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RPC基本原理以及如何用Netty来实现RPC

前言

在微服务大行其道的今天,分布式系统越来越重要,实现服务化首先就要考虑服务之间的通信问题。这里面涉及序列化、反序列化、寻址、连接等等问题。。不过,有了RPC框架,我们就无需苦恼。

一、什么是RPC?

RPC(Remote Procedure Call)— 远程过程调用,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。

值得注意是,两个或多个应用程序都分布在不同的服务器上,它们之间的调用都像是本地方法调用一样。

RPC远程过程调用

RPC框架有很多,比较知名的如阿里的Dubbo、google的gRPC、Go语言的rpcx、Apache的thrift。当然了,还有Spring Cloud,不过对于Spring Cloud来说,RPC只是它的一个功能模块。

复杂的先不讲,如果要实现一个基本功能、简单的RPC,要涉及哪些东西呢?

  • 动态代理
  • 反射
  • 序列化、反序列化
  • 网络通信
  • 编解码
  • 服务发现和注册
  • 心跳与链路检测
  • ......

下面我们一起通过代码来分析,怎么把这些技术点串到一起,实现我们自己的RPC。

二、环境准备

在开始之前,笔者先介绍一下所用到的软件环境。

SpringBoot、Netty、zookeeper、zkclient、fastjson

  • SpringBoot 项目的基础框架,方便打成JAR包,便于测试。
  • Netty 通信服务器
  • zookeeper 服务的发现与注册
  • zkclient zookeeper客户端
  • fastjson 序列化、反序列化

三、RPC生产者

1、服务接口API

整个RPC,我们分为生产者和消费者。首先它们有一个共同的服务接口API。在这里,我们搞一个操作用户信息的service接口。

public interface InfoUserService {
    List<InfoUser> insertInfoUser(InfoUser infoUser);
    InfoUser getInfoUserById(String id);
    void deleteInfoUserById(String id);
    String getNameById(String id);
    Map<String,InfoUser> getAllUser();
}
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2、服务类实现

作为生产者,它当然要有实现类,我们创建InfoUserServiceImpl实现类,并用注解把它标注为RPC的服务,然后注册到Spring的Bean容器中。在这里,我们把infoUserMap当做数据库,存储用户信息。

package com.viewscenes.netsupervisor.service.impl;

@RpcService
public class InfoUserServiceImpl implements InfoUserService {

    Logger logger = LoggerFactory.getLogger(this.getClass());
	//当做数据库,存储用户信息
    Map<String,InfoUser> infoUserMap = new HashMap<>();

    public List<InfoUser> insertInfoUser(InfoUser infoUser) {
        logger.info("新增用户信息:{}", JSONObject.toJSONString(infoUser));
        infoUserMap.put(infoUser.getId(),infoUser);
        return getInfoUserList();
    }
    public InfoUser getInfoUserById(String id) {
        InfoUser infoUser = infoUserMap.get(id);
        logger.info("查询用户ID:{}",id);
        return infoUser;
    }

    public List<InfoUser> getInfoUserList() {
        List<InfoUser> userList = new ArrayList<>();
        Iterator<Map.Entry<String, InfoUser>> iterator = infoUserMap.entrySet().iterator();
        while (iterator.hasNext()){
            Map.Entry<String, InfoUser> next = iterator.next();
            userList.add(next.getValue());
        }
        logger.info("返回用户信息记录数:{}",userList.size());
        return userList;
    }
    public void deleteInfoUserById(String id) {
        logger.info("删除用户信息:{}",JSONObject.toJSONString(infoUserMap.remove(id)));
    }
    public String getNameById(String id){
        logger.info("根据ID查询用户名称:{}",id);
        return infoUserMap.get(id).getName();
    }
    public Map<String,InfoUser> getAllUser(){
        logger.info("查询所有用户信息{}",infoUserMap.keySet().size());
        return infoUserMap;
    }
}
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元注解定义如下:

package com.viewscenes.netsupervisor.annotation;

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Component
public @interface RpcService {}
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3、请求信息和返回信息

所有的请求信息和返回信息,我们用两个JavaBean来表示。其中的重点是,返回信息要带有请求信息的ID。

package com.viewscenes.netsupervisor.entity;
public class Request {
	private String id;
	private String className;// 类名
	private String methodName;// 函数名称
	private Class<?>[] parameterTypes;// 参数类型
	private Object[] parameters;// 参数列表
	get/set ...
}
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package com.viewscenes.netsupervisor.entity;
public class Response {
	private String requestId;
	private int code;
	private String error_msg;
	private Object data;
	get/set ...
}
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4、Netty服务端

