| /* |
| * 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.lang.ref.Reference; |
| import java.lang.ref.ReferenceQueue; |
| import java.lang.ref.SoftReference; |
| import java.util.HashMap; |
| import java.util.Iterator; |
| import java.util.Map; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.commons.vfs2.FileName; |
| import org.apache.commons.vfs2.FileObject; |
| import org.apache.commons.vfs2.FileSystem; |
| |
| /** |
| * This implementation caches every file as long as it is strongly reachable by the JVM. As soon as the JVM needs |
| * memory - every softly reachable file will be discarded. |
| * |
| * @see SoftReference |
| */ |
| public class SoftRefFilesCache extends AbstractFilesCache { |
| |
| /** |
| * This thread will listen on the ReferenceQueue and remove the entry in the file cache as soon as the JVM removes |
| * the reference. |
| */ |
| private final class ReleaseThread extends Thread { |
| private ReleaseThread() { |
| setName(ReleaseThread.class.getName()); |
| setDaemon(true); |
| } |
| |
| @Override |
| public void run() { |
| try { |
| while (true) { |
| removeFile(refQueue.remove(0)); |
| } |
| } catch (final InterruptedException e) { |
| // end thread run. |
| // System.out.println("Thread caught InterruptedException, ending " + getId()); |
| // System.out.flush(); |
| } |
| } |
| } |
| |
| private static final Log log = LogFactory.getLog(SoftRefFilesCache.class); |
| private final Map<FileSystem, Map<FileName, Reference<FileObject>>> fileSystemCache = new HashMap<>(); |
| private final Map<Reference<FileObject>, FileSystemAndNameKey> refReverseMap = new HashMap<>(100); |
| private final ReferenceQueue<FileObject> refQueue = new ReferenceQueue<>(); |
| private ReleaseThread releaseThread; |
| |
| /** |
| * Constructs a new instance. |
| */ |
| public SoftRefFilesCache() { |
| // empty |
| } |
| |
| @Override |
| public synchronized void clear(final FileSystem fileSystem) { |
| final Map<FileName, Reference<FileObject>> files = getOrCreateFilesystemCache(fileSystem); |
| final Iterator<FileSystemAndNameKey> iterKeys = refReverseMap.values().iterator(); |
| |
| while (iterKeys.hasNext()) { |
| final FileSystemAndNameKey key = iterKeys.next(); |
| if (key.getFileSystem() == fileSystem) { |
| iterKeys.remove(); |
| files.remove(key.getFileName()); |
| } |
| } |
| |
| if (files.isEmpty()) { |
| close(fileSystem); |
| } |
| } |
| |
| @Override |
| public synchronized void close() { |
| super.close(); |
| endThread(); |
| fileSystemCache.clear(); |
| refReverseMap.clear(); |
| } |
| |
| /** |
| * @param fileSystem The file system to close. |
| */ |
| private synchronized void close(final FileSystem fileSystem) { |
| if (log.isDebugEnabled()) { |
| log.debug("Close FileSystem: " + fileSystem.getRootName()); |
| } |
| |
| fileSystemCache.remove(fileSystem); |
| if (fileSystemCache.isEmpty()) { |
| endThread(); |
| } |
| } |
| |
| protected Reference<FileObject> createReference(final FileObject file, final ReferenceQueue<FileObject> refqueue) { |
| return new SoftReference<>(file, refqueue); |
| } |
| |
| private synchronized void endThread() { |
| final ReleaseThread thread = releaseThread; |
| releaseThread = null; |
| if (thread != null) { |
| thread.interrupt(); |
| } |
| } |
| |
| @Override |
| public synchronized FileObject getFile(final FileSystem fileSystem, final FileName fileName) { |
| final Map<FileName, Reference<FileObject>> files = getOrCreateFilesystemCache(fileSystem); |
| |
| final Reference<FileObject> ref = files.get(fileName); |
| if (ref == null) { |
| return null; |
