1 /*******************************************************************************
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2 * Copyright (c) 2010- Association for Decentralized Information Management in
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4 * All rights reserved. This program and the accompanying materials
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5 * are made available under the terms of the Eclipse Public License v1.0
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6 * which accompanies this distribution, and is available at
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7 * http://www.eclipse.org/legal/epl-v10.html
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10 * VTT Technical Research Centre of Finland - initial API and implementation
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11 *******************************************************************************/
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12 package org.simantics.databoard.accessor.impl;
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14 import java.io.File;
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15 import java.io.FileFilter;
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16 import java.util.ArrayList;
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17 import java.util.HashSet;
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18 import java.util.List;
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19 import java.util.Set;
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20 import java.util.Timer;
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21 import java.util.TimerTask;
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22 import java.util.concurrent.CopyOnWriteArrayList;
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25 * DirectoryWatch monitors a directory for file additions / removals.
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27 * DirectoryWatch is used in the long wait for WatchService.
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29 * @author Toni Kalajainen <toni.kalajainen@vtt.fi>
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31 public class DirectoryWatch {
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33 public static final long POLL_INTERVAL = 10000; // seconds
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38 List<File> knownFiles;
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39 CopyOnWriteArrayList<DirectoryListener> listeners = new CopyOnWriteArrayList<DirectoryListener>();
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41 TimerTask task = new TimerTask() {
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47 public DirectoryWatch(File directory, FileFilter filter) {
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48 this.directory = directory;
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49 this.filter = filter;
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50 knownFiles = readFiles();
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51 timer = new Timer(directory.toString()+" watcher", true);
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52 timer.schedule(task, 1, POLL_INTERVAL);
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57 * This method does one last poll.
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59 public void close() {
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64 public static class DirectoryEvent {
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65 public Set<File> filesAdded = new HashSet<File>();
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66 public Set<File> filesRemoved = new HashSet<File>();
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69 public interface DirectoryListener {
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70 void onWatchEvent(DirectoryEvent e);
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73 public void addListener(DirectoryListener listener) {
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74 listeners.add(listener);
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77 public void removeListener(DirectoryListener listener) {
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78 listeners.remove(listener);
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82 * Get a snapshot of currently known files
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84 * @return a snapshot of files
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86 public List<File> files() {
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91 * Reload the directory
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93 public void refresh() {
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98 * Add file to the known list without reading the disk.
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99 * The modification is void after next timer refresh.
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103 public synchronized void add(File f) {
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104 ArrayList<File> newList = new ArrayList<File>( knownFiles );
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106 knownFiles = newList;
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110 * Remove file from the known list without reading the disk.
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111 * The modification is void after next timer refresh.
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115 public synchronized void remove(File f) {
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116 ArrayList<File> newList = new ArrayList<File>( knownFiles );
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118 knownFiles = newList;
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123 * @return a list of absolute files
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125 private List<File> readFiles() {
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126 File[] files = directory.listFiles(filter);
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127 List<File> newFiles = new ArrayList<File>( files.length );
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128 for (File f : files) {
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129 // System.out.println(f);
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130 // f = f.getAbsoluteFile();
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131 // System.out.println(f);
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138 * Read files and spawn events
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140 private synchronized void poll() {
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141 DirectoryEvent e = read();
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142 if (e.filesAdded.isEmpty() && e.filesRemoved.isEmpty()) return;
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144 for (DirectoryListener l : listeners)
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148 private DirectoryEvent read() {
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149 List<File> oldFiles = knownFiles;
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150 List<File> newFiles = readFiles();
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151 knownFiles = newFiles;
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153 DirectoryEvent result = new DirectoryEvent();
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154 result.filesAdded.addAll(newFiles);
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155 result.filesAdded.removeAll(oldFiles);
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157 result.filesRemoved.addAll(oldFiles);
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158 result.filesRemoved.removeAll(newFiles);
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