Netty作为高性能的NIO通信框架,在很多RPC框架中都有它的身影。我们也采用它当做通信服务器。说到这,我们先看个配置文件,重点有两个,zookeeper的注册地址和Netty通信服务器的地址。

TOMCAT端口
server.port=8001
#zookeeper注册地址
registry.address=192.168.245.131:2181,192.168.245.131:2182,192.168.245.131:2183
#RPC服务提供者地址
rpc.server.address=192.168.197.1:18868
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为了方便管理,我们把它也注册成Bean,同时实现ApplicationContextAware接口,把上面@RpcService注解的服务类捞出来,缓存起来,供消费者调用。同时,作为服务器,还要对客户端的链路进行心跳检测,超过60秒未读写数据,关闭此连接。

package com.viewscenes.netsupervisor.netty.server;
@Component
public class NettyServer implements ApplicationContextAware,InitializingBean{

    private static final Logger logger = LoggerFactory.getLogger(NettyServer.class);
    private static final EventLoopGroup bossGroup = new NioEventLoopGroup(1);
    private static final EventLoopGroup workerGroup = new NioEventLoopGroup(4);

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

    @Value("${rpc.server.address}")
    private String serverAddress;

    @Autowired
    ServiceRegistry registry;

    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        Map<String, Object> beans = applicationContext.getBeansWithAnnotation(RpcService.class);
        for(Object serviceBean:beans.values()){
            Class<?> clazz = serviceBean.getClass();
            Class<?>[] interfaces = clazz.getInterfaces();
            for (Class<?> inter : interfaces){
                String interfaceName = inter.getName();
                logger.info("加载服务类: {}", interfaceName);
                serviceMap.put(interfaceName, serviceBean);
            }
        }
        logger.info("已加载全部服务接口:{}", serviceMap);
    }
    public void afterPropertiesSet() throws Exception {
        start();
    }
    public void start(){
        final NettyServerHandler handler = new NettyServerHandler(serviceMap);
        new Thread(() -> {
            try {
                ServerBootstrap bootstrap = new ServerBootstrap();
                bootstrap.group(bossGroup,workerGroup).
                        channel(NioServerSocketChannel.class).
                        option(ChannelOption.SO_BACKLOG,1024).
                        childOption(ChannelOption.SO_KEEPALIVE,true).
                        childOption(ChannelOption.TCP_NODELAY,true).
                        childHandler(new ChannelInitializer<SocketChannel>() {
                            //创建NIOSocketChannel成功后,在进行初始化时,将它的ChannelHandler设置到ChannelPipeline中,用于处理网络IO事件
                            protected void initChannel(SocketChannel channel) throws Exception {
                                ChannelPipeline pipeline = channel.pipeline();
                                pipeline.addLast(new IdleStateHandler(0, 0, 60));
                                pipeline.addLast(new JSONEncoder());
                                pipeline.addLast(new JSONDecoder());
                                pipeline.addLast(handler);
                            }
                        });
                String[] array = serverAddress.split(":");
                String host = array[0];
                int port = Integer.parseInt(array[1]);
                ChannelFuture cf = bootstrap.bind(host,port).sync();
                logger.info("RPC 服务器启动.监听端口:"+port);
                registry.register(serverAddress);
                //等待服务端监听端口关闭
                cf.channel().closeFuture().sync();
            } catch (Exception e) {
                e.printStackTrace();
                bossGroup.shutdownGracefully();
                workerGroup.shutdownGracefully();
            }
        }).start();
    }
}
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上面的代码就把Netty服务器启动了,在处理器中的构造函数中,我们先把服务Bean的Map传进来,所有的处理要基于这个Map才能找到对应的实现类。在channelRead中,获取请求方法的信息,然后通过反射调用方法获取返回值。

package com.viewscenes.netsupervisor.netty.server;
@ChannelHandler.Sharable
public class NettyServerHandler extends ChannelInboundHandlerAdapter {

    private final Logger logger = LoggerFactory.getLogger(NettyServerHandler.class);
    private final Map<String, Object> serviceMap;

