【知识库】--Dubbo ReferenceBean获取-- 调用RegistryDirectory.notify -- 源码过程（254）

回顾上一篇文章：获取ReferenceBean过程中SPI自适应到RegistryProtocol类后，调用refer方法：

@SuppressWarnings("unchecked")public <T> Invoker<T> refer(Class<T> type, URL url) throws RpcException {    url = url.setProtocol(url.getParameter(Constants.REGISTRY_KEY, Constants.DEFAULT_REGISTRY)).removeParameter(Constants.REGISTRY_KEY);    Registry registry = registryFactory.getRegistry(url);    if (RegistryService.class.equals(type)) {        return proxyFactory.getInvoker((T) registry, type, url);    }    // group="a,b" or group="*"    Map<String, String> qs = StringUtils.parseQueryString(url.getParameterAndDecoded(Constants.REFER_KEY));    String group = qs.get(Constants.GROUP_KEY);    if (group != null && group.length() > 0) {        if ((Constants.COMMA_SPLIT_PATTERN.split(group)).length > 1                || "*".equals(group)) {            return doRefer(getMergeableCluster(), registry, type, url);        }    }    return doRefer(cluster, registry, type, url);}private Cluster getMergeableCluster() {    return ExtensionLoader.getExtensionLoader(Cluster.class).getExtension("mergeable");}private <T> Invoker<T> doRefer(Cluster cluster, Registry registry, Class<T> type, URL url) {    RegistryDirectory<T> directory = new RegistryDirectory<T>(type, url);    directory.setRegistry(registry);    directory.setProtocol(protocol);    URL subscribeUrl = new URL(Constants.CONSUMER_PROTOCOL, NetUtils.getLocalHost(), 0, type.getName(), directory.getUrl().getParameters());    if (!Constants.ANY_VALUE.equals(url.getServiceInterface())            && url.getParameter(Constants.REGISTER_KEY, true)) {        registry.register(subscribeUrl.addParameters(Constants.CATEGORY_KEY, Constants.CONSUMERS_CATEGORY,                Constants.CHECK_KEY, String.valueOf(false)));    }    directory.subscribe(subscribeUrl.addParameter(Constants.CATEGORY_KEY,            Constants.PROVIDERS_CATEGORY                    + "," + Constants.CONFIGURATORS_CATEGORY                    + "," + Constants.ROUTERS_CATEGORY));    return cluster.join(directory);}

1

自适应到：com.alibaba.dubbo.registry.integration.RegistryDirectory#subscribe方法

 directory.subscribe(subscribeUrl.addParameter(Constants.CATEGORY_KEY,            Constants.PROVIDERS_CATEGORY                    + "," + Constants.CONFIGURATORS_CATEGORY                    + "," + Constants.ROUTERS_CATEGORY));

2 方法实现：

public void subscribe(URL url) {    setConsumerUrl(url);    registry.subscribe(url, this);}

3 订阅实现：

com.alibaba.dubbo.registry.support.FailbackRegistry#subscribe

@Overridepublic void subscribe(URL url, NotifyListener listener) {    super.subscribe(url, listener);    removeFailedSubscribed(url, listener);    try {        // 向服务器端发送订阅请求        doSubscribe(url, listener);    } catch (Exception e) {        Throwable t = e;        List<URL> urls = getCacheUrls(url);        if (urls != null && urls.size() > 0) {            notify(url, listener, urls);            logger.error("Failed to subscribe " + url + ", Using cached list: " + urls + " from cache file: " + getUrl().getParameter(Constants.FILE_KEY, System.getProperty("user.home") + "/dubbo-registry-" + url.getHost() + ".cache") + ", cause: " + t.getMessage(), t);        } else {            // 如果开启了启动时检测，则直接抛出异常            boolean check = getUrl().getParameter(Constants.CHECK_KEY, true)                    && url.getParameter(Constants.CHECK_KEY, true);            boolean skipFailback = t instanceof SkipFailbackWrapperException;            if (check || skipFailback) {                if (skipFailback) {                    t = t.getCause();                }                throw new IllegalStateException("Failed to subscribe " + url + ", cause: " + t.getMessage(), t);            } else {                logger.error("Failed to subscribe " + url + ", waiting for retry, cause: " + t.getMessage(), t);            }        }        // 将失败的订阅请求记录到失败列表，定时重试        addFailedSubscribed(url, listener);    }}

