base/files/file_path_watcher_fsevents.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_FILES_FILE_PATH_WATCHER_FSEVENTS_H_
   6 #define BASE_FILES_FILE_PATH_WATCHER_FSEVENTS_H_
   7
   8 #include <CoreServices/CoreServices.h>
   9
  10 #include <vector>
  11
  12 #include "base/files/file_path.h"
  13 #include "base/files/file_path_watcher.h"
  14
  15 namespace base {
  16
  17 // Mac-specific file watcher implementation based on FSEvents.
  18 // There are trade-offs between the FSEvents implementation and a kqueue
  19 // implementation. The biggest issues are that FSEvents on 10.6 sometimes drops
  20 // events and kqueue does not trigger for modifications to a file in a watched
  21 // directory. See file_path_watcher_mac.cc for the code that decides when to
  22 // use which one.
  23 class FilePathWatcherFSEvents : public FilePathWatcher::PlatformDelegate {
  24  public:
  25   FilePathWatcherFSEvents();
  26
  27   // Called from the FSEvents callback whenever there is a change to the paths.
  28   void OnFilePathsChanged(const std::vector<FilePath>& paths);
  29
  30   // (Re-)Initialize the event stream to start reporting events from
  31   // |start_event|.
  32   void UpdateEventStream(FSEventStreamEventId start_event);
  33
  34   // Returns true if resolving the target path got a different result than
  35   // last time it was done.
  36   bool ResolveTargetPath();
  37
  38   // FilePathWatcher::PlatformDelegate overrides.
  39   virtual bool Watch(const FilePath& path,
  40                      bool recursive,
  41                      const FilePathWatcher::Callback& callback) OVERRIDE;
  42   virtual void Cancel() OVERRIDE;
  43
  44  private:
  45   virtual ~FilePathWatcherFSEvents();
  46
  47   // Destroy the event stream.
  48   void DestroyEventStream();
  49
  50   // Start watching the FSEventStream.
  51   void StartEventStream(FSEventStreamEventId start_event);
  52
  53   // Cleans up and stops the event stream.
  54   virtual void CancelOnMessageLoopThread() OVERRIDE;
  55
  56   // Callback to notify upon changes.
  57   FilePathWatcher::Callback callback_;
  58
  59   // Target path to watch (passed to callback).
  60   FilePath target_;
  61
  62   // Target path with all symbolic links resolved.
  63   FilePath resolved_target_;
  64
  65   // Backend stream we receive event callbacks from (strong reference).
  66   FSEventStreamRef fsevent_stream_;
  67
  68   DISALLOW_COPY_AND_ASSIGN(FilePathWatcherFSEvents);
  69 };
  70
  71 }  // namespace base
  72
  73 #endif  // BASE_FILES_FILE_PATH_WATCHER_FSEVENTS_H_