cmsflexcache.java

cms是开源的框架

/*
 * File   : $Source: /usr/local/cvs/opencms/src/org/opencms/flex/CmsFlexCache.java,v $
 * Date   : $Date: 2006/03/27 14:52:35 $
 * Version: $Revision: 1.52 $
 *
 * This library is part of OpenCms -
 * the Open Source Content Mananagement System
 *
 * Copyright (c) 2005 Alkacon Software GmbH (http://www.alkacon.com)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * For further information about Alkacon Software GmbH, please see the
 * company website: http://www.alkacon.com
 *
 * For further information about OpenCms, please see the
 * project website: http://www.opencms.org
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package org.opencms.flex;

import org.opencms.cache.CmsLruCache;
import org.opencms.cache.I_CmsLruCacheObject;
import org.opencms.file.CmsObject;
import org.opencms.main.CmsLog;
import org.opencms.main.I_CmsEventListener;
import org.opencms.main.OpenCms;
import org.opencms.security.CmsRole;
import org.opencms.util.CmsFileUtil;
import org.opencms.util.CmsStringUtil;

import java.io.File;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.apache.commons.collections.map.LRUMap;
import org.apache.commons.logging.Log;

/**
 * This class implements the FlexCache.<p>
 *
 * The data structure used is a two-level hashtable.
 * This is optimized for the structure of the keys that are used to describe the
 * caching behaviour of the entries.
 * The first hash-level is calculated from the resource name, i.e. the
 * name of the resource as it is referred to in the VFS of OpenCms.
 * The second hash-level is calculated from the cache-key of the resource,
 * which also is a String representing the specifc variation of the cached entry.<p>
 *
 * A suffix [online] or [offline] is appended to te resource name
 * to distinguish between the online and offline projects of OpenCms.
 * Also, for support of JSP based workplace pages, a suffix [workplace]
 * is appended. The same cached workplace pages are used both in the online and 
 * all offline projects.<p> 
 * 
 * Entries in the first level of the cache are of type CmsFlexCacheVariation,
 * which is a sub-class of CmsFlexCache.
 * This class is a simple data type that contains of a Map of CmsFlexCacheEntries,
 * with variations - Strings as keys.<p>
 *
 * Here's a short summary of used terms:
 * <ul>
 * <li><b>key:</b>
 * A combination of a resource name and a variation.
 * The data structure used is CmsFlexCacheKey.
 * <li><b>resource:</b>
 * A String with the resource name and an appended [online] of [offline] suffix.
 * <li><b>variation:</b>
 * A String describing a variation of a cached entry in the CmsFlexCache language.
 * <li><b>entry:</b>
 * A CmsFlexCacheEntry data structure which is describes a cached OpenCms resource.
 * For every entry a key is saved which contains the resource name and the variation.
 * </ul>
 *
 * Cache clearing is handled using events.
 * The cache is fully flushed if an event {@link I_CmsEventListener#EVENT_PUBLISH_PROJECT} 
 * or {@link I_CmsEventListener#EVENT_CLEAR_CACHES} is caught.<p>
 *
 * @author Alexander Kandzior 
 * @author Thomas Weckert  
 * 
 * @version $Revision: 1.52 $ 
 * 
 * @since 6.0.0 
 * 
 * @see org.opencms.flex.CmsFlexCacheKey
 * @see org.opencms.flex.CmsFlexCacheEntry
 * @see org.opencms.cache.CmsLruCache
 * @see org.opencms.cache.I_CmsLruCacheObject
 */
public class CmsFlexCache extends Object implements I_CmsEventListener {

    /**
     * A simple data container class for the FlexCache variations.<p>
     * 
     * @author Alexander Kandzior 
     */
    public class CmsFlexCacheVariation extends Object {

        /** The key belonging to the resource. */
        public CmsFlexCacheKey m_key;

        /** Maps variations to CmsFlexCacheEntries. */
        public Map m_map;

        /**
         * Generates a new instance of CmsFlexCacheVariation.<p>
         *
         * @param theKey The (resource) key to contruct this variation list for
         */
        public CmsFlexCacheVariation(CmsFlexCacheKey theKey) {

            m_key = theKey;
            m_map = new Hashtable(INITIAL_CAPACITY_VARIATIONS);
        }
    }

    /**
     * Extended LRUMap that handles the variations in case a key is removed.<p>
     * 
     * @author Alexander Kandzior 
     */
    class CmsFlexKeyMap extends LRUMap {

        /** Serial version UID required for safe serialization. */
        private static final long serialVersionUID = 6931995916013396902L;

        /**
         * Initialize the map with the given size.<p>
         * 
         * @param maxSize the maximum number of key to cache 
         */
        public CmsFlexKeyMap(int maxSize) {

            super(maxSize);
        }

        /**
         * Ensures that all variations that referenced by this key are released
         * if the key is released.<p>
         */
        protected boolean removeLRU(LinkEntry entry) {