4 重点：

        // 向服务器端发送订阅请求        doSubscribe(url, listener);

5 参考zookeeper实现：

com.alibaba.dubbo.registry.zookeeper.ZookeeperRegistry#doSubscribe

protected void doSubscribe(final URL url, final NotifyListener listener) {    try {        if (Constants.ANY_VALUE.equals(url.getServiceInterface())) {            String root = toRootPath();            ConcurrentMap<NotifyListener, ChildListener> listeners = zkListeners.get(url);            if (listeners == null) {                zkListeners.putIfAbsent(url, new ConcurrentHashMap<NotifyListener, ChildListener>());                listeners = zkListeners.get(url);            }            ChildListener zkListener = listeners.get(listener);            if (zkListener == null) {                listeners.putIfAbsent(listener, new ChildListener() {                    public void childChanged(String parentPath, List<String> currentChilds) {                        for (String child : currentChilds) {                            if (! anyServices.contains(child)) {                                anyServices.add(child);                                subscribe(url.setPath(child).addParameters(Constants.INTERFACE_KEY, child,                                         Constants.CHECK_KEY, String.valueOf(false)), listener);                            }                        }                    }                });                zkListener = listeners.get(listener);            }            zkClient.create(root, false);            List<String> services = zkClient.addChildListener(root, zkListener);            if (services != null && services.size() > 0) {                anyServices.addAll(services);                for (String service : services) {                    subscribe(url.setPath(service).addParameters(Constants.INTERFACE_KEY, service,                             Constants.CHECK_KEY, String.valueOf(false)), listener);                }            }        } else {            List<URL> urls = new ArrayList<URL>();            for (String path : toCategoriesPath(url)) {                ConcurrentMap<NotifyListener, ChildListener> listeners = zkListeners.get(url);                if (listeners == null) {                    zkListeners.putIfAbsent(url, new ConcurrentHashMap<NotifyListener, ChildListener>());                    listeners = zkListeners.get(url);                }                ChildListener zkListener = listeners.get(listener);                if (zkListener == null) {                    listeners.putIfAbsent(listener, new ChildListener() {                        public void childChanged(String parentPath, List<String> currentChilds) {                           ZookeeperRegistry.this.notify(url, listener, toUrlsWithEmpty(url, parentPath, currentChilds));                        }                    });                    zkListener = listeners.get(listener);                }                zkClient.create(path, false);                List<String> children = zkClient.addChildListener(path, zkListener);                if (children != null) {                   urls.addAll(toUrlsWithEmpty(url, path, children));                }            }            notify(url, listener, urls);        }    } catch (Throwable e) {        throw new RpcException("Failed to subscribe " + url + " to zookeeper " + getUrl() + ", cause: " + e.getMessage(), e);    }}

6 上面除了注册回调函数外，最后调用了（回调函数，主动触发）

notify(url, listener, urls);

即：

com.alibaba.dubbo.registry.support.FailbackRegistry#notify

实现：

@Overrideprotected void notify(URL url, NotifyListener listener, List<URL> urls) {    if (url == null) {        throw new IllegalArgumentException("notify url == null");    }    if (listener == null) {        throw new IllegalArgumentException("notify listener == null");    }    try {        doNotify(url, listener, urls);    } catch (Exception t) {        // 将失败的通知请求记录到失败列表，定时重试        Map<NotifyListener, List<URL>> listeners = failedNotified.get(url);        if (listeners == null) {            failedNotified.putIfAbsent(url, new ConcurrentHashMap<NotifyListener, List<URL>>());            listeners = failedNotified.get(url);        }        listeners.put(listener, urls);        logger.error("Failed to notify for subscribe " + url + ", waiting for retry, cause: " + t.getMessage(), t);    }}

跟进：

protected void doNotify(URL url, NotifyListener listener, List<URL> urls) {    super.notify(url, listener, urls);}

