sofa-rpc 服务端源码流程走读

sofa-rpc是阿里开源的一款高性能的rpc框架，这篇文章主要是对sofa-rpc provider启动服务流程的一个代码走读，下面是我简单绘制的一个基本的关系流程图

下面我们根据sofa-rpc代码，对流程进行一个跟踪与走读。我们以BoltServer的为例

    public static void main(String[] args) {
        ApplicationConfig application = new ApplicationConfig().setAppName("test-server");

        ServerConfig serverConfig = new ServerConfig()
            .setPort(22000)
            .setDaemon(false);

        ProviderConfig<HelloService> providerConfig = new ProviderConfig<HelloService>()
            .setInterfaceId(HelloService.class.getName())
            .setApplication(application)
            .setRef(new HelloServiceImpl())
            .setServer(serverConfig)
            .setRegister(false);

        ProviderConfig<EchoService> providerConfig2 = new ProviderConfig<EchoService>()
            .setInterfaceId(EchoService.class.getName())
            .setApplication(application)
            .setRef(new EchoServiceImpl())
            .setServer(serverConfig)
            .setRegister(false);

        providerConfig.export();
        providerConfig2.export();

        LOGGER.warn("started at pid {}", RpcRuntimeContext.PID);
    }

可以看到sofa-rpc通过ProviderConfig类对服务提供方Provider进行了配置信息的初始化，同时也提供了export做为服务启动的入口。

    public synchronized void export() {
        if (providerBootstrap == null) {
            providerBootstrap = Bootstraps.from(this);
        }
        providerBootstrap.export();
    }

根据ProviderConfig中setBootstrap()配置的Bootstrap类型，我们通过Bootstaps.from(this)可以获取到不同的Bootstrap引导服务，分别是DefaultProviderBootstrap与 DubboProviderBootstrap 

    /**
     * 发布一个服务
     *
     * @param providerConfig 服务发布者配置
     * @param <T>            接口类型
     * @return 发布启动类
     */
    public static <T> ProviderBootstrap<T> from(ProviderConfig<T> providerConfig) {
        String bootstrap = providerConfig.getBootstrap();
        if (StringUtils.isEmpty(bootstrap)) {
            // Use default provider bootstrap 无的话就返回默认DefaultProviderBootstrap
            bootstrap = RpcConfigs.getStringValue(RpcOptions.DEFAULT_PROVIDER_BOOTSTRAP);
            providerConfig.setBootstrap(bootstrap);
        }
        ProviderBootstrap providerBootstrap = ExtensionLoaderFactory.getExtensionLoader(ProviderBootstrap.class)
            .getExtension(bootstrap, new Class[] { ProviderConfig.class }, new Object[] { providerConfig });
        return (ProviderBootstrap<T>) providerBootstrap;
    }

DefaultProviderBootstrap与 DubboProviderBootstrap 都继承自ProviderBootstrap。

DefaultProviderBootstrap又被BoltProviderBootstrap、Http2ClearTextProviderBootstrap、RestProviderBootstrap三个类所继承，这其实对应了sofa-rpc中的三种server服务方式。

我们看下DefaultProviderBootstrap服务启动源码

    @Override
    public void export() {
        if (providerConfig.getDelay() > 0) { // 延迟加载,单位毫秒
            Thread thread = factory.newThread(new Runnable() {
                @Override
                public void run() {
                    try {
                        Thread.sleep(providerConfig.getDelay());
                    } catch (Throwable ignore) { // NOPMD
                    }
                    doExport();
                }
            });
            thread.start();
        } else {
            doExport();
        }
    }

    private void doExport() {
        if (exported) {
            return;
        }

        // 检查参数
        checkParameters();

        String appName = providerConfig.getAppName();

        //key  is the protocol of server,for concurrent safe
        Map<String, Boolean> hasExportedInCurrent = new ConcurrentHashMap<String, Boolean>();
        // 将处理器注册到server
        List<ServerConfig> serverConfigs = providerConfig.getServer();
        for (ServerConfig serverConfig : serverConfigs) {
            String protocol = serverConfig.getProtocol();

            String key = providerConfig.buildKey() + ":" + protocol;

            if (LOGGER.isInfoEnabled(appName)) {
                LOGGER.infoWithApp(appName, "Export provider config : {} with bean id {}", key, providerConfig.getId());
            }

