[3.0] fix service discovery implementation and introduce ClusterFiIlter

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

@@ -65,4 +65,8 @@ default boolean isServiceDiscovery() {
     void discordAddresses();
 
     RouterChain<T> getRouterChain();
+
+    default boolean isNotificationReceived() {
+        return false;
+    }
 }

dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/filter/ClusterFilter.java

@@ -0,0 +1,24 @@
+/*
+ * 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 org.apache.dubbo.rpc.cluster.filter;
+
+import org.apache.dubbo.common.extension.SPI;
+import org.apache.dubbo.rpc.BaseFilter;
+
+@SPI
+public interface ClusterFilter extends BaseFilter {
+}

dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/filter/DefaultFilterChainBuilder.java

@@ -27,6 +27,9 @@
 @Activate(order = 0)
 public class DefaultFilterChainBuilder implements FilterChainBuilder {
 
+    /**
+     * build consumer/provider filter chain
+     */
     @Override
     public <T> Invoker<T> buildInvokerChain(final Invoker<T> originalInvoker, String key, String group) {
         Invoker<T> last = originalInvoker;
@@ -43,14 +46,17 @@ public <T> Invoker<T> buildInvokerChain(final Invoker<T> originalInvoker, String
         return last;
     }
 
+    /**
+     * build consumer cluster filter chain
+     */
     @Override
     public <T> ClusterInvoker<T> buildClusterInvokerChain(final ClusterInvoker<T> originalInvoker, String key, String group) {
         ClusterInvoker<T> last = originalInvoker;
-        List<Filter> filters = ExtensionLoader.getExtensionLoader(Filter.class).getActivateExtension(originalInvoker.getUrl(), key, group);
+        List<ClusterFilter> filters = ExtensionLoader.getExtensionLoader(ClusterFilter.class).getActivateExtension(originalInvoker.getUrl(), key, group);
 
         if (!filters.isEmpty()) {
             for (int i = filters.size() - 1; i >= 0; i--) {
-                final Filter filter = filters.get(i);
+                final ClusterFilter filter = filters.get(i);
                 final Invoker<T> next = last;
                 last = new ClusterFilterChainNode<>(originalInvoker, next, filter);
             }

dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/filter/FilterChainBuilder.java

@@ -18,6 +18,7 @@
 
 import org.apache.dubbo.common.URL;
 import org.apache.dubbo.common.extension.SPI;
+import org.apache.dubbo.rpc.BaseFilter;
 import org.apache.dubbo.rpc.Filter;
 import org.apache.dubbo.rpc.Invocation;
 import org.apache.dubbo.rpc.Invoker;
@@ -29,16 +30,27 @@
 
 @SPI("default")
 public interface FilterChainBuilder {
+    /**
+     * build consumer/provider filter chain
+     */
     <T> Invoker<T> buildInvokerChain(final Invoker<T> invoker, String key, String group);
 
+    /**
+     * build consumer cluster filter chain
+     */
     <T> ClusterInvoker<T> buildClusterInvokerChain(final ClusterInvoker<T> invoker, String key, String group);
 
-    class FilterChainNode<T, TYPE extends Invoker<T>> implements Invoker<T>{
+    /**
+     * Works on provider side
+     * @param <T>
+     * @param <TYPE>
+     */
+    class FilterChainNode<T, TYPE extends Invoker<T>, FILTER extends BaseFilter> implements Invoker<T>{
         TYPE originalInvoker;
         Invoker<T> nextNode;
-        Filter filter;
+        FILTER filter;
 