    public NettyServerHandler(Map<String, Object> serviceMap) {
        this.serviceMap = serviceMap;
    }
    public void channelActive(ChannelHandlerContext ctx)   {
        logger.info("客户端连接成功!"+ctx.channel().remoteAddress());
    }
    public void channelInactive(ChannelHandlerContext ctx)   {
        logger.info("客户端断开连接!{}",ctx.channel().remoteAddress());
        ctx.channel().close();
    }
    public void channelRead(ChannelHandlerContext ctx, Object msg)   {
        Request request = JSON.parseObject(msg.toString(),Request.class);

        if ("heartBeat".equals(request.getMethodName())) {
            logger.info("客户端心跳信息..."+ctx.channel().remoteAddress());
        }else{
            logger.info("RPC客户端请求接口:"+request.getClassName()+"   方法名:"+request.getMethodName());
            Response response = new Response();
            response.setRequestId(request.getId());
            try {
                Object result = this.handler(request);
                response.setData(result);
            } catch (Throwable e) {
                e.printStackTrace();
                response.setCode(1);
                response.setError_msg(e.toString());
                logger.error("RPC Server handle request error",e);
            }
            ctx.writeAndFlush(response);
        }
    }
    /**
     * 通过反射,执行本地方法
     * @param request
     * @return
     * @throws Throwable
     */
    private Object handler(Request request) throws Throwable{
        String className = request.getClassName();
        Object serviceBean = serviceMap.get(className);

        if (serviceBean!=null){
            Class<?> serviceClass = serviceBean.getClass();
            String methodName = request.getMethodName();
            Class<?>[] parameterTypes = request.getParameterTypes();
            Object[] parameters = request.getParameters();

            Method method = serviceClass.getMethod(methodName, parameterTypes);
            method.setAccessible(true);
            return method.invoke(serviceBean, getParameters(parameterTypes,parameters));
        }else{
            throw new Exception("未找到服务接口,请检查配置!:"+className+"#"+request.getMethodName());
        }
    }
    /**
     * 获取参数列表
     * @param parameterTypes
     * @param parameters
     * @return
     */
    private Object[] getParameters(Class<?>[] parameterTypes,Object[] parameters){
        if (parameters==null || parameters.length==0){
            return parameters;
        }else{
            Object[] new_parameters = new Object[parameters.length];
            for(int i=0;i<parameters.length;i++){
                new_parameters[i] = JSON.parseObject(parameters[i].toString(),parameterTypes[i]);
            }
            return new_parameters;
        }
    }
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt)throws Exception {
        if (evt instanceof IdleStateEvent){
            IdleStateEvent event = (IdleStateEvent)evt;
            if (event.state()== IdleState.ALL_IDLE){
                logger.info("客户端已超过60秒未读写数据,关闭连接.{}",ctx.channel().remoteAddress());
                ctx.channel().close();
            }
        }else{
            super.userEventTriggered(ctx,evt);
        }
    }
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)   {
        logger.info(cause.getMessage());
        ctx.close();
    }
}
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4、服务注册

我们启动了Netty通信服务器,并且把服务实现类加载到缓存,等待请求时调用。这一步,我们要进行服务注册。为了简单化处理,我们只注册通信服务器的监听地址即可。 在上面代码中,bind之后我们执行了registry.register(serverAddress); 它的作用就是,将Netty监听的IP端口注册到zookeeper。

package com.viewscenes.netsupervisor.registry;
@Component
public class ServiceRegistry {
    Logger logger = LoggerFactory.getLogger(this.getClass());
    @Value("${registry.address}")
    private String registryAddress;
    private static final String ZK_REGISTRY_PATH = "/rpc";

    public void register(String data) {
        if (data != null) {
            ZkClient client = connectServer();
            if (client != null) {
                AddRootNode(client);
                createNode(client, data);
            }
        }
    }
	//连接zookeeper
    private ZkClient connectServer() {
        ZkClient client = new ZkClient(registryAddress,20000,20000);
        return client;
    }
	//创建根目录/rpc
    private void AddRootNode(ZkClient client){
        boolean exists = client.exists(ZK_REGISTRY_PATH);
        if (!exists){
            client.createPersistent(ZK_REGISTRY_PATH);
            logger.info("创建zookeeper主节点 {}",ZK_REGISTRY_PATH);
        }
    }
	//在/rpc根目录下,创建临时顺序子节点
    private void createNode(ZkClient client, String data) {
        String path = client.create(ZK_REGISTRY_PATH + "/provider", data, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
        logger.info("创建zookeeper数据节点 ({} => {})", path, data);
    }
}
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有一点需要注意,子节点必须是临时节点。这样,生产者端停掉之后,才能通知到消费者,把此服务从服务列表中剔除。到此为止,生产者端已经完成。我们看一下它的启动日志:

