[GitHub] [dubbo-go] Mulavar commented on a change in pull request #1372: Ftr: Add config loader hooks for 1.5

[GitBox <gi...@apache.org>]

Mulavar commented on a change in pull request #1372:
URL: https://github.com/apache/dubbo-go/pull/1372#discussion_r694947646



##########
File path: config/config_loader_hook.go
##########
@@ -0,0 +1,367 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package config
+
+import (
+	"fmt"
+	"reflect"
+)
+
+import (
+	"github.com/apache/dubbo-go/common/constant"
+)
+
+const (
+	hookParams = constant.HookParams
+)
+
+type LoaderHook interface {
+	emit() bool
+	// if you want to use emitWithParams, you must add HookParams field and make emit return false
+	emitWithParams(params interface{}) bool
+}
+
+func getLoaderHookType(t LoaderHook) reflect.Type {
+	hookType := reflect.TypeOf(t)
+	if reflect.Ptr == hookType.Kind() {
+		hookType = hookType.Elem()
+	}
+	return hookType
+}
+
+func getLoaderHookTypeString(t LoaderHook) string {
+	return getLoaderHookType(t).String()
+}
+
+func getLoaderHookInfo(v reflect.Value) reflect.Value {
+	if reflect.Ptr == v.Kind() {
+		v = v.Elem()
+	}
+	return v
+}
+
+func getLoaderHookParams(t LoaderHook) interface{} {
+	hookType := getLoaderHookType(t)
+	_, existed := hookType.FieldByName(hookParams)
+	if !existed {
+		panic(fmt.Sprintf("Hook field [%s] not existed for %s", hookParams, hookType.Name()))
+	}
+	hookParams := getLoaderHookInfo(reflect.ValueOf(t)).FieldByName(hookParams)
+	return getLoaderHookInfo(hookParams).Interface()
+}
+
+func AddLoaderHooks(hooks ...LoaderHook) {
+	if len(hooks) > 0 {
+		if loaderHooks == nil {
+			loaderHooks = map[string][]LoaderHook{}
+		}
+		for _, hook := range hooks {
+			hookType := getLoaderHookTypeString(hook)
+			var hooks []LoaderHook
+			if hs, ok := loaderHooks[hookType]; ok {
+				hooks = hs
+			}
+			if hooks == nil {
+				hooks = []LoaderHook{}
+			}
+			loaderHooks[hookType] = append(hooks, hook)
+		}
+	}
+}
+
+func RemoveLoaderHooks(hooks ...LoaderHook) {
+	if loaderHooks != nil && len(loaderHooks) > 0 {
+		for _, rmHook := range hooks {
+			hookType := getLoaderHookTypeString(rmHook)
+			if hooks, ok := loaderHooks[hookType]; ok {
+				for index, targetHook := range hooks {
+					if rmHook == targetHook {
+						newHooks := append(hooks[:index], hooks[index+1:]...)
+						if len(newHooks) == 0 {
+							delete(loaderHooks, hookType)
+						} else {
+							loaderHooks[hookType] = newHooks
+						}
+						break
+					}

Review comment:
       1. 嵌套过深，建议将提前终止的分支代码放前面，比如最外层的if
   if loaderHooks == nil || len(loaderHooks) <= 0 {
       return
   }
   for _,  rmHook := range hooks { 
   // ...
   这样阅读上清晰一些
   2. 好像缩进有点问题，目前dubbogo都是4格。




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