跟进到：com.alibaba.dubbo.registry.support.AbstractRegistry#notify

protected void notify(URL url, NotifyListener listener, List<URL> urls) {    if (url == null) {        throw new IllegalArgumentException("notify url == null");    }    if (listener == null) {        throw new IllegalArgumentException("notify listener == null");    }    if ((urls == null || urls.size() == 0)            && !Constants.ANY_VALUE.equals(url.getServiceInterface())) {        logger.warn("Ignore empty notify urls for subscribe url " + url);        return;    }    if (logger.isInfoEnabled()) {        logger.info("Notify urls for subscribe url " + url + ", urls: " + urls);    }    Map<String, List<URL>> result = new HashMap<String, List<URL>>();    for (URL u : urls) {        if (UrlUtils.isMatch(url, u)) {            String category = u.getParameter(Constants.CATEGORY_KEY, Constants.DEFAULT_CATEGORY);            List<URL> categoryList = result.get(category);            if (categoryList == null) {                categoryList = new ArrayList<URL>();                result.put(category, categoryList);            }            categoryList.add(u);        }    }    if (result.size() == 0) {        return;    }    Map<String, List<URL>> categoryNotified = notified.get(url);    if (categoryNotified == null) {        notified.putIfAbsent(url, new ConcurrentHashMap<String, List<URL>>());        categoryNotified = notified.get(url);    }    for (Map.Entry<String, List<URL>> entry : result.entrySet()) {        String category = entry.getKey();        List<URL> categoryList = entry.getValue();        categoryNotified.put(category, categoryList);        saveProperties(url);        listener.notify(categoryList);    }}

7 上面最终执行了 回调！

 listener.notify(categoryList);

也就是com.alibaba.dubbo.registry.integration.RegistryDirectory#notify

public synchronized void notify(List<URL> urls) {    List<URL> invokerUrls = new ArrayList<URL>();    List<URL> routerUrls = new ArrayList<URL>();    List<URL> configuratorUrls = new ArrayList<URL>();    for (URL url : urls) {        String protocol = url.getProtocol();        String category = url.getParameter(Constants.CATEGORY_KEY, Constants.DEFAULT_CATEGORY);        if (Constants.ROUTERS_CATEGORY.equals(category) || Constants.ROUTE_PROTOCOL.equals(protocol)) {            routerUrls.add(url);        } else if (Constants.CONFIGURATORS_CATEGORY.equals(category) || Constants.OVERRIDE_PROTOCOL.equals(protocol)) {            configuratorUrls.add(url);        } else if (Constants.PROVIDERS_CATEGORY.equals(category)) {            invokerUrls.add(url);        } else {            logger.warn("Unsupported category " + category + " in notified url: " + url + " from registry " + getUrl().getAddress() + " to consumer " + NetUtils.getLocalHost());        }    }    // routers    if (routerUrls.size() > 0) {        List<Router> routers = toRouters(routerUrls);        if (routers != null) { // null - do nothing            setRouters(routers);        }    }    // configurators    if (configuratorUrls.size() > 0) {        this.configurators = toConfigurators(configuratorUrls);    }    List<Configurator> localConfigurators = this.configurators; // local reference    // 合并override参数    this.overrideDirectoryUrl = directoryUrl;    if (localConfigurators != null && localConfigurators.size() > 0) {        for (Configurator configurator : localConfigurators) {            this.overrideDirectoryUrl = configurator.configure(overrideDirectoryUrl);        }    }    if (configuratorUrls.size() > 0) {        logger.info("unconfigured directory url without provider params: " + this.directoryUrl                + ", configured directory url without provider params: " + this.overrideDirectoryUrl);    }    // providers    refreshInvoker(invokerUrls);}