加载服务类: com.viewscenes.netsupervisor.service.InfoUserService
已加载全部服务接口:{com.viewscenes.netsupervisor.service.InfoUserService=com.viewscenes.netsupervisor.service.impl.InfoUserServiceImpl@46cc127b}
Initializing ExecutorService 'applicationTaskExecutor'
Tomcat started on port(s): 8001 (http) with context path ''
Started RpcProviderApplication in 2.003 seconds (JVM running for 3.1)
RPC 服务器启动.监听端口:18868
Starting ZkClient event thread.
Socket connection established to 192.168.245.131/192.168.245.131:2183, initiating session
Session establishment complete on server 192.168.245.131/192.168.245.131:2183, sessionid = 0x367835b48970010, negotiated timeout = 4000
zookeeper state changed (SyncConnected)
创建zookeeper主节点 /rpc
创建zookeeper数据节点 (/rpc/provider0000000000 => 192.168.197.1:28868)
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四、RPC消费者

首先,我们需要把生产者端的服务接口API,即InfoUserService。以相同的目录放到消费者端。路径不同,调用会找不到的哦。

1、代理

RPC的目标其中有一条,《程序员无需额外地为这个交互作用编程。》所以,我们在调用的时候,就像调用本地方法一样。就像下面这样:

@Controller
public class IndexController {	
	@Autowired
    InfoUserService userService;
	
	@RequestMapping("getById")
    @ResponseBody
    public InfoUser getById(String id){
        logger.info("根据ID查询用户信息:{}",id);
        return userService.getInfoUserById(id);
    }
}
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那么,问题来了。消费者端并没有此接口的实现,怎么调用到的呢?这里,首先就是代理。笔者这里用的是Spring的工厂Bean机制创建的代理对象,涉及的代码较多,就不在文章中体现了,如果有不懂的同学,请想象一下,MyBatis中的Mapper接口怎么被调用的。可以参考笔者文章:Mybatis源码分析(四)mapper接口方法是怎样被调用到的

总之,在调用userService方法的时候,会调用到代理对象的invoke方法。在这里,封装请求信息,然后调用Netty的客户端方法发送消息。然后根据方法返回值类型,转成相应的对象返回。

package com.viewscenes.netsupervisor.configurer.rpc;

@Component
public class RpcFactory<T> implements InvocationHandler {

    @Autowired
    NettyClient client;

    Logger logger = LoggerFactory.getLogger(this.getClass());
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        Request request = new Request();
        request.setClassName(method.getDeclaringClass().getName());
        request.setMethodName(method.getName());
        request.setParameters(args);
        request.setParameterTypes(method.getParameterTypes());
        request.setId(IdUtil.getId());

        Object result = client.send(request);
        Class<?> returnType = method.getReturnType();

        Response response = JSON.parseObject(result.toString(), Response.class);
        if (response.getCode()==1){
            throw new Exception(response.getError_msg());
        }
        if (returnType.isPrimitive() || String.class.isAssignableFrom(returnType)){
            return response.getData();
        }else if (Collection.class.isAssignableFrom(returnType)){
            return JSONArray.parseArray(response.getData().toString(),Object.class);
        }else if(Map.class.isAssignableFrom(returnType)){
            return JSON.parseObject(response.getData().toString(),Map.class);
        }else{
            Object data = response.getData();
            return JSONObject.parseObject(data.toString(), returnType);
        }
    }
}
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2、服务发现

在生产者端,我们把服务IP端口都注册到zookeeper中,所以这里,我们要去拿到服务地址,然后通过Netty连接。重要的是,还要对根目录进行监听子节点变化,这样随着生产者的上线和下线,消费者端可以及时感知。

package com.viewscenes.netsupervisor.connection;

@Component
public class ServiceDiscovery {

    @Value("${registry.address}")
    private String registryAddress;
    @Autowired
    ConnectManage connectManage;

    // 服务地址列表
    private volatile List<String> addressList = new ArrayList<>();
    private static final String ZK_REGISTRY_PATH = "/rpc";
    private ZkClient client;

    Logger logger = LoggerFactory.getLogger(this.getClass());

    @PostConstruct
    public void init(){
        client = connectServer();
        if (client != null) {
            watchNode(client);
        }
    }
	
