GH-240 - Republication of outstanding events can now be disabled.

Via the spring.modulith.republish-outstanding-events-on-restart (boolean) property.

Author: odrotbohm

spring-modulith-events/spring-modulith-events-core/src/main/java/org/springframework/modulith/events/config/EventPublicationConfiguration.java

@@ -62,8 +62,10 @@ EventPublicationRegistry eventPublicationRegistry(EventPublicationRepository rep
 	@Bean
 	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
 	static PersistentApplicationEventMulticaster applicationEventMulticaster(
-			ObjectFactory<EventPublicationRegistry> eventPublicationRegistry) {
-		return new PersistentApplicationEventMulticaster(() -> eventPublicationRegistry.getObject());
+			ObjectFactory<EventPublicationRegistry> eventPublicationRegistry, ObjectFactory<Environment> environment) {
+
+		return new PersistentApplicationEventMulticaster(() -> eventPublicationRegistry.getObject(),
+				() -> environment.getObject());
 	}
 
 	@Bean

spring-modulith-events/spring-modulith-events-core/src/main/java/org/springframework/modulith/events/support/PersistentApplicationEventMulticaster.java

@@ -33,6 +33,7 @@
 import org.springframework.context.event.ApplicationListenerMethodAdapter;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.annotation.AnnotationAwareOrderComparator;
+import org.springframework.core.env.Environment;
 import org.springframework.lang.NonNull;
 import org.springframework.modulith.events.EventPublication;
 import org.springframework.modulith.events.EventPublicationRegistry;
@@ -60,8 +61,10 @@ public class PersistentApplicationEventMulticaster extends AbstractApplicationEv
 	private static final Logger LOGGER = LoggerFactory.getLogger(PersistentApplicationEventMulticaster.class);
 	private static final Field DECLARED_EVENT_TYPES_FIELD = ReflectionUtils
 			.findField(ApplicationListenerMethodAdapter.class, "declaredEventTypes");
+	static final String REPUBLISH_ON_RESTART = "spring.modulith.republish-outstanding-events-on-restart";
 
 	private final @NonNull Supplier<EventPublicationRegistry> registry;
+	private final @NonNull Supplier<Environment> environment;
 
 	static {
 		ReflectionUtils.makeAccessible(DECLARED_EVENT_TYPES_FIELD);
@@ -71,12 +74,16 @@ public class PersistentApplicationEventMulticaster extends AbstractApplicationEv
 	 * Creates a new {@link PersistentApplicationEventMulticaster} for the given {@link EventPublicationRegistry}.
 	 *
 	 * @param registry must not be {@literal null}.
+	 * @param environment must not be {@literal null}.
 	 */
-	public PersistentApplicationEventMulticaster(Supplier<EventPublicationRegistry> registry) {
+	public PersistentApplicationEventMulticaster(Supplier<EventPublicationRegistry> registry,
+			Supplier<Environment> environment) {
 
 		Assert.notNull(registry, "EventPublicationRegistry must not be null!");
+		Assert.notNull(environment, "Environment must not be null!");
 
 		this.registry = registry;
+		this.environment = environment;
 	}
 
 	/*
@@ -118,6 +125,10 @@ public void multicastEvent(ApplicationEvent event, ResolvableType eventType) {
 	@Override
 	public void afterSingletonsInstantiated() {
 
+		if (Boolean.FALSE.equals(environment.get().getProperty(REPUBLISH_ON_RESTART, Boolean.class))) {
+			return;
+		}
+
 		LOGGER.debug("Looking up previously pending event publications…");
 
 		var publications = registry.get().findIncompletePublications();

spring-modulith-events/spring-modulith-events-core/src/main/resources/META-INF/spring-configuration-metadata.json

@@ -5,6 +5,12 @@
 			"type": "java.lang.boolean",
 			"description": "Whether to configure defaults for the async processing termination, namely to wait for task completion for 2 seconds. See TaskExecutionProperties for details.",
 			"defaultValue": "true"
+		},
+		{
+			"name": "spring.modulith.republish-outstanding-events-on-restart",
+			"type": "java.lang.boolean",
+			"description": "Whether to republish outstanding event publications on restarts of the application.",
+			"defaultValue": "true"
 		}
 	]
 }

spring-modulith-events/spring-modulith-events-core/src/test/java/org/springframework/modulith/events/support/PersistentApplicationEventMulticasterUnitTests.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2023 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.modulith.events.support;
+
+import static org.mockito.Mockito.*;
+
+import java.util.Map;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.core.env.MapPropertySource;
+import org.springframework.core.env.StandardEnvironment;
+import org.springframework.modulith.events.EventPublicationRegistry;
+
+/**
+ * Unit tests for {@link PersistentApplicationEventMulticaster}.
+ *
+ * @author Oliver Drotbohm
+ */
+class PersistentApplicationEventMulticasterUnitTests {
+
+	PersistentApplicationEventMulticaster multicaster;
+
+	StandardEnvironment environment = new StandardEnvironment();
+	EventPublicationRegistry registry = mock(EventPublicationRegistry.class);
+
+	@BeforeEach
+	void setUp() {
+		this.multicaster = new PersistentApplicationEventMulticaster(() -> registry, () -> environment);
+	}
+
+	@Test // GH-240
+	void doesNotRepublishEventsOnRestartIfExplicitlyDisabled() {
+
+		var source = new MapPropertySource("test",
+				Map.of(PersistentApplicationEventMulticaster.REPUBLISH_ON_RESTART, "false"));
+		environment.getPropertySources().addFirst(source);
+
+		multicaster.afterSingletonsInstantiated();
+
+		verify(registry, never()).findIncompletePublications();
+	}
+
+	@Test // GH-240
+	void triggersRepublicationIfExplicitlyEnabled() {
+
+		multicaster.afterSingletonsInstantiated();
+
+		verify(registry).findIncompletePublications();
+	}
+}