GH-375 - Avoid initialization of ApplicationModulesRuntime if possible.

spring-modulith-runtime/src/main/java/org/springframework/modulith/runtime/autoconfigure/SpringModulithRuntimeAutoConfiguration.java

@@ -15,15 +15,13 @@
  */
 package org.springframework.modulith.runtime.autoconfigure;
 
-import java.util.concurrent.Future;
-import java.util.function.Supplier;
-
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.aop.support.AopUtils;
-import org.springframework.beans.factory.ListableBeanFactory;
+import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.boot.autoconfigure.AutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingClass;
 import org.springframework.boot.context.event.ApplicationStartedEvent;
@@ -40,6 +38,7 @@
 import org.springframework.modulith.runtime.ApplicationModulesRuntime;
 import org.springframework.modulith.runtime.ApplicationRuntime;
 import org.springframework.util.Assert;
+import org.springframework.util.function.ThrowingSupplier;
 
 /**
  * Auto-configuration to register a {@link SpringBootApplicationRuntime}, a {@link ApplicationModulesRuntime} and an
@@ -65,23 +64,25 @@ static SpringBootApplicationRuntime modulithsApplicationRuntime(ApplicationConte
 	@ConditionalOnMissingBean
 	static ApplicationModulesRuntime modulesRuntime(ApplicationRuntime runtime) {
 
-		var mainClass = runtime.getMainApplicationClass();
-		var modules = EXECUTOR
-				.submit(() -> ApplicationModulesBootstrap.initializeApplicationModules(mainClass));
+		ThrowingSupplier<ApplicationModules> modules = () -> EXECUTOR
+				.submit(() -> ApplicationModulesBootstrap.initializeApplicationModules(runtime.getMainApplicationClass()))
+				.get();
 
-		return new ApplicationModulesRuntime(toSupplier(modules), runtime);
+		return new ApplicationModulesRuntime(modules, runtime);
 	}
 
 	@Bean
 	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
+	@ConditionalOnBean(ApplicationModuleInitializer.class)
 	static ApplicationListener<ApplicationStartedEvent> applicationModuleInitializingListener(
-			ListableBeanFactory beanFactory) {
+			ObjectProvider<ApplicationModulesRuntime> runtime,
+			ObjectProvider<ApplicationModuleInitializer> initializers) {
 
 		return event -> {
 
-			var modules = beanFactory.getBean(ApplicationModulesRuntime.class).get();
+			var modules = runtime.getObject().get();
 
-			beanFactory.getBeanProvider(ApplicationModuleInitializer.class).stream() //
+			initializers.stream() //
 					.sorted(modules.getComparator()) //
 					.map(it -> LOGGER.isDebugEnabled() ? new LoggingApplicationModuleInitializerAdapter(it, modules) : it)
 					.forEach(ApplicationModuleInitializer::initialize);
@@ -160,17 +161,6 @@ static ApplicationModules initializeApplicationModules(Class<?> applicationMainC
 		}
 	}
 
-	private static Supplier<ApplicationModules> toSupplier(Future<ApplicationModules> modules) {
-
-		return () -> {
-			try {
-				return modules.get();
-			} catch (Exception o_O) {
-				throw new RuntimeException(o_O);
-			}
-		};
-	}
-
 	/**
 	 * Auto-configuration to react to ArchUnit missing on the runtime classpath.
 	 *

spring-modulith-runtime/src/test/java/org/springframework/modulith/runtime/autoconfigure/SpringModulithRuntimeAutoConfigurationIntegrationTests.java

@@ -23,6 +23,7 @@
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.boot.test.context.FilteredClassLoader;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.modulith.ApplicationModuleInitializer;
 import org.springframework.modulith.runtime.ApplicationModulesRuntime;
 import org.springframework.modulith.runtime.ApplicationRuntime;
 
@@ -46,11 +47,8 @@ void bootstrapRegistersRuntimeInstances() {
 				.withUserConfiguration(SampleApp.class)
 				.withConfiguration(AutoConfigurations.of(SpringModulithRuntimeAutoConfiguration.class))
 				.run(context -> {
-
 					assertThat(context.getBean(ApplicationRuntime.class)).isNotNull();
 					assertThat(context.getBean(ApplicationModulesRuntime.class)).isNotNull();
-
-					context.close();
 				});
 	}
 
@@ -62,13 +60,25 @@ void missingArchUnitRuntimeDependencyEscalatesOnContextStartup() {
 				.withConfiguration(AutoConfigurations.of(SpringModulithRuntimeAutoConfiguration.class))
 				.withClassLoader(new FilteredClassLoader(ClassFileImporter.class))
 				.run(context -> {
-
 					assertThat(context).hasFailed();
 					assertThat(context.getStartupFailure().getCause())
 							.isInstanceOf(BeanInstantiationException.class)
 							.cause().isInstanceOf(MissingRuntimeDependency.class);
-
-					context.close();
 				});
 	}
+
+	@Test // GH-375
+	void registersInitializingListenerIfInitializersPresent() {
+
+		var beanName = "applicationModuleInitializingListener";
+		var runner = new ApplicationContextRunner()
+				.withConfiguration(AutoConfigurations.of(SpringModulithRuntimeAutoConfiguration.class));
+
+		// No initializer -> no listener
+		runner.run(context -> assertThat(context).doesNotHaveBean(beanName));
+
+		// Initializer -> listener
+		runner.withBean(ApplicationModuleInitializer.class, () -> () -> {})
+				.run(context -> assertThat(context).hasBean(beanName));
+	}
 }