	//连接zookeeper
    private ZkClient connectServer() {
        ZkClient client = new ZkClient(registryAddress,30000,30000);
        return client;
    }
	//监听子节点数据变化
    private void watchNode(final ZkClient client) {
        List<String> nodeList = client.subscribeChildChanges(ZK_REGISTRY_PATH, (s, nodes) -> {
            logger.info("监听到子节点数据变化{}",JSONObject.toJSONString(nodes));
            addressList.clear();
            getNodeData(nodes);
            updateConnectedServer();
        });
        getNodeData(nodeList);
        logger.info("已发现服务列表...{}", JSONObject.toJSONString(addressList));
        updateConnectedServer();
    }
	//连接生产者端服务
    private void updateConnectedServer(){
        connectManage.updateConnectServer(addressList);
    }

    private void getNodeData(List<String> nodes){
        logger.info("/rpc子节点数据为:{}", JSONObject.toJSONString(nodes));
        for(String node:nodes){
            String address = client.readData(ZK_REGISTRY_PATH+"/"+node);
            addressList.add(address);
        }
    }
}
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其中,connectManage.updateConnectServer(addressList);就是根据服务地址,去连接生产者端的Netty服务。然后创建一个Channel列表,在发送消息的时候,从中选取一个Channel和生产者端进行通信。

3、Netty客户端

Netty客户端有两个方法比较重要,一个是根据IP端口连接服务器,返回Channel,加入到连接管理器;一个是用Channel发送请求数据。同时,作为客户端,空闲的时候还要往服务端发送心跳信息。

package com.viewscenes.netsupervisor.netty.client;

@Component
public class NettyClient {
    Logger logger = LoggerFactory.getLogger(this.getClass());
    private EventLoopGroup group = new NioEventLoopGroup(1);
    private Bootstrap bootstrap = new Bootstrap();
    @Autowired
    NettyClientHandler clientHandler;
    @Autowired
    ConnectManage connectManage;
   
    public Object send(Request request) throws InterruptedException{

        Channel channel = connectManage.chooseChannel();
        if (channel!=null && channel.isActive()) {
            SynchronousQueue<Object> queue = clientHandler.sendRequest(request,channel);
            Object result = queue.take();
            return JSONArray.toJSONString(result);
        }else{
            Response res = new Response();
            res.setCode(1);
            res.setError_msg("未正确连接到服务器.请检查相关配置信息!");
            return JSONArray.toJSONString(res);
        }
    }
    public Channel doConnect(SocketAddress address) throws InterruptedException {
        ChannelFuture future = bootstrap.connect(address);
        Channel channel = future.sync().channel();
        return channel;
    }
	....其他方法略
}
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我们必须重点关注send方法,它是在代理对象invoke方法调用到的。首先从连接器中轮询选择一个Channel,然后发送数据。但是,Netty是异步操作,我们还要转为同步,就是说要等待生产者端返回数据才往下执行。笔者在这里用的是同步队列SynchronousQueue,它的take方法会阻塞在这里,直到里面有数据可读。然后在处理器中,拿到返回信息写到队列中,take方法返回。

package com.viewscenes.netsupervisor.netty.client;
@Component
@ChannelHandler.Sharable
public class NettyClientHandler extends ChannelInboundHandlerAdapter {

    @Autowired
    NettyClient client;
    @Autowired
    ConnectManage connectManage;
    Logger logger = LoggerFactory.getLogger(this.getClass());
    private ConcurrentHashMap<String,SynchronousQueue<Object>> queueMap = new ConcurrentHashMap<>();

