chromium/base/files/important_file_writer.h

// Copyright 2012 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_IMPORTANT_FILE_WRITER_H_
#define BASE_FILES_IMPORTANT_FILE_WRITER_H_

#include <memory>
#include <optional>
#include <string>
#include <string_view>

#include "base/base_export.h"
#include "base/files/file_path.h"
#include "base/functional/callback.h"
#include "base/memory/raw_ptr.h"
#include "base/sequence_checker.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "third_party/abseil-cpp/absl/types/variant.h"

namespace base {

class SequencedTaskRunner;

// Helper for atomically writing a file to ensure that it won't be corrupted by
// *application* crash during write (implemented as create, flush, rename).
//
// As an added benefit, ImportantFileWriter makes it less likely that the file
// is corrupted by *system* crash, though even if the ImportantFileWriter call
// has already returned at the time of the crash it is not specified which
// version of the file (old or new) is preserved. And depending on system
// configuration (hardware and software) a significant likelihood of file
// corruption may remain, thus using ImportantFileWriter is not a valid
// substitute for file integrity checks and recovery codepaths for malformed
// files.
//
// Also note that ImportantFileWriter can be *really* slow (cf. File::Flush()
// for details) and thus please don't block shutdown on ImportantFileWriter.
class BASE_EXPORT ImportