Nacos深入浅出（九）

然而Nacos的发布操作并不是上面我们想的那样通过代理去实现，通过下面的代码我们分析下：

public class NacosConfigurationPropertiesBindingPostProcessor implements BeanPostProcessor, ApplicationContextAware {

    /**
     * The name of {@link NacosConfigurationPropertiesBindingPostProcessor} Bean
     */
    public static final String BEAN_NAME = "nacosConfigurationPropertiesBindingPostProcessor";

    private Properties globalNacosProperties;

    private NacosServiceFactory nacosServiceFactory;

    private Environment environment;

    private ApplicationEventPublisher applicationEventPublisher;

    private ConfigurableApplicationContext applicationContext;
    // 类初始化之前，进行绑定监听的操作
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {

        NacosConfigurationProperties nacosConfigurationProperties = findAnnotation(bean.getClass(), NacosConfigurationProperties.class);

        if (nacosConfigurationProperties != null) {
            bind(bean, beanName, nacosConfigurationProperties);
        }

        return bean;
    }

    private void bind(Object bean, String beanName, NacosConfigurationProperties nacosConfigurationProperties) {

        NacosConfigurationPropertiesBinder binder = new NacosConfigurationPropertiesBinder(applicationContext);

        binder.bind(bean, beanName, nacosConfigurationProperties);

    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        return bean;
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = (ConfigurableApplicationContext) applicationContext;
    }
}

下面进行绑定监听操作！

protected void bind(final Object bean, final String beanName, final NacosConfigurationProperties properties) {

        Assert.notNull(bean, "Bean must not be null!");

        Assert.notNull(properties, "NacosConfigurationProperties must not be null!");

        final String dataId = properties.dataId();

        final String groupId = properties.groupId();

        final ConfigService configService = configServiceBeanBuilder.build(properties.properties());
        // 这个就是注解里面的autoRefresh的属性是否自动刷新的值，ture的话就会触发下面的操作
        if (properties.autoRefreshed()) { // Add a Listener if auto-refreshed

            try {
                configService.addListener(dataId, groupId, new AbstractListener() {
                    @Override
                    public void receiveConfigInfo(String config) {
                        doBind(bean, beanName, dataId, groupId, properties, config, configService);
                    }
                });
            } catch (NacosException e) {
                if (logger.isErrorEnabled()) {
                    logger.error(e.getMessage(), e);
                }
            }
        }

        String content = getContent(configService, dataId, groupId);

        if (hasText(content)) {
            doBind(bean, beanName, dataId, groupId, properties, content, configService);
        }
    }

 @Override
    public void addListener(String dataId, String group, Listener listener) throws NacosException {
        Listener listenerAdapter = new DelegatingEventPublishingListener(configService, dataId, group, applicationEventPublisher, executor, listener);
        configService.addListener(dataId, group, listenerAdapter);
        publishEvent(new NacosConfigListenerRegisteredEvent(configService, dataId, group, listener, true));
    }

public class NacosConfigService implements ConfigService {
    public static final Logger log = LogUtils.logger(NacosConfigService.class);
    public final long POST_TIMEOUT = 3000L;
    private ServerHttpAgent agent;
    private ClientWorker worker;
    private String namespace;
    private String encode;
    private ConfigFilterChainManager configFilterChainManager = new ConfigFilterChainManager();

    public NacosConfigService(Properties properties) throws NacosException {
        String encodeTmp = properties.getProperty("encode");
        if (StringUtils.isBlank(encodeTmp)) {
            this.encode = "UTF-8";
        } else {
            this.encode = encodeTmp.trim();
        }

        String namespaceTmp = properties.getProperty("namespace");
        if (StringUtils.isBlank(namespaceTmp)) {
            this.namespace = TenantUtil.getUserTenant();
            properties.put("namespace", this.namespace);
        } else {
            this.namespace = namespaceTmp;
            properties.put("namespace", this.namespace);
        }

        this.agent = new ServerHttpAgent(properties);
        this.agent.start();
        this.worker = new ClientWorker(this.agent, this.configFilterChainManager);
    }

    public String getConfig(String dataId, String group, long timeoutMs) throws NacosException {
        return this.getConfigInner(this.namespace, dataId, group, timeoutMs);
    }

    public void addListener(String dataId, String group, Listener listener) throws NacosException {
        this.worker.addTenantListeners(dataId, group, Arrays.asList(listener));
    }

