Fix cache decoration

Prior to this commit, a cache that is added on-the-fly is not properly
decorated by the provided CacheManager implementation that supports
it (EhCache and JCache).

This commits adds an extra getMissingCache method to
the AbstractCacheManager that can be extended to provide a cache that
may exist in the native cache manager but is not yet known by the
spring abstraction.

Issue: SPR-11518

spring-context/src/main/java/org/springframework/cache/support/AbstractCacheManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -33,6 +33,7 @@ import org.springframework.cache.CacheManager;
  *
  * @author Costin Leau
  * @author Juergen Hoeller
+ * @author Stephane Nicoll
  * @since 3.1
  */
 public abstract class AbstractCacheManager implements CacheManager, InitializingBean {
@@ -70,10 +71,36 @@ public abstract class AbstractCacheManager implements CacheManager, Initializing
 		return cache;
 	}
 
+	/**
+	 * Return a missing cache with the specified {@code name} or {@code null} if
+	 * such cache does not exist or could not be created on the fly.
+	 * <p>Some caches may be created at runtime in the native provided. If a lookup
+	 * by name does not yield any result, a subclass gets a chance to register
+	 * such a cache at runtime. The returned cache will be automatically added to
+	 * this instance.
+	 * @param name the name of the cache to retrieve
+	 * @return the missing cache or {@code null} if no such cache exists or could be
+	 * created
+	 * @see #getCache(String)
+	 */
+	protected Cache getMissingCache(String name) {
+		return null;
+	}
 
 	@Override
 	public Cache getCache(String name) {
-		return this.cacheMap.get(name);
+		Cache cache = lookupCache(name);
+		if (cache != null) {
+			return cache;
+		}
+		else {
+			Cache missingCache = getMissingCache(name);
+			if (missingCache != null) {
+				addCache(missingCache);
+				return lookupCache(name); // May be decorated
+			}
+			return null;
+		}
 	}
 
 	@Override
@@ -81,6 +108,9 @@ public abstract class AbstractCacheManager implements CacheManager, Initializing
 		return Collections.unmodifiableSet(this.cacheNames);
 	}
 
+	private Cache lookupCache(String name) {
+		return this.cacheMap.get(name);
+	}
 
 	/**
 	 * Load the caches for this cache manager. Occurs at startup.