Prevent ApplicationListener that depends on EMF from creating a cycle

Previously, when an EntityManagerFactory was being initialized
synchronously, the DataSourceSchemaCreatedEvent would be published
during its initialization. This meant that an application listener that
depends on the EntityManagerFactory would create a dependency cycle if
it was a potential recipient of the event.

For the synchronous case, this commit moves the publication of the
event so that it occurs after the initialisation of the entity manager
factory. This allows an application listener that is a potential
recipient of the DataSourceSchemaCreatedEvent to depend on the
EntityManagerFactory without creating a cycle.

Closes gh-14651

Author: wilkinsona

Diff for: spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/orm/jpa/DataSourceInitializedPublisher.java

@@ -82,6 +82,12 @@ public Object postProcessAfterInitialization(Object bean, String beanName)
 		if (bean instanceof HibernateProperties) {
 			this.hibernateProperties = (HibernateProperties) bean;
 		}
+		if (bean instanceof LocalContainerEntityManagerFactoryBean) {
+			LocalContainerEntityManagerFactoryBean factory = (LocalContainerEntityManagerFactoryBean) bean;
+			if (factory.getBootstrapExecutor() == null) {
+				publishEventIfRequired(factory.getNativeEntityManagerFactory());
+			}
+		}
 		return bean;
 	}
 
@@ -195,9 +201,6 @@ public void postProcessEntityManagerFactory(EntityManagerFactory emf) {
 				bootstrapExecutor.execute(() -> DataSourceInitializedPublisher.this
 						.publishEventIfRequired(emf));
 			}
-			else {
-				DataSourceInitializedPublisher.this.publishEventIfRequired(emf);
-			}
 		}
 
 	}

Diff for: spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaAutoConfigurationTests.java

@@ -19,6 +19,7 @@
 import java.io.IOException;
 import java.net.URL;
 import java.net.URLClassLoader;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Enumeration;
@@ -46,9 +47,11 @@
 import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.autoconfigure.TestAutoConfigurationPackage;
 import org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration;
+import org.springframework.boot.autoconfigure.jdbc.DataSourceSchemaCreatedEvent;
 import org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration;
 import org.springframework.boot.autoconfigure.jdbc.XADataSourceAutoConfiguration;
 import org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration;
+import org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfigurationTests.JpaUsingApplicationListenerConfiguration.EventCapturingApplicationListener;
 import org.springframework.boot.autoconfigure.orm.jpa.mapping.NonAnnotatedEntity;
 import org.springframework.boot.autoconfigure.orm.jpa.test.City;
 import org.springframework.boot.autoconfigure.transaction.jta.JtaAutoConfiguration;
@@ -57,10 +60,13 @@
 import org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy;
 import org.springframework.boot.test.context.assertj.AssertableApplicationContext;
 import org.springframework.boot.test.context.runner.ContextConsumer;
+import org.springframework.context.ApplicationEvent;
+import org.springframework.context.ApplicationListener;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.orm.jpa.JpaTransactionManager;
 import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
+import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.entry;
@@ -383,6 +389,52 @@ public void hibernatePropertiesCustomizerCanDisableBeanContainer() {
 				.run((context) -> assertThat(context).doesNotHaveBean(City.class));
 	}
 
+	@Test
+	public void withSyncBootstrappingAnApplicationListenerThatUsesJpaDoesNotTriggerABeanCurrentlyInCreationException() {
+		contextRunner()
+				.withUserConfiguration(JpaUsingApplicationListenerConfiguration.class)
+				.withPropertyValues("spring.datasource.initialization-mode=never")
+				.run((context) -> {
+					assertThat(context).hasNotFailed();
+					assertThat(context
+							.getBean(EventCapturingApplicationListener.class).events
+									.stream()
+									.filter(DataSourceSchemaCreatedEvent.class::isInstance))
+											.hasSize(1);
+				});
+	}
+
+	@Test
+	public void withAsyncBootstrappingAnApplicationListenerThatUsesJpaDoesNotTriggerABeanCurrentlyInCreationException() {
+		contextRunner()
+				.withUserConfiguration(AsyncBootstrappingConfiguration.class,
+						JpaUsingApplicationListenerConfiguration.class)
+				.withPropertyValues("spring.datasource.initialization-mode=never")
+				.run((context) -> {
+					assertThat(context).hasNotFailed();
+					EventCapturingApplicationListener listener = context
+							.getBean(EventCapturingApplicationListener.class);
+					long end = System.currentTimeMillis() + 30000;
+					while ((System.currentTimeMillis() < end)
+							&& !dataSourceSchemaCreatedEventReceived(listener)) {
+						Thread.sleep(100);
+					}
+					assertThat(listener.events.stream()
+							.filter(DataSourceSchemaCreatedEvent.class::isInstance))
+									.hasSize(1);
+				});
+	}
+
+	private boolean dataSourceSchemaCreatedEventReceived(
+			EventCapturingApplicationListener listener) {
+		for (ApplicationEvent event : listener.events) {
+			if (event instanceof DataSourceSchemaCreatedEvent) {
+				return true;
+			}
+		}
+		return false;
+	}
+
 	@Configuration
 	@TestAutoConfigurationPackage(City.class)
 	static class TestInitializedJpaConfiguration {
@@ -506,4 +558,45 @@ public Enumeration<URL> getResources(String name) throws IOException {
 
 	}
 
+	@org.springframework.context.annotation.Configuration
+	static class JpaUsingApplicationListenerConfiguration {
+
+		@Bean
+		public EventCapturingApplicationListener jpaUsingApplicationListener(
+				EntityManagerFactory emf) {
+			return new EventCapturingApplicationListener();
+		}
+
+		static class EventCapturingApplicationListener
+				implements ApplicationListener<ApplicationEvent> {
+
+			private final List<ApplicationEvent> events = new ArrayList<>();
+
+			@Override
+			public void onApplicationEvent(ApplicationEvent event) {
+				this.events.add(event);
+			}
+
+		}
+
+	}
+
+	@Configuration
+	static class AsyncBootstrappingConfiguration {
+
+		@Bean
+		ThreadPoolTaskExecutor ThreadPoolTaskExecutor() {
+			return new ThreadPoolTaskExecutor();
+		}
+
+		@Bean
+		public EntityManagerFactoryBuilderCustomizer asyncBoostrappingCustomizer(
+				ThreadPoolTaskExecutor executor) {
+			return (builder) -> {
+				builder.setBootstrapExecutor(executor);
+			};
+		}
+
+	}
+
 }