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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.vfs2.cache;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import org.apache.commons.vfs2.FileName;
import org.apache.commons.vfs2.FileObject;
import org.apache.commons.vfs2.FileSystem;

/**
 * A simple {@link org.apache.commons.vfs2.FilesCache FilesCache} implementation.
 * 

* This implementation caches every file with no expire or limit. All files and filesystems are hard reachable * references. This implementation holds a list of filesystem specific {@linkplain ConcurrentHashMap ConcurrentHashMaps} * in the main cache map. *

* Cached {@linkplain FileObject FileObjects} as well as {@linkplain FileSystem FileSystems} are only removed when * {@link #clear(FileSystem)} is called (i.e. on filesystem close). When the used * {@link org.apache.commons.vfs2.FileSystemManager FileSystemManager} is closed, it will also {@linkplain #close() * close} this cache (which frees all entries). *

* Despite its name, this is not the fallback implementation used by * {@link org.apache.commons.vfs2.impl.DefaultFileSystemManager#init() DefaultFileSystemManager#init()} anymore. */ public class DefaultFilesCache extends AbstractFilesCache { /** The FileSystem cache. Keeps one Map for each FileSystem. */ private final ConcurrentMap> filesystemCache = new ConcurrentHashMap<>( 10); @Override public void putFile(final FileObject file) { final Map files = getOrCreateFilesystemCache(file.getFileSystem()); files.put(file.getName(), file); } @Override public boolean putFileIfAbsent(final FileObject file) { final ConcurrentMap files = getOrCreateFilesystemCache(file.getFileSystem()); return files.putIfAbsent(file.getName(), file) == null; } @Override public FileObject getFile(final FileSystem filesystem, final FileName name) { // avoid creating filesystem entry for empty filesystem cache: final Map files = filesystemCache.get(filesystem); if (files == null) { // cache for filesystem is not known => file is not cached: return null; } return files.get(name); // or null } @Override public void clear(final FileSystem filesystem) { // avoid keeping a reference to the FileSystem (key) object final Map files = filesystemCache.remove(filesystem); if (files != null) { files.clear(); // help GC } } protected ConcurrentMap getOrCreateFilesystemCache(final FileSystem filesystem) { ConcurrentMap files = filesystemCache.get(filesystem); // we loop to make sure we never return null even when concurrent clean is called while (files == null) { filesystemCache.putIfAbsent(filesystem, new ConcurrentHashMap(200, 0.75f, 8)); files = filesystemCache.get(filesystem); } return files; } @Override public void close() { super.close(); filesystemCache.clear(); } @Override public void removeFile(final FileSystem filesystem, final FileName name) { // avoid creating filesystem entry for empty filesystem cache: final Map files = filesystemCache.get(filesystem); if (files != null) { files.remove(name); // This would be too racey: // if (files.empty()) filesystemCache.remove(filessystem); } } }





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