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 CacheManager[] cacheManagers;
+	private List<CacheManager> cacheManagers;
+	private boolean noOpManager = false;
+
+	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;
 	}
 }

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

@@ -0,0 +1,99 @@
+/*
+ * 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);
+	}
+}