    public void channelActive(ChannelHandlerContext ctx)   {
        logger.info("已连接到RPC服务器.{}",ctx.channel().remoteAddress());
    }
    public void channelInactive(ChannelHandlerContext ctx)   {
        InetSocketAddress address =(InetSocketAddress) ctx.channel().remoteAddress();
        logger.info("与RPC服务器断开连接."+address);
        ctx.channel().close();
        connectManage.removeChannel(ctx.channel());
    }
    public void channelRead(ChannelHandlerContext ctx, Object msg)throws Exception {
        Response response = JSON.parseObject(msg.toString(),Response.class);
        String requestId = response.getRequestId();
        SynchronousQueue<Object> queue = queueMap.get(requestId);
        queue.put(response);
        queueMap.remove(requestId);
    }
    public SynchronousQueue<Object> sendRequest(Request request,Channel channel) {
        SynchronousQueue<Object> queue = new SynchronousQueue<>();
        queueMap.put(request.getId(), queue);
        channel.writeAndFlush(request);
        return queue;
    }
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt)throws Exception {
        logger.info("已超过30秒未与RPC服务器进行读写操作!将发送心跳消息...");
        if (evt instanceof IdleStateEvent){
            IdleStateEvent event = (IdleStateEvent)evt;
            if (event.state()== IdleState.ALL_IDLE){
                Request request = new Request();
                request.setMethodName("heartBeat");
                ctx.channel().writeAndFlush(request);
            }
        }else{
            super.userEventTriggered(ctx,evt);
        }
    }
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause){
        logger.info("RPC通信服务器发生异常.{}",cause);
        ctx.channel().close();
    }
}
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至此,消费者端也基本完成。同样的,我们先看一下启动日志:

Waiting for keeper state SyncConnected
Opening socket connection to server 192.168.139.129/192.168.139.129:2181. Will not attempt to authenticate using SASL (unknown error)
Socket connection established to 192.168.139.129/192.168.139.129:2181, initiating session
Session establishment complete on server 192.168.139.129/192.168.139.129:2181, sessionid = 0x100000273ba002c, negotiated timeout = 20000
zookeeper state changed (SyncConnected)
/rpc子节点数据为:["provider0000000015"]
已发现服务列表...["192.168.100.74:18868"]
加入Channel到连接管理器./192.168.100.74:18868
已连接到RPC服务器./192.168.100.74:18868
Initializing ExecutorService 'applicationTaskExecutor'
Tomcat started on port(s): 7002 (http) with context path ''
Started RpcConsumerApplication in 4.218 seconds (JVM running for 5.569)
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五、测试

我们以Controller里面的两个方法为例,先开启100个线程调用insertInfoUser方法,然后开启1000个线程调用查询方法getAllUser。

public class IndexController {

    Logger logger = LoggerFactory.getLogger(this.getClass());
    @Autowired
    InfoUserService userService;

    @RequestMapping("insert")
    @ResponseBody
    public List<InfoUser> getUserList() throws InterruptedException {
        long start = System.currentTimeMillis();
        int thread_count = 100;
        CountDownLatch countDownLatch = new CountDownLatch(thread_count);
        for (int i=0;i<thread_count;i++){
            new Thread(() -> {
                InfoUser infoUser = new InfoUser(IdUtil.getId(),"Jeen","BeiJing");
                List<InfoUser> users = userService.insertInfoUser(infoUser);
                logger.info("返回用户信息记录:{}", JSON.toJSONString(users));
                countDownLatch.countDown();
            }).start();
        }
        countDownLatch.await();
        long end = System.currentTimeMillis();
        logger.info("线程数:{},执行时间:{}",thread_count,(end-start));
        return null;
    }
	@RequestMapping("getAllUser")
    @ResponseBody
    public Map<String,InfoUser> getAllUser() throws InterruptedException {

        long start = System.currentTimeMillis();
        int thread_count = 1000;
        CountDownLatch countDownLatch = new CountDownLatch(thread_count);
        for (int i=0;i<thread_count;i++){
            new Thread(() -> {
                Map<String, InfoUser> allUser = userService.getAllUser();
                logger.info("查询所有用户信息:{}",JSONObject.toJSONString(allUser));
                countDownLatch.countDown();
            }).start();
        }
        countDownLatch.await();
        long end = System.currentTimeMillis();
        logger.info("线程数:{},执行时间:{}",thread_count,(end-start));

        return null;
    }
}
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结果如下:

新增用户信息
查询用户信息.png

六、总结

本文简单介绍了RPC的整个流程,如果你正在学习RPC的相关知识,可以根据文中的例子,自己实现一遍。相信写完之后,你会对RPC会有更深一些的认识。

生产者端流程:

  • 加载服务,并缓存
  • 启动通讯服务器(Netty)
  • 服务注册(把通讯地址放入zookeeper,也可以把加载到的服务也放进去)
  • 反射,本地调用

消费者端流程:

  • 代理服务接口
  • 服务发现(连接zookeeper,拿到服务地址列表)
  • 远程调用(轮询生产者服务列表,发送消息)

限于篇幅,本文代码并不完整,如有需要,访问:https://github.com/taoxun/simple_rpc 或者添加笔者微信公众号:<清幽之地的博客>),获取完整项目。

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