等待被动回调和本次主动回调最终都会调用RegistryDirectory.notify。

8 最后就会触发refreshInvoker

 ／* 根据invokerURL列表转换为invoker列表。转换规则如下： * 1.如果url已经被转换为invoker，则不在重新引用，直接从缓存中获取，注意如果url中任何一个参数变更也会重新引用 * 2.如果传入的invoker列表不为空，则表示最新的invoker列表 * 3.如果传入的invokerUrl列表是空，则表示只是下发的override规则或route规则，需要重新交叉对比，决定是否需要重新引用。 * * @param invokerUrls 传入的参数不能为null */private void refreshInvoker(List<URL> invokerUrls) {    if (invokerUrls != null && invokerUrls.size() == 1 && invokerUrls.get(0) != null && Constants.EMPTY_PROTOCOL.equals(invokerUrls.get(0).getProtocol())) {        this.forbidden = true; // 禁止访问        overrideDirectoryUrl = overrideDirectoryUrl.addParameters(Constants.INVOKER_INSIDE_INVOKERS_KEY, "", Constants.INVOKER_INSIDE_INVOKER_COUNT_KEY, "0");        this.methodInvokerMap = null; // 置空列表        destroyAllInvokers(); // 关闭所有Invoker    } else {        this.forbidden = false; // 允许访问        Map<String, Invoker<T>> oldUrlInvokerMap = this.urlInvokerMap; // local reference        if (invokerUrls.size() == 0 && this.lastInvokerUrls != null) {            invokerUrls.addAll(this.lastInvokerUrls);        } else {            this.lastInvokerUrls = new HashSet<URL>();            this.lastInvokerUrls.addAll(invokerUrls);//缓存invokerUrls列表，便于交叉对比        }        if (invokerUrls.size() == 0) return;        Map<String, Invoker<T>> newUrlInvokerMap = toInvokers(invokerUrls);// 将URL列表转成Invoker列表        // state change        //如果计算错误，则不进行处理.        //比如所有provider都标记为下线状态，这样其实最后一个provider是下不了的        if (newUrlInvokerMap == null || newUrlInvokerMap.size() == 0) {            logger.error(new IllegalStateException("urls to invokers error .invokerUrls.size :" + invokerUrls.size() + ", invoker.size :0. urls :" + invokerUrls.toString()));            return;        }        Map<String, List<Invoker<T>>> newMethodInvokerMap = toMethodInvokers(newUrlInvokerMap); // 换方法名映射Invoker列表        this.methodInvokerMap = multiGroup ? toMergeMethodInvokerMap(newMethodInvokerMap) : newMethodInvokerMap;        this.urlInvokerMap = newUrlInvokerMap;        try {            destroyUnusedInvokers(oldUrlInvokerMap, newUrlInvokerMap); // 关闭未使用的Invoker        } catch (Exception e) {            logger.warn("destroyUnusedInvokers error. ", e);        }        List<String> invokerUrlString = new ArrayList<String>();        for (URL invoker : invokerUrls) {            invokerUrlString.add(invoker.toString());        }        overrideDirectoryUrl = overrideDirectoryUrl.addParameters(                Constants.INVOKER_INSIDE_INVOKERS_KEY, URL.encode(CollectionUtils.join(invokerUrlString, ";")),                Constants.INVOKER_INSIDE_INVOKER_COUNT_KEY, String.valueOf(invokerUrls.size()));    }}

9 跟进com.alibaba.dubbo.registry.integration.RegistryDirectory#toInvokers

/** * 将urls转成invokers,如果url已经被refer过，不再重新引用。 * * @param urls * @return invokers */private Map<String, Invoker<T>> toInvokers(List<URL> urls) {    Map<String, Invoker<T>> result = new HashMap<String, Invoker<T>>();    if (urls == null || urls.size() == 0) return result;    Set<String> keys = new HashSet<String>();    for (URL providerUrl : urls) {        if (!acceptProtocol(providerUrl)) {            continue;        }        if (!acceptTransport(providerUrl)) {            continue;        }        URL url = mergeUrl(providerUrl);        String key = url.toFullString(); // URL参数是排序的        if (keys.contains(key)) { // 重复URL            continue;        }        keys.add(key);        // 缓存key为没有合并消费端参数的URL，不管消费端如何合并参数，如果服务端URL发生变化，则重新refer        Map<String, Invoker<T>> localUrlInvokerMap = this.urlInvokerMap; // local reference        Invoker<T> invoker = localUrlInvokerMap == null ? null : localUrlInvokerMap.get(key);        if (invoker == null) { // 缓存中没有，重新refer            try {                if (isEnable(url)) {                    invoker = new InvokerDelegete<T>(protocol.refer(serviceType, url), url, providerUrl);                }            } catch (Throwable t) {                logger.error("Failed to refer invoker for interface:" + serviceType + ",url:(" + url + ")" + t.getMessage(), t);            }            if (invoker != null) { // 将新的引用放入缓存                result.put(key, invoker);            }        } else {            result.put(key, invoker);        }    }    keys.clear();    return result;}

到此目录notify方法调用 源码过程完毕！