SPR-8477

+ add no-op cache implementations suitable for cache declarations w/o a backing store

org.springframework.context/src/main/java/org/springframework/cache/support/CompositeCacheManager.java

@@ -21,6 +21,7 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 
+import org.springframework.beans.factory.InitializingBean;
 import org.springframework.cache.Cache;
 import org.springframework.cache.CacheManager;
 import org.springframework.util.Assert;
@@ -29,11 +30,21 @@ import org.springframework.util.Assert;
  * Composite {@link CacheManager} implementation that iterates
  * over a given collection of {@link CacheManager} instances.
  * 
+ * Allows {@link NoOpCacheManager} to be automatically added to the list for handling
+ * the cache declarations without a backing store.
+ * 
  * @author Costin Leau
  */
-public class CompositeCacheManager implements CacheManager {
+public class CompositeCacheManager implements InitializingBean, CacheManager {
+
+	private List<CacheManager> cacheManagers;
+	private boolean noOpManager = false;
 
-	private CacheManager[] cacheManagers;
+	public void afterPropertiesSet() {
+		if (noOpManager) {
+			cacheManagers.add(new NoOpCacheManager());
+		}
+	}
 
 	public Cache getCache(String name) {
 		Cache cache = null;
@@ -55,8 +66,20 @@ public class CompositeCacheManager implements CacheManager {
 		return Collections.unmodifiableCollection(names);
 	}
 
-	public void setCacheManagers(CacheManager[] cacheManagers) {
+	public void setCacheManagers(Collection<CacheManager> cacheManagers) {
 		Assert.notEmpty(cacheManagers, "non-null/empty array required");
-		this.cacheManagers = cacheManagers.clone();
+		this.cacheManagers = new ArrayList<CacheManager>();
+		this.cacheManagers.addAll(cacheManagers);
+	}
+
+	/**
+	 * Indicates whether a {@link NoOpCacheManager} will be added at the end of the manager lists.
+	 * Any cache requests not handled by the configured cache managers will be automatically handled
+	 * by the {@link NoOpCacheManager}.
+	 * 
+	 * @param add whether a {@link NoOpCacheManager} instance will be added or not
+	 */
+	public void setAddNoOpCache(boolean add) {
+		this.noOpManager = add;
 	}
 }
\ No newline at end of file

org.springframework.context/src/main/java/org/springframework/cache/support/NoOpCacheManager.java

+/*
+ * Copyright 2011 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.cache.support;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.LinkedHashSet;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+
+import org.springframework.cache.Cache;
+import org.springframework.cache.CacheManager;
+
+/**
+ * A basic, no operation {@link CacheManager} implementation suitable for disabling caching, 
+ * typically used for backing cache declarations without an actual backing store.
+ * 
+ * Will simply accept any items into the cache not actually storing them.
+ * 
+ * @see CompositeCacheManager
+ * @author Costin Leau
+ */
+public class NoOpCacheManager implements CacheManager {
+
+	private final ConcurrentMap<String, Cache> caches = new ConcurrentHashMap<String, Cache>();
+	private Set<String> names = new LinkedHashSet<String>();
+
+	private static class NoOpCache implements Cache {
+
+		private final String name;
+
+		public NoOpCache(String name) {
+			this.name = name;
+		}
+
+		public void clear() {
+		}
+
+		public void evict(Object key) {
+		}
+
+		public ValueWrapper get(Object key) {
+			return null;
+		}
+
+		public String getName() {
+			return name;
+		}
+
+		public Object getNativeCache() {
+			return null;
+		}
+
+		public void put(Object key, Object value) {
+		}
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * 
+	 *  This implementation always returns a {@link Cache} implementation that will not
+	 *  store items. Additionally, the request cache will be remembered by the manager for consistency.
+	 */
+	public Cache getCache(String name) {
+		Cache cache = caches.get(name);
+		if (cache == null) {
+			caches.putIfAbsent(name, new NoOpCache(name));
+			synchronized (names) {
+				names.add(name);
+			}
+		}
+
+		return caches.get(name);
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * 
+	 * This implementation returns the name of the caches previously requested.  
+	 */
+	public Collection<String> getCacheNames() {
+		return Collections.unmodifiableSet(names);
+	}
+}
\ No newline at end of file

org.springframework.context/src/test/java/org/springframework/cache/NoOpCacheManagerTest.java

+/*
+ * Copyright 2011 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.cache;
+
+import static org.junit.Assert.*;
+
+import java.util.UUID;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.springframework.cache.support.NoOpCacheManager;
+
+public class NoOpCacheManagerTest {
+
+	private CacheManager manager;
+
+	@Before
+	public void setup() {
+		manager = new NoOpCacheManager();
+	}
+
+	@Test
+	public void testGetCache() throws Exception {
+		Cache cache = manager.getCache("bucket");
+		assertNotNull(cache);
+		assertSame(cache, manager.getCache("bucket"));
+	}
+
+	@Test
+	public void testNoOpCache() throws Exception {
+		String name = UUID.randomUUID().toString();
+		Cache cache = manager.getCache(name);
+		assertEquals(name, cache.getName());
+		Object key = new Object();
+		cache.put(key, new Object());
+		assertNull(cache.get(key));
+		assertNull(cache.getNativeCache());
+	}
+
+	@Test
+	public void testCacheName() throws Exception {
+		String name = "bucket";
+		assertFalse(manager.getCacheNames().contains(name));
+		manager.getCache(name);
+		assertTrue(manager.getCacheNames().contains(name));
+	}
+}

spring-framework-reference/src/cache.xml

@@ -383,6 +383,7 @@ public Book findBook(ISBN isbn, boolean checkWarehouse, boolean includeUsed)]]><
 	</section>
   </section>
   
+  
   <section id="cache-store-configuration">
 	<title>Configuring the cache storage</title>
 	
@@ -429,6 +430,27 @@ public Book findBook(ISBN isbn, boolean checkWarehouse, boolean includeUsed)]]><
 		implementation. Note the entire ehcache-specific configuration is read from the resource <literal>ehcache.xml</literal>.</para>
 	</section>
 	
+	<section id="cache-store-configuration-noop">
+		<title>Dealing with caches without a backing store</title>
+	
+		<para>Sometimes when switching environments or doing testing, one might have cache declarations without an actual backing cache configured. As this is an invalid configuration, at runtime an
+		exception will be through since the caching infrastructure is unable to find a suitable store. In situations like this, rather then removing the cache declarations (which can prove tedious),
+		one can wire in a simple, dummy cache that performs no caching - that is, forces the cached methods to be executed every time:</para>
+
+		<programlisting language="xml"><![CDATA[<bean id="cacheManager" class="org.springframework.cache.support.CompositeCacheManager">
+		<property name="cacheManagers"><list>
+		   <ref bean="jdkCache"/>
+		   <ref bean="gemfireCache"/>
+		</list></property>
+		<property name="addNoOpCache" value="true"/>
+</bean>]]></programlisting>
+		
+		<para>The <literal>CompositeCacheManager</literal> above chains multiple <literal>CacheManager</literal>s and aditionally, through the <literal>addNoOpManager</literal> flag, adds a 
+		<emphasis>no op</emphasis> cache that for all the definitions not handled by the configured cache managers. That is, every cache definition not found in either <literal>jdkCache</literal>
+		or <literal>gemfireCache</literal> (configured above) will be handled by the no op cache, which will not store any information causing the target method to be executed every time.
+		</para>
+	</section>
+	
   </section>
   
   <section id="cache-plug">