ClientWorker.java

 public void addTenantListeners(String dataId, String group, List<? extends Listener> listeners) {
        group = null2defaultGroup(group);
        String tenant = agent.getTenant();
        CacheData cache = addCacheDataIfAbsent(dataId, group, tenant);
        for (Listener listener : listeners) {
            cache.addListener(listener);
        }
    }

DEBUG就能看出来初始化的时候，client把每个config封装成一个cache，每个cache再增加监听listener;

CacheData.java

 public void addListener(Listener listener) {
        if (null == listener) {
            throw new IllegalArgumentException("listener is null");
        }
        ManagerListenerWrap wrap = new ManagerListenerWrap(listener);
        if (listeners.addIfAbsent(wrap)) {
            LOGGER.info("[{}] [add-listener] ok, tenant={}, dataId={}, group={}, cnt={}", name, tenant, dataId, group,
                listeners.size());
        }
    }

 DelegatingEventPublishingListener(ConfigService configService, String dataId, String groupId,
                                      ApplicationEventPublisher applicationEventPublisher,
                                      Executor executor, Listener delegate) {
        this.configService = configService;
        this.dataId = dataId;
        this.groupId = groupId;
        this.applicationEventPublisher = applicationEventPublisher;
        this.executor = executor;
        this.delegate = delegate;
    }

    private void doBind(Object bean, String beanName, String dataId, String groupId,
                        NacosConfigurationProperties properties, String content, ConfigService configService) {
        PropertyValues propertyValues = resolvePropertyValues(bean, content);
        doBind(bean, properties, propertyValues);
        publishBoundEvent(bean, beanName, dataId, groupId, properties, content, configService);
        publishMetadataEvent(bean, beanName, dataId, groupId, properties);
    }

    private void publishMetadataEvent(Object bean, String beanName, String dataId, String groupId,
                                      NacosConfigurationProperties properties) {

        NacosProperties nacosProperties = properties.properties();

        NacosConfigMetadataEvent metadataEvent = new NacosConfigMetadataEvent(properties);

        // Nacos Metadata
        metadataEvent.setDataId(dataId);
        metadataEvent.setGroupId(groupId);
        Properties resolvedNacosProperties = configServiceBeanBuilder.resolveProperties(nacosProperties);
        Map<String, Object> nacosPropertiesAttributes = getAnnotationAttributes(nacosProperties);
        metadataEvent.setNacosPropertiesAttributes(nacosPropertiesAttributes);
        metadataEvent.setNacosProperties(resolvedNacosProperties);

        // Bean Metadata
        Class<?> beanClass = bean.getClass();
        metadataEvent.setBeanName(beanName);
        metadataEvent.setBean(bean);
        metadataEvent.setBeanType(beanClass);
        metadataEvent.setAnnotatedElement(beanClass);

        // Publish event
        applicationEventPublisher.publishEvent(metadataEvent);
    }

这样就自动发布了事件，然后我们的监听就收到了事件，然后触发相应的操作；下面我们结合Nacos一起debug下，看下效果！

ClientWorker.java

  /**
     * groupKey -> cacheData
     */
    AtomicReference<Map<String, CacheData>> cacheMap = new AtomicReference<Map<String, CacheData>>(
        new HashMap<String, CacheData>());

public ClientWorker(final HttpAgent agent, final ConfigFilterChainManager configFilterChainManager) {
        this.agent = agent;
        this.configFilterChainManager = configFilterChainManager;

        executor = Executors.newScheduledThreadPool(1, new ThreadFactory() {
            @Override
            public Thread newThread(Runnable r) {
                Thread t = new Thread(r);
                t.setName("com.alibaba.nacos.client.Worker." + agent.getName());
                t.setDaemon(true);
                return t;
            }
        });