-        public FilterChainNode(TYPE originalInvoker, Invoker<T> nextNode, Filter filter) {
+        public FilterChainNode(TYPE originalInvoker, Invoker<T> nextNode, FILTER filter) {
             this.originalInvoker = originalInvoker;
             this.nextNode = nextNode;
             this.filter = filter;
@@ -79,8 +91,8 @@ public Result invoke(Invocation invocation) throws RpcException {
                     } finally {
                         listenableFilter.removeListener(invocation);
                     }
-                } else if (filter instanceof Filter.Listener) {
-                    Filter.Listener listener = (Filter.Listener) filter;
+                } else if (filter instanceof FILTER.Listener) {
+                    FILTER.Listener listener = (FILTER.Listener) filter;
                     listener.onError(e, originalInvoker, invocation);
                 }
                 throw e;
@@ -102,8 +114,8 @@ public Result invoke(Invocation invocation) throws RpcException {
                     } finally {
                         listenableFilter.removeListener(invocation);
                     }
-                } else if (filter instanceof Filter.Listener) {
-                    Filter.Listener listener = (Filter.Listener) filter;
+                } else if (filter instanceof FILTER.Listener) {
+                    FILTER.Listener listener = (FILTER.Listener) filter;
                     if (t == null) {
                         listener.onResponse(r, originalInvoker, invocation);
                     } else {
@@ -124,8 +136,14 @@ public String toString() {
         }
     }
 
-    class ClusterFilterChainNode<T, TYPE extends ClusterInvoker<T>> extends FilterChainNode<T, TYPE> implements ClusterInvoker<T> {
-        public ClusterFilterChainNode(TYPE originalInvoker, Invoker<T> nextNode, Filter filter) {
+    /**
+     * Works on consumer side
+     * @param <T>
+     * @param <TYPE>
+     */
+    class ClusterFilterChainNode<T, TYPE extends ClusterInvoker<T>, FILTER extends BaseFilter>
+            extends FilterChainNode<T, TYPE, FILTER> implements ClusterInvoker<T> {
+        public ClusterFilterChainNode(TYPE originalInvoker, Invoker<T> nextNode, FILTER filter) {
             super(originalInvoker, nextNode, filter);
         }
 

dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/filter/ProtocolFilterWrapper.java

@@ -28,10 +28,9 @@
 import org.apache.dubbo.rpc.RpcException;
 
 import java.util.List;
-import java.util.Objects;
 
+import static org.apache.dubbo.common.constants.CommonConstants.REFERENCE_FILTER_KEY;
 import static org.apache.dubbo.common.constants.CommonConstants.SERVICE_FILTER_KEY;
-import static org.apache.dubbo.rpc.cluster.Constants.PEER_KEY;
 
 /**
  * ListenerProtocol
@@ -68,11 +67,7 @@ public <T> Invoker<T> refer(Class<T> type, URL url) throws RpcException {
         if (UrlUtils.isRegistry(url)) {
             return protocol.refer(type, url);
         }
-        // if it's peer-to-peer url
-        if (!Objects.isNull(url.getAttribute(PEER_KEY))) {
-            return builder.buildInvokerChain(protocol.refer(type, url), SERVICE_FILTER_KEY, CommonConstants.CONSUMER);
-        }
-        return protocol.refer(type, url);
+        return builder.buildInvokerChain(protocol.refer(type, url), REFERENCE_FILTER_KEY, CommonConstants.CONSUMER);
     }
 
     @Override

dubbo-rpc/dubbo-rpc-api/src/main/java/org/apache/dubbo/rpc/filter/ConsumerContextFilter.java → dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/filter/support/ConsumerContextFilter.java

@@ -14,7 +14,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.apache.dubbo.rpc.filter;
+package org.apache.dubbo.rpc.cluster.filter.support;
 
 import org.apache.dubbo.common.extension.Activate;
 import org.apache.dubbo.common.utils.CollectionUtils;
@@ -28,6 +28,7 @@
 import org.apache.dubbo.rpc.RpcException;
 import org.apache.dubbo.rpc.RpcInvocation;
 import org.apache.dubbo.rpc.TimeoutCountDown;
+import org.apache.dubbo.rpc.cluster.filter.ClusterFilter;
 
 import java.util.Map;
 
