/*
* This library is part of OpenCms -
* the Open Source Content Management System
*
* Copyright (c) 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, 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.cache;
import org.opencms.file.CmsResource;
import org.opencms.util.CmsFileUtil;
import java.io.File;
import java.io.IOException;
/**
* Implements a name based RFS file based disk cache, that handles parameter based versions of VFS files.<p>
*
* This RFS cache operates on file names, plus a hash code calculated from
* {@link org.opencms.file.CmsResource#getDateLastModified()}, {@link org.opencms.file.CmsResource#getDateCreated()}
* and {@link org.opencms.file.CmsResource#getLength()}. Optional parameters can be appended to this name,
* which will be added as a second hash code. This way a file can have multiple versions based on different parameters.<p>
*
* This cache is usable for resources from the online AND the offline project at the same time,
* because any change to a resource will result in a changed hash code. This means a resource changed in the offline
* project will have a new hash code compared to the online project. If the resource is identical in the online and
* the offline project, the generated hash codes will be the same.<p>
*
* @since 6.2.0
*/
public class CmsVfsNameBasedDiskCache {
/** The name of the cache base repository folder in the RFS. */
private String m_rfsRepository;
/**
* Creates a new disk cache.<p>
*
* @param basepath the base path for the cache in the RFS
* @param foldername the folder name for this cache, to be used a sub-folder for the base folder
*/
public CmsVfsNameBasedDiskCache(String basepath, String foldername) {
// normalize the given folder name
m_rfsRepository = CmsFileUtil.normalizePath(basepath + foldername + File.separatorChar);
}
/**
* Returns the content of the requested file in the disk cache, or <code>null</code> if the
* file is not found in the cache, or is found but outdated.<p>
*
* @param rfsName the file RFS name to look up in the cache
*
* @return the content of the requested file in the disk cache, or <code>null</code>
*/
public byte[] getCacheContent(String rfsName) {
try {
File f = new File(rfsName);
if (f.exists()) {
long age = f.lastModified();
if ((System.currentTimeMillis() - age) > 3600000) {
// file has not been touched for 1 hour, touch the file with the current date
f.setLastModified(System.currentTimeMillis());
}
return CmsFileUtil.readFile(f);
}
} catch (IOException e) {
// unable to read content
}
return null;
}
/**
* Returns the RFS name to use for caching the given VFS resource with parameters in the disk cache.<p>
*
* @param resource the VFS resource to generate the cache name for
* @param parameters the parameters of the request to the VFS resource
*
* @return the RFS name to use for caching the given VFS resource with parameters
*/
public String getCacheName(CmsResource resource, String parameters) {
// calculate the base cache path for the resource
String rfsName = m_rfsRepository + resource.getRootPath();
String extension = CmsFileUtil.getExtension(rfsName);
// create a StringBuffer for the result
StringBuffer buf = new StringBuffer(rfsName.length() + 24);
buf.append(rfsName.substring(0, rfsName.length() - extension.length()));
// calculate a hash code that contains the resource DateLastModified, DateCreated and Length
StringBuffer ext = new StringBuffer(48);
ext.append(resource.getDateLastModified());
ext.append(';');
ext.append(resource.getDateCreated());
if (resource.getLength() > 0) {
ext.append(';');
ext.append(resource.getLength());
}
// append hash code to the result buffer
buf.append('_');
buf.append(ext.toString().hashCode());
// check if parameters are provided, if so add them as well
if (parameters != null) {
buf.append('_');
buf.append(parameters.hashCode());
}
// finally append the extension from the original file name
buf.append(extension);
return buf.toString();
}
/**
* Returns the absolute path of the cache repository in the RFS.<p>
*
* @return the absolute path of the cache repository in the RFS
*/
public String getRepositoryPath() {
return m_rfsRepository;
}
/**
* Saves the given file content in the disk cache.<p>
*
* @param rfsName the RFS name of the file to save the content in
* @param content the content of the file to save
*
* @throws IOException in case of disk access errors
*/
public void saveCacheFile(String rfsName, byte[] content) throws IOException {
CmsVfsDiskCache.saveFile(rfsName, content);
}
}