Improve caching configuration

Rather than creating a `CacheManager` ourselves, we now rely on JCache
to provide a `CacheManager` that we'll augment with the caches that
initializr needs.

If Initializr is embedded in another app and that app uses JCache, then
its cache manager will be transparently upgraded to define the caches
that initializr needs. If not, such caches will have to be created as
part of the custom config.

Also, caching only kicks in if required at the service level.

This commit also switches the cache implementation to EhCache 3.

See gh-389

initializr-service/pom.xml

@@ -26,6 +26,15 @@
 			<artifactId>initializr-actuator</artifactId>
 		</dependency>
 
+		<dependency>
+			<groupId>javax.cache</groupId>
+			<artifactId>cache-api</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.ehcache</groupId>
+			<artifactId>ehcache</artifactId>
+		</dependency>
+
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-devtools</artifactId>

initializr-service/src/main/java/io/spring/initializr/service/InitializrService.java

@@ -23,6 +23,7 @@ import io.spring.initializr.web.project.LegacyStsController;
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.cache.annotation.EnableCaching;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.scheduling.annotation.AsyncConfigurerSupport;
@@ -37,6 +38,7 @@ import org.springframework.web.servlet.resource.ResourceUrlProvider;
  * @author Stephane Nicoll
  */
 @SpringBootApplication
+@EnableCaching
 public class InitializrService {
 
 	public static void main(String[] args) {

initializr-web/pom.xml

@@ -19,12 +19,13 @@
 
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
-			<artifactId>spring-boot-autoconfigure</artifactId>
+			<artifactId>spring-boot-starter-mustache</artifactId>
 		</dependency>
 		<dependency>
-			<groupId>org.springframework</groupId>
-			<artifactId>spring-context-support</artifactId>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-cache</artifactId>
 		</dependency>
+
 		<dependency>
 			<groupId>org.springframework</groupId>
 			<artifactId>spring-webmvc</artifactId>
@@ -33,10 +34,6 @@
 			<groupId>org.springframework.hateoas</groupId>
 			<artifactId>spring-hateoas</artifactId>
 		</dependency>
-		<dependency>
-			<groupId>com.github.ben-manes.caffeine</groupId>
-			<artifactId>caffeine</artifactId>
-		</dependency>
 		<dependency>
 			<groupId>org.apache.ant</groupId>
 			<artifactId>ant</artifactId>
@@ -45,10 +42,11 @@
 			<groupId>org.json</groupId>
 			<artifactId>json</artifactId>
 		</dependency>
-
+		
 		<dependency>
-			<groupId>org.springframework.boot</groupId>
-			<artifactId>spring-boot-starter-mustache</artifactId>
+			<groupId>javax.cache</groupId>
+			<artifactId>cache-api</artifactId>
+			<optional>true</optional>
 		</dependency>
 
 		<dependency>

initializr-web/src/main/java/io/spring/initializr/web/autoconfigure/InitializrAutoConfiguration.java

@@ -17,11 +17,11 @@
 package io.spring.initializr.web.autoconfigure;
 
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.List;
-import java.util.concurrent.TimeUnit;
+import javax.cache.configuration.MutableConfiguration;
+import javax.cache.expiry.CreatedExpiryPolicy;
+import javax.cache.expiry.Duration;
 
-import com.github.benmanes.caffeine.cache.Caffeine;
 import io.spring.initializr.generator.ProjectGenerator;
 import io.spring.initializr.generator.ProjectRequestPostProcessor;
 import io.spring.initializr.generator.ProjectRequestResolver;
@@ -38,15 +38,13 @@ import io.spring.initializr.web.support.DefaultInitializrMetadataProvider;
 import io.spring.initializr.web.ui.UiController;
 
 import org.springframework.beans.factory.ObjectProvider;
+import org.springframework.boot.autoconfigure.AutoConfigureAfter;
+import org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration;
+import org.springframework.boot.autoconfigure.cache.JCacheManagerCustomizer;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.bind.RelaxedPropertyResolver;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
-import org.springframework.cache.Cache;
-import org.springframework.cache.CacheManager;
-import org.springframework.cache.annotation.EnableCaching;
-import org.springframework.cache.caffeine.CaffeineCache;
-import org.springframework.cache.concurrent.ConcurrentMapCache;
-import org.springframework.cache.support.SimpleCacheManager;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.env.Environment;
@@ -65,9 +63,9 @@ import org.springframework.web.servlet.resource.ResourceUrlProvider;
  * @author Stephane Nicoll
  */
 @Configuration
-@EnableCaching
 @EnableConfigurationProperties(InitializrProperties.class)
-public class 	InitializrAutoConfiguration {
+@AutoConfigureAfter(CacheAutoConfiguration.class)
+public class InitializrAutoConfiguration {
 
 	private final List<ProjectRequestPostProcessor> postProcessors;
 
@@ -144,22 +142,26 @@ public class 	InitializrAutoConfiguration {
 		return new DefaultDependencyMetadataProvider();
 	}
 
-	@Bean
-	@ConditionalOnMissingBean
-	public CacheManager cacheManager() {
-		SimpleCacheManager cacheManager = new SimpleCacheManager();
-		cacheManager.setCaches(Arrays.asList(
-				createConcurrentMapCache(600L, "initializr"),
-				new ConcurrentMapCache("dependency-metadata"),
-				new ConcurrentMapCache("project-resources")));
-		return cacheManager;
-	}
+	@Configuration
+	@ConditionalOnClass(javax.cache.CacheManager.class)
+	static class CacheConfiguration {
+
+		@Bean
+		public JCacheManagerCustomizer initializrCacheManagerCustomizer() {
+			return cm -> {
+				cm.createCache("initializr", config().setExpiryPolicyFactory(
+						CreatedExpiryPolicy.factoryOf(Duration.TEN_MINUTES)));
+				cm.createCache("dependency-metadata", config());
+				cm.createCache("project-resources", config());
+			};
+		}
+
+		private MutableConfiguration<Object, Object> config() {
+			return new MutableConfiguration<>()
+					.setStoreByValue(false)
+					.setManagementEnabled(true).setStatisticsEnabled(true);
+		}
 
-	private static Cache createConcurrentMapCache(Long timeToLive, String name) {
-		return new CaffeineCache(name, Caffeine
-				.newBuilder()
-				.expireAfterWrite(timeToLive, TimeUnit.SECONDS)
-				.build());
 	}
 
 }