Split bean registration and creation for stubs

GrpcClientRegistry was responsible for both, which causes lifecycle
issues when users don't follow recommendations. This change
pushes the bean registration firmly down a level into an
ImportBeanDefinitionRegistrar. Also helps with AOT because the AOT
processor only runs the IBDR at build time.

Author: Dave Syer

samples/grpc-oauth2/src/test/java/org/springframework/grpc/sample/GrpcServerApplicationTests.java

@@ -22,7 +22,7 @@
 import org.springframework.experimental.boot.test.context.OAuth2ClientProviderIssuerUri;
 import org.springframework.grpc.client.ChannelBuilderOptions;
 import org.springframework.grpc.client.ImportGrpcClients;
-import org.springframework.grpc.client.GrpcClientRegistryCustomizer;
+import org.springframework.grpc.client.GrpcClientFactoryCustomizer;
 import org.springframework.grpc.client.interceptor.security.BearerTokenAuthenticationInterceptor;
 import org.springframework.grpc.sample.proto.HelloReply;
 import org.springframework.grpc.sample.proto.HelloRequest;
@@ -41,7 +41,7 @@
 import io.grpc.stub.StreamObserver;
 
 @SpringBootTest(properties = { "spring.grpc.server.port=0",
-		"spring.grpc.client.channels.stub.address=static://0.0.0.0:${local.grpc.port}" })
+		"spring.grpc.client.default-channel.address=static://0.0.0.0:${local.grpc.port}" })
 @DirtiesContext
 public class GrpcServerApplicationTests {
 
@@ -115,6 +115,7 @@ void authenticated() {
 	@EnableDynamicProperty
 	@ImportGrpcClients(target = "stub",
 			types = { SimpleGrpc.SimpleBlockingStub.class, ServerReflectionGrpc.ServerReflectionStub.class })
+	@ImportGrpcClients(target = "secure", prefix = "secure", types = { SimpleGrpc.SimpleBlockingStub.class })
 	static class ExtraConfiguration {
 
 		private String token;
@@ -129,13 +130,9 @@ static CommonsExecWebServerFactoryBean authServer() {
 		}
 
 		@Bean
-		GrpcClientRegistryCustomizer stubs(ObjectProvider<ClientRegistrationRepository> context) {
-			return registry -> registry
-				.channel("stub",
-						ChannelBuilderOptions.defaults()
-							.withInterceptors(List.of(new BearerTokenAuthenticationInterceptor(() -> token(context)))))
-				.prefix("secure")
-				.register(SimpleGrpc.SimpleBlockingStub.class);
+		GrpcClientFactoryCustomizer stubs(ObjectProvider<ClientRegistrationRepository> context) {
+			return registry -> registry.channel("secure", ChannelBuilderOptions.defaults()
+				.withInterceptors(List.of(new BearerTokenAuthenticationInterceptor(() -> token(context)))));
 		}
 
 		private String token(ObjectProvider<ClientRegistrationRepository> context) {

samples/grpc-secure/src/test/java/org/springframework/grpc/sample/GrpcServerApplicationTests.java

@@ -15,10 +15,9 @@
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.context.TestConfiguration;
 import org.springframework.context.annotation.Bean;
-import org.springframework.grpc.client.BlockingStubFactory;
 import org.springframework.grpc.client.ChannelBuilderOptions;
+import org.springframework.grpc.client.GrpcClientFactoryCustomizer;
 import org.springframework.grpc.client.ImportGrpcClients;
-import org.springframework.grpc.client.GrpcClientRegistryCustomizer;
 import org.springframework.grpc.client.interceptor.security.BasicAuthenticationInterceptor;
 import org.springframework.grpc.sample.proto.HelloReply;
 import org.springframework.grpc.sample.proto.HelloRequest;
@@ -109,17 +108,14 @@ void basic() {
 
 	@TestConfiguration(proxyBeanMethods = false)
 	@ImportGrpcClients(target = "stub", prefix = "unsecured", types = { SimpleGrpc.SimpleBlockingStub.class })
+	@ImportGrpcClients(target = "secure", types = { SimpleGrpc.SimpleBlockingStub.class })
 	@ImportGrpcClients(target = "default", types = { ServerReflectionGrpc.ServerReflectionStub.class })
 	static class ExtraConfiguration {
 
