dubbo的启动过程（三）--服务方暴露的配置更新

spring的finishRefresh中，有个步骤是回调监听事件。因为实现了ApplicationListener接口，因此回调onApplicationEvent方法。

onApplicationEvent

没有暴露过且没有取消暴露

public void onApplicationEvent(ContextRefreshedEvent event) {
    if (!isExported() && !isUnexported()) {
        if (logger.isInfoEnabled()) {
            logger.info("The service ready on spring started. service: " + getInterface());
        }
        export();
    }
}

public void export() {
    super.export();
    // Publish ServiceBeanExportedEvent
    publishExportEvent();
}
private void publishExportEvent() {
    ServiceBeanExportedEvent exportEvent = new ServiceBeanExportedEvent(this);
    applicationEventPublisher.publishEvent(exportEvent);
}

export

服务的暴露，在ServiceConfig中

public synchronized void export() {
    // 各类配置的更新
    checkAndUpdateSubConfigs();
    
    if (!shouldExport()) {
        return;
    }
    // 延迟暴露
    if (shouldDelay()) {
        DELAY_EXPORT_EXECUTOR.schedule(this::doExport, getDelay(), TimeUnit.MILLISECONDS);
    } else {
        // 服务暴露
        doExport();
    }
}

checkAndUpdateSubConfigs

public void checkAndUpdateSubConfigs() {
    // Use default configs defined explicitly on global configs
    // 设置registries、monitor的优先级，优先级application<module<provider
    // 除了上面两个，还有的设置configCenter、protocols
    completeCompoundConfigs();
    // Config Center should always being started first.
    // 设置配置中心，而且把CompositeConfiguration的配置设置到Application、Monitor、Module、Protocols、Registries、Providers、Consumers中
    startConfigCenter();
    // 检查provider是否存在，若是不存在，就默认一个，并调用refresh方法
    checkDefault();
    // 若是没有设置protocols，会从provider中取protocols，并设置ProtocolConfig及调用refresh方法
    checkProtocol();
    // 检查provider是否存在，若是不存在，就默认一个，并调用refresh方法。再根据SHUTDOWN_WAIT_KEY和SHUTDOWN_WAIT_SECONDS_KEY用于停机
    checkApplication();
    // if protocol is not injvm checkRegistry
    // 若是没有injvm协议，就去检查Registry
    if (!isOnlyInJvm()) {
        // 若是registries为空，就从dubbo.registry.address获取地址，并设置RegistryConfig及调用refresh方法
        // 这里会把注册中心的配置，赋值给配置中心，并调用refresh方法
        // 刷新后会调用prepareEnvironment方法，这里经过SPI的方式获取注册中心
        checkRegistry();
    }
    // 刷新ServiceConfig
    this.refresh();
    // 检查metadataReportConfig是否存在，若是不存在，就默认MetadataReportConfig，并调用refresh方法。
    checkMetadataReport();
    // 必须有interfaceName
    if (StringUtils.isEmpty(interfaceName)) {
        throw new IllegalStateException("<dubbo:service interface=\"\" /> interface not allow null!");
    }
    // 泛化
    if (ref instanceof GenericService) {
        interfaceClass = GenericService.class;
        if (StringUtils.isEmpty(generic)) {
            generic = Boolean.TRUE.toString();
        }
    } else {
        try {
            interfaceClass = Class.forName(interfaceName, true, Thread.currentThread()
                    .getContextClassLoader());
        } catch (ClassNotFoundException e) {
            throw new IllegalStateException(e.getMessage(), e);
        }
        // 检查接口和方法
        checkInterfaceAndMethods(interfaceClass, methods);
        // 检查ref是否有继承关系
        checkRef();
        generic = Boolean.FALSE.toString();
    }
    if (local != null) {
        if (Boolean.TRUE.toString().equals(local)) {
            local = interfaceName + "Local";
        }
        Class<?> localClass;
        try {
            localClass = ClassUtils.forNameWithThreadContextClassLoader(local);
        } catch (ClassNotFoundException e) {
            throw new IllegalStateException(e.getMessage(), e);
        }
        if (!interfaceClass.isAssignableFrom(localClass)) {
            throw new IllegalStateException("The local implementation class " + localClass.getName() + " not implement interface " + interfaceName);
        }
    }
    if (stub != null) {
        if (Boolean.TRUE.toString().equals(stub)) {
            stub = interfaceName + "Stub";
        }
        Class<?> stubClass;
        try {
            stubClass = ClassUtils.forNameWithThreadContextClassLoader(stub);
        } catch (ClassNotFoundException e) {
            throw new IllegalStateException(e.getMessage(), e);
        }
        if (!interfaceClass.isAssignableFrom(stubClass)) {
            throw new IllegalStateException("The stub implementation class " + stubClass.getName() + " not implement interface " + interfaceName);
        }
    }
    checkStubAndLocal(interfaceClass);
    checkMock(interfaceClass);
}

