file_path_watcher_fsevents.h revision 0d205d712abd16eeed2f5d5b1052a367d23a223f 
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#include <stddef.h>
10
11#include <vector>
12
13#include "base/files/file_path.h"
14#include "base/files/file_path_watcher.h"
15#include "base/macros.h"
16
17namespace base {
18
19// Mac-specific file watcher implementation based on FSEvents.
20// There are trade-offs between the FSEvents implementation and a kqueue
21// implementation. The biggest issues are that FSEvents on 10.6 sometimes drops
22// events and kqueue does not trigger for modifications to a file in a watched
23// directory. See file_path_watcher_mac.cc for the code that decides when to
24// use which one.
25class FilePathWatcherFSEvents : public FilePathWatcher::PlatformDelegate {
26 public:
27  FilePathWatcherFSEvents();
28
29  // FilePathWatcher::PlatformDelegate overrides.
30  bool Watch(const FilePath& path,
31             bool recursive,
32             const FilePathWatcher::Callback& callback) override;
33  void Cancel() override;
34
35 private:
36  static void FSEventsCallback(ConstFSEventStreamRef stream,
37                               void* event_watcher,
38                               size_t num_events,
39                               void* event_paths,
40                               const FSEventStreamEventFlags flags[],
41                               const FSEventStreamEventId event_ids[]);
42
43  ~FilePathWatcherFSEvents() override;
44
45  // Called from FSEventsCallback whenever there is a change to the paths.
46  void OnFilePathsChanged(const std::vector<FilePath>& paths);
47
48  // Called on the message_loop() thread to dispatch path events. Can't access
49  // target_ and resolved_target_ directly as those are modified on the
50  // libdispatch thread.
51  void DispatchEvents(const std::vector<FilePath>& paths,
52                      const FilePath& target,
53                      const FilePath& resolved_target);
54
55  // Cleans up and stops the event stream.
56  void CancelOnMessageLoopThread() override;
57
58  // (Re-)Initialize the event stream to start reporting events from
59  // |start_event|.
60  void UpdateEventStream(FSEventStreamEventId start_event);
61
62  // Returns true if resolving the target path got a different result than
63  // last time it was done.
64  bool ResolveTargetPath();
65
66  // Report an error watching the given target.
67  void ReportError(const FilePath& target);
68
69  // Destroy the event stream.
70  void DestroyEventStream();
71
72  // Start watching the FSEventStream.
73  void StartEventStream(FSEventStreamEventId start_event, const FilePath& path);
74
75  // Callback to notify upon changes.
76  // (Only accessed from the message_loop() thread.)
77  FilePathWatcher::Callback callback_;
78
79  // Target path to watch (passed to callback).
80  // (Only accessed from the libdispatch thread.)
81  FilePath target_;
82
83  // Target path with all symbolic links resolved.
84  // (Only accessed from the libdispatch thread.)
85  FilePath resolved_target_;
86
87  // Backend stream we receive event callbacks from (strong reference).
88  // (Only accessed from the libdispatch thread.)
89  FSEventStreamRef fsevent_stream_;
90
91  DISALLOW_COPY_AND_ASSIGN(FilePathWatcherFSEvents);
92};
93
94}  // namespace base
95
96#endif  // BASE_FILES_FILE_PATH_WATCHER_FSEVENTS_H_
97