Auto-configure Neo4J BookmarkManager when possible

Add `Neo4jBookmarkManagementConfiguration` which provides an instance
of `BookmarkManager` if necessary and Caffeine cache is on the
classpath. Depending on the kind of application, the `BookmarkManager`
will be request scoped or singleton, as recommended by Spring Data
Neo4j.

See gh-14568

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/neo4j/Neo4jBookmarkManagementConfiguration.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2012-2018 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
+ *
+ *      http://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.boot.autoconfigure.data.neo4j;
+
+import com.github.benmanes.caffeine.cache.Caffeine;
+
+import org.springframework.beans.factory.config.ConfigurableBeanFactory;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnNotWebApplication;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
+import org.springframework.cache.caffeine.CaffeineCacheManager;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Scope;
+import org.springframework.context.annotation.ScopedProxyMode;
+import org.springframework.data.neo4j.bookmark.BeanFactoryBookmarkOperationAdvisor;
+import org.springframework.data.neo4j.bookmark.BookmarkInterceptor;
+import org.springframework.data.neo4j.bookmark.BookmarkManager;
+import org.springframework.data.neo4j.bookmark.CaffeineBookmarkManager;
+import org.springframework.web.context.WebApplicationContext;
+
+/**
+ * Provides a {@link BookmarkManager} for Neo4j's bookmark support based on Caffeine if
+ * available. Depending on the applications kind (web or not) the bookmark manager will be
+ * bound to the application or the request, as recommend by Spring Data Neo4j.
+ *
+ * @author Michael Simons
+ * @since 2.1
+ */
+@Configuration
+@ConditionalOnClass({ Caffeine.class, CaffeineCacheManager.class })
+@ConditionalOnMissingBean(BookmarkManager.class)
+@ConditionalOnBean({ BeanFactoryBookmarkOperationAdvisor.class,
+		BookmarkInterceptor.class })
+class Neo4jBookmarkManagementConfiguration {
+
+	static final String BOOKMARK_MANAGER_BEAN_NAME = "bookmarkManager";
+
+	@Bean(BOOKMARK_MANAGER_BEAN_NAME)
+	@Scope(value = WebApplicationContext.SCOPE_REQUEST, proxyMode = ScopedProxyMode.INTERFACES)
+	@ConditionalOnWebApplication
+	public BookmarkManager requestScopedBookmarkManager() {
+		return new CaffeineBookmarkManager();
+	}
+
+	@Bean(BOOKMARK_MANAGER_BEAN_NAME)
+	@Scope(ConfigurableBeanFactory.SCOPE_SINGLETON)
+	@ConditionalOnNotWebApplication
+	public BookmarkManager singletonScopedBookmarkManager() {
+		return new CaffeineBookmarkManager();
+	}
+
+}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/neo4j/Neo4jDataAutoConfiguration.java

@@ -37,6 +37,7 @@ import org.springframework.boot.context.properties.EnableConfigurationProperties
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
 import org.springframework.data.neo4j.transaction.Neo4jTransactionManager;
 import org.springframework.data.neo4j.web.support.OpenSessionInViewInterceptor;
 import org.springframework.transaction.PlatformTransactionManager;
@@ -52,6 +53,7 @@ import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
  * @author Vince Bickers
  * @author Stephane Nicoll
  * @author Kazuki Shimizu
+ * @author Michael Simons
  * @since 1.4.0
  */
 @Configuration
@@ -59,6 +61,7 @@ import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
 		PlatformTransactionManager.class })
 @ConditionalOnMissingBean(SessionFactory.class)
 @EnableConfigurationProperties(Neo4jProperties.class)
+@Import(Neo4jBookmarkManagementConfiguration.class)
 public class Neo4jDataAutoConfiguration {
 
 	@Bean

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/data/neo4j/Neo4jDataAutoConfigurationTests.java

@@ -16,6 +16,10 @@
 
 package org.springframework.boot.autoconfigure.data.neo4j;
 