            // 注意同一interface，同一uniqleId，不同server情况
            AtomicInteger cnt = EXPORTED_KEYS.get(key); // 计数器
            if (cnt == null) { // 没有发布过
                cnt = CommonUtils.putToConcurrentMap(EXPORTED_KEYS, key, new AtomicInteger(0));
            }
            int c = cnt.incrementAndGet();
            hasExportedInCurrent.put(serverConfig.getProtocol(), true);
            int maxProxyCount = providerConfig.getRepeatedExportLimit();
            if (maxProxyCount > 0) {
                if (c > maxProxyCount) {
                    decrementCounter(hasExportedInCurrent);
                    // 超过最大数量，直接抛出异常
                    throw new SofaRpcRuntimeException("Duplicate provider config with key " + key
                        + " has been exported more than " + maxProxyCount + " times!"
                        + " Maybe it's wrong config, please check it."
                        + " Ignore this if you did that on purpose!");
                } else if (c > 1) {
                    if (LOGGER.isInfoEnabled(appName)) {
                        LOGGER.infoWithApp(appName, "Duplicate provider config with key {} has been exported!"
                            + " Maybe it's wrong config, please check it."
                            + " Ignore this if you did that on purpose!", key);
                    }
                }
            }

        }

        try {
            // 构造请求调用器
            providerProxyInvoker = new ProviderProxyInvoker(providerConfig);
            // 初始化注册中心
            if (providerConfig.isRegister()) {
                List<RegistryConfig> registryConfigs = providerConfig.getRegistry();
                if (CommonUtils.isNotEmpty(registryConfigs)) {
                    for (RegistryConfig registryConfig : registryConfigs) {
                        RegistryFactory.getRegistry(registryConfig); // 提前初始化Registry
                    }
                }
            }
            // 将处理器注册到server
            for (ServerConfig serverConfig : serverConfigs) {
                try {
                    //构建Server
                    Server server = serverConfig.buildIfAbsent();
                    // 注册序列化接口
                    server.registerProcessor(providerConfig, providerProxyInvoker);
                    if (serverConfig.isAutoStart()) {
                        //启动服务
                        server.start();
                    }

                } catch (SofaRpcRuntimeException e) {
                    throw e;
                } catch (Exception e) {
                    LOGGER.errorWithApp(appName, "Catch exception when register processor to server: "
                        + serverConfig.getId(), e);
                }
            }

            // 注册到注册中心
            providerConfig.setConfigListener(new ProviderAttributeListener());
            register();
        } catch (Exception e) {
            decrementCounter(hasExportedInCurrent);

            if (e instanceof SofaRpcRuntimeException) {
                throw (SofaRpcRuntimeException) e;
            } else {
                throw new SofaRpcRuntimeException("Build provider proxy error!", e);
            }
        }

        // 记录一些缓存数据
        RpcRuntimeContext.cacheProviderConfig(this);
        exported = true;
    }

代码中通过serverConfig.buildIfAbsent()构建Server服务对象，而在buildIfAbsent()函数中我们可以看到，sever是通过SeverFactory工厂获取到的，在SeverFactory的getSever()中根据SeverConfig的配置获取Sever的具体实例，并执行Init()进行初始化。

    /**
     * 启动服务
     *
     * @return the server
     */
    public synchronized Server buildIfAbsent() {
        if (server != null) {
            return server;
        }
        // 提前检查协议+序列化方式
        // ConfigValueHelper.check(ProtocolType.valueOf(getProtocol()),
        //                SerializationType.valueOf(getSerialization()));
        
        //在sever工厂中拿到sever实例
        server = ServerFactory.getServer(this);
        return server;
    }

    /**
     * 初始化Server实例
     *
     * @param serverConfig 服务端配置
     * @return Server
     */
    public synchronized static Server getServer(ServerConfig serverConfig) {
        try {
            Server server = SERVER_MAP.get(Integer.toString(serverConfig.getPort()));
            if (server == null) {
                // 算下网卡和端口
                resolveServerConfig(serverConfig);

                ExtensionClass<Server> ext = ExtensionLoaderFactory.getExtensionLoader(Server.class)
                    .getExtensionClass(serverConfig.getProtocol());
                if (ext == null) {
                    throw ExceptionUtils.buildRuntime("server.protocol", serverConfig.getProtocol(),
                        "Unsupported protocol of server!");
                }
                server = ext.getExtInstance();
                //服务初始化
                server.init(serverConfig);
                SERVER_MAP.put(serverConfig.getPort() + "", server);
            }
            return server;
        } catch (SofaRpcRuntimeException e) {
            throw e;
        } catch (Throwable e) {
            throw new SofaRpcRuntimeException(e.getMessage(), e);
        }
    }

sofa-rpc提供了三种server类型 BoltServer，RestServer与AbstractHttpServer

BoltServer中通讯底层通过RemotingServer实现的，RemotingServer是基于阿里sofa-bolt通信框架开发的。

    /**
     * Bolt服务端
     */
    protected RemotingServer       remotingServer;