@@ -39,11 +40,11 @@
  * ConsumerContextFilter set current RpcContext with invoker,invocation, local host, remote host and port
  * for consumer invoker.It does it to make the requires info available to execution thread's RpcContext.
  *
- * @see org.apache.dubbo.rpc.Filter
+ * @see Filter
  * @see RpcContext
  */
 @Activate(group = CONSUMER, order = -10000)
-public class ConsumerContextFilter implements Filter {
+public class ConsumerContextFilter implements ClusterFilter, ClusterFilter.Listener {
 
     @Override
     public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
@@ -76,7 +77,24 @@ public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcExcept
                                 + invocation.getMethodName() + ", terminate directly."), invocation);
             }
         }
-        return invoker.invoke(invocation);
+
+        try {
+            RpcContext.removeServerContext();
+            return invoker.invoke(invocation);
+        } finally {
+            RpcContext.removeContext();
+        }
+    }
+
+    @Override
+    public void onResponse(Result appResponse, Invoker<?> invoker, Invocation invocation) {
+        // pass attachments to result
+        RpcContext.getServerContext().setObjectAttachments(appResponse.getObjectAttachments());
+    }
+
+    @Override
+    public void onError(Throwable t, Invoker<?> invoker, Invocation invocation) {
+
     }
 
 }

dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/interceptor/ZoneAwareClusterInterceptor.java → dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/filter/support/ZoneAwareFilter.java

@@ -14,15 +14,19 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.apache.dubbo.rpc.cluster.interceptor;
+package org.apache.dubbo.rpc.cluster.filter.support;
 
+import org.apache.dubbo.common.constants.CommonConstants;
 import org.apache.dubbo.common.extension.Activate;
 import org.apache.dubbo.common.extension.ExtensionLoader;
 import org.apache.dubbo.common.utils.StringUtils;
 import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.Result;
 import org.apache.dubbo.rpc.RpcContext;
+import org.apache.dubbo.rpc.RpcException;
 import org.apache.dubbo.rpc.ZoneDetector;
-import org.apache.dubbo.rpc.cluster.support.AbstractClusterInvoker;
+import org.apache.dubbo.rpc.cluster.filter.ClusterFilter;
 
 import static org.apache.dubbo.common.constants.RegistryConstants.REGISTRY_ZONE;
 import static org.apache.dubbo.common.constants.RegistryConstants.REGISTRY_ZONE_FORCE;
@@ -32,11 +36,11 @@
  *
  * active only when url has key 'cluster=zone-aware'
  */
-@Activate(value = "cluster:zone-aware")
-public class ZoneAwareClusterInterceptor implements ClusterInterceptor {
+@Activate(group = CommonConstants.CONSUMER, value = "cluster:zone-aware")
+public class ZoneAwareFilter implements ClusterFilter {
 
     @Override
-    public void before(AbstractClusterInvoker<?> clusterInvoker, Invocation invocation) {
+    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
         RpcContext rpcContext = RpcContext.getContext();
         String zone = (String) rpcContext.getAttachment(REGISTRY_ZONE);
         String force = (String) rpcContext.getAttachment(REGISTRY_ZONE_FORCE);
@@ -53,10 +57,7 @@ public void before(AbstractClusterInvoker<?> clusterInvoker, Invocation invocati
         if (StringUtils.isNotEmpty(force)) {
             invocation.setAttachment(REGISTRY_ZONE_FORCE, force);
         }
-    }
-
-    @Override
-    public void after(AbstractClusterInvoker<?> clusterInvoker, Invocation invocation) {
 
+        return invoker.invoke(invocation);
     }
 }

dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/interceptor/ClusterInterceptor.java

@@ -26,6 +26,7 @@
 /**
  * Different from {@link Filter}, ClusterInterceptor works at the outmost layer, before one specific address/invoker is picked.
  */
+@Deprecated
 @SPI
 public interface ClusterInterceptor {