mcs/class/System/System.IO/DefaultWatcher.cs

   1 //
   2 // System.IO.DefaultWatcher.cs: default IFileWatcher
   3 //
   4 // Authors:
   5 //      Gonzalo Paniagua Javier (gonzalo@ximian.com)
   6 //
   7 // (c) 2004 Novell, Inc. (http://www.novell.com)
   8 //
   9
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30
  31 using System;
  32 using System.Collections;
  33 using System.Collections.Generic;
  34 using System.IO;
  35 using System.Threading;
  36
  37 namespace System.IO {
  38         class DefaultWatcherData {
  39                 public FileSystemWatcher FSW;
  40                 public string Directory;
  41                 public string FileMask; // If NoWildcards, contains the full path to the file.
  42                 public bool IncludeSubdirs;
  43                 public bool Enabled;
  44                 public bool NoWildcards;
  45                 public DateTime DisabledTime;
  46
  47                 public object FilesLock = new object ();
  48                 public Hashtable Files;
  49         }
  50
  51         class FileData {
  52                 public string Directory;
  53                 public FileAttributes Attributes;
  54                 public bool NotExists;
  55                 public DateTime CreationTime;
  56                 public DateTime LastWriteTime;
  57         }
  58
  59         class DefaultWatcher : IFileWatcher
  60         {
  61                 static DefaultWatcher instance;
  62                 static Thread thread;
  63                 static Hashtable watches;
  64
  65                 private DefaultWatcher ()
  66                 {
  67                 }
  68
  69                 // Locked by caller
  70                 public static bool GetInstance (out IFileWatcher watcher)
  71                 {
  72                         if (instance != null) {
  73                                 watcher = instance;
  74                                 return true;
  75                         }
  76
  77                         instance = new DefaultWatcher ();
  78                         watcher = instance;
  79                         return true;
  80                 }
  81
  82                 public void StartDispatching (FileSystemWatcher fsw)
  83                 {
  84                         DefaultWatcherData data;
  85                         lock (this) {
  86                                 if (watches == null)
  87                                         watches = new Hashtable ();
  88
  89                                 if (thread == null) {
  90                                         thread = new Thread (new ThreadStart (Monitor));
  91                                         thread.IsBackground = true;
  92                                         thread.Start ();
  93                                 }
  94                         }
  95
  96                         lock (watches) {
  97                                 data = (DefaultWatcherData) watches [fsw];
  98                                 if (data == null) {
  99                                         data = new DefaultWatcherData ();
 100                                         data.Files = new Hashtable ();
 101                                         watches [fsw] = data;
 102                                 }
 103
 104                                 data.FSW = fsw;
 105                                 data.Directory = fsw.FullPath;
 106                                 data.NoWildcards = !fsw.Pattern.HasWildcard;
 107                                 if (data.NoWildcards)
 108                                         data.FileMask = Path.Combine (data.Directory, fsw.MangledFilter);
 109                                 else
 110                                         data.FileMask = fsw.MangledFilter;
 111
 112                                 data.IncludeSubdirs = fsw.IncludeSubdirectories;
 113                                 data.Enabled = true;
 114                                 data.DisabledTime = DateTime.MaxValue;
 115                                 UpdateDataAndDispatch (data, false);
 116                         }
 117                 }
 118
 119                 public void StopDispatching (FileSystemWatcher fsw)
 120                 {
 121                         DefaultWatcherData data;
 122                         lock (this) {
 123                                 if (watches == null) return;
 124                         }
 125
 126                         lock (watches) {
 127                                 data = (DefaultWatcherData) watches [fsw];
 128                                 if (data != null) {
 129                                         data.Enabled = false;
 130                                         data.DisabledTime = DateTime.UtcNow;
 131                                 }
 132                         }
 133                 }
 134
 135
 136                 void Monitor ()
 137                 {
 138                         int zeroes = 0;
 139
 140                         while (true) {
 141                                 Thread.Sleep (750);
 142
 143                                 Hashtable my_watches;
 144                                 lock (watches) {
 145                                         if (watches.Count == 0) {
 146                                                 if (++zeroes == 20)
 147                                                         break;
 148                                                 continue;
 149                                         }
 150
 151                                         my_watches = (Hashtable) watches.Clone ();
 152                                 }
 153
 154                                 if (my_watches.Count != 0) {
 155                                         zeroes = 0;
 156                                         foreach (DefaultWatcherData data in my_watches.Values) {
 157                                                 bool remove = UpdateDataAndDispatch (data, true);
 158                                                 if (remove)
 159                                                         lock (watches)
 160                                                                 watches.Remove (data.FSW);
 161                                         }
 162                                 }
 163                         }
 164
 165                         lock (this) {
 166                                 thread = null;
 167                         }
 168                 }
 169
 170                 bool UpdateDataAndDispatch (DefaultWatcherData data, bool dispatch)
 171                 {
 172                         if (!data.Enabled) {
 173                                 return (data.DisabledTime != DateTime.MaxValue &&
 174                                         (DateTime.UtcNow - data.DisabledTime).TotalSeconds > 5);
 175                         }
 176
 177                         DoFiles (data, data.Directory, dispatch);
 178                         return false;
 179                 }
 180
 181                 static void DispatchEvents (FileSystemWatcher fsw, FileAction action, string filename)
 182                 {
