Optimize service discovery and metadata service mechanism

dubbo-bootstrap/dubbo-bootstrap-api/src/main/java/org/apache/dubbo/bootstrap/DubboBootstrap.java

@@ -71,6 +71,7 @@
 import org.apache.dubbo.metadata.report.MetadataReportInstance;
 import org.apache.dubbo.registry.client.DefaultServiceInstance;
 import org.apache.dubbo.registry.client.ServiceDiscovery;
+import org.apache.dubbo.registry.client.ServiceDiscoveryRegistry;
 import org.apache.dubbo.registry.client.ServiceInstance;
 import org.apache.dubbo.registry.support.AbstractRegistryFactory;
 import org.apache.dubbo.rpc.Exporter;
@@ -115,6 +116,7 @@
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Consumer;
+import java.util.stream.Collectors;
 
 import static java.util.Arrays.asList;
 import static java.util.concurrent.Executors.newSingleThreadExecutor;
@@ -682,11 +684,12 @@ private void initEventListener() {
     }
 
     private List<ServiceDiscovery> getServiceDiscoveries() {
-        return Collections.unmodifiableList(
-                ExtensionLoader
-                        .getExtensionLoader(ServiceDiscovery.class)
-                        .getLoadedExtensionInstances()
-        );
+        return AbstractRegistryFactory.getRegistries()
+                .stream()
+                .filter(registry -> registry instanceof ServiceDiscoveryRegistry)
+                .map(registry -> (ServiceDiscoveryRegistry) registry)
+                .map(ServiceDiscoveryRegistry::getServiceDiscovery)
+                .collect(Collectors.toList());
     }
 
     /**
@@ -933,6 +936,9 @@ private void unreferServices() {
     }
 
     private void registerServiceInstance() {
+        if (CollectionUtils.isEmpty(getServiceDiscoveries())) {
+            return;
+        }
 
         ApplicationConfig application = getApplication();
 
@@ -957,6 +963,9 @@ private URL selectMetadataServiceExportedURL() {
 
         for (String urlValue : urlValues) {
             URL url = URL.valueOf(urlValue);
+            if (MetadataService.class.getName().equals(url.getServiceInterface())) {
+                continue;
+            }
             if ("rest".equals(url.getProtocol())) { // REST first
                 selectedURL = url;
                 break;
@@ -965,6 +974,10 @@ private URL selectMetadataServiceExportedURL() {
             }
         }
 
+        if (selectedURL == null && CollectionUtils.isNotEmpty(urlValues)) {
+            selectedURL = URL.valueOf(urlValues.iterator().next());
+        }
+
         return selectedURL;
     }
 

dubbo-bootstrap/dubbo-bootstrap-api/src/main/java/org/apache/dubbo/config/metadata/ConfigurableMetadataServiceExporter.java

@@ -33,7 +33,6 @@
 import java.util.ArrayList;
 import java.util.List;
 
-import static java.util.Arrays.asList;
 import static java.util.Collections.emptyList;
 import static org.apache.dubbo.common.constants.CommonConstants.DUBBO;
 
@@ -76,7 +75,7 @@ public ConfigurableMetadataServiceExporter export() {
             ServiceConfig<MetadataService> serviceConfig = new ServiceConfig<>();
             serviceConfig.setApplication(getApplicationConfig());
             serviceConfig.setRegistries(getRegistries());
-            serviceConfig.setProtocols(getProtocols());
+            serviceConfig.setProtocol(generateMetadataProtocol());
             serviceConfig.setInterface(MetadataService.class);
             serviceConfig.setRef(metadataService);
             serviceConfig.setGroup(getApplicationConfig().getName());
@@ -127,13 +126,10 @@ private List<RegistryConfig> getRegistries() {
         return new ArrayList<>(ApplicationModel.getConfigManager().getRegistries());
     }
 
-    private List<ProtocolConfig> getProtocols() {
-        return asList(getDefaultProtocol());
-    }
-
-    private ProtocolConfig getDefaultProtocol() {
+    private ProtocolConfig generateMetadataProtocol() {
         ProtocolConfig defaultProtocol = new ProtocolConfig();
         defaultProtocol.setName(DUBBO);
+        // defaultProtocol.setHost() ?
         // auto-increment port
         defaultProtocol.setPort(-1);
         return defaultProtocol;

dubbo-bootstrap/dubbo-bootstrap-api/src/main/java/org/apache/dubbo/config/metadata/ServiceInstancePortCustomizer.java

@@ -16,11 +16,16 @@
  */
 package org.apache.dubbo.config.metadata;
 