            CmsFlexCacheVariation v = (CmsFlexCacheVariation)entry.getValue();
            if (v == null) {
                return true;
            }
            Map m = v.m_map;
            if ((m == null) || (m.size() == 0)) {
                return true;
            }
            Object[] entries = m.values().toArray();
            synchronized (m_variationCache) {
                for (int i = 0, s = entries.length; i < s; i++) {
                    CmsFlexCacheEntry e = (CmsFlexCacheEntry)entries[i];
                    m_variationCache.remove(e);
                }
                v.m_map.clear();
                v.m_map = null;
                v.m_key = null;
            }
            return true;
        }
    }

    /** Suffix to append to online cache entries. */
    public static final String CACHE_OFFLINESUFFIX = " [offline]";

    /** Suffix to append to online cache entries. */
    public static final String CACHE_ONLINESUFFIX = " [online]";

    /** Trigger for clearcache event: Clear complete cache. */
    public static final int CLEAR_ALL = 0;

    /** Trigger for clearcache event: Clear only entries. */
    public static final int CLEAR_ENTRIES = 1;

    /** Trigger for clearcache event: Clear complete offine cache. */
    public static final int CLEAR_OFFLINE_ALL = 4;

    /** Trigger for clearcache event: Clear only offline entries. */
    public static final int CLEAR_OFFLINE_ENTRIES = 5;

    /** Trigger for clearcache event: Clear complete online cache. */
    public static final int CLEAR_ONLINE_ALL = 2;

    /** Trigger for clearcache event: Clear only online entries. */
    public static final int CLEAR_ONLINE_ENTRIES = 3;

    /** Initial cache size, this should be a power of 2 because of the Java collections implementation. */
    public static final int INITIAL_CAPACITY_CACHE = 512;

    /** Initial size for variation lists, should be a power of 2. */
    public static final int INITIAL_CAPACITY_VARIATIONS = 8;

    /** Offline repository constant. */
    public static final String REPOSITORY_OFFLINE = "offline";

    /** Online repository constant. */
    public static final String REPOSITORY_ONLINE = "online";

    /** The log object for this class. */
    private static final Log LOG = CmsLog.getLog(CmsFlexCache.class);

    /** The LRU cache to organize the cached entries. */
    protected CmsLruCache m_variationCache;

    /** Indicates if offline resources should be cached or not. */
    private boolean m_cacheOffline;

    /** Indicates if the cache is enabled or not. */
    private boolean m_enabled;

    /** Hashmap to store the entries for fast lookup. */
    private Map m_keyCache;

    /** Counter for the size. */
    private int m_size;

    /**
     * Constructor for class CmsFlexCache.<p>
     *
     * The parameter "enabled" is used to control if the cache is
     * actually on or off. Even if you don't need the cache, you still
     * have to create an instance of it with enabled=false.
     * This is because you need some of the FlexCache data structures
     * for JSP inclusion buffering.<p>
     *
     * @param configuration the flex cache configuration
     */
    public CmsFlexCache(CmsFlexCacheConfiguration configuration) {

        m_enabled = configuration.isCacheEnabled();
        m_cacheOffline = configuration.isCacheOffline();

        int maxCacheBytes = configuration.getMaxCacheBytes();
        int avgCacheBytes = configuration.getAvgCacheBytes();
        int maxEntryBytes = configuration.getMaxEntryBytes();
        int maxKeys = configuration.getMaxKeys();

        m_variationCache = new CmsLruCache(maxCacheBytes, avgCacheBytes, maxEntryBytes);

        if (OpenCms.getMemoryMonitor().enabled()) {
            OpenCms.getMemoryMonitor().register(getClass().getName() + ".m_entryLruCache", m_variationCache);
        }

        if (m_enabled) {
            CmsFlexKeyMap flexKeyMap = new CmsFlexKeyMap(maxKeys);
            m_keyCache = Collections.synchronizedMap(flexKeyMap);

            if (OpenCms.getMemoryMonitor().enabled()) {
                OpenCms.getMemoryMonitor().register(getClass().getName() + ".m_resourceMap", flexKeyMap);
            }

            OpenCms.addCmsEventListener(this, new int[] {
                I_CmsEventListener.EVENT_PUBLISH_PROJECT,
                I_CmsEventListener.EVENT_CLEAR_CACHES,
                I_CmsEventListener.EVENT_FLEX_PURGE_JSP_REPOSITORY,
                I_CmsEventListener.EVENT_FLEX_CACHE_CLEAR});
        }

        if (LOG.isInfoEnabled()) {
            LOG.info(Messages.get().getBundle().key(
                Messages.INIT_FLEXCACHE_CREATED_2,
                new Boolean(m_enabled),
                new Boolean(m_cacheOffline)));
        }
    }

    /**
     * Indicates if offline project resources are cached.<p>
     *
     * @return true if offline projects are cached, false if not
     */
    public boolean cacheOffline() {

        return m_cacheOffline;
    }

    /**
     * Implements the CmsEvent interface,
     * the FlexCache uses the events to clear itself in case a project is published.<p>
     *
     * @param event CmsEvent that has occurred
     */
    public void cmsEvent(org.opencms.main.CmsEvent event) {

        if (!isEnabled()) {
            return;
        }

        switch (event.getType()) {