 183                         RenamedEventArgs renamed = null;
 184
 185                         lock (fsw) {
 186                                 fsw.DispatchEvents (action, filename, ref renamed);
 187                                 if (fsw.Waiting) {
 188                                         fsw.Waiting = false;
 189                                         System.Threading.Monitor.PulseAll (fsw);
 190                                 }
 191                         }
 192                 }
 193
 194                 static string [] NoStringsArray = new string [0];
 195                 void DoFiles (DefaultWatcherData data, string directory, bool dispatch)
 196                 {
 197                         bool direxists = Directory.Exists (directory);
 198                         if (direxists && data.IncludeSubdirs) {
 199                                 foreach (string d in Directory.GetDirectories (directory))
 200                                         DoFiles (data, d, dispatch);
 201                         }
 202
 203                         string [] files = null;
 204                         if (!direxists) {
 205                                 files = NoStringsArray;
 206                         } else if (!data.NoWildcards) {
 207                                 files = Directory.GetFileSystemEntries (directory, data.FileMask);
 208                         } else {
 209                                 // The pattern does not have wildcards
 210                                 if (File.Exists (data.FileMask) || Directory.Exists (data.FileMask))
 211                                         files = new string [] { data.FileMask };
 212                                 else
 213                                         files = NoStringsArray;
 214                         }
 215
 216                         lock (data.FilesLock) {
 217                                 IterateAndModifyFilesData (data, directory, dispatch, files);
 218                         }
 219                 }
 220
 221                 void IterateAndModifyFilesData (DefaultWatcherData data, string directory, bool dispatch, string[] files)
 222                 {
 223                         /* Set all as untested */
 224                         foreach (string filename in data.Files.Keys) {
 225                                 FileData fd = (FileData) data.Files [filename];
 226                                 if (fd.Directory == directory)
 227                                         fd.NotExists = true;
 228                         }
 229
 230                         /* New files */
 231                         foreach (string filename in files) {
 232                                 FileData fd = (FileData) data.Files [filename];
 233                                 if (fd == null) {
 234                                         try {
 235                                                 data.Files.Add (filename, CreateFileData (directory, filename));
 236                                         } catch {
 237                                                 // The file might have been removed in the meanwhile
 238                                                 data.Files.Remove (filename);
 239                                                 continue;
 240                                         }
 241
 242                                         if (dispatch)
 243                                                 DispatchEvents (data.FSW, FileAction.Added, filename);
 244                                 } else if (fd.Directory == directory) {
 245                                         fd.NotExists = false;
 246                                 }
 247                         }
 248
 249                         if (!dispatch) // We only initialize the file list
 250                                 return;
 251
 252                         /* Removed files */
 253                         List<string> removed = null;
 254                         foreach (string filename in data.Files.Keys) {
 255                                 FileData fd = (FileData) data.Files [filename];
 256                                 if (fd.NotExists) {
 257                                         if (removed == null)
 258                                                 removed = new List<string> ();
 259
 260                                         removed.Add (filename);
 261                                         DispatchEvents (data.FSW, FileAction.Removed, filename);
 262                                 }
 263                         }
 264
 265                         if (removed != null) {
 266                                 foreach (string filename in removed)
 267                                         data.Files.Remove (filename);
 268
 269                                 removed = null;
 270                         }
 271
 272                         /* Changed files */
 273                         foreach (string filename in data.Files.Keys) {
 274                                 FileData fd = (FileData) data.Files [filename];
 275                                 DateTime creation, write;
 276                                 try {
 277                                         creation = File.GetCreationTime (filename);
 278                                         write = File.GetLastWriteTime (filename);
 279                                 } catch {
 280                                         /* Deleted */
 281                                         if (removed == null)
 282                                                 removed = new List<string> ();
 283
 284                                         removed.Add (filename);
 285                                         DispatchEvents (data.FSW, FileAction.Removed, filename);
 286                                         continue;
 287                                 }
 288
 289                                 if (creation != fd.CreationTime || write != fd.LastWriteTime) {
 290                                         fd.CreationTime = creation;
 291                                         fd.LastWriteTime = write;
 292                                         DispatchEvents (data.FSW, FileAction.Modified, filename);
 293                                 }
 294                         }
 295
 296                         if (removed != null) {
 297                                 foreach (string filename in removed)
 298                                         data.Files.Remove (filename);
 299                         }
 300
 301                 }
 302
 303                 static FileData CreateFileData (string directory, string filename)
 304                 {
 305                         FileData fd = new FileData ();
 306                         string fullpath = Path.Combine (directory, filename);
 307                         fd.Directory = directory;
 308                         fd.Attributes = File.GetAttributes (fullpath);
 309                         fd.CreationTime = File.GetCreationTime (fullpath);
 310                         fd.LastWriteTime = File.GetLastWriteTime (fullpath);
 311                         return fd;
 312                 }
 313         }
 314 }
 315