   @Override
    public void start() {
        if (started) {
            return;
        }
        synchronized (this) {
            if (started) {
                return;
            }
            // 生成阿里基于netty的bolt服务Server对象 
            remotingServer = initRemotingServer();
            try {
                if (remotingServer.start(serverConfig.getBoundHost())) {
                    if (LOGGER.isInfoEnabled()) {
                        LOGGER.info("Bolt server has been bind to {}:{}", serverConfig.getBoundHost(),
                            serverConfig.getPort());
                    }
                } else {
                    throw new SofaRpcRuntimeException("Failed to start bolt server, see more detail from bolt log.");
                }
                started = true;

                if (EventBus.isEnable(ServerStartedEvent.class)) {
                    EventBus.post(new ServerStartedEvent(serverConfig, bizThreadPool));
                }

            } catch (SofaRpcRuntimeException e) {
                throw e;
            } catch (Exception e) {
                throw new SofaRpcRuntimeException("Failed to start bolt server!", e);
            }
        }
    }

AbstractHttpServer 提供http服务，底层通信通过ServerTransport类实现的

    /**
     * 服务端通讯层
     */
    private ServerTransport         serverTransport;

    @Override
    public void init(ServerConfig serverConfig) {
        this.serverConfig = serverConfig;
        this.serverTransportConfig = convertConfig(serverConfig);
        // 启动线程池
        this.bizThreadPool = initThreadPool(serverConfig);
        // 服务端处理器
        this.serverHandler = new HttpServerHandler();

        // set default transport config
        this.serverTransportConfig.setContainer(container);
        this.serverTransportConfig.setServerHandler(serverHandler);
    }

    @Override
    public void start() {
        if (started) {
            return;
        }
        synchronized (this) {
            if (started) {
                return;
            }
            try {
                // 启动线程池
                this.bizThreadPool = initThreadPool(serverConfig);
                this.serverHandler.setBizThreadPool(bizThreadPool);
                //实例化服务，具体代码见
                serverTransport = ServerTransportFactory.getServerTransport(serverTransportConfig);
                started = serverTransport.start();

                if (started) {
                    if (EventBus.isEnable(ServerStartedEvent.class)) {
                        EventBus.post(new ServerStartedEvent(serverConfig, bizThreadPool));
                    }
                }
            } catch (SofaRpcRuntimeException e) {
                throw e;
            } catch (Exception e) {
                throw new SofaRpcRuntimeException("Failed to start HTTP/2 server!", e);
            }
        }
    }

ServerTransport是个抽象类，具体实现为transport包下AbstractHttp2ServerTransport

    /**
     * 构造函数
     *
     * @param transportConfig 服务端配置
     */
    protected AbstractHttp2ServerTransport(ServerTransportConfig transportConfig) {
        super(transportConfig);
    }

 @Override
    public boolean start() {
        if (serverBootstrap != null) {
            return true;
        }
        synchronized (this) {
            if (serverBootstrap != null) {
                return true;
            }
            boolean flag = false;
            SslContext sslCtx = SslContextBuilder.build();

            // Configure the server.
            EventLoopGroup bossGroup = NettyHelper.getServerBossEventLoopGroup(transportConfig);

            //可以看到然是基于Netty
            HttpServerHandler httpServerHandler = (HttpServerHandler) transportConfig.getServerHandler();
            bizGroup = NettyHelper.getServerBizEventLoopGroup(transportConfig, httpServerHandler.getBizThreadPool());

            serverBootstrap = new ServerBootstrap();