 		@Bean
-		GrpcClientRegistryCustomizer basicStubs() {
-			return registry -> registry
-				.channel("stub",
-						ChannelBuilderOptions.defaults()
-							.withInterceptors(List.of(new BasicAuthenticationInterceptor("user", "user"))))
-				.scan(BlockingStubFactory.class)
-				.packageClasses(SimpleGrpc.class);
+		GrpcClientFactoryCustomizer basicStubs() {
+			return registry -> registry.channel("secure", ChannelBuilderOptions.defaults()
+				.withInterceptors(List.of(new BasicAuthenticationInterceptor("user", "user"))));
 		}
 
 	}

spring-grpc-core/src/main/java/org/springframework/grpc/client/AbstractGrpcClientRegistrar.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2024-2024 the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      https://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.springframework.grpc.client;
+
+import org.springframework.beans.factory.support.BeanDefinitionRegistry;
+import org.springframework.beans.factory.support.RootBeanDefinition;
+import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
+import org.springframework.core.type.AnnotationMetadata;
+import org.springframework.grpc.client.GrpcClientFactory.GrpcClientRegistrationSpec;
+
+public abstract class AbstractGrpcClientRegistrar implements ImportBeanDefinitionRegistrar {
+
+	@Override
+	public final void registerBeanDefinitions(AnnotationMetadata meta, BeanDefinitionRegistry registry) {
+		GrpcClientRegistrationSpec[] specs = collect(meta);
+		String name = GrpcClientFactoryPostProcessor.class.getName();
+		for (GrpcClientRegistrationSpec spec : specs) {
+			GrpcClientFactory.register(registry, spec);
+		}
+		if (!registry.containsBeanDefinition(name)) {
+			registry.registerBeanDefinition(name, new RootBeanDefinition(GrpcClientFactoryPostProcessor.class));
+		}
+	}
+
+	protected abstract GrpcClientRegistrationSpec[] collect(AnnotationMetadata meta);
+
+}

spring-grpc-core/src/main/java/org/springframework/grpc/client/AnnotationGrpcClientRegistrar.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2024-2024 the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      https://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.springframework.grpc.client;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.springframework.core.annotation.AnnotationAttributes;
+import org.springframework.core.type.AnnotationMetadata;
+import org.springframework.grpc.client.GrpcClientFactory.GrpcClientRegistrationSpec;
+import org.springframework.util.ClassUtils;
+
+public class AnnotationGrpcClientRegistrar extends AbstractGrpcClientRegistrar {
+
+	@Override
+	protected GrpcClientRegistrationSpec[] collect(AnnotationMetadata meta) {
+		Set<AnnotationAttributes> attrs = meta.getMergedRepeatableAnnotationAttributes(ImportGrpcClients.class,
+				ImportGrpcClients.Container.class, false);
+		Set<GrpcClientRegistrationSpec> specs = new HashSet<>();
+		for (AnnotationAttributes attr : attrs) {
+			specs.add(register(meta, attr));
+		}
+		return specs.toArray(new GrpcClientRegistrationSpec[0]);
+	}
+
+	private GrpcClientRegistrationSpec register(AnnotationMetadata meta, AnnotationAttributes attr) {
+		String target = attr.getString("target");
+		String prefix = attr.getString("prefix");
+		Class<?>[] types = attr.getClassArray("types");
+		Class<?>[] basePackageClasses = attr.getClassArray("basePackageClasses");
+		String[] basePackages = attr.getStringArray("basePackages");
+		Class<? extends StubFactory<?>> factory = attr.getClass("factory");
+		if (factory == UnspecifiedStubFactory.class) {
+			factory = null;
+		}
+		if (types.length == 0 && basePackageClasses.length == 0 && basePackages.length == 0) {
+			basePackages = new String[] { ClassUtils.getPackageName(meta.getClassName()) };
+		}
+		return GrpcClientRegistrationSpec.of(target)
+			.factory(factory)
+			.types(types)
+			.packages(basePackages)
+			.packageClasses(basePackageClasses)
+			.prefix(prefix);
+	}
+
+}