content: /*
   * This library is part of OpenCms -
   * the Open Source Content Management System
   *
   * Copyright (c) Alkacon Software GmbH & Co. KG (https://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 & Co. KG, please see the
   * company website: https://www.alkacon.com
   *
   * For further information about OpenCms, please see the
   * project website: https://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.cache;
  
  import org.opencms.main.CmsEvent;
  import org.opencms.main.CmsLog;
  import org.opencms.main.I_CmsEventListener;
  import org.opencms.main.OpenCms;
  import org.opencms.monitor.CmsMemoryMonitor;
  
  import org.apache.commons.logging.Log;
  
  /**
   * A singleton memory cache, that stores objects related with keys.<p>
   *
   * This cache listens to the {@link I_CmsEventListener#EVENT_CLEAR_CACHES} event only.<p>
   *
   * @since 6.2.3
   */
  public final class CmsMemoryObjectCache implements I_CmsEventListener {
  
      /** The log object for this class. */
      private static final Log LOG = CmsLog.getLog(CmsMemoryObjectCache.class);
  
      /** A cache that maps VFS resource names to Objects. */
      private static CmsMemoryObjectCache m_instance;
  
      /**
       * Constructor, creates a new CmsVfsMemoryObjectCache.<p>
       */
      private CmsMemoryObjectCache() {
  
          // register the event listeners
          registerEventListener();
      }
  
      /**
       * Returns the singleton memory Object cache instance.<p>
       *
       * @return the singleton memory Object cache instance
       */
      public static CmsMemoryObjectCache getInstance() {
  
          if (m_instance == null) {
              m_instance = new CmsMemoryObjectCache();
          }
          return m_instance;
      }
  
      /**
       * @see org.opencms.main.I_CmsEventListener#cmsEvent(org.opencms.main.CmsEvent)
       */
      public void cmsEvent(CmsEvent event) {
  
          switch (event.getType()) {
              case I_CmsEventListener.EVENT_CLEAR_CACHES:
                  // flush cache
                  OpenCms.getMemoryMonitor().flushCache(CmsMemoryMonitor.CacheType.MEMORY_OBJECT);
                  if (LOG.isDebugEnabled()) {
                      LOG.debug(
                          org.opencms.xml.Messages.get().getBundle().key(
                              org.opencms.xml.Messages.LOG_ERR_FLUSHED_CACHES_0));
                  }
                  break;
              default:
                  // no operation
          }
      }
  
      /**
       * Returns an object from the cache.<p>
       *
       * @param owner the owner class of the cached object (used to ensure keys don't overlap)
       * @param key the key to lookup the object for
       *
       * @return an object from the cache, or <code>null</code> if no object matches the given key
       */
      public Object getCachedObject(Class<?> owner, String key) {
  
          key = owner.getName().concat(key);
          return OpenCms.getMemoryMonitor().getCachedMemObject(key);
      }
  
      /**
       * Puts an object into the cache.<p>
       *
       * @param owner the owner class of the cached object (used to ensure keys don't overlap)
       * @param key the key to store the object at
       * @param value the object to store
       */
      public void putCachedObject(Class<?> owner, String key, Object value) {
  
          key = owner.getName().concat(key);
          OpenCms.getMemoryMonitor().cacheMemObject(key, value);
      }
  
      /**
       * Registers all required event listeners.<p>
       */
      protected void registerEventListener() {
  
          // register this object as event listener
          OpenCms.addCmsEventListener(this, new int[] {I_CmsEventListener.EVENT_CLEAR_CACHES});
      }
  }