protected synchronized void doExport() {
    // 已经暴露了，就再也不暴露
    if (unexported) {
        throw new IllegalStateException("The service " + interfaceClass.getName() + " has already unexported!");
    }
    if (exported) {
        return;
    }
    exported = true;

    if (StringUtils.isEmpty(path)) {
        path = interfaceName;
    }
    doExportUrls();
}

completeCompoundConfigs

设置registries、monitor的优先级，优先级application<module<provider

private void completeCompoundConfigs() {
    if (provider != null) {
        if (application == null) {
            setApplication(provider.getApplication());
        }
        if (module == null) {
            setModule(provider.getModule());
        }
        if (registries == null) {
            setRegistries(provider.getRegistries());
        }
        if (monitor == null) {
            setMonitor(provider.getMonitor());
        }
        if (protocols == null) {
            setProtocols(provider.getProtocols());
        }
        if (configCenter == null) {
            setConfigCenter(provider.getConfigCenter());
        }
    }
    if (module != null) {
        // 为空说明上面还没设置，这里能够设置。若是不为空，说明上面设置了，就不能设置。
        if (registries == null) {
            setRegistries(module.getRegistries());
        }
        if (monitor == null) {
            setMonitor(module.getMonitor());
        }
    }
    if (application != null) {
        if (registries == null) {
            setRegistries(application.getRegistries());
        }
        if (monitor == null) {
            setMonitor(application.getMonitor());
        }
    }
}

startConfigCenter

void startConfigCenter() {
    // 为空，从饿汉单例获取
    if (configCenter == null) {
        ConfigManager.getInstance().getConfigCenter().ifPresent(cc -> this.configCenter = cc);
    }
    // 不为空，刷新并环境准备、检查
    if (this.configCenter != null) {
        // TODO there may have duplicate refresh
        this.configCenter.refresh();
        prepareEnvironment();
    }
    // 刷新ApplicationConfig、MonitorConfig、ModuleConfig、ProtocolConfig、RegistryConfig、ProviderConfig、ConsumerConfig
    ConfigManager.getInstance().refreshAll();
}

prepareEnvironment

private void prepareEnvironment() {
    // 检查address、protocol的合法性
    if (configCenter.isValid()) {
        // 已经初始化的就再也不初始化
        if (!configCenter.checkOrUpdateInited()) {
            return;
        }
        // 获取配置中心（这里就有用到SPI）
        DynamicConfiguration dynamicConfiguration = getDynamicConfiguration(configCenter.toUrl());
        // 从配置中心获取配置
        String configContent = dynamicConfiguration.getProperties(configCenter.getConfigFile(), configCenter.getGroup());

        String appGroup = application != null ? application.getName() : null;
        String appConfigContent = null;
        if (StringUtils.isNotEmpty(appGroup)) {
            appConfigContent = dynamicConfiguration.getProperties
                    (StringUtils.isNotEmpty(configCenter.getAppConfigFile()) ? configCenter.getAppConfigFile() : configCenter.getConfigFile(),
                     appGroup
                    );
        }
        try {
            // 是否最高优先级
            Environment.getInstance().setConfigCenterFirst(configCenter.isHighestPriority());
            // 把configContent的Properties格式转为map并存入externalConfigurationMap
            Environment.getInstance().updateExternalConfigurationMap(parseProperties(configContent));
            // 把appConfigContent的Properties格式转为map并存入appExternalConfigurationMap
            Environment.getInstance().updateAppExternalConfigurationMap(parseProperties(appConfigContent));
        } catch (IOException e) {
            throw new IllegalStateException("Failed to parse configurations from Config Center.", e);
        }
    }
}

refreshAll

刷新ApplicationConfig、MonitorConfig、ModuleConfig、ProtocolConfig、RegistryConfig、ProviderConfig、ConsumerConfig

public void refreshAll() {
    // refresh all configs here,
    getApplication().ifPresent(ApplicationConfig::refresh);
    getMonitor().ifPresent(MonitorConfig::refresh);
    getModule().ifPresent(ModuleConfig::refresh);

    getProtocols().values().forEach(ProtocolConfig::refresh);
    getRegistries().values().forEach(RegistryConfig::refresh);
    getProviders().values().forEach(ProviderConfig::refresh);
    getConsumers().values().forEach(ConsumerConfig::refresh);
}

checkDefault

若是没有provider，则建立一个，并refresh

private void checkDefault() {
    createProviderIfAbsent();
}

private void createProviderIfAbsent() {
    if (provider != null) {
        return;
    }
    setProvider(
            ConfigManager.getInstance()
                    .getDefaultProvider()
                    .orElseGet(() -> {
                        ProviderConfig providerConfig = new ProviderConfig();
                        providerConfig.refresh();
                        return providerConfig;
                    })
    );
}

checkProtocol

设置Protocol

private void checkProtocol() {
    // 若是protocols为空，从provider取
    if (CollectionUtils.isEmpty(protocols) && provider != null) {
        setProtocols(provider.getProtocols());
    }
    convertProtocolIdsToProtocols();
}

