1 /*
2 * Copyright 2010-2026 the original author or authors.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * https://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package org.mybatis.caches.ehcache;
17
18 import net.sf.ehcache.Ehcache;
19 import net.sf.ehcache.Element;
20 import net.sf.ehcache.constructs.blocking.BlockingCache;
21
22 /**
23 * Cache implementation that wraps Ehcache 2 with {@link BlockingCache} semantics.
24 * <p>
25 * {@link BlockingCache} acquires a per-key lock when a cache miss occurs so that only one thread computes the missing
26 * value while others block. This prevents cache-stampede on a cold or expired entry.
27 * </p>
28 *
29 * @author Iwao AVE!
30 */
31 public class EhBlockingCache extends AbstractEhcacheCache {
32
33 /**
34 * Instantiates a new eh blocking cache.
35 *
36 * @param id
37 * the id
38 */
39 public EhBlockingCache(final String id) {
40 super(id);
41 if (!CACHE_MANAGER.cacheExists(id)) {
42 CACHE_MANAGER.addCache(this.id);
43 Ehcache ehcache = CACHE_MANAGER.getEhcache(this.id);
44 BlockingCache blockingCache = new BlockingCache(ehcache);
45 CACHE_MANAGER.replaceCacheWithDecoratedCache(ehcache, blockingCache);
46 }
47 this.cache = CACHE_MANAGER.getEhcache(id);
48 }
49
50 @Override
51 public Object removeObject(Object key) {
52 // this method is called during a rollback just to
53 // release any previous lock
54 cache.put(new Element(key, null));
55 return null;
56 }
57
58 /**
59 * {@inheritDoc}
60 * <p>
61 * Re-wraps the rebuilt cache in a {@link BlockingCache} after replacing it.
62 * </p>
63 */
64 @Override
65 protected void rebuildCacheWith(net.sf.ehcache.config.CacheConfiguration newConfig) {
66 CACHE_MANAGER.removeCache(id);
67 CACHE_MANAGER.addCache(new net.sf.ehcache.Cache(newConfig));
68 Ehcache ehcache = CACHE_MANAGER.getEhcache(id);
69 BlockingCache blockingCache = new BlockingCache(ehcache);
70 CACHE_MANAGER.replaceCacheWithDecoratedCache(ehcache, blockingCache);
71 this.cache = CACHE_MANAGER.getEhcache(id);
72 }
73
74 }