+import java.util.function.Predicate;
+
+import com.github.benmanes.caffeine.cache.Caffeine;
+import org.assertj.core.api.Condition;
 import org.junit.Test;
 import org.neo4j.ogm.session.Session;
 import org.neo4j.ogm.session.SessionFactory;
@@ -29,13 +33,19 @@ import org.springframework.boot.autoconfigure.data.neo4j.city.City;
 import org.springframework.boot.autoconfigure.data.neo4j.country.Country;
 import org.springframework.boot.autoconfigure.domain.EntityScan;
 import org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration;
+import org.springframework.boot.test.context.FilteredClassLoader;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.boot.test.context.runner.WebApplicationContextRunner;
+import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.data.neo4j.annotation.EnableBookmarkManagement;
+import org.springframework.data.neo4j.bookmark.BookmarkManager;
 import org.springframework.data.neo4j.mapping.Neo4jMappingContext;
 import org.springframework.data.neo4j.transaction.Neo4jTransactionManager;
 import org.springframework.data.neo4j.web.support.OpenSessionInViewInterceptor;
+import org.springframework.web.context.WebApplicationContext;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.ArgumentMatchers.any;
@@ -51,6 +61,7 @@ import static org.mockito.Mockito.verify;
  * @author Vince Bickers
  * @author Andy Wilkinson
  * @author Kazuki Shimizu
+ * @author Michael Simons
  */
 public class Neo4jDataAutoConfigurationTests {
 
@@ -69,6 +80,7 @@ public class Neo4jDataAutoConfigurationTests {
 					assertThat(context).hasSingleBean(SessionFactory.class);
 					assertThat(context).hasSingleBean(Neo4jTransactionManager.class);
 					assertThat(context).hasSingleBean(OpenSessionInViewInterceptor.class);
+					assertThat(context).doesNotHaveBean(BookmarkManager.class);
 				});
 	}
 
@@ -146,6 +158,41 @@ public class Neo4jDataAutoConfigurationTests {
 				});
 	}
 
+	@Test
+	public void providesARequestScopedBookmarkManangerIfNecessaryAndPossible() {
+		Predicate<ConfigurableApplicationContext> hasRequestScopedBookmarkManager = (
+				context) -> context.getBeanFactory() //
+						.getBeanDefinition("scopedTarget."
+								+ Neo4jBookmarkManagementConfiguration.BOOKMARK_MANAGER_BEAN_NAME) //
+						.getScope() //
+						.equals(WebApplicationContext.SCOPE_REQUEST);
+
+		this.contextRunner
+				.withUserConfiguration(BookmarkManagementEnabledConfiguration.class)
+				.run((context) -> assertThat(context)
+						.satisfies(new Condition<>(hasRequestScopedBookmarkManager,
+								"hasRequestScopedBookmarkManager")));
+	}
+
+	@Test
+	public void providesASingletonScopedBookmarkManangerIfNecessaryAndPossible() {
+		new ApplicationContextRunner()
+				.withUserConfiguration(TestConfiguration.class,
+						BookmarkManagementEnabledConfiguration.class)
+				.withConfiguration(AutoConfigurations.of(Neo4jDataAutoConfiguration.class,
+						TransactionAutoConfiguration.class))
+				.run((context) -> assertThat(context)
+						.hasSingleBean(BookmarkManager.class));
+	}
+
+	@Test
+	public void doesNotProvideABookmarkManagerIfNotPossible() {
+		this.contextRunner.withClassLoader(new FilteredClassLoader(Caffeine.class))
+				.withUserConfiguration(BookmarkManagementEnabledConfiguration.class)
+				.run((context) -> assertThat(context)
+						.doesNotHaveBean(BookmarkManager.class));
+	}
+
 	private static void assertDomainTypesDiscovered(Neo4jMappingContext mappingContext,
 			Class<?>... types) {
 		for (Class<?> type : types) {
@@ -180,6 +227,12 @@ public class Neo4jDataAutoConfigurationTests {
 
 	}
 
+	@Configuration
+	@EnableBookmarkManagement
+	static class BookmarkManagementEnabledConfiguration {
+
+	}
+
 	@Configuration
 	static class EventListenerConfiguration {