        executorService = Executors.newCachedThreadPool(new ThreadFactory() {
            @Override
            public Thread newThread(Runnable r) {
                Thread t = new Thread(r);
                t.setName("com.alibaba.nacos.client.Worker.longPolling" + agent.getName());
                t.setDaemon(true);
                return t;
            }
        });

        executor.scheduleWithFixedDelay(new Runnable() {
            public void run() {
                try {
                    checkConfigInfo();
                } catch (Throwable e) {
                    LOGGER.error("[" + agent.getName() + "] [sub-check] rotate check error", e);
                }
            }
        }, 1L, 10L, TimeUnit.MILLISECONDS);
    }

public void checkConfigInfo() {
        // 分任务
        int listenerSize = cacheMap.get().size();
        // 向上取整为批数
        int longingTaskCount = (int)Math.ceil(listenerSize / ParamUtil.getPerTaskConfigSize());
        if (longingTaskCount > currentLongingTaskCount) {
            for (int i = (int)currentLongingTaskCount; i < longingTaskCount; i++) {
                // 要判断任务是否在执行 这块需要好好想想。 任务列表现在是无序的。变化过程可能有问题
                executorService.execute(new LongPollingRunnable(i));
            }
            currentLongingTaskCount = longingTaskCount;
        }
    }

线程任务！

class LongPollingRunnable implements Runnable {
        private int taskId;

        public LongPollingRunnable(int taskId) {
            this.taskId = taskId;
        }

        public void run() {
            try {
                List<CacheData> cacheDatas = new ArrayList<CacheData>();
                // check failover config
                for (CacheData cacheData : cacheMap.get().values()) {
                    if (cacheData.getTaskId() == taskId) {
                        cacheDatas.add(cacheData);
                        try {
                            checkLocalConfig(cacheData);
                            if (cacheData.isUseLocalConfigInfo()) {
                                cacheData.checkListenerMd5();
                            }
                        } catch (Exception e) {
                            LOGGER.error("get local config info error", e);
                        }
                    }
                }

                List<String> inInitializingCacheList = new ArrayList<String>();
                // check server config
                List<String> changedGroupKeys = checkUpdateDataIds(cacheDatas, inInitializingCacheList);

                for (String groupKey : changedGroupKeys) {
                    String[] key = GroupKey.parseKey(groupKey);
                    String dataId = key[0];
                    String group = key[1];
                    String tenant = null;
                    if (key.length == 3) {
                        tenant = key[2];
                    }
                    try {
                        String content = getServerConfig(dataId, group, tenant, 3000L);
                        CacheData cache = cacheMap.get().get(GroupKey.getKeyTenant(dataId, group, tenant));
                        cache.setContent(content);
                        LOGGER.info("[{}] [data-received] dataId={}, group={}, tenant={}, md5={}, content={}",
                            agent.getName(), dataId, group, tenant, cache.getMd5(),
                            ContentUtils.truncateContent(content));
                    } catch (NacosException ioe) {
                        String message = String.format(
                            "[%s] [get-update] get changed config exception. dataId=%s, group=%s, tenant=%s",
                            agent.getName(), dataId, group, tenant);
                        LOGGER.error(message, ioe);
                    }
                }
                for (CacheData cacheData : cacheDatas) {
                    if (!cacheData.isInitializing() || inInitializingCacheList
                        .contains(GroupKey.getKeyTenant(cacheData.dataId, cacheData.group, cacheData.tenant))) {
                        cacheData.checkListenerMd5();
                        cacheData.setInitializing(false);
                    }
                }
                inInitializingCacheList.clear();
            } catch (Throwable e) {
                LOGGER.error("longPolling error", e);
            } finally {
                executorService.execute(this);
            }
        }
    }

private void checkLocalConfig(CacheData cacheData) {
        final String dataId = cacheData.dataId;
        final String group = cacheData.group;
        final String tenant = cacheData.tenant;
        File path = LocalConfigInfoProcessor.getFailoverFile(agent.getName(), dataId, group, tenant);

        // 没有 -> 有
        if (!cacheData.isUseLocalConfigInfo() && path.exists()) {
            String content = LocalConfigInfoProcessor.getFailover(agent.getName(), dataId, group, tenant);
            String md5 = MD5.getInstance().getMD5String(content);
            cacheData.setUseLocalConfigInfo(true);
            cacheData.setLocalConfigInfoVersion(path.lastModified());
            cacheData.setContent(content);

