1 /**
2 * This file Copyright (c) 2008-2010 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.Cache;
41 import info.magnolia.module.cache.mbean.CacheMonitor;
42 import net.sf.ehcache.Ehcache;
43 import net.sf.ehcache.Element;
44 import net.sf.ehcache.constructs.blocking.LockTimeoutException;
45
46 /**
47 *
48 * @author gjoseph
49 * @version $Revision: $ ($Author: $)
50 */
51 public class EhCacheWrapper implements Cache {
52
53 private static final Logger log = LoggerFactory.getLogger(EhCacheWrapper.class);
54 private final Ehcache ehcache;
55 private String name;
56
57 public EhCacheWrapper(Ehcache ehcache, String name) {
58 this.ehcache = ehcache;
59 this.name = name;
60 }
61
62 public Object get(Object key) {
63 final Element element = ehcache.get(key);
64 try {
65 return element != null ? element.getObjectValue() : null;
66 } catch (LockTimeoutException e) {
67 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);
68 throw e;
69 }
70 }
71
72 public boolean hasElement(Object key) {
73 // we can't use isKeyInCache(), as it does not check for the element's expiration
74 // which may lead to unexpected results.
75 // return ehcache.isKeyInCache(key);
76 try {
77 // get() and getQuiet() do check for expiration and return null if the element was expired.
78 // we can't use getQuiet, as it's non-blocking which could lead to multiple copies of same page to be generated
79 // if page is requested while previous request for same page is still being processed by different thread
80 return ehcache.get(key) != null;
81 } catch (LockTimeoutException e) {
82 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);
83 // 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.
84 // returning false would mean server attempts to generate the response again, possibly loosing another thread in the process
85 // returning true means server will assume resource exists and will try to retrieve it later, possibly failing with the same error
86 throw e;
87 }
88 }
89
90 public void put(Object key, Object value) {
91 final Element element = new Element(key, value);
92 ehcache.put(element);
93 }
94
95 public void remove(Object key) {
96 ehcache.remove(key);
97 }
98
99 public void clear() {
100 CacheMonitor.getInstance().countFlush(this.name);
101 ehcache.removeAll();
102 }
103
104 public Ehcache getWrappedEhcache() {
105 return ehcache;
106 }
107
108 public String getName() {
109 return name;
110 }
111
112 public int getSize() {
113 return ehcache.getSize();
114 }
115
116 }