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, 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.db.CmsDriverManager;
  import org.opencms.file.CmsResource;
  import org.opencms.main.CmsEvent;
  import org.opencms.main.I_CmsEventListener;
  import org.opencms.main.OpenCms;
  import org.opencms.util.CmsCollectionsGenericWrapper;
  
  import java.util.List;
  
  /**
   * Configurable VFS based cache, for caching objects related to offline/online resources.<p>
   *
   * @since 7.6
   */
  public abstract class CmsVfsCache implements I_CmsEventListener {
  
      /**
       * Initializes the cache. Only intended to be called during startup.<p>
       */
      protected CmsVfsCache() {
  
          // empty
      }
  
      /**
       * @see org.opencms.main.I_CmsEventListener#cmsEvent(org.opencms.main.CmsEvent)
       */
      public void cmsEvent(CmsEvent event) {
  
          CmsResource resource = null;
          List<CmsResource> resources = null;
  
          switch (event.getType()) {
              case I_CmsEventListener.EVENT_RESOURCE_AND_PROPERTIES_MODIFIED:
              case I_CmsEventListener.EVENT_RESOURCE_MODIFIED:
                  Object change = event.getData().get(I_CmsEventListener.KEY_CHANGE);
                  if ((change != null) && change.equals(Integer.valueOf(CmsDriverManager.NOTHING_CHANGED))) {
                      // skip lock & unlock
                      return;
                  }
                  // a resource has been modified in a way that it *IS NOT* necessary also to clear
                  // lists of cached sub-resources where the specified resource might be contained inside.
                  resource = (CmsResource)event.getData().get(I_CmsEventListener.KEY_RESOURCE);
                  uncacheResource(resource);
                  break;
  
              case I_CmsEventListener.EVENT_RESOURCES_AND_PROPERTIES_MODIFIED:
                  // a list of resources and all of their properties have been modified
                  resources = CmsCollectionsGenericWrapper.list(event.getData().get(I_CmsEventListener.KEY_RESOURCES));
                  uncacheResources(resources);
                  break;
  
              case I_CmsEventListener.EVENT_RESOURCE_MOVED:
              case I_CmsEventListener.EVENT_RESOURCE_DELETED:
              case I_CmsEventListener.EVENT_RESOURCES_MODIFIED:
                  // a list of resources has been modified
                  resources = CmsCollectionsGenericWrapper.list(event.getData().get(I_CmsEventListener.KEY_RESOURCES));
                  uncacheResources(resources);
                  break;
  
              case I_CmsEventListener.EVENT_CLEAR_ONLINE_CACHES:
              case I_CmsEventListener.EVENT_PUBLISH_PROJECT:
                  flush(true);
                  break;
  
              case I_CmsEventListener.EVENT_CLEAR_CACHES:
                  flush(true);
                  flush(false);
                  break;
  
              case I_CmsEventListener.EVENT_CLEAR_OFFLINE_CACHES:
                  flush(false);
                  break;
  
              default:
                  // noop
                  break;
          }
      }
  
      /**
       * Clean up at shutdown time. Only intended to be called at system shutdown.<p>
       *
       * @see org.opencms.main.OpenCmsCore#shutDown
       */
      public void shutdown() {
  
          if (OpenCms.getMemoryMonitor() != null) {
              // prevent accidental calls
              return;
  
          }
          flush(true);
          flush(false);
      }
  
      /**
       * Flushes the caches.<p>
       *
       * @param online if to flush the online or offline caches
       */
      protected abstract void flush(boolean online);
  
      /**
       * Adds this instance as an event listener to the CMS event manager.<p>
       */
      protected void registerEventListener() {
  
          OpenCms.addCmsEventListener(
              this,
              new int[] {
                  I_CmsEventListener.EVENT_RESOURCE_AND_PROPERTIES_MODIFIED,
                  I_CmsEventListener.EVENT_RESOURCES_AND_PROPERTIES_MODIFIED,
                  I_CmsEventListener.EVENT_RESOURCE_MODIFIED,
                  I_CmsEventListener.EVENT_RESOURCES_MODIFIED,
                  I_CmsEventListener.EVENT_RESOURCE_MOVED,
                  I_CmsEventListener.EVENT_RESOURCE_DELETED,
                  I_CmsEventListener.EVENT_PUBLISH_PROJECT,
                  I_CmsEventListener.EVENT_CLEAR_CACHES,
                  I_CmsEventListener.EVENT_CLEAR_ONLINE_CACHES,
                  I_CmsEventListener.EVENT_CLEAR_OFFLINE_CACHES});
      }
  
      /**
       * Removes a cached resource from the cache.<p>
       *
       * @param resource the resource
       */
      protected abstract void uncacheResource(CmsResource resource);
  
      /**
       * Removes a bunch of cached resources from the cache.<p>
       *
       * @param resources a list of resources
       *
       * @see #uncacheResource(CmsResource)
       */
      protected void uncacheResources(List<CmsResource> resources) {
  
          if (resources == null) {
              return;
          }
          for (int i = 0, n = resources.size(); i < n; i++) {
              // remove the resource
              uncacheResource(resources.get(i));
          }
      }
  }
  