Merge pull request apache#3083 beiwei30/incubator-dubbo, more code re…

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* refactor ScriptRouter

* refactor TagRouter

* refactor AbstractConfiguratorListener

* make sure parameter should not be null

* correct comments

* make ReferenceConfigurationListener private static

* avoid dup code in init

* add fixme for potential useless code

* clean up useless variables

* move methods into UrlUtils

* make method private

* reformat javadoc

* avoid dup code

* reformat log message

* reformat log message

* reformat the code

* remove useless imports

* remove useless code

* refactor ScriptRouter

* refactor TagRouter

* refactor AbstractConfiguratorListener

* Add comment

* Fix UT

* make sure parameter should not be null

* correct comments

* make ReferenceConfigurationListener private static

* Revert demo changes

* Revert code to avoid NPE in RPC wire after providers are cleared.

* make ListenableRouter code thread safe

* Fix UT

* Remove assert check to continue with execute.

* avoid dup code in init

* solve compile error

* add fixme for potential useless code

* clean up useless variables

* move methods into UrlUtils

* make method private

* reformat javadoc

* avoid dup code

* reformat log message

* reformat log message

* reformat the code

* remove useless imports

* remove useless code

* code review comments from @khanimteyaz

* code review from @khanimteyaz

dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/RouterChain.java

@@ -67,10 +67,6 @@ public void initWithRouters(List<Router> builtinRouters) {
         this.sort();
     }
 
-    public void addRouter(Router router) {
-        this.routers.add(router);
-    }
-
     /**
      * If we use route:// protocol in version before 2.7.0, each URL will generate a Router instance, so we should
      * keep the routers up to date, that is, each time router URLs changes, we should update the routers list, only

dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/directory/AbstractDirectory.java

@@ -28,7 +28,7 @@
 import org.apache.dubbo.rpc.cluster.Router;
 import org.apache.dubbo.rpc.cluster.RouterChain;
 
-import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 
@@ -96,8 +96,7 @@ public void setRouterChain(RouterChain<T> routerChain) {
     }
 
     protected void addRouters(List<Router> routers) {
-        // copy list
-        routers = routers == null ? new ArrayList<>() : new ArrayList<>(routers);
+        routers = routers == null ? Collections.emptyList() : routers;
         routerChain.addRouters(routers);
     }
 

dubbo-common/src/main/java/org/apache/dubbo/common/utils/UrlUtils.java

@@ -27,6 +27,14 @@
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
+import static org.apache.dubbo.common.Constants.CATEGORY_KEY;
+import static org.apache.dubbo.common.Constants.CONFIGURATORS_CATEGORY;
+import static org.apache.dubbo.common.Constants.DEFAULT_CATEGORY;
+import static org.apache.dubbo.common.Constants.OVERRIDE_PROTOCOL;
+import static org.apache.dubbo.common.Constants.PROVIDERS_CATEGORY;
+import static org.apache.dubbo.common.Constants.ROUTERS_CATEGORY;
+import static org.apache.dubbo.common.Constants.ROUTE_PROTOCOL;
+
 public class UrlUtils {
 
     /**
@@ -343,14 +351,14 @@ public static URL getEmptyUrl(String service, String category) {
             service = service.substring(0, i);
         }
         return URL.valueOf(Constants.EMPTY_PROTOCOL + "://0.0.0.0/" + service + URL_PARAM_STARTING_SYMBOL
-                + Constants.CATEGORY_KEY + "=" + category
+                + CATEGORY_KEY + "=" + category
                 + (group == null ? "" : "&" + Constants.GROUP_KEY + "=" + group)
                 + (version == null ? "" : "&" + Constants.VERSION_KEY + "=" + version));
     }
 
     public static boolean isMatchCategory(String category, String categories) {
         if (categories == null || categories.length() == 0) {
-            return Constants.DEFAULT_CATEGORY.equals(category);
+            return DEFAULT_CATEGORY.equals(category);
         } else if (categories.contains(Constants.ANY_VALUE)) {
             return true;
         } else if (categories.contains(Constants.REMOVE_VALUE_PREFIX)) {
@@ -370,8 +378,8 @@ public static boolean isMatch(URL consumerUrl, URL providerUrl) {
             return false;
         }
 
-        if (!isMatchCategory(providerUrl.getParameter(Constants.CATEGORY_KEY, Constants.DEFAULT_CATEGORY),
-                consumerUrl.getParameter(Constants.CATEGORY_KEY, Constants.DEFAULT_CATEGORY))) {
+        if (!isMatchCategory(providerUrl.getParameter(CATEGORY_KEY, DEFAULT_CATEGORY),
+                consumerUrl.getParameter(CATEGORY_KEY, DEFAULT_CATEGORY))) {
             return false;
         }
         if (!providerUrl.getParameter(Constants.ENABLED_KEY, true)
@@ -445,6 +453,22 @@ public static List<URL> classifyUrls(List<URL> urls, Predicate<URL> predicate) {
         return urls.stream().filter(predicate).collect(Collectors.toList());
     }
 
+    public static boolean isConfigurator(URL url) {
+        return OVERRIDE_PROTOCOL.equals(url.getProtocol()) ||
+                CONFIGURATORS_CATEGORY.equals(url.getParameter(CATEGORY_KEY, DEFAULT_CATEGORY));
+    }
+
+    public static boolean isRoute(URL url) {
+        return ROUTE_PROTOCOL.equals(url.getProtocol()) ||
+                ROUTERS_CATEGORY.equals(url.getParameter(CATEGORY_KEY, DEFAULT_CATEGORY));
+    }
+
+    public static boolean isProvider(URL url) {
+        return !OVERRIDE_PROTOCOL.equals(url.getProtocol()) &&
+                !ROUTE_PROTOCOL.equals(url.getProtocol()) &&
+                PROVIDERS_CATEGORY.equals(url.getParameter(CATEGORY_KEY, PROVIDERS_CATEGORY));
+    }
+
     /**
      * Check if the given value matches the given pattern. The pattern supports wildcard "*".
      *
@@ -459,4 +483,4 @@ static boolean isItemMatch(String pattern, String value) {
             return "*".equals(pattern) || pattern.equals(value);
         }
     }
-}
+}