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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.executor;
35  
36  import info.magnolia.module.cache.Cache;
37  import info.magnolia.module.cache.CachePolicyResult;
38  import info.magnolia.module.cache.filter.CachedEntry;
39  import info.magnolia.module.cache.filter.ContentCachedEntry;
40  
41  import java.io.IOException;
42  
43  import javax.servlet.FilterChain;
44  import javax.servlet.ServletException;
45  import javax.servlet.http.HttpServletRequest;
46  import javax.servlet.http.HttpServletResponse;
47  
48  /**
49   * Serves the content from the cache.
50   *
51   * @author pbracher
52   * @version $Revision: $ ($Author: $)
53   */
54  public class UseCache extends AbstractExecutor {
55      private final static org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(UseCache.class);
56  
57      public void processCacheRequest(HttpServletRequest request,
58              HttpServletResponse response, FilterChain chain, Cache cache,
59              CachePolicyResult cachePolicy) throws IOException, ServletException {
60          CachedEntry cached = (CachedEntry) cachePolicy.getCachedEntry();
61          processCachedEntry(cached, request, response, chain);
62      }
63  
64      protected void processCachedEntry(CachedEntry cached, HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws IOException, ServletException {
65          log.debug("Serving {}", cached);
66          if (cached instanceof ContentCachedEntry) {
67              final ContentCachedEntry page = (ContentCachedEntry) cached;
68              if (!ifModifiedSince(request, page.getLastModificationTime())) {
69                  if (response.isCommitted()) {
70                      // this should not happen ... if it does, log it and _serve_the_data_ otherwise we will confuse client
71                      log.warn("Unable to change status on already commited response {}.", response.getClass().getName());
72                  } else {
73                      response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
74                      return;
75                  }
76              }
77  
78  
79          }
80  
81          if (cached != null) {
82              cached.replay(request, response, chain);
83              response.flushBuffer();
84          } else {
85              // not modified (304) or nothing to write to the output
86          }
87      }
88  
89  }