscoverer
 */
public class ZookeeperExportServiceRegister extends DefaultServiceRegister implements ServiceRegister {

	private ZkClient client;

	private String centerRootPath = "/Rpc-framework";

	public ZookeeperExportServiceRegister() {
		String addr = PropertiesUtils.getProperties("zk.address");
		client = new ZkClient(addr);
		client.setZkSerializer(new MyZkSerializer());
	}

	@Override
	public void register(ServiceObject so, String protocolName, int port) throws Exception {
		super.register(so, protocolName, port);
		ServiceInfo soInf = new ServiceInfo();

		String host = InetAddress.getLocalHost().getHostAddress();
		String address = host + ":" + port;
		soInf.setAddress(address);
		soInf.setName(so.getInterf().getName());
		soInf.setProtocol(protocolName);
		this.exportService(soInf);

	}

	private void exportService(ServiceInfo serviceResource) {
		String serviceName = serviceResource.getName();
		String uri = JSON.toJSONString(serviceResource);
		try {
			uri = URLEncoder.encode(uri, "UTF-8");
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		}
		String servicePath = centerRootPath + "/" + serviceName + "/service";
		if (!client.exists(servicePath)) {
			client.createPersistent(servicePath, true);
		}
		String uriPath = servicePath + "/" + uri;
		if (client.exists(uriPath)) {
			client.delete(uriPath);
		}
		client.createEphemeral(uriPath);
	}
}

实现高并发 RPC 框架的要素

实现高并发 RPC 框架的要素，总结起来有三个要点：

1. 选择高性能的 I/O 模型，这里推荐使用同步多路 I/O 复用模型；
2. 调试网络参数，这里面有一些经验值的推荐。比如将 tcp_nodelay 设置为 true，也有一些参数需要在运行中来调试，比如接受缓冲区和发送缓冲区的大小，客户端连接请求缓冲队列的大小（back log）等等；
3. 序列化协议依据具体业务来选择。如果对性能要求不高可以选择 JSON，否则可以从 Thrift 和 Protobuf 中选择其一。

来源：CSDN

作者：xiao_fo

链接：https://blog.csdn.net/u010397795/article/details/104198363