| } |
| |
| final FileObject fo = ref.get(); |
| if (fo == null) { |
| removeFile(fileSystem, fileName); |
| } |
| return fo; |
| } |
| |
| protected synchronized Map<FileName, Reference<FileObject>> getOrCreateFilesystemCache(final FileSystem fileSystem) { |
| if (fileSystemCache.isEmpty()) { |
| startThread(); |
| } |
| |
| return fileSystemCache.computeIfAbsent(fileSystem, k -> new HashMap<>()); |
| } |
| |
| private String getSafeName(final FileName fileName) { |
| return fileName.getFriendlyURI(); |
| } |
| |
| private String getSafeName(final FileObject fileObject) { |
| return this.getSafeName(fileObject.getName()); |
| } |
| |
| @Override |
| public void putFile(final FileObject fileObject) { |
| if (log.isDebugEnabled()) { |
| log.debug("putFile: " + this.getSafeName(fileObject)); |
| } |
| |
| synchronized(this) { |
| final Map<FileName, Reference<FileObject>> files = getOrCreateFilesystemCache(fileObject.getFileSystem()); |
| |
| final Reference<FileObject> ref = createReference(fileObject, refQueue); |
| final FileSystemAndNameKey key = new FileSystemAndNameKey(fileObject.getFileSystem(), fileObject.getName()); |
| |
| final Reference<FileObject> old = files.put(fileObject.getName(), ref); |
| if (old != null) { |
| refReverseMap.remove(old); |
| } |
| refReverseMap.put(ref, key); |
| } |
| } |
| |
| @Override |
| public boolean putFileIfAbsent(final FileObject fileObject) { |
| if (log.isDebugEnabled()) { |
| log.debug("putFile: " + this.getSafeName(fileObject)); |
| } |
| |
| synchronized(this) { |
| final Map<FileName, Reference<FileObject>> files = getOrCreateFilesystemCache(fileObject.getFileSystem()); |
| |
| final Reference<FileObject> ref = createReference(fileObject, refQueue); |
| final FileSystemAndNameKey key = new FileSystemAndNameKey(fileObject.getFileSystem(), fileObject.getName()); |
| |
| if (files.containsKey(fileObject.getName()) && files.get(fileObject.getName()).get() != null) { |
| return false; |
| } |
| final Reference<FileObject> old = files.put(fileObject.getName(), ref); |
| if (old != null) { |
| refReverseMap.remove(old); |
| } |
| refReverseMap.put(ref, key); |
| return true; |
| } |
| } |
| |
| @Override |
| public synchronized void removeFile(final FileSystem fileSystem, final FileName fileName) { |
| if (removeFile(new FileSystemAndNameKey(fileSystem, fileName))) { |
| close(fileSystem); |
| } |
| } |
| |
| private synchronized boolean removeFile(final FileSystemAndNameKey key) { |
| if (log.isDebugEnabled()) { |
| log.debug("removeFile: " + this.getSafeName(key.getFileName())); |
| } |
| |
| final Map<?, ?> files = getOrCreateFilesystemCache(key.getFileSystem()); |
| |
| final Object ref = files.remove(key.getFileName()); |
| if (ref != null) { |
| refReverseMap.remove(ref); |
| } |
| |
| return files.isEmpty(); |
| } |
| |
| private synchronized void removeFile(final Reference<?> ref) { |
| final FileSystemAndNameKey key = refReverseMap.get(ref); |
| if (key != null && removeFile(key)) { |
| close(key.getFileSystem()); |
| } |
| } |
| |
| private synchronized void startThread() { |
| if (releaseThread == null) { |
| releaseThread = new ReleaseThread(); |
| releaseThread.start(); |
| // System.out.println("Started thread ID " + releaseThread.getId()); |
| // System.out.flush(); |
| // Thread.dumpStack(); |
| } |
| } |
| |
| @Override |
| public String toString() { |
| return super.toString() + " [releaseThread=" + releaseThread |
| + (releaseThread == null ? "" : "(ID " + releaseThread.getId() + " is " + releaseThread.getState() + ")") |
| + "]"; |
| } |
| } |