[GitHub] hupuxiaojun edited a comment on issue #2228: [Dubbo- support tag router feature] Add a new Router implement -- TagRouter

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hupuxiaojun edited a comment on issue #2228: [Dubbo- support tag router feature] Add a new Router implement -- TagRouter
URL: https://github.com/apache/incubator-dubbo/pull/2228#issuecomment-418067095
 
 
   TagRouter feature is very good, but i think an LoadBalance Wrapper can get same result ,and has smaller changes with source code:
   ```java
   
   import com.alibaba.dubbo.common.URL;
   import com.alibaba.dubbo.common.logger.Logger;
   import com.alibaba.dubbo.common.logger.LoggerFactory;
   import com.alibaba.dubbo.common.utils.StringUtils;
   import com.alibaba.dubbo.rpc.Invocation;
   import com.alibaba.dubbo.rpc.Invoker;
   import com.alibaba.dubbo.rpc.RpcContext;
   import com.alibaba.dubbo.rpc.RpcException;
   import com.alibaba.dubbo.rpc.cluster.LoadBalance;
   
   import java.util.ArrayList;
   import java.util.List;
   
   
   public class LoadbalanceTagFilterWrapper implements LoadBalance {
       private static final Logger logger = LoggerFactory.getLogger(LoadbalanceTagFilterWrapper.class);
       private LoadBalance loadBalance;
   
       public LoadbalanceTagFilterWrapper(LoadBalance loadBalance) {
           this.loadBalance = loadBalance;
       }
   
       @Override
       public <T> Invoker<T> select(List<Invoker<T>> invokers, URL url, Invocation invocation) throws RpcException {
           List<Invoker<T>> filteredInvokers = filterInvokers(invokers);
           return loadBalance.select(filteredInvokers, url, invocation);
       }
   
       private <T> List<Invoker<T>> filterInvokers(List<Invoker<T>> invokers) {
           // filter
           List<Invoker<T>> result = new ArrayList<>();
           // all invokers that don't have "tag" parameter in url is a normal invoker
           List<Invoker<T>> normalResult = new ArrayList<>();
           try {
               // Dynamic param
               String tag = RpcContext.getContext().getAttachment(Constants.REQUEST_TAG_KEY);
   
               for (Invoker<T> invoker : invokers) {
                   if (StringUtils.isEmpty(invoker.getUrl().getParameter(Constants.TAG_KEY))) {
                       // all invokers that don't have "tag" parameter in url is a normal invoker
                       normalResult.add(invoker);
                   } else {
                       String[] tags = invoker.getUrl().getParameter(Constants.TAG_KEY).split(",");
                       for (String s : tags) {
                           if (s.equals(tag)) {
                               result.add(invoker);
                               break;
                           }
                       }
                   }
               }
               // If no invoker be selected, downgrade to normal invokers
               if (result.isEmpty()) {
                   return normalResult;
               }
               return result;
           } catch (Exception e) {
               logger.error("Route by tag error,return all invokers.", e);
           }
           // Downgrade to all invokers
           return invokers;
       }
   }
   ```
   
   

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