            LOGGER.warn("[{}] [failover-change] failover file created. dataId={}, group={}, tenant={}, md5={}, content={}",
                agent.getName(), dataId, group, tenant, md5, ContentUtils.truncateContent(content));
            return;
        }

        // 有 -> 没有。不通知业务监听器，从server拿到配置后通知。
        if (cacheData.isUseLocalConfigInfo() && !path.exists()) {
            cacheData.setUseLocalConfigInfo(false);
            LOGGER.warn("[{}] [failover-change] failover file deleted. dataId={}, group={}, tenant={}", agent.getName(),
                dataId, group, tenant);
            return;
        }

        // 有变更
        if (cacheData.isUseLocalConfigInfo() && path.exists()
            && cacheData.getLocalConfigInfoVersion() != path.lastModified()) {
            String content = LocalConfigInfoProcessor.getFailover(agent.getName(), dataId, group, tenant);
            String md5 = MD5.getInstance().getMD5String(content);
            cacheData.setUseLocalConfigInfo(true);
            cacheData.setLocalConfigInfoVersion(path.lastModified());
            cacheData.setContent(content);
            LOGGER.warn("[{}] [failover-change] failover file changed. dataId={}, group={}, tenant={}, md5={}, content={}",
                agent.getName(), dataId, group, tenant, md5, ContentUtils.truncateContent(content));
            return;
        }
    }

void checkListenerMd5() {
        for (ManagerListenerWrap wrap : listeners) {
            if (!md5.equals(wrap.lastCallMd5)) {
                safeNotifyListener(dataId, group, content, md5, wrap);
            }
        }
    }

private void safeNotifyListener(final String dataId, final String group, final String content,
                                    final String md5, final ManagerListenerWrap listenerWrap) {
        final Listener listener = listenerWrap.listener;

        Runnable job = new Runnable() {
            public void run() {
                ClassLoader myClassLoader = Thread.currentThread().getContextClassLoader();
                ClassLoader appClassLoader = listener.getClass().getClassLoader();
                try {
                    if (listener instanceof AbstractSharedListener) {
                        AbstractSharedListener adapter = (AbstractSharedListener)listener;
                        adapter.fillContext(dataId, group);
                        LOGGER.info("[{}] [notify-context] dataId={}, group={}, md5={}", name, dataId, group, md5);
                    }
                    // 执行回调之前先将线程classloader设置为具体webapp的classloader，以免回调方法中调用spi接口是出现异常或错用（多应用部署才会有该问题）。
                    Thread.currentThread().setContextClassLoader(appClassLoader);

                    ConfigResponse cr = new ConfigResponse();
                    cr.setDataId(dataId);
                    cr.setGroup(group);
                    cr.setContent(content);
                    configFilterChainManager.doFilter(null, cr);
                    String contentTmp = cr.getContent();
                    listener.receiveConfigInfo(contentTmp);
                    listenerWrap.lastCallMd5 = md5;
                    LOGGER.info("[{}] [notify-ok] dataId={}, group={}, md5={}, listener={} ", name, dataId, group, md5,
                        listener);
                } catch (NacosException de) {
                    LOGGER.error("[{}] [notify-error] dataId={}, group={}, md5={}, listener={} errCode={} errMsg={}", name,
                        dataId, group, md5, listener, de.getErrCode(), de.getErrMsg());
                } catch (Throwable t) {
                    LOGGER.error("[{}] [notify-error] dataId={}, group={}, md5={}, listener={} tx={}", name, dataId, group,
                        md5, listener, t.getCause());
                } finally {
                    Thread.currentThread().setContextClassLoader(myClassLoader);
                }
            }
        };

        final long startNotify = System.currentTimeMillis();
        try {
            if (null != listener.getExecutor()) {
                listener.getExecutor().execute(job);
            } else {
                job.run();
            }
        } catch (Throwable t) {
            LOGGER.error("[{}] [notify-error] dataId={}, group={}, md5={}, listener={} throwable={}", name, dataId, group,
                md5, listener, t.getCause());
        }
        final long finishNotify = System.currentTimeMillis();
        LOGGER.info("[{}] [notify-listener] time cost={}ms in ClientWorker, dataId={}, group={}, md5={}, listener={} ",
            name, (finishNotify - startNotify), dataId, group, md5, listener);
    }

listener.receiveConfigInfo(contentTmp);

