beagled/FileSystemQueryable/InotifyBackend.cs

   1 //
   2 // InotifyEventBackend.cs
   3 //
   4 // Copyright (C) 2005 Novell, Inc.
   5 //
   6
   7 //
   8 // Permission is hereby granted, free of charge, to any person obtaining a
   9 // copy of this software and associated documentation files (the "Software"),
  10 // to deal in the Software without restriction, including without limitation
  11 // the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12 // and/or sell copies of the Software, and to permit persons to whom the
  13 // Software is furnished to do so, subject to the following conditions:
  14 //
  15 // The above copyright notice and this permission notice shall be included in
  16 // all copies or substantial portions of the Software.
  17 //
  18 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  21 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23 // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  24 // DEALINGS IN THE SOFTWARE.
  25 //
  26
  27 using System;
  28 using System.Collections;
  29 using System.IO;
  30
  31 using Beagle.Util;
  32 using Beagle.Daemon;
  33
  34 namespace Beagle.Daemon.FileSystemQueryable {
  35
  36         public class InotifyBackend : IFileEventBackend {
  37
  38                 FileSystemQueryable queryable;
  39
  40                 public object CreateWatch (string path)
  41                 {
  42                         object watch = null;
  43                         try {
  44                                 watch = Inotify.Subscribe (path, OnInotifyEvent,
  45                                                            Inotify.EventType.Create
  46                                                            | Inotify.EventType.Delete
  47                                                            | Inotify.EventType.CloseWrite
  48                                                            | Inotify.EventType.MovedFrom
  49                                                            | Inotify.EventType.MovedTo);
  50
  51                         }
  52                         catch (IOException) {
  53                                 // We can race and files can disappear.  No big deal.
  54                         }
  55                         return watch;
  56                 }
  57
  58                 public bool ForgetWatch (object watch_handle)
  59                 {
  60                         try {
  61                                 ((Inotify.Watch) watch_handle).Unsubscribe ();
  62                         } catch (Exception ex) {
  63                                 Logger.Log.Error (ex, "Caught exception while doing ForgetWatch");
  64                                 return false;
  65                         }
  66                         return true;
  67                 }
  68
  69                 public void Start (FileSystemQueryable queryable)
  70                 {
  71                         this.queryable = queryable;
  72                 }
  73
  74                 private void OnInotifyEvent (Inotify.Watch     watch,
  75                                              string            path,
  76                                              string            subitem,
  77                                              string            srcpath,
  78                                              Inotify.EventType type)
  79                 {
  80                         bool is_directory;
  81                         is_directory = (type & Inotify.EventType.IsDirectory) != 0;
  82
  83                         queryable.ReportEventInDirectory (path);
  84
  85                         // The case of matched move events
  86                         if ((type & Inotify.EventType.MovedTo) != 0 && srcpath != null) {
  87                                 queryable.HandleMoveEvent (Path.GetDirectoryName (srcpath),
  88                                                            Path.GetFileName (srcpath),
  89                                                            path, subitem, is_directory);
  90                                 return;
  91                         }
  92
  93                         // Then this must be an unmatched moveto
  94                         // An unmatched MovedTo is like a create
  95                         if ((type & Inotify.EventType.MovedTo) != 0) {
  96
  97                                 // Synthesize the appropriate Create event.  Note that we could check for the
  98                                 // IsDirectory event here, but this also shrinks the race window.
  99                                 if (is_directory)
 100                                         type |= Inotify.EventType.Create;
 101                                 else
 102                                         type |= Inotify.EventType.CloseWrite;
 103                                 Logger.Log.Debug ("Synthesizing event on unpaired MoveTo", type);
 104                         }
 105
 106                         // An unmatched MovedFrom is like a delete
 107                         if ((type & Inotify.EventType.MovedFrom) != 0) {
 108                                 type |= Inotify.EventType.Delete;
 109                                 Logger.Log.Debug ("Synthesizing event on unpaired MoveFrom", type);
 110                         }
 111
 112                         if ((type & Inotify.EventType.Delete) != 0) {
 113                                 queryable.HandleRemoveEvent (path, subitem, is_directory);
 114                                 return;
 115                         }
 116
 117                         if ((type & Inotify.EventType.Create) != 0) {
 118                                 if (is_directory)
 119                                         queryable.HandleAddEvent (path, subitem, is_directory);
 120                                 return;
 121                         }
 122
 123                         if ((type & Inotify.EventType.CloseWrite) != 0) {
 124                                 queryable.HandleAddEvent (path, subitem, is_directory);
 125                                 return;
 126                         }
 127
 128                         if ((type & Inotify.EventType.QueueOverflow) != 0) {
 129                                 Logger.Log.Warn ("Inotify queue overflowed: file system is in an unknown state");
 130                                 queryable.HandleOverflowEvent ();
 131                                 return;
 132                         }
 133                 }
 134         }
 135 }