001: /* ====================================================================
002: * The Jcorporate Apache Style Software License, Version 1.2 05-07-2002
003: *
004: * Copyright (c) 1995-2002 Jcorporate Ltd. All rights reserved.
005: *
006: * Redistribution and use in source and binary forms, with or without
007: * modification, are permitted provided that the following conditions
008: * are met:
009: *
010: * 1. Redistributions of source code must retain the above copyright
011: * notice, this list of conditions and the following disclaimer.
012: *
013: * 2. Redistributions in binary form must reproduce the above copyright
014: * notice, this list of conditions and the following disclaimer in
015: * the documentation and/or other materials provided with the
016: * distribution.
017: *
018: * 3. The end-user documentation included with the redistribution,
019: * if any, must include the following acknowledgment:
020: * "This product includes software developed by Jcorporate Ltd.
021: * (http://www.jcorporate.com/)."
022: * Alternately, this acknowledgment may appear in the software itself,
023: * if and wherever such third-party acknowledgments normally appear.
024: *
025: * 4. "Jcorporate" and product names such as "Expresso" must
026: * not be used to endorse or promote products derived from this
027: * software without prior written permission. For written permission,
028: * please contact info@jcorporate.com.
029: *
030: * 5. Products derived from this software may not be called "Expresso",
031: * or other Jcorporate product names; nor may "Expresso" or other
032: * Jcorporate product names appear in their name, without prior
033: * written permission of Jcorporate Ltd.
034: *
035: * 6. No product derived from this software may compete in the same
036: * market space, i.e. framework, without prior written permission
037: * of Jcorporate Ltd. For written permission, please contact
038: * partners@jcorporate.com.
039: *
040: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
041: * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
042: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
043: * DISCLAIMED. IN NO EVENT SHALL JCORPORATE LTD OR ITS CONTRIBUTORS
044: * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
045: * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
046: * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
047: * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
048: * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
049: * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
050: * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
051: * SUCH DAMAGE.
052: * ====================================================================
053: *
054: * This software consists of voluntary contributions made by many
055: * individuals on behalf of the Jcorporate Ltd. Contributions back
056: * to the project(s) are encouraged when you make modifications.
057: * Please send them to support@jcorporate.com. For more information
058: * on Jcorporate Ltd. and its products, please see
059: * <http://www.jcorporate.com/>.
060: *
061: * Portions of this software are based upon other open source
062: * products and are subject to their respective licenses.
063: */
064:
065: package com.jcorporate.expresso.core.cache;
066:
067: import EDU.oswego.cs.dl.util.concurrent.CopyOnWriteArrayList;
068: import com.jcorporate.expresso.core.registry.ExpressoThread;
069: import org.apache.log4j.Logger;
070:
071: import java.util.Iterator;
072:
073: /**
074: * This thread is initialized by CacheManager and slowly iterates through the
075: * Caches clearing out expired items. It often is given a lower thread priority
076: * so it doesn't take away from the app server during high use times.
077: * <p/>
078: * By using this thread, we save significant memory by removing expired items before
079: * they are accessed again.
080: * </p>
081: * <p>Typical Usage:<br/>
082: * <code><pre>
083: * CacheCleaner cacheCleaner = new CacheCleaner();
084: * cacheCleaner.registerCacheSystem(defaultContextCacheSystem);
085: * cacheCleaner.start();
086: * .....
087: * .....
088: * //To shut down. May take a while.
089: * cacheCleaner.interrupt();
090: * cacheCleaner.join();
091: * <p/>
092: * </pre></code></p>
093: *
094: * @author Michael Rimov
095: */
096:
097: public class CacheCleaner extends ExpressoThread {
098: private static final transient Logger log = Logger
099: .getLogger(CacheCleaner.class);
100:
101: private CopyOnWriteArrayList cacheSystems = new CopyOnWriteArrayList();
102:
103: private boolean done = false;
104:
105: protected CacheCleaner() {
106: super ();
107: }
108:
109: /**
110: * Register a cache system for iteration. During a pass of the cache,
111: * the CacheCleaner will iterate all registered CacheSystems
112: *
113: * @param newCache the CacheSystem instance to be cleaning.
114: */
115: public void registerCacheSystem(CacheSystem newCache) {
116: cacheSystems.add(newCache);
117: if (log.isDebugEnabled()) {
118: log.debug("Registering cache system: "
119: + ((Object) newCache).toString() + " for cleaning");
120: }
121: }
122:
123: /**
124: * The cache cleaner run method iterates through all the cache systems installed
125: * in the system and forces the removal of any items that have expired. It
126: * automatically runs every 30 seconds.
127: */
128: public void run() {
129: super .run();
130:
131: if (log.isDebugEnabled()) {
132: log.debug("Starting Cache Cleaning");
133: }
134:
135: while (!this .isInterrupted() && !done) {
136: for (Iterator i = cacheSystems.iterator(); i.hasNext();) {
137: //
138: //Check for interruption after each cache system iteration
139: //
140: if (this .isInterrupted()) {
141: return;
142: }
143:
144: CacheSystem oneCacheSystem = (CacheSystem) i.next();
145:
146: if (log.isDebugEnabled()) {
147: log.debug("Cleaning cache system: "
148: + ((Object) oneCacheSystem).toString());
149: }
150:
151: oneCacheSystem.adjustForMemory();
152:
153: for (Iterator j = oneCacheSystem.getAllCacheNames()
154: .iterator(); j.hasNext();) {
155: String oneCacheName = (String) j.next();
156: Cache oneCache = oneCacheSystem
157: .getCache(oneCacheName);
158: if (oneCache != null) {
159: //
160: //GetItems will automatically check each item in the
161: //cache and remove any expired items.
162: //
163: oneCache.getItems();
164: }
165: }
166: }
167:
168: if (isInterrupted()) {
169: break;
170: } else {
171: try {
172: //Free some CPU time... we don't always need to be running
173: //So we take a 30 second break.
174: sleep(30000);
175: } catch (InterruptedException ex) {
176: break;
177: }
178: }
179: }
180:
181: if (log.isDebugEnabled()) {
182: log.debug("Cache cleaner exiting.");
183: }
184: }
185:
186: public void interrupt() {
187: done = true;
188: super.interrupt();
189: }
190: }
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