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Posted to notifications@dubbo.apache.org by GitBox <gi...@apache.org> on 2021/11/05 07:10:19 UTC
[GitHub] [dubbo] bran2015 opened a new issue #9212: RegistryService#subscribe为和在服务导出时也要执行？
bran2015 opened a new issue #9212:
URL: https://github.com/apache/dubbo/issues/9212
在2.7.8版本中，RegistryService#subscribe到入口为RegistryProtocol#export和RegistryProtocol#doRefer方法，前者为服务导出时调用，后者为服务引用是调用，RegistryProtocol#export方法处理过后的overrideSubscribeUrl格式为：provider://127.0.0.1:20880/com.example.DemoService?category=configurators&check=false&Xxxx=xxxx,当使用nacos作为注册中心时，该调用路径为：RegistryProtocol#export->ListenerRegistryWrapper#subscribe->FailbackRegistry#subscribe->NacosRegistry#doSubscribe->NacosRegistry#notifySubscriber->FailbackRegistry#notify->AbstractRegistry#notify.在这个调用链中，并没有发现有用信息，请问在服务导出时，为啥要调用RegistryService#subscribe方法？
再看下AbstractRegistry#notify方法：
```
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 ((CollectionUtils.isEmpty(urls))
&& !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);
}
// 保留每个provider的category
Map<String, List<URL>> result = new HashMap<>();
for (URL u : urls) {
if (UrlUtils.isMatch(url, u)) {
String category = u.getParameter(CATEGORY_KEY, DEFAULT_CATEGORY);
List<URL> categoryList = result.computeIfAbsent(category, k -> new ArrayList<>());
categoryList.add(u);
}
}
// 服务导出时的订阅，执行到此就结束了
if (result.size() == 0) {
return;
}
// 添加缓存
Map<String, List<URL>> categoryNotified = notified.computeIfAbsent(url, u -> new ConcurrentHashMap<>());
for (Map.Entry<String, List<URL>> entry : result.entrySet()) {
String category = entry.getKey();
List<URL> categoryList = entry.getValue();
categoryNotified.put(category, categoryList);
listener.notify(categoryList);
// 我们将在每次通知后更新缓存文件。
// 当我们的注册表由于网络抖动而订阅失败时，我们至少可以返回现有的缓存URL。
saveProperties(url);
}
}
```
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[GitHub] [dubbo] LiujunjieALiling commented on issue #9212: RegistryService#subscribe为和在服务导出时也要执行？
Posted by GitBox <gi...@apache.org>.
LiujunjieALiling commented on issue #9212:
URL: https://github.com/apache/dubbo/issues/9212#issuecomment-987007426
> 在2.7.8版本中，RegistryService#subscribe到入口为RegistryProtocol#export和RegistryProtocol#doRefer方法，前者为服务导出时调用，后者为服务引用是调用，RegistryProtocol#export方法处理过后的overrideSubscribeUrl格式为：provider://127.0.0.1:20880/com.example.DemoService?category=configurators&check=false&Xxxx=xxxx,当使用nacos作为注册中心时，该调用路径为：RegistryProtocol#export->ListenerRegistryWrapper#subscribe->FailbackRegistry#subscribe->NacosRegistry#doSubscribe->NacosRegistry#notifySubscriber->FailbackRegistry#notify->AbstractRegistry#notify.在这个调用链中，并没有发现有用信息，请问在服务导出时，为啥要调用RegistryService#subscribe方法？
>
> 再看下AbstractRegistry#notify方法：
>
> ```
> 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 ((CollectionUtils.isEmpty(urls))
> && !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);
> }
> // 保留每个provider的category
> Map<String, List<URL>> result = new HashMap<>();
> for (URL u : urls) {
> if (UrlUtils.isMatch(url, u)) {
> String category = u.getParameter(CATEGORY_KEY, DEFAULT_CATEGORY);
> List<URL> categoryList = result.computeIfAbsent(category, k -> new ArrayList<>());
> categoryList.add(u);
> }
> }
> // 服务导出时的订阅，执行到此就结束了
> if (result.size() == 0) {
> return;
> }
> // 添加缓存
> Map<String, List<URL>> categoryNotified = notified.computeIfAbsent(url, u -> new ConcurrentHashMap<>());
> for (Map.Entry<String, List<URL>> entry : result.entrySet()) {
> String category = entry.getKey();
> List<URL> categoryList = entry.getValue();
> categoryNotified.put(category, categoryList);
> listener.notify(categoryList);
> // 我们将在每次通知后更新缓存文件。
> // 当我们的注册表由于网络抖动而订阅失败时，我们至少可以返回现有的缓存URL。
> saveProperties(url);
> }
> }
> ```
// Deprecated! Subscribe to override rules in 2.6.x or before.
registry.subscribe(overrideSubscribeUrl, overrideSubscribeListener);
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