/*
* Copyright 2002-2005 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.vfs.cache;
import org.apache.commons.collections.map.AbstractLinkedMap;
import org.apache.commons.collections.map.LRUMap;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.commons.vfs.FileName;
import org.apache.commons.vfs.FileObject;
import org.apache.commons.vfs.FileSystem;
import org.apache.commons.vfs.FileSystemException;
import org.apache.commons.vfs.VfsLog;
import org.apache.commons.vfs.provider.AbstractFileObject;
import org.apache.commons.vfs.util.Messages;
import java.util.HashMap;
import java.util.Map;
/**
* This implementation caches every file using {@link LRUMap}.<br>
* The default constructor uses a LRU size of 100 per filesystem.
*
* @author <a href="mailto:imario@apache.org">Mario Ivankovits</a>
*/
public class LRUFilesCache extends AbstractFilesCache
{
/**
* The logger to use.
*/
private Log log = LogFactory.getLog(LRUFilesCache.class);
private final Map filesystemCache = new HashMap(10);
private final int lruSize;
private class MyLRUMap extends LRUMap
{
final FileSystem filesystem;
public MyLRUMap(final FileSystem filesystem, int size)
{
super(size, true);
this.filesystem = filesystem;
}
protected boolean removeLRU(final AbstractLinkedMap.LinkEntry linkEntry)
{
synchronized (LRUFilesCache.this)
{
AbstractFileObject file = (AbstractFileObject) linkEntry.getValue();
// System.err.println(">>> " + size() + " check removeLRU:" + linkEntry.getKey().toString());
if (file.isAttached() || file.isContentOpen())
{
// do not allow open or attached files to be removed
// System.err.println(">>> " + size() + " VETO removeLRU:" + linkEntry.getKey().toString() + " (" + file.isAttached() + "/" + file.isContentOpen() + ")");
return false;
}
// System.err.println(">>> " + size() + " removeLRU:" + linkEntry.getKey().toString());
if (super.removeLRU(linkEntry))
{
try
{
// force detach
file.close();
}
catch (FileSystemException e)
{
VfsLog.warn(getLogger(), log, Messages.getString("vfs.impl/LRUFilesCache-remove-ex.warn"), e);
}
Map files = (Map) filesystemCache.get(filesystem);
if (files.size() < 1)
{
filesystemCache.remove(filesystem);
}
return true;
}
return false;
}
}
}
/**
* Default constructor. Uses a LRU size of 100 per filesystem.
*/
public LRUFilesCache()
{
this(100);
}
/**
* Set the desired LRU size.
*
* @param lruSize the LRU size
*/
public LRUFilesCache(int lruSize)
{
this.lruSize = lruSize;
}
public void putFile(final FileObject file)
{
synchronized (this)
{
Map files = getOrCreateFilesystemCache(file.getFileSystem());
// System.err.println(">>> " + files.size() + " put:" + file.toString());
files.put(file.getName(), file);
}
}
public FileObject getFile(final FileSystem filesystem, final FileName name)
{
synchronized (this)
{
Map files = getOrCreateFilesystemCache(filesystem);
// FileObject fo = (FileObject) files.get(name);
// System.err.println(">>> " + files.size() + " get:" + name.toString() + " " + fo);
return (FileObject) files.get(name);
}
}
public void clear(final FileSystem filesystem)
{
synchronized (this)
{
// System.err.println(">>> clear fs " + filesystem);
Map files = getOrCreateFilesystemCache(filesystem);
files.clear();
filesystemCache.remove(filesystem);
}
}
protected Map getOrCreateFilesystemCache(final FileSystem filesystem)
{
Map files = (Map) filesystemCache.get(filesystem);
if (files == null)
{
// System.err.println(">>> create fs " + filesystem);
files = new MyLRUMap(filesystem, lruSize);
filesystemCache.put(filesystem, files);
}
return files;
}
public void close()
{
super.close();
synchronized (this)
{
// System.err.println(">>> clear all");
filesystemCache.clear();
}
}
public void removeFile(final FileSystem filesystem, final FileName name)
{
synchronized (this)
{
Map files = getOrCreateFilesystemCache(filesystem);
// System.err.println(">>> " + files.size() + " remove:" + name.toString());
files.remove(name);
if (files.size() < 1)
{
filesystemCache.remove(filesystem);
}
}
}
public void touchFile(final FileObject file)
{
// this moves the file back on top
getFile(file.getFileSystem(), file.getName());
}
}