[GitHub] [dubbo] veenter commented on pull request #13015: Fix ClassPool issue when multi-classloader

[via GitHub]

veenter commented on PR #13015:
URL: https://github.com/apache/dubbo/pull/13015#issuecomment-1711716234

   我最新一次的提交终于让解决了sonarcloud的 
https://sonarcloud.io/organizations/apache/rules?open=java%3AS2445&rule_key=java%3AS2445&tab=why
 这个报错，但是现在的这个写法我真的是受不了，我认为这个检测是一个误报
   
   原写法是这样的，很明显没有考虑线程安全
   ```
        public static ClassPool getClassPool(ClassLoader loader) {
           if (loader == null) {
               return ClassPool.getDefault();
           }
   
           ClassPool pool = POOL_MAP.get(loader);
           if (pool == null) {
               pool = new ClassPool(true);
               pool.insertClassPath(new LoaderClassPath(loader));
               pool.insertClassPath(new DubboLoaderClassPath());
               POOL_MAP.put(loader, pool);
           }
           return pool;
       }
   ```
   
   第一次优化为下面这样，但检测出现了sonarcloud的报错
   ```
       public static ClassPool getClassPool(ClassLoader loader) {
           if (loader == null) {
               return ClassPool.getDefault();
           }
   
           ClassPool pool = POOL_MAP.get(loader);
           if (pool == null) {
               synchronized (loader) {
                   pool = POOL_MAP.get(loader);
                   if (pool == null) {
                       pool = new ClassPool(true);
                       pool.insertClassPath(new LoaderClassPath(loader));
                       pool.insertClassPath(new DubboLoaderClassPath());
                       POOL_MAP.put(loader, pool);
                   }
               }
           }
           return pool;
       }
   ```
   
   第二次我改成这样，依然不行
   ```
       public static ClassPool getClassPool(final ClassLoader loader) {
           if (loader == null) {
               return ClassPool.getDefault();
           }
   
           ClassPool pool = POOL_MAP.get(loader);
           if (pool == null) {
               synchronized (loader) {
                   pool = POOL_MAP.get(loader);
                   if (pool == null) {
                       pool = new ClassPool(true);
                       pool.insertClassPath(new LoaderClassPath(loader));
                       pool.insertClassPath(new DubboLoaderClassPath());
                       POOL_MAP.put(loader, pool);
                   }
               }
           }
           return pool;
       }
   ```
   
   最终我改成这样通过了sonarcloud检测，修改方案只是简单的赋值给一个final 变量，但是这样的写法也太愚蠢了
   ```
       public static ClassPool getClassPool(ClassLoader loader) {
           if (loader == null) {
               return ClassPool.getDefault();
           }
           
//https://sonarcloud.io/organizations/apache/rules?open=java%3AS2445&rule_key=java%3AS2445&tab=why
           final ClassLoader currentLoader = loader;
           ClassPool pool = POOL_MAP.get(currentLoader);
           if (pool == null) {
               synchronized (currentLoader) {
                   pool = POOL_MAP.get(currentLoader);
                   if (pool == null) {
                       pool = new ClassPool(true);
                       pool.insertClassPath(new LoaderClassPath(currentLoader));
                       pool.insertClassPath(new DubboLoaderClassPath());
                       POOL_MAP.put(currentLoader, pool);
                   }
               }
           }
           return pool;
       }
   ```
   
   所以我认为sonarcloud的这个检测是有问题的。
   
   而且我发现，搜索dubbo的整个代码库 类似这样的写法（锁方法参数）有好几处，不明白为何他们没被扫描到
   
   比如：
   
![image](https://github.com/apache/dubbo/assets/5327221/983298f0-758d-44bc-96f1-de2060e55105)
   
![image](https://github.com/apache/dubbo/assets/5327221/7d5ebd12-85cd-4f4f-92d7-b380750b9d8c)
   
![image](https://github.com/apache/dubbo/assets/5327221/b8da27d2-a299-4314-ba34-c80a41395af6)
   
![image](https://github.com/apache/dubbo/assets/5327221/7b1ce6e6-6d76-4af0-b53d-9a3807abecdd)
   
   
   
   


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