Polish apache#3942 : Add Event Publishing ServiceRegistry implementation

dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/client/EventPublishingServiceRegistry.java

@@ -0,0 +1,145 @@
+/*
+ * 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.registry.client;
+
+import org.apache.dubbo.common.event.Event;
+import org.apache.dubbo.common.event.EventDispatcher;
+import org.apache.dubbo.common.event.EventListener;
+import org.apache.dubbo.registry.client.event.ServiceInstancePreRegisteredEvent;
+import org.apache.dubbo.registry.client.event.ServiceInstanceRegisteredEvent;
+
+import java.util.List;
+import java.util.Optional;
+
+import static java.util.Optional.empty;
+import static java.util.Optional.of;
+
+/**
+ * The abstract {@link ServiceRegistry} implementation publishes the {@link Event Dubbo event} on methods executing.
+ *
+ * @since 2.7.2
+ */
+public abstract class EventPublishingServiceRegistry implements ServiceRegistry {
+
+    private final EventDispatcher eventDispatcher = EventDispatcher.getDefaultExtension();
+
+    @Override
+    public final void register(ServiceInstance serviceInstance) throws RuntimeException {
+        executeWithEvents(
+                of(new ServiceInstancePreRegisteredEvent(this, serviceInstance)),
+                () -> doRegister(serviceInstance),
+                of(new ServiceInstanceRegisteredEvent(this, serviceInstance))
+        );
+    }
+
+    @Override
+    public final void update(ServiceInstance serviceInstance) throws RuntimeException {
+        // TODO publish event
+        executeWithEvents(
+                empty(),
+                () -> doUpdate(serviceInstance),
+                empty()
+        );
+    }
+
+    @Override
+    public final void unregister(ServiceInstance serviceInstance) throws RuntimeException {
+        // TODO publish event
+        executeWithEvents(
+                empty(),
+                () -> doUnregister(serviceInstance),
+                empty()
+        );
+    }
+
+    @Override
+    public final void start() {
+        // TODO publish event
+        executeWithEvents(
+                empty(),
+                this::doStart,
+                empty()
+        );
+    }
+
+    @Override
+    public final void stop() {
+        // TODO publish event
+        executeWithEvents(
+                empty(),
+                this::doStop,
+                empty()
+        );
+    }
+
+    protected final void executeWithEvents(Optional<? extends Event> beforeEvent,
+                                           Runnable action,
+                                           Optional<? extends Event> afterEvent) {
+        beforeEvent.ifPresent(eventDispatcher::dispatch);
+        action.run();
+        afterEvent.ifPresent(eventDispatcher::dispatch);
+    }
+
+    /**
+     * Registers an instance of {@link ServiceInstance}.
+     *
+     * @param serviceInstance an instance of {@link ServiceInstance} to be registered
+     * @throws RuntimeException if failed
+     */
+    protected abstract void doRegister(ServiceInstance serviceInstance) throws RuntimeException;
+
+    /**
+     * Updates the registered {@link ServiceInstance}.
+     *
+     * @param serviceInstance the registered {@link ServiceInstance}
+     * @throws RuntimeException if failed
+     */
+    protected abstract void doUpdate(ServiceInstance serviceInstance) throws RuntimeException;
+
+    /**
+     * Unregisters an instance of {@link ServiceInstance}.
+     *
+     * @param serviceInstance an instance of {@link ServiceInstance} to be deregistered
+     * @throws RuntimeException if failed
+     */
+    protected abstract void doUnregister(ServiceInstance serviceInstance) throws RuntimeException;
+
+    /**
+     * Starts the ServiceRegistry. This is a lifecycle method.
+     */
+    protected abstract void doStart();
+
+    /**
+     * Stops the ServiceRegistry. This is a lifecycle method.
+     */
+    protected abstract void doStop();
+
+    @Override
+    public void addEventListener(EventListener<?> listener) throws NullPointerException, IllegalArgumentException {
+        eventDispatcher.addEventListener(listener);
+    }
+
+    @Override
+    public void removeEventListener(EventListener<?> listener) throws NullPointerException, IllegalArgumentException {
+        eventDispatcher.removeEventListener(listener);
+    }
+
+    @Override
+    public List<EventListener<?>> getAllEventListeners() {
+        return eventDispatcher.getAllEventListeners();
+    }
+}

dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/client/ServiceRegistry.java

@@ -16,12 +16,14 @@
  */
 package org.apache.dubbo.registry.client;
 
