001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.vfs2.cache; 018 019import java.util.Map; 020import java.util.concurrent.ConcurrentHashMap; 021import java.util.concurrent.ConcurrentMap; 022 023import org.apache.commons.vfs2.FileName; 024import org.apache.commons.vfs2.FileObject; 025import org.apache.commons.vfs2.FileSystem; 026 027/** 028 * A simple {@link org.apache.commons.vfs2.FilesCache FilesCache} implementation. 029 * <p> 030 * This implementation caches every file with no expire or limit. All files and filesystems are hard reachable 031 * references. This implementation holds a list of filesystem specific {@linkplain ConcurrentHashMap ConcurrentHashMaps} 032 * in the main cache map. 033 * <p> 034 * Cached {@linkplain FileObject FileObjects} as well as {@linkplain FileSystem FileSystems} are only removed when 035 * {@link #clear(FileSystem)} is called (i.e. on filesystem close). When the used 036 * {@link org.apache.commons.vfs2.FileSystemManager FileSystemManager} is closed, it will also {@linkplain #close() 037 * close} this cache (which frees all entries). 038 * <p> 039 * Despite its name, this is not the fallback implementation used by 040 * {@link org.apache.commons.vfs2.impl.DefaultFileSystemManager#init() DefaultFileSystemManager#init()} anymore. 041 */ 042public class DefaultFilesCache extends AbstractFilesCache { 043 /** The FileSystem cache. Keeps one Map for each FileSystem. */ 044 private final ConcurrentMap<FileSystem, ConcurrentMap<FileName, FileObject>> filesystemCache = new ConcurrentHashMap<>( 045 10); 046 047 @Override 048 public void putFile(final FileObject file) { 049 final Map<FileName, FileObject> files = getOrCreateFilesystemCache(file.getFileSystem()); 050 files.put(file.getName(), file); 051 } 052 053 @Override 054 public boolean putFileIfAbsent(final FileObject file) { 055 final ConcurrentMap<FileName, FileObject> files = getOrCreateFilesystemCache(file.getFileSystem()); 056 return files.putIfAbsent(file.getName(), file) == null; 057 } 058 059 @Override 060 public FileObject getFile(final FileSystem filesystem, final FileName name) { 061 // avoid creating filesystem entry for empty filesystem cache: 062 final Map<FileName, FileObject> files = filesystemCache.get(filesystem); 063 if (files == null) { 064 // cache for filesystem is not known => file is not cached: 065 return null; 066 } 067 068 return files.get(name); // or null 069 } 070 071 @Override 072 public void clear(final FileSystem filesystem) { 073 // avoid keeping a reference to the FileSystem (key) object 074 final Map<FileName, FileObject> files = filesystemCache.remove(filesystem); 075 if (files != null) { 076 files.clear(); // help GC 077 } 078 } 079 080 protected ConcurrentMap<FileName, FileObject> getOrCreateFilesystemCache(final FileSystem filesystem) { 081 ConcurrentMap<FileName, FileObject> files = filesystemCache.get(filesystem); 082 // we loop to make sure we never return null even when concurrent clean is called 083 while (files == null) { 084 filesystemCache.putIfAbsent(filesystem, new ConcurrentHashMap<FileName, FileObject>(200, 0.75f, 8)); 085 files = filesystemCache.get(filesystem); 086 } 087 088 return files; 089 } 090 091 @Override 092 public void close() { 093 super.close(); 094 095 filesystemCache.clear(); 096 } 097 098 @Override 099 public void removeFile(final FileSystem filesystem, final FileName name) { 100 // avoid creating filesystem entry for empty filesystem cache: 101 final Map<FileName, FileObject> files = filesystemCache.get(filesystem); 102 if (files != null) { 103 files.remove(name); 104 // This would be too racey: 105 // if (files.empty()) filesystemCache.remove(filessystem); 106 } 107 } 108}