// Copyright 2014 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #ifndef BASE_FILES_FILE_PATH_WATCHER_FSEVENTS_H_ #define BASE_FILES_FILE_PATH_WATCHER_FSEVENTS_H_ #include #include #include #include "base/files/file_path.h" #include "base/files/file_path_watcher.h" #include "base/mac/scoped_dispatch_object.h" #include "base/memory/weak_ptr.h" namespace base { // Mac-specific file watcher implementation based on FSEvents. // There are trade-offs between the FSEvents implementation and a kqueue // implementation. The biggest issues are that FSEvents on 10.6 sometimes drops // events and kqueue does not trigger for modifications to a file in a watched // directory. See file_path_watcher_mac.cc for the code that decides when to // use which one. class FilePathWatcherFSEvents : public FilePathWatcher::PlatformDelegate { public: FilePathWatcherFSEvents(); FilePathWatcherFSEvents(const FilePathWatcherFSEvents&) = delete; FilePathWatcherFSEvents& operator=(const FilePathWatcherFSEvents&) = delete; ~FilePathWatcherFSEvents() override; // FilePathWatcher::PlatformDelegate overrides. bool Watch(const FilePath& path, Type type, const FilePathWatcher::Callback& callback) override; void Cancel() override; private: static void FSEventsCallback(ConstFSEventStreamRef stream, void* event_watcher, size_t num_events, void* event_paths, const FSEventStreamEventFlags flags[], const FSEventStreamEventId event_ids[]); // Called from FSEventsCallback whenever there is a change to the paths. void OnFilePathsChanged(const std::vector& paths); // Called on the task_runner() thread to dispatch path events. Can't access // target_ and resolved_target_ directly as those are modified on the // libdispatch thread. void DispatchEvents(const std::vector& paths, const FilePath& target, const FilePath& resolved_target); // (Re-)Initialize the event stream to start reporting events from // |start_event|. void UpdateEventStream(FSEventStreamEventId start_event); // Returns true if resolving the target path got a different result than // last time it was done. bool ResolveTargetPath(); // Report an error watching the given target. void ReportError(const FilePath& target); // Destroy the event stream. void DestroyEventStream(); // Start watching the FSEventStream. void StartEventStream(FSEventStreamEventId start_event, const FilePath& path); // Callback to notify upon changes. // (Only accessed from the task_runner() thread.) FilePathWatcher::Callback callback_; // The dispatch queue on which the event stream is scheduled. ScopedDispatchObject queue_; // Target path to watch (passed to callback). // (Only accessed from the libdispatch queue.) FilePath target_; // Target path with all symbolic links resolved. // (Only accessed from the libdispatch queue.) FilePath resolved_target_; // Backend stream we receive event callbacks from (strong reference). // (Only accessed from the libdispatch queue.) FSEventStreamRef fsevent_stream_ = nullptr; WeakPtrFactory weak_factory_{this}; }; } // namespace base #endif // BASE_FILES_FILE_PATH_WATCHER_FSEVENTS_H_