1 /**
2 * This file Copyright (c) 2008-2011 Magnolia International
3 * Ltd. (http://www.magnolia-cms.com). All rights reserved.
4 *
5 *
6 * This file is dual-licensed under both the Magnolia
7 * Network Agreement and the GNU General Public License.
8 * You may elect to use one or the other of these licenses.
9 *
10 * This file is distributed in the hope that it will be
11 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
12 * implied warranty of MERCHANTABILITY or FITNESS FOR A
13 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
14 * Redistribution, except as permitted by whichever of the GPL
15 * or MNA you select, is prohibited.
16 *
17 * 1. For the GPL license (GPL), you can redistribute and/or
18 * modify this file under the terms of the GNU General
19 * Public License, Version 3, as published by the Free Software
20 * Foundation. You should have received a copy of the GNU
21 * General Public License, Version 3 along with this program;
22 * if not, write to the Free Software Foundation, Inc., 51
23 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
24 *
25 * 2. For the Magnolia Network Agreement (MNA), this file
26 * and the accompanying materials are made available under the
27 * terms of the MNA which accompanies this distribution, and
28 * is available at http://www.magnolia-cms.com/mna.html
29 *
30 * Any modifications to this file must keep this entire header
31 * intact.
32 *
33 */
34 package info.magnolia.module.cache.ehcache;
35
36
37 import org.slf4j.Logger;
38 import org.slf4j.LoggerFactory;
39
40 import info.magnolia.module.cache.mbean.CacheMonitor;
41 import net.sf.ehcache.Ehcache;
42 import net.sf.ehcache.Element;
43 import net.sf.ehcache.constructs.blocking.BlockingCache;
44 import net.sf.ehcache.constructs.blocking.LockTimeoutException;
45
46 /**
47 * Magnolia cache wrapper for underlying ehCache implementation.
48 * @author gjoseph
49 * @version $Revision: $ ($Author: $)
50 */
51 public class EhCacheWrapper implements info.magnolia.module.cache.BlockingCache {
52
53 private static final Logger log = LoggerFactory.getLogger(EhCacheWrapper.class);
54 private final BlockingCache ehcache;
55 private String name;
56
57 public EhCacheWrapper(BlockingCache ehcache, String name) {
58 this.ehcache = ehcache;
59 this.name = name;
60 }
61
62 public EhCacheWrapper(Ehcache ehcache, String name) {
63 this(castToBlockingCacheOrThrowException(ehcache), name);
64 }
65
66 private static BlockingCache castToBlockingCacheOrThrowException(Ehcache ehcache) {
67 if(!(ehcache instanceof BlockingCache)){
68 throw new RuntimeException("The current caching framework depends on the fact the a blocking cache is used.");
69 }
70 return (BlockingCache) ehcache;
71 }
72
73 public Object get(Object key) {
74 final Element element = ehcache.get(key);
75 try {
76 return element != null ? element.getObjectValue() : null;
77 } catch (LockTimeoutException e) {
78 log.error("Detected 1 thread stuck in generating response for {}. This might be temporary if obtaining the response is resource intensive or when accessing remote resources.", key);
79 throw e;
80 }
81 }
82
83 public boolean hasElement(Object key) {
84 // we can't use isKeyInCache(), as it does not check for the element's expiration
85 // which may lead to unexpected results.
86 // return ehcache.isKeyInCache(key);
87 try {
88 // get() and getQuiet() do check for expiration and return null if the element was expired.
89 // we can't use getQuiet, as it's non-blocking which could lead to multiple copies of same page to be generated
90 // if page is requested while previous request for same page is still being processed by different thread
91 return ehcache.get(key) != null;
92 } catch (LockTimeoutException e) {
93 log.error("Detected 1 thread stuck in generating response for {}. This might be temporary if obtaining the response is resource intensive or when accessing remote resources.", key);
94 // FYI: in case you want to return some value instead of re-throwing exception: this is a dilemma ... obviously resource does not exist yet, but being stuck here for while means that it is either being generated or it takes time to generate.
95 // returning false would mean server attempts to generate the response again, possibly loosing another thread in the process
96 // returning true means server will assume resource exists and will try to retrieve it later, possibly failing with the same error
97 throw e;
98 }
99 }
100
101 public void put(Object key, Object value) {
102 final Element element = new Element(key, value);
103 ehcache.put(element);
104 }
105
106 public void put(Object key, Object value, int timeToLiveInSeconds) {
107 final Element element = new Element(key, value);
108 element.setTimeToLive(timeToLiveInSeconds);
109 ehcache.put(element);
110 }
111
112 public void remove(Object key) {
113 ehcache.remove(key);
114 }
115
116 public void clear() {
117 CacheMonitor.getInstance().countFlush(this.name);
118 ehcache.removeAll();
119 }
120
121 public void unlock(Object key) {
122 if(ehcache.getQuiet(key) == null) {
123 put(key, null);
124 remove(key);
125 }
126 }
127
128 public int getBlockingTimeout() {
129 return ehcache.getTimeoutMillis();
130 }
131
132 public Ehcache getWrappedEhcache() {
133 return ehcache;
134 }
135
136 public String getName() {
137 return name;
138 }
139
140 public int getSize() {
141 return ehcache.getSize();
142 }
143
144
145
146 }