bundles/org.simantics.databoard/src/org/simantics/databoard/accessor/impl/DirectoryWatch.java

   1 /*******************************************************************************\r
   2  * Copyright (c) 2010- Association for Decentralized Information Management in\r
   3  * Industry THTH ry.\r
   4  * All rights reserved. This program and the accompanying materials\r
   5  * are made available under the terms of the Eclipse Public License v1.0\r
   6  * which accompanies this distribution, and is available at\r
   7  * http://www.eclipse.org/legal/epl-v10.html\r
   8  * \r
   9  * Contributors:\r
  10  *    VTT Technical Research Centre of Finland - initial API and implementation\r
  11  *******************************************************************************/\r
  12 package org.simantics.databoard.accessor.impl;\r
  13 \r
  14 import java.io.File;\r
  15 import java.io.FileFilter;\r
  16 import java.util.ArrayList;\r
  17 import java.util.HashSet;\r
  18 import java.util.List;\r
  19 import java.util.Set;\r
  20 import java.util.Timer;\r
  21 import java.util.TimerTask;\r
  22 import java.util.concurrent.CopyOnWriteArrayList;\r
  23 \r
  24 /**\r
  25  * DirectoryWatch monitors a directory for file additions / removals.\r
  26  * <p>\r
  27  * DirectoryWatch is used in the long wait for WatchService.   \r
  28  *\r
  29  * @author Toni Kalajainen <toni.kalajainen@vtt.fi>\r
  30  */\r
  31 public class DirectoryWatch {\r
  32 \r
  33         public static final long POLL_INTERVAL = 10000; // seconds\r
  34         \r
  35         Timer timer;\r
  36         FileFilter filter;\r
  37         File directory;\r
  38         List<File> knownFiles;\r
  39         CopyOnWriteArrayList<DirectoryListener> listeners = new CopyOnWriteArrayList<DirectoryListener>();\r
  40 \r
  41         TimerTask task = new TimerTask() { \r
  42                 public void run() {\r
  43                         poll();\r
  44                 } \r
  45         };\r
  46         \r
  47         public DirectoryWatch(File directory, FileFilter filter) {\r
  48                 this.directory = directory;\r
  49                 this.filter = filter;\r
  50                 knownFiles = readFiles();\r
  51                 timer = new Timer(directory.toString()+" watcher", true);\r
  52                 timer.schedule(task, 1, POLL_INTERVAL);\r
  53         }\r
  54         \r
  55         /**\r
  56          * Close the timer. \r
  57          * This method does one last poll.\r
  58          */\r
  59         public void close() {           \r
  60                 timer.cancel();\r
  61                 poll();\r
  62         }\r
  63         \r
  64         public static class DirectoryEvent {\r
  65                 public Set<File> filesAdded = new HashSet<File>();\r
  66                 public Set<File> filesRemoved = new HashSet<File>();\r
  67         }\r
  68         \r
  69         public interface DirectoryListener {\r
  70                 void onWatchEvent(DirectoryEvent e);\r
  71         }\r
  72         \r
  73         public void addListener(DirectoryListener listener) {\r
  74                 listeners.add(listener);                \r
  75         }\r
  76         \r
  77         public void removeListener(DirectoryListener listener) {                \r
  78                 listeners.remove(listener);\r
  79         }\r
  80         \r
  81         /**\r
  82          * Get a snapshot of currently known files\r
  83          * \r
  84          * @return a snapshot of files\r
  85          */\r
  86         public List<File> files() {\r
  87                 return knownFiles;\r
  88         }\r
  89         \r
  90         /**\r
  91          * Reload the directory\r
  92          */\r
  93         public void refresh() {\r
  94                 poll();\r
  95         }\r
  96         \r
  97         /**\r
  98          * Add file to the known list without reading the disk. \r
  99          * The modification is void after next timer refresh. \r
 100          * \r
 101          * @param f\r
 102          */\r
 103         public synchronized void add(File f) {\r
 104                 ArrayList<File> newList = new ArrayList<File>( knownFiles );\r
 105                 newList.add(f);\r
 106                 knownFiles = newList;\r
 107         }\r
 108         \r
 109         /**\r
 110          * Remove file from the known list without reading the disk.\r
 111          * The modification is void after next timer refresh. \r
 112          * \r
 113          * @param f\r
 114          */\r
 115         public synchronized void remove(File f) {\r
 116                 ArrayList<File> newList = new ArrayList<File>( knownFiles );\r
 117                 newList.remove(f);\r
 118                 knownFiles = newList;           \r
 119         }\r
 120         \r
 121         /**\r
 122          * Read files\r
 123          * @return a list of absolute files\r
 124          */\r
 125         private List<File> readFiles() {                \r
 126                 File[] files = directory.listFiles(filter);\r
 127                 List<File> newFiles = new ArrayList<File>( files.length );\r
 128                 for (File f : files) {\r
 129 //                      System.out.println(f);\r
 130 //                      f = f.getAbsoluteFile();\r
 131 //                      System.out.println(f);\r
 132                         newFiles.add(f);                \r
 133                 }\r
 134                 return newFiles;\r
 135         }\r
 136         \r
 137         /**\r
 138          * Read files and spawn events\r
 139          */\r
 140         private synchronized void poll() {\r
 141                 DirectoryEvent e = read();\r
 142                 if (e.filesAdded.isEmpty() && e.filesRemoved.isEmpty()) return;\r
 143                 // Spawn an event\r
 144                 for (DirectoryListener l : listeners)\r
 145                         l.onWatchEvent(e);\r
 146         }\r
 147         \r
 148         private DirectoryEvent read() {\r
 149                 List<File> oldFiles = knownFiles;\r
 150                 List<File> newFiles = readFiles();\r
 151                 knownFiles = newFiles;\r
 152 \r
 153                 DirectoryEvent result = new DirectoryEvent();\r
 154                 result.filesAdded.addAll(newFiles);\r
 155                 result.filesAdded.removeAll(oldFiles);\r
 156 \r
 157                 result.filesRemoved.addAll(oldFiles);\r
 158                 result.filesRemoved.removeAll(newFiles);\r
 159                 \r
 160                 return result;\r
 161         }\r
 162         \r
 163 }\r
 164 \r