+import org.apache.dubbo.common.utils.CollectionUtils;
+import org.apache.dubbo.config.ProtocolConfig;
 import org.apache.dubbo.registry.client.DefaultServiceInstance;
 import org.apache.dubbo.registry.client.ServiceInstance;
 import org.apache.dubbo.registry.client.ServiceInstanceCustomizer;
 import org.apache.dubbo.rpc.model.ApplicationModel;
 
+import java.util.Collection;
+import java.util.stream.Stream;
+
 /**
  * The {@link ServiceInstanceCustomizer} to customize the {@link ServiceInstance#getPort() port} of service instance.
  *
@@ -35,17 +40,25 @@ public void customize(ServiceInstance serviceInstance) {
             return;
         }
 
-        ApplicationModel.getConfigManager()
-                .getProtocols()
-                .stream()
+        Collection<ProtocolConfig> protocols = ApplicationModel.getConfigManager()
+                .getProtocols();
+
+        if (CollectionUtils.isEmpty(protocols)) {
+            throw new IllegalStateException("We should have at least one protocol configured at this point.");
+        }
+
+        Stream<ProtocolConfig> protocolStream = protocols.stream();
+        ProtocolConfig protocolConfig = protocolStream
+                // use rest as service instance's default protocol.
+                .filter(protocol -> "rest".equals(protocol.getName()))
                 .findFirst()
-                .ifPresent(protocolConfig -> {
-                    if (serviceInstance instanceof DefaultServiceInstance) {
-                        DefaultServiceInstance instance = (DefaultServiceInstance) serviceInstance;
-                        if (protocolConfig.getPort() != null) {
-                            instance.setPort(protocolConfig.getPort());
-                        }
-                    }
-                });
+                .orElseGet(() -> protocolStream.findFirst().get());
+
+        if (serviceInstance instanceof DefaultServiceInstance) {
+            DefaultServiceInstance instance = (DefaultServiceInstance) serviceInstance;
+            if (protocolConfig.getPort() != null) {
+                instance.setPort(protocolConfig.getPort());
+            }
+        }
     }
 }

dubbo-bootstrap/dubbo-bootstrap-spring/src/main/java/org/apache/dubbo/config/spring/beans/factory/annotation/ReferenceAnnotationBeanPostProcessor.java

@@ -234,7 +234,8 @@ private InvocationHandler buildInvocationHandler(String referencedBeanName, Refe
             localReferenceBeanInvocationHandlerCache.put(referencedBeanName, handler);
         } else {
             // Remote Reference Bean should initialize immediately
-            handler.init();
+            // FIXME
+            // handler.init();
         }
 
         return handler;

dubbo-metadata/dubbo-metadata-api/src/main/java/org/apache/dubbo/metadata/store/InMemoryWritableMetadataService.java

@@ -158,7 +158,10 @@ boolean addURL(Map<String, SortedSet<URL>> serviceURLs, URL url) {
     boolean removeURL(Map<String, SortedSet<URL>> serviceURLs, URL url) {
         return executeMutually(() -> {
             String key = url.getServiceKey();
-            SortedSet<URL> urls = serviceURLs.getOrDefault(key, emptySortedSet());
+            SortedSet<URL> urls = serviceURLs.getOrDefault(key, null);
+            if (urls == null) {
+                return true;
+            }
             boolean r = urls.remove(url);
             // if it is empty
             if (urls.isEmpty()) {

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

@@ -156,6 +156,10 @@ public ServiceDiscoveryRegistry(URL registryURL) {
         this.subscribedURLsSynthesizers = initSubscribedURLsSynthesizers();
     }
 
+    public ServiceDiscovery getServiceDiscovery() {
+        return serviceDiscovery;
+    }
+
     /**
      * Get the subscribed services from the specified registry {@link URL url}
      *
@@ -744,7 +748,7 @@ private List<URL> getExportedURLs(ServiceInstance providerServiceInstance) {
             exportedURLs = toURLs(urls);
         } catch (Throwable e) {
             if (logger.isErrorEnabled()) {
-                logger.error(format("It's failed to get the exported URLs from the target service instance[%s]",
+                logger.error(format("Failed to get the exported URLs from the target service instance[%s]",
                         providerServiceInstance), e);
             }
             exportedURLs = null; // set the result to be null if failed to get
@@ -792,6 +796,12 @@ protected Set<String> getServices(URL subscribedURL) {
         if (isEmpty(serviceNames)) {
             serviceNames = findMappedServices(subscribedURL);
         }
+        if (isEmpty(serviceNames)) {
+            throw new IllegalStateException(String.format("Could not resolve interface %s for its application (service), " +
+                    "you should either specify service name explicitly or make sure there's at least one active provider " +
+                    " instance and it has registered the service-app mapping info to config center automatically. \n" +
+                    "The full subscribing url is %s", subscribedURL.getServiceInterface(), subscribedURL));
+        }
         return serviceNames;
     }
 

