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/mac/scoped_dispatch_object.h" 16 #include "base/macros.h" 17 18 namespace base { 19 20 // Mac-specific file watcher implementation based on FSEvents. 21 // There are trade-offs between the FSEvents implementation and a kqueue 22 // implementation. The biggest issues are that FSEvents on 10.6 sometimes drops 23 // events and kqueue does not trigger for modifications to a file in a watched 24 // directory. See file_path_watcher_mac.cc for the code that decides when to 25 // use which one. 26 class FilePathWatcherFSEvents : public FilePathWatcher::PlatformDelegate { 27 public: 28 FilePathWatcherFSEvents(); 29 30 // FilePathWatcher::PlatformDelegate overrides. 31 bool Watch(const FilePath& path, 32 bool recursive, 33 const FilePathWatcher::Callback& callback) override; 34 void Cancel() override; 35 36 private: 37 static void FSEventsCallback(ConstFSEventStreamRef stream, 38 void* event_watcher, 39 size_t num_events, 40 void* event_paths, 41 const FSEventStreamEventFlags flags[], 42 const FSEventStreamEventId event_ids[]); 43 44 ~FilePathWatcherFSEvents() override; 45 46 // Called from FSEventsCallback whenever there is a change to the paths. 47 void OnFilePathsChanged(const std::vector<FilePath>& paths); 48 49 // Called on the message_loop() thread to dispatch path events. Can't access 50 // target_ and resolved_target_ directly as those are modified on the 51 // libdispatch thread. 52 void DispatchEvents(const std::vector<FilePath>& paths, 53 const FilePath& target, 54 const FilePath& resolved_target); 55 56 // Cleans up and stops the event stream. 57 void CancelOnMessageLoopThread() override; 58 59 // (Re-)Initialize the event stream to start reporting events from 60 // |start_event|. 61 void UpdateEventStream(FSEventStreamEventId start_event); 62 63 // Returns true if resolving the target path got a different result than 64 // last time it was done. 65 bool ResolveTargetPath(); 66 67 // Report an error watching the given target. 68 void ReportError(const FilePath& target); 69 70 // Destroy the event stream. 71 void DestroyEventStream(); 72 73 // Start watching the FSEventStream. 74 void StartEventStream(FSEventStreamEventId start_event, const FilePath& path); 75 76 // Callback to notify upon changes. 77 // (Only accessed from the message_loop() thread.) 78 FilePathWatcher::Callback callback_; 79 80 // The dispatch queue on which the the event stream is scheduled. 81 ScopedDispatchObject<dispatch_queue_t> queue_; 82 83 // Target path to watch (passed to callback). 84 // (Only accessed from the libdispatch queue.) 85 FilePath target_; 86 87 // Target path with all symbolic links resolved. 88 // (Only accessed from the libdispatch queue.) 89 FilePath resolved_target_; 90 91 // Backend stream we receive event callbacks from (strong reference). 92 // (Only accessed from the libdispatch queue.) 93 FSEventStreamRef fsevent_stream_; 94 95 DISALLOW_COPY_AND_ASSIGN(FilePathWatcherFSEvents); 96 }; 97 98 } // namespace base 99 100 #endif // BASE_FILES_FILE_PATH_WATCHER_FSEVENTS_H_ 101