feat: 杂\n test \n Closes apache#1

dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/support/wrapper/MockClusterInvoker.java

@@ -88,20 +88,25 @@ public Class<T> getInterface() {
     @Override
     public Result invoke(Invocation invocation) throws RpcException {
         Result result;
-
+        // 获取 mock 配置值
         String value = getUrl().getMethodParameter(invocation.getMethodName(), MOCK_KEY, Boolean.FALSE.toString()).trim();
         if (value.length() == 0 || "false".equalsIgnoreCase(value)) {
             //no mock
+            // 无 mock 逻辑，直接调用其他 Invoker 对象的 invoke 方法，
+            // 比如 FailoverClusterInvoker
             result = this.invoker.invoke(invocation);
         } else if (value.startsWith(FORCE_KEY)) {
             if (logger.isWarnEnabled()) {
                 logger.warn("force-mock: " + invocation.getMethodName() + " force-mock enabled , url : " + getUrl());
             }
             //force:direct mock
+            // force:xxx 直接执行 mock 逻辑，不发起远程调用
             result = doMockInvoke(invocation, null);
         } else {
             //fail-mock
+            //// fail:xxx 表示消费方对调用服务失败后，再执行 mock 逻辑，不抛出异常
             try {
+                //// 调用其他 Invoker 对象的 invoke 方法
                 result = this.invoker.invoke(invocation);
 
                 //fix:#4585
@@ -122,6 +127,7 @@ public Result invoke(Invocation invocation) throws RpcException {
                 if (logger.isWarnEnabled()) {
                     logger.warn("fail-mock: " + invocation.getMethodName() + " fail-mock enabled , url : " + getUrl(), e);
                 }
+                // 调用失败，执行 mock 逻辑
                 result = doMockInvoke(invocation, e);
             }
         }

dubbo-config/dubbo-config-api/src/main/java/org/apache/dubbo/config/ServiceConfig.java

@@ -380,8 +380,9 @@ private void doExportUrls() {
 
         repository.registerProvider(providerModel);
 
+        // 加载注册中心链接
         List<URL> registryURLs = ConfigValidationUtils.loadRegistries(this, true);
-
+        // 遍历 protocols，并在每个协议下导出服务
         for (ProtocolConfig protocolConfig : protocols) {
             String pathKey = URL.buildKey(getContextPath(protocolConfig)
                     .map(p -> p + "/" + path)

dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/client/migration/MigrationInvoker.java

@@ -273,6 +273,7 @@ public Result invoke(Invocation invocation) throws RpcException {
                     return invoker.invoke(invocation);
                 }
             }
+            //MockClusterInvoker(MockClusterInvoker(服务降级逻辑))
             return currentAvailableInvoker.invoke(invocation);
         }
 

dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/integration/RegistryProtocol.java

@@ -234,10 +234,14 @@ public <T> Exporter<T> export(final Invoker<T> originInvoker) throws RpcExceptio
 
         providerUrl = overrideUrlWithConfig(providerUrl, overrideSubscribeListener);
         //export invoker
+        // 导出服务
         final ExporterChangeableWrapper<T> exporter = doLocalExport(originInvoker, providerUrl);
 
         // url to registry
+        // 根据 URL 加载 Registry 实现类，比如 ZookeeperRegistry
         final Registry registry = getRegistry(registryUrl);
+        // 获取注册中心 URL，以 zookeeper 注册中心为例，得到的示例 URL 如下：
+        // zookeeper://127.0.0.1:2181/com.alibaba.dubbo.registry.RegistryService?application=demo-provider&dubbo=2.0.2&export=dubbo%3A%2F%2F172.17.48.52%3A20880%2Fcom.alibaba.dubbo.demo.DemoService%3Fanyhost%3Dtrue%26application%3Ddemo-provider
         final URL registeredProviderUrl = getUrlToRegistry(providerUrl, registryUrl);
 
         // decide if we need to delay publish
@@ -288,7 +292,9 @@ private <T> ExporterChangeableWrapper<T> doLocalExport(final Invoker<T> originIn
         String key = getCacheKey(originInvoker);
 
         return (ExporterChangeableWrapper<T>) bounds.computeIfAbsent(key, s -> {
+            // 创建 Invoker 为委托类对象
             Invoker<?> invokerDelegate = new InvokerDelegate<>(originInvoker, providerUrl);
+            // 调用 protocol 的 export 方法导出服务 DubboProtocol
             return new ExporterChangeableWrapper<>((Exporter<T>) protocol.export(invokerDelegate), originInvoker);
         });
     }

dubbo-rpc/dubbo-rpc-api/src/main/java/org/apache/dubbo/rpc/protocol/ProtocolListenerWrapper.java

@@ -61,7 +61,7 @@ public int getDefaultPort() {
     @Override
     public <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {
         if (UrlUtils.isRegistry(invoker.getUrl())) {
-            //InjvmProtocol
+            //本地导出用InjvmProtocol，远程导出用RegistryProtocol
             return protocol.export(invoker);
         }
         //protocol = DubboProtocol

dubbo-rpc/dubbo-rpc-api/src/main/java/org/apache/dubbo/rpc/proxy/InvokerInvocationHandler.java

@@ -89,6 +89,7 @@ public Object invoke(Object proxy, Method method, Object[] args) throws Throwabl
             rpcInvocation.put(Constants.METHOD_MODEL, ((ConsumerModel) serviceModel).getMethodModel(method));
         }
 
+        //MigrationInvoker
         return invoker.invoke(rpcInvocation).recreate();
     }
 }