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// Copyright 2014 The Chromium Authors
// 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 <CoreServices/CoreServices.h>
#include <stddef.h>
#include <vector>
#include "base/apple/scoped_dispatch_object.h"
#include "base/files/file_path.h"
#include "base/files/file_path_watcher.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<FilePath>& 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<FilePath>& 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.
apple::ScopedDispatchObject<dispatch_queue_t> 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<FilePathWatcherFSEvents> weak_factory_{this};
};
} // namespace base
#endif // BASE_FILES_FILE_PATH_WATCHER_FSEVENTS_H_
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