Only require an exception CacheResolver if necessary

Previously, a cache infrastructure with only a CacheResolver would have
worked fine until the JSR-107 API is added to the classpath. When this is
the case, the JCache support kicks in and an exception cache resolver is
all of the sudden required.

The CacheResolver _is_ different as the default implementation does look
different attributes so if a custom CacheResolver is set, it is not
possible to "reuse" it as a fallback exception CacheResolver.

Now, an exception CacheResolver is only required if a JSR-107 annotation
with an "exceptionCacheName" attribute is processed (i.e. the exception
CacheResolver is lazily instantiated if necessary).

The use case of having a CachingConfigurerSupport with only a
CacheResolver was still broken though since the JCache support only looks
for a JCacheConfigurer bean (per the generic type set on
AbstractCachingConfiguration). This has been fixed as well.

Issue: SPR-12850

Author: snicoll

spring-context-support/src/main/java/org/springframework/cache/jcache/config/AbstractJCacheConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2015 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.
@@ -18,6 +18,7 @@
 
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.cache.annotation.AbstractCachingConfiguration;
+import org.springframework.cache.annotation.CachingConfigurer;
 import org.springframework.cache.interceptor.CacheResolver;
 import org.springframework.cache.jcache.interceptor.DefaultJCacheOperationSource;
 import org.springframework.cache.jcache.interceptor.JCacheOperationSource;
@@ -34,14 +35,16 @@
  * @see JCacheConfigurer
  */
 @Configuration
-public class AbstractJCacheConfiguration extends AbstractCachingConfiguration<JCacheConfigurer> {
+public class AbstractJCacheConfiguration extends AbstractCachingConfiguration {
 
 	protected CacheResolver exceptionCacheResolver;
 
 	@Override
-	protected void useCachingConfigurer(JCacheConfigurer config) {
+	protected void useCachingConfigurer(CachingConfigurer config) {
 		super.useCachingConfigurer(config);
-		this.exceptionCacheResolver = config.exceptionCacheResolver();
+		if (config instanceof JCacheConfigurer) {
+			this.exceptionCacheResolver = ((JCacheConfigurer) config).exceptionCacheResolver();
+		}
 	}
 
 	@Bean(name = "jCacheOperationSource")

spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/DefaultJCacheOperationSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2015 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.
@@ -128,9 +128,9 @@ public void afterPropertiesSet() {
 
 	@Override
 	public void afterSingletonsInstantiated() {
-		// Make sure those are initialized on startup...
+		// Make sure that the cache resolver is initialized. An exception cache resolver is only
+		// required if the exceptionCacheName attribute is set on an operation
 		Assert.notNull(getDefaultCacheResolver(), "Cache resolver should have been initialized");
-		Assert.notNull(getDefaultExceptionCacheResolver(), "Exception cache resolver should have been initialized");
 	}
 
 

spring-context-support/src/test/java/org/springframework/cache/jcache/config/JCacheJavaConfigTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2015 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.
@@ -18,12 +18,15 @@
 
 import java.util.Arrays;
 
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 
 import org.springframework.cache.Cache;
 import org.springframework.cache.CacheManager;
 import org.springframework.cache.annotation.EnableCaching;
 import org.springframework.cache.concurrent.ConcurrentMapCache;
+import org.springframework.cache.concurrent.ConcurrentMapCacheManager;
 import org.springframework.cache.config.SomeKeyGenerator;
 import org.springframework.cache.interceptor.CacheErrorHandler;
 import org.springframework.cache.interceptor.CacheResolver;
@@ -35,7 +38,6 @@
 import org.springframework.cache.jcache.interceptor.AnnotatedJCacheableService;
 import org.springframework.cache.jcache.interceptor.DefaultJCacheOperationSource;
 import org.springframework.cache.jcache.interceptor.JCacheInterceptor;
-import org.springframework.cache.jcache.interceptor.SimpleExceptionCacheResolver;
 import org.springframework.cache.support.NoOpCacheManager;
 import org.springframework.cache.support.SimpleCacheManager;
 import org.springframework.context.ApplicationContext;
@@ -51,6 +53,9 @@
  */
 public class JCacheJavaConfigTests extends AbstractJCacheAnnotationTests {
 
