file_path_watcher_fsevents.h revision b8cf94937c52feb53b55c39e3f82094d27de464c 
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
15namespace 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.
23class FilePathWatcherFSEvents : public FilePathWatcher::PlatformDelegate {
24 public:
25  FilePathWatcherFSEvents();
26
27  // FilePathWatcher::PlatformDelegate overrides.
28  bool Watch(const FilePath& path,
29             bool recursive,
30             const FilePathWatcher::Callback& callback) override;
31  void Cancel() override;
32
33 private:
34  static void FSEventsCallback(ConstFSEventStreamRef stream,
35                               void* event_watcher,
36                               size_t num_events,
37                               void* event_paths,
38                               const FSEventStreamEventFlags flags[],
39                               const FSEventStreamEventId event_ids[]);
40
41  ~FilePathWatcherFSEvents() override;
42
43  // Called from FSEventsCallback whenever there is a change to the paths.
44  void OnFilePathsChanged(const std::vector<FilePath>& paths);
45
46  // Called on the message_loop() thread to dispatch path events. Can't access
47  // target_ and resolved_target_ directly as those are modified on the
48  // libdispatch thread.
49  void DispatchEvents(const std::vector<FilePath>& paths,
50                      const FilePath& target,
51                      const FilePath& resolved_target);
52
53  // Cleans up and stops the event stream.
54  void CancelOnMessageLoopThread() override;
55
56  // (Re-)Initialize the event stream to start reporting events from
57  // |start_event|.
58  void UpdateEventStream(FSEventStreamEventId start_event);
59
60  // Returns true if resolving the target path got a different result than
61  // last time it was done.
62  bool ResolveTargetPath();
63
64  // Report an error watching the given target.
65  void ReportError(const FilePath& target);
66
67  // Destroy the event stream.
68  void DestroyEventStream();
69
70  // Start watching the FSEventStream.
71  void StartEventStream(FSEventStreamEventId start_event, const FilePath& path);
72
73  // Callback to notify upon changes.
74  // (Only accessed from the message_loop() thread.)
75  FilePathWatcher::Callback callback_;
76
77  // Target path to watch (passed to callback).
78  // (Only accessed from the libdispatch thread.)
79  FilePath target_;
80
81  // Target path with all symbolic links resolved.
82  // (Only accessed from the libdispatch thread.)
83  FilePath resolved_target_;
84
85  // Backend stream we receive event callbacks from (strong reference).
86  // (Only accessed from the libdispatch thread.)
87  FSEventStreamRef fsevent_stream_;
88
89  DISALLOW_COPY_AND_ASSIGN(FilePathWatcherFSEvents);
90};
91
92}  // namespace base
93
94#endif  // BASE_FILES_FILE_PATH_WATCHER_FSEVENTS_H_
95