            serverBootstrap.group(bossGroup, bizGroup)
                .channel(transportConfig.isUseEpoll() ? EpollServerSocketChannel.class : NioServerSocketChannel.class)
                .option(ChannelOption.SO_BACKLOG, transportConfig.getBacklog())
                .option(ChannelOption.SO_REUSEADDR, transportConfig.isReuseAddr())
                .option(ChannelOption.RCVBUF_ALLOCATOR, NettyHelper.getRecvByteBufAllocator())
                .option(ChannelOption.ALLOCATOR, NettyHelper.getByteBufAllocator())
                .childOption(ChannelOption.SO_KEEPALIVE, transportConfig.isKeepAlive())
                .childOption(ChannelOption.TCP_NODELAY, transportConfig.isTcpNoDelay())
                .childOption(ChannelOption.SO_RCVBUF, 8192 * 128)
                .childOption(ChannelOption.SO_SNDBUF, 8192 * 128)
                .handler(new LoggingHandler(LogLevel.DEBUG))
                .childOption(ChannelOption.ALLOCATOR, NettyHelper.getByteBufAllocator())
                .childOption(ChannelOption.WRITE_BUFFER_WATER_MARK, new WriteBufferWaterMark(
                    transportConfig.getBufferMin(), transportConfig.getBufferMax()))
                .childHandler(new Http2ServerChannelInitializer(bizGroup, sslCtx,
                    httpServerHandler, transportConfig.getPayload()));

            // 绑定到全部网卡 或者 指定网卡
            ChannelFuture future = serverBootstrap.bind(
                new InetSocketAddress(transportConfig.getHost(), transportConfig.getPort()));
            ChannelFuture channelFuture = future.addListener(new ChannelFutureListener() {
                @Override
                public void operationComplete(ChannelFuture future) throws Exception {
                    if (future.isSuccess()) {
                        if (LOGGER.isInfoEnabled()) {
                            LOGGER.info("HTTP/2 Server bind to {}:{} success!",
                                transportConfig.getHost(), transportConfig.getPort());
                        }
                    } else {
                        LOGGER.error("HTTP/2 Server bind to {}:{} failed!",
                            transportConfig.getHost(), transportConfig.getPort());
                        stop();
                    }
                }
            });

            try {
                channelFuture.await();
                if (channelFuture.isSuccess()) {
                    flag = Boolean.TRUE;
                } else {
                    throw new SofaRpcRuntimeException("Server start fail!", future.cause());
                }
            } catch (InterruptedException e) {
                LOGGER.error(e.getMessage(), e);
            }
            return flag;
        }
    }

RestServer 提供Rest服务，底层通信实现具体可见SofaNettyJaxrsServer。

    /**
     * Rest服务端
     */
    protected SofaNettyJaxrsServer httpServer;

    @Override
    public void init(ServerConfig serverConfig) {
        this.serverConfig = serverConfig;
        httpServer = buildServer();
    }

SofaNettyJaxrsServer中服务启动的具体代码

 @Override
    public void start() {
        // CHANGE: 增加线程名字
        boolean daemon = serverConfig.isDaemon();
        boolean isEpoll = serverConfig.isEpoll();
        NamedThreadFactory ioFactory = new NamedThreadFactory("SEV-REST-IO-" + port, daemon);
        NamedThreadFactory bizFactory = new NamedThreadFactory("SEV-REST-BIZ-" + port, daemon);
        eventLoopGroup = isEpoll ? new EpollEventLoopGroup(ioWorkerCount, ioFactory)
            : new NioEventLoopGroup(ioWorkerCount, ioFactory);
        eventExecutor = isEpoll ? new EpollEventLoopGroup(executorThreadCount, bizFactory)
            : new NioEventLoopGroup(executorThreadCount, bizFactory);
        // Configure the server.
        bootstrap = new ServerBootstrap()
            .group(eventLoopGroup)
            .channel(isEpoll ? EpollServerSocketChannel.class : NioServerSocketChannel.class)
            .childHandler(createChannelInitializer())
            .option(ChannelOption.SO_BACKLOG, backlog)
            .childOption(ChannelOption.SO_KEEPALIVE, serverConfig.isKeepAlive()); // CHANGE: setKeepAlive

        for (Map.Entry<ChannelOption, Object> entry : channelOptions.entrySet()) {
            bootstrap.option(entry.getKey(), entry.getValue());
        }

        for (Map.Entry<ChannelOption, Object> entry : childChannelOptions.entrySet()) {
            bootstrap.childOption(entry.getKey(), entry.getValue());
        }

        final InetSocketAddress socketAddress;
        if (null == hostname || hostname.isEmpty()) {
            socketAddress = new InetSocketAddress(port);
        } else {
            socketAddress = new InetSocketAddress(hostname, port);
        }

        bootstrap.bind(socketAddress).syncUninterruptibly();
    }

 OK，以上就是sofa-rpc服务端启动的一个基本的流程，这里关注的只是简单的服务启动流程，没有深入代码功能进行分析，在此基础上，我们可以进一步探究代码的具体实现。

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