+import org.apache.dubbo.common.event.Listenable;
+
 /**
  * The common interface to register and unregister for a service registry
  *
  * @since 2.7.2
  */
-public interface ServiceRegistry {
+public interface ServiceRegistry extends Listenable {
 
     /**
      * A human-readable description of the implementation

dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/client/event/ServiceInstanceEvent.java

@@ -0,0 +1,47 @@
+/*
+ * 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.registry.client.event;
+
+import org.apache.dubbo.common.event.Event;
+import org.apache.dubbo.registry.client.ServiceInstance;
+
+/**
+ * The {@link Event Dubbo event} for {@link ServiceInstance an service instance}
+ *
+ * @since 2.7.2
+ */
+public abstract class ServiceInstanceEvent extends Event {
+
+    private final ServiceInstance serviceInstance;
+
+    /**
+     * @param serviceInstance {@link ServiceInstance an service instance}
+     */
+    public ServiceInstanceEvent(Object source, ServiceInstance serviceInstance) {
+        super(source);
+        this.serviceInstance = serviceInstance;
+    }
+
+    /**
+     * Get current {@link ServiceInstance service instance}
+     *
+     * @return current {@link ServiceInstance service instance}
+     */
+    public ServiceInstance getServiceInstance() {
+        return serviceInstance;
+    }
+}

dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/client/event/ServiceInstancePreRegisteredEvent.java

@@ -0,0 +1,33 @@
+/*
+ * 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.registry.client.event;
+
+import org.apache.dubbo.registry.client.ServiceInstance;
+import org.apache.dubbo.registry.client.ServiceRegistry;
+
+
+/**
+ * The before-{@link ServiceRegistry#register(ServiceInstance) register} event for {@link ServiceInstance}
+ *
+ * @since 2.7.2
+ */
+public class ServiceInstancePreRegisteredEvent extends ServiceInstanceEvent {
+
+    public ServiceInstancePreRegisteredEvent(Object source, ServiceInstance serviceInstance) {
+        super(source, serviceInstance);
+    }
+}

dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/client/event/ServiceInstanceRegisteredEvent.java

@@ -0,0 +1,33 @@
+/*
+ * 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.registry.client.event;
+
+import org.apache.dubbo.registry.client.ServiceInstance;
+import org.apache.dubbo.registry.client.ServiceRegistry;
+
+
+/**
+ * The after-{@link ServiceRegistry#register(ServiceInstance) register} event for {@link ServiceInstance}
+ *
+ * @since 2.7.2
+ */
+public class ServiceInstanceRegisteredEvent extends ServiceInstanceEvent {
+
+    public ServiceInstanceRegisteredEvent(Object source, ServiceInstance serviceInstance) {
+        super(source, serviceInstance);
+    }
+}

dubbo-registry/dubbo-registry-api/src/test/java/org/apache/dubbo/registry/client/DefaultServiceInstanceTest.java

@@ -29,26 +29,26 @@
  */
 public class DefaultServiceInstanceTest {
 
-    private final DefaultServiceInstance serviceInstance =
+    public static final DefaultServiceInstance INSTANCE =
             new DefaultServiceInstance("A", "127.0.0.1", 8080);
 
     @Test
     public void testDefaultValues() {
-        assertTrue(serviceInstance.isEnabled());
-        assertTrue(serviceInstance.isHealthy());
-        assertTrue(serviceInstance.getMetadata().isEmpty());
+        assertTrue(INSTANCE.isEnabled());
+        assertTrue(INSTANCE.isHealthy());
+        assertTrue(INSTANCE.getMetadata().isEmpty());
     }
 
     @Test
     public void testSetAndGetValues() {
-        serviceInstance.setEnabled(false);
-        serviceInstance.setHealthy(false);
+        INSTANCE.setEnabled(false);
+        INSTANCE.setHealthy(false);
 
-        assertEquals("A", serviceInstance.getServiceName());
-        assertEquals("127.0.0.1", serviceInstance.getHost());
-        assertEquals(8080, serviceInstance.getPort());
-        assertFalse(serviceInstance.isEnabled());
-        assertFalse(serviceInstance.isHealthy());
-        assertTrue(serviceInstance.getMetadata().isEmpty());
+        assertEquals("A", INSTANCE.getServiceName());
+        assertEquals("127.0.0.1", INSTANCE.getHost());
+        assertEquals(8080, INSTANCE.getPort());
+        assertFalse(INSTANCE.isEnabled());
+        assertFalse(INSTANCE.isHealthy());
+        assertTrue(INSTANCE.getMetadata().isEmpty());
     }
 }