private void convertProtocolIdsToProtocols() {
    if (StringUtils.isEmpty(protocolIds) && CollectionUtils.isEmpty(protocols)) {
        List<String> configedProtocols = new ArrayList<>();
        configedProtocols.addAll(getSubProperties(Environment.getInstance()
                .getExternalConfigurationMap(), PROTOCOLS_SUFFIX));
        configedProtocols.addAll(getSubProperties(Environment.getInstance()
                .getAppExternalConfigurationMap(), PROTOCOLS_SUFFIX));

        protocolIds = String.join(",", configedProtocols);
    }
    // 若是仍是没有ProtocolConfig，则建立一个并refresh
    if (StringUtils.isEmpty(protocolIds)) {
        if (CollectionUtils.isEmpty(protocols)) {
            setProtocols(
                    ConfigManager.getInstance().getDefaultProtocols()
                            .filter(CollectionUtils::isNotEmpty)
                            .orElseGet(() -> {
                                ProtocolConfig protocolConfig = new ProtocolConfig();
                                protocolConfig.refresh();
                                return new ArrayList<>(Arrays.asList(protocolConfig));
                            })
            );
        }
    } else {
        // id赋值后refresh
        String[] arr = COMMA_SPLIT_PATTERN.split(protocolIds);
        List<ProtocolConfig> tmpProtocols = CollectionUtils.isNotEmpty(protocols) ? protocols : new ArrayList<>();
        Arrays.stream(arr).forEach(id -> {
            if (tmpProtocols.stream().noneMatch(prot -> prot.getId().equals(id))) {
                tmpProtocols.add(ConfigManager.getInstance().getProtocol(id).orElseGet(() -> {
                    ProtocolConfig protocolConfig = new ProtocolConfig();
                    protocolConfig.setId(id);
                    protocolConfig.refresh();
                    return protocolConfig;
                }));
            }
        });
        if (tmpProtocols.size() > arr.length) {
            throw new IllegalStateException("Too much protocols found, the protocols comply to this service are :" + protocolIds + " but got " + protocols
                    .size() + " registries!");
        }
        setProtocols(tmpProtocols);
    }
}

checkApplication

protected void checkApplication() {
    // for backward compatibility
    // 若是没有Application，则建立一个并refresh
    createApplicationIfAbsent();
    // 验证name是否为空
    if (!application.isValid()) {
        throw new IllegalStateException("No application config found or it's not a valid config! " +
                "Please add <dubbo:application name=\"...\" /> to your spring config.");
    }
    // 把name赋值给ApplicationModel的Application
    ApplicationModel.setApplication(application.getName());

    // backward compatibility
    // 用于优雅停机
    String wait = ConfigUtils.getProperty(SHUTDOWN_WAIT_KEY);
    if (wait != null && wait.trim().length() > 0) {
        System.setProperty(SHUTDOWN_WAIT_KEY, wait.trim());
    } else {
        wait = ConfigUtils.getProperty(SHUTDOWN_WAIT_SECONDS_KEY);
        if (wait != null && wait.trim().length() > 0) {
            System.setProperty(SHUTDOWN_WAIT_SECONDS_KEY, wait.trim());
        }
    }
}

checkRegistry

protected void checkRegistry() {
    //加载RegistryConfig
    loadRegistriesFromBackwardConfig();
    //加载RegistryConfig
    convertRegistryIdsToRegistries();
    // 验证address
    for (RegistryConfig registryConfig : registries) {
        if (!registryConfig.isValid()) {
            throw new IllegalStateException("No registry config found or it's not a valid config! " +
                    "The registry config is: " + registryConfig);
        }
    }

    useRegistryForConfigIfNecessary();
}
private void useRegistryForConfigIfNecessary() {
    registries.stream().filter(RegistryConfig::isZookeeperProtocol).findFirst().ifPresent(rc -> {
        // we use the loading status of DynamicConfiguration to decide whether ConfigCenter has been initiated.
        Environment.getInstance().getDynamicConfiguration().orElseGet(() -> {
            ConfigManager configManager = ConfigManager.getInstance();
            // 建立ConfigCenterConfig
            ConfigCenterConfig cc = configManager.getConfigCenter().orElse(new ConfigCenterConfig());
            // 设置参数
            if (cc.getParameters() == null) {
                cc.setParameters(new HashMap<>());
            }
            if (rc.getParameters() != null) {
                cc.getParameters().putAll(rc.getParameters());
            }
            cc.getParameters().put(org.apache.dubbo.remoting.Constants.CLIENT_KEY,rc.getClient());
            cc.setProtocol(rc.getProtocol());
            cc.setAddress(rc.getAddress());
            cc.setUsername(rc.getUsername());
            cc.setPassword(rc.getPassword());
            cc.setHighestPriority(false);
            //设置ConfigCenterConfig
            setConfigCenter(cc);
            //刷新配置
            startConfigCenter();
            return null;
        });
    });
}

配置信息都好了，后面看看怎么暴露的