+	@Rule
+	public final ExpectedException thrown = ExpectedException.none();
+
 	@Override
 	protected ApplicationContext getApplicationContext() {
 		return new AnnotationConfigApplicationContext(EnableCachingConfig.class);
@@ -80,10 +85,7 @@ public void emptyConfigSupport() {
 		assertEquals(SimpleCacheResolver.class, cos.getCacheResolver().getClass());
 		assertSame(context.getBean(CacheManager.class),
 				((SimpleCacheResolver) cos.getCacheResolver()).getCacheManager());
-		assertNotNull(cos.getExceptionCacheResolver());
-		assertEquals(SimpleExceptionCacheResolver.class, cos.getExceptionCacheResolver().getClass());
-		assertSame(context.getBean(CacheManager.class),
-				((SimpleExceptionCacheResolver) cos.getExceptionCacheResolver()).getCacheManager());
+		assertNull(cos.getExceptionCacheResolver());
 		context.close();
 	}
 
@@ -99,6 +101,28 @@ public void bothSetOnlyResolverIsUsed() {
 		context.close();
 	}
 
+	@Test
+	public void exceptionCacheResolverFallbacksToMainOne() {
+		ConfigurableApplicationContext context = new AnnotationConfigApplicationContext(
+				NoExceptionCacheResolverConfig.class);
+		try {
+			DefaultJCacheOperationSource cos = context.getBean(DefaultJCacheOperationSource.class);
+			assertSame(context.getBean("cacheResolver"), cos.getCacheResolver());
+			assertNull(cos.getExceptionCacheResolver());
+
+			JCacheableService<?> service = context.getBean(JCacheableService.class);
+
+			service.cache("id");
+
+			// This call requires the cache manager to be set
+			thrown.expect(IllegalStateException.class);
+			service.cacheWithException("test", false);
+		}
+		finally {
+			context.close();
+		}
+	}
+
 
 	@Configuration
 	@EnableCaching
@@ -200,4 +224,20 @@ public CacheResolver exceptionCacheResolver() {
 		}
 	}
 
+	@Configuration
+	@EnableCaching
+	static class NoExceptionCacheResolverConfig extends JCacheConfigurerSupport {
+
+		@Override
+		@Bean
+		public CacheResolver cacheResolver() {
+			return new NamedCacheResolver(new ConcurrentMapCacheManager(), "default");
+		}
+
+		@Bean
+		public JCacheableService<?> cacheableService() {
+			return new AnnotatedJCacheableService(new ConcurrentMapCache("default"));
+		}
+	}
+
 }

spring-context/src/main/java/org/springframework/cache/annotation/AbstractCachingConfiguration.java

@@ -39,7 +39,7 @@
  * @see EnableCaching
  */
 @Configuration
-public abstract class AbstractCachingConfiguration<C extends CachingConfigurer> implements ImportAware {
+public abstract class AbstractCachingConfiguration implements ImportAware {
 
 	protected AnnotationAttributes enableCaching;
 
@@ -63,7 +63,7 @@ public void setImportMetadata(AnnotationMetadata importMetadata) {
 	}
 
 	@Autowired(required = false)
-	void setConfigurers(Collection<C> configurers) {
+	void setConfigurers(Collection<CachingConfigurer> configurers) {
 		if (CollectionUtils.isEmpty(configurers)) {
 			return;
 		}
@@ -73,14 +73,14 @@ void setConfigurers(Collection<C> configurers) {
 					"Refactor the configuration such that CachingConfigurer is " +
 					"implemented only once or not at all.");
 		}
-		C configurer = configurers.iterator().next();
+		CachingConfigurer configurer = configurers.iterator().next();
 		useCachingConfigurer(configurer);
 	}
 
 	/**
 	 * Extract the configuration from the nominated {@link CachingConfigurer}.
 	 */
-	protected void useCachingConfigurer(C config) {
+	protected void useCachingConfigurer(CachingConfigurer config) {
 		this.cacheManager = config.cacheManager();
 		this.cacheResolver = config.cacheResolver();
 		this.keyGenerator = config.keyGenerator();

spring-context/src/main/java/org/springframework/cache/annotation/ProxyCachingConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2015 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.
@@ -35,7 +35,7 @@
  * @see CachingConfigurationSelector
  */
 @Configuration
-public class ProxyCachingConfiguration extends AbstractCachingConfiguration<CachingConfigurer> {
+public class ProxyCachingConfiguration extends AbstractCachingConfiguration {
 
 	@Bean(name = CacheManagementConfigUtils.CACHE_ADVISOR_BEAN_NAME)
 	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)