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

@@ -22,15 +22,9 @@
 import org.apache.dubbo.registry.client.ServiceInstanceCustomizer;
 import org.apache.dubbo.registry.client.event.ServiceInstancePreRegisteredEvent;
 
-import java.util.ServiceLoader;
-
 /**
- * An {@link EventListener event listener} to customize {@link ServiceInstance the service instance} by the instances of
- * {@link ServiceInstanceCustomizer} {@link ServiceLoader SPI}.
+ * Customize the {@link ServiceInstance} before registering to Registry.
  *
- * @see EventListener
- * @see ServiceInstancePreRegisteredEvent
- * @see ServiceInstanceCustomizer
  * @since 2.7.4
  */
 public class CustomizableServiceInstanceListener implements EventListener<ServiceInstancePreRegisteredEvent> {
@@ -39,6 +33,7 @@ public class CustomizableServiceInstanceListener implements EventListener<Servic
     public void onEvent(ServiceInstancePreRegisteredEvent event) {
         ExtensionLoader<ServiceInstanceCustomizer> loader =
                 ExtensionLoader.getExtensionLoader(ServiceInstanceCustomizer.class);
+        // FIXME, sort customizer before apply
         loader.getSupportedExtensionInstances().forEach(customizer -> {
             // customizes
             customizer.customize(event.getServiceInstance());

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

@@ -18,18 +18,13 @@
 
 import org.apache.dubbo.common.URL;
 import org.apache.dubbo.common.extension.SPI;
-import org.apache.dubbo.metadata.MetadataService;
 import org.apache.dubbo.registry.client.ServiceInstance;
 
 import java.util.List;
-import java.util.ServiceLoader;
 
 /**
- * The builder interface of {@link MetadataService} to build {@link URL URLs}, the multiple implementations
- * will be loaded by Java standard {@link ServiceLoader} and {@link #composite() composited},
- * whose building {@link URL URLs} will be aggregated
+ * Used to build metadata service url from ServiceInstance.
  *
- * @see CompositeMetadataServiceURLBuilder
  * @since 2.7.4
  */
 @SPI
@@ -39,17 +34,7 @@ public interface MetadataServiceURLBuilder {
      * Build the {@link URL URLs} from the specified {@link ServiceInstance}
      *
      * @param serviceInstance {@link ServiceInstance}
-     * @return non-null
+     * @return TODO, usually, we generate one metadata url from one instance. There's no scenario to return a metadta url list.
      */
     List<URL> build(ServiceInstance serviceInstance);
-
-    /**
-     * Get the composite implementation of {@link MetadataServiceURLBuilder}
-     *
-     * @return the instance of {@link CompositeMetadataServiceURLBuilder}
-     * @see CompositeMetadataServiceURLBuilder
-     */
-    static MetadataServiceURLBuilder composite() {
-        return new CompositeMetadataServiceURLBuilder();
-    }
 }

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

@@ -17,14 +17,18 @@
 package org.apache.dubbo.registry.client.metadata;
 
 import org.apache.dubbo.common.URL;
+import org.apache.dubbo.metadata.MetadataService;
 import org.apache.dubbo.metadata.WritableMetadataService;
 import org.apache.dubbo.registry.client.ServiceInstance;
 import org.apache.dubbo.registry.client.ServiceInstanceCustomizer;
 import org.apache.dubbo.rpc.Protocol;
 
+import java.util.HashMap;
+import java.util.Map;
+
 import static org.apache.dubbo.metadata.WritableMetadataService.getExtension;
 import static org.apache.dubbo.registry.client.metadata.ServiceInstanceMetadataUtils.getMetadataStorageType;
-import static org.apache.dubbo.registry.client.metadata.ServiceInstanceMetadataUtils.setProtocolPort;
+import static org.apache.dubbo.registry.client.metadata.ServiceInstanceMetadataUtils.setEndpoints;
 
 /**
  * A Class to customize the ports of {@link Protocol protocols} into
@@ -41,11 +45,16 @@ public void customize(ServiceInstance serviceInstance) {
 
         WritableMetadataService writableMetadataService = getExtension(metadataStoredType);
 
+        Map<String, Integer> protocols = new HashMap<>();
         writableMetadataService.getExportedURLs()
                 .stream()
                 .map(URL::valueOf)
+                .filter(url -> !MetadataService.class.getName().equals(url.getServiceInterface()))
                 .forEach(url -> {
-                    setProtocolPort(serviceInstance, url.getProtocol(), url.getPort());
+                    // TODO, same protocol listen on different ports will override with each other.
+                    protocols.put(url.getProtocol(), url.getPort());
                 });
+
+        setEndpoints(serviceInstance, protocols);
     }
 }