Dump TagRouterRule (#3536)

Dump TagRouterRule since the TagRouterRule can be changed to `null` by ConfigCenter

dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/router/tag/TagRouter.java

@@ -87,7 +87,9 @@ public <T> List<Invoker<T>> route(List<Invoker<T>> invokers, URL url, Invocation
             return invokers;
         }
 
-        if (tagRouterRule == null || !tagRouterRule.isValid() || !tagRouterRule.isEnabled()) {
+        // since the rule can be changed by config center, we should copy one to use.
+        final TagRouterRule tagRouterRuleCopy = tagRouterRule;
+        if (tagRouterRuleCopy == null || !tagRouterRuleCopy.isValid() || !tagRouterRuleCopy.isEnabled()) {
             return filterUsingStaticTag(invokers, url, invocation);
         }
 
@@ -97,12 +99,12 @@ public <T> List<Invoker<T>> route(List<Invoker<T>> invokers, URL url, Invocation
 
         // if we are requesting for a Provider with a specific tag
         if (StringUtils.isNotEmpty(tag)) {
-            List<String> addresses = tagRouterRule.getTagnameToAddresses().get(tag);
+            List<String> addresses = tagRouterRuleCopy.getTagnameToAddresses().get(tag);
             // filter by dynamic tag group first
             if (CollectionUtils.isNotEmpty(addresses)) {
                 result = filterInvoker(invokers, invoker -> addressMatches(invoker.getUrl(), addresses));
                 // if result is not null OR it's null but force=true, return result directly
-                if (CollectionUtils.isNotEmpty(result) || tagRouterRule.isForce()) {
+                if (CollectionUtils.isNotEmpty(result) || tagRouterRuleCopy.isForce()) {
                     return result;
                 }
             } else {
@@ -118,13 +120,13 @@ public <T> List<Invoker<T>> route(List<Invoker<T>> invokers, URL url, Invocation
             // FAILOVER: return all Providers without any tags.
             else {
                 List<Invoker<T>> tmp = filterInvoker(invokers, invoker -> addressNotMatches(invoker.getUrl(),
-                        tagRouterRule.getAddresses()));
+                        tagRouterRuleCopy.getAddresses()));
                 return filterInvoker(tmp, invoker -> StringUtils.isEmpty(invoker.getUrl().getParameter(TAG_KEY)));
             }
         } else {
             // List<String> addresses = tagRouterRule.filter(providerApp);
             // return all addresses in dynamic tag group.
-            List<String> addresses = tagRouterRule.getAddresses();
+            List<String> addresses = tagRouterRuleCopy.getAddresses();
             if (CollectionUtils.isNotEmpty(addresses)) {
                 result = filterInvoker(invokers, invoker -> addressNotMatches(invoker.getUrl(), addresses));
                 // 1. all addresses are in dynamic tag group, return empty list.
@@ -136,17 +138,17 @@ public <T> List<Invoker<T>> route(List<Invoker<T>> invokers, URL url, Invocation
             }
             return filterInvoker(result, invoker -> {
                 String localTag = invoker.getUrl().getParameter(TAG_KEY);
-                return StringUtils.isEmpty(localTag) || !tagRouterRule.getTagNames().contains(localTag);
+                return StringUtils.isEmpty(localTag) || !tagRouterRuleCopy.getTagNames().contains(localTag);
             });
         }
     }
 
     /**
      * If there's no dynamic tag rule being set, use static tag in URL.
-     *
+     * <p>
      * A typical scenario is a Consumer using version 2.7.x calls Providers using version 2.6.x or lower,
      * the Consumer should always respect the tag in provider URL regardless of whether a dynamic tag rule has been set to it or not.
-     *
+     * <p>
      * TODO, to guarantee consistent behavior of interoperability between 2.6- and 2.7+, this method should has the same logic with the TagRouter in 2.6.x.
      *
      * @param invokers