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 #include "base/memory/weak_ptr.h" 18 19 namespace base { 20 21 // Mac-specific file watcher implementation based on FSEvents. 22 // There are trade-offs between the FSEvents implementation and a kqueue 23 // implementation. The biggest issues are that FSEvents on 10.6 sometimes drops 24 // events and kqueue does not trigger for modifications to a file in a watched 25 // directory. See file_path_watcher_mac.cc for the code that decides when to 26 // use which one. 27 class FilePathWatcherFSEvents : public FilePathWatcher::PlatformDelegate { 28 public: 29 FilePathWatcherFSEvents(); 30 ~FilePathWatcherFSEvents() override; 31 32 // FilePathWatcher::PlatformDelegate overrides. 33 bool Watch(const FilePath& path, 34 bool recursive, 35 const FilePathWatcher::Callback& callback) override; 36 void Cancel() override; 37 38 private: 39 static void FSEventsCallback(ConstFSEventStreamRef stream, 40 void* event_watcher, 41 size_t num_events, 42 void* event_paths, 43 const FSEventStreamEventFlags flags[], 44 const FSEventStreamEventId event_ids[]); 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 // (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 // The dispatch queue on which the the event stream is scheduled. 78 ScopedDispatchObject<dispatch_queue_t> queue_; 79 80 // Target path to watch (passed to callback). 81 // (Only accessed from the libdispatch queue.) 82 FilePath target_; 83 84 // Target path with all symbolic links resolved. 85 // (Only accessed from the libdispatch queue.) 86 FilePath resolved_target_; 87 88 // Backend stream we receive event callbacks from (strong reference). 89 // (Only accessed from the libdispatch queue.) 90 FSEventStreamRef fsevent_stream_; 91 92 WeakPtrFactory<FilePathWatcherFSEvents> weak_factory_; 93 94 DISALLOW_COPY_AND_ASSIGN(FilePathWatcherFSEvents); 95 }; 96 97 } // namespace base 98 99 #endif // BASE_FILES_FILE_PATH_WATCHER_FSEVENTS_H_ 100