DelegatingEventPublishingListener.java就会发布事件，一个闭环就形成了！

  public void receiveConfigInfo(String content) {
        this.publishEvent(content);
        this.onReceived(content);
    }

客户端会有个长轮询不断去Nacos平台去取值，更新缓存；所以并不是Nacos推过来，而是client主动去取值的！

但是我们还有个核心的问题没搞明白，我们取值的时候，怎么去cacheData里面取值的？

这些成熟的产品都是经过N次迭代，不断的打磨才完善的，多人多日，现在我们自己看的时候有疑惑是很正常的，想办法，加油！

下面是在网上查的资料

• BeanFactoryPostProcessor.postProcessBeanFactory接口函数处理注解@NacosPropertySource和xml property source配置，获取配置，插入spring配置源，注册配置变更监听回调函数
• InstantiationAwareBeanPostProcessor.postProcessPropertyValues接口函数
  处理@NacosInjected注入configservice服务
  处理@NacosValue注入属性的配置值信息，
• BeanPostProcessor.postProcessBeforeInitialization
  处理@NacosConfigurationProperties，注入配置到目标bean，注册配置变更监听回调更新目标bean
  处理@NacosValue，缓存标记的配置项用做后续动态更新
• ContextRefreshedEvent监听，spring初始化完成时触发。
  处理@NacosConfigListener, 注册配置变更监听回调。
• ApplicationListener.onApplicationEvent监听spring事件NacosConfigReceivedEvent，每次从配置服务端获取配置时都会触发该事件，用于动态变更@NacosValue注解目标。

基本上就是这样一个逻辑，

NacosValueAnnotationBeanPostProcessor.java

public void onApplicationEvent(NacosConfigReceivedEvent event) {
        String content = event.getContent();
        if (content != null) {
            Properties configProperties = NacosUtils.toProperties(content);
            Iterator var4 = configProperties.keySet().iterator();

            while(true) {
                String propertyKey;
                List beanPropertyList;
                do {
                    if (!var4.hasNext()) {
                        return;
                    }

                    Object key = var4.next();
                    propertyKey = (String)key;
                    beanPropertyList = (List)this.placeholderNacosValueTargetMap.get(propertyKey);
                } while(beanPropertyList == null);

                String propertyValue = configProperties.getProperty(propertyKey);
                Iterator var9 = beanPropertyList.iterator();

                while(var9.hasNext()) {
                    NacosValueAnnotationBeanPostProcessor.NacosValueTarget nacosValueTarget = (NacosValueAnnotationBeanPostProcessor.NacosValueTarget)var9.next();
                    if (nacosValueTarget.method == null) {
                        this.setField(nacosValueTarget, propertyValue);
                    } else {
                        this.setMethod(nacosValueTarget, propertyValue);
                    }
                }
            }
        }
    }

他会变更这个property对应的key值；我们结合上面的代码看下：

下面标色的这些类复杂，很多我们专注也业务端代码的同学们可能都没见过，后面我们就一一分析归类

public class NacosConfigBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar, EnvironmentAware, BeanFactoryAware 

public class NacosPropertySourcePostProcessor implements BeanDefinitionRegistryPostProcessor, BeanFactoryPostProcessor, EnvironmentAware, Ordered 

public abstract class AbstractNacosPropertySourceBuilder<T extends BeanDefinition> implements EnvironmentAware, BeanFactoryAware, BeanClassLoaderAware, ApplicationContextAware, InitializingBean 

public class CacheableEventPublishingNacosServiceFactory implements NacosServiceFactory, ApplicationContextAware 

public class NacosConfigurationPropertiesBindingPostProcessor implements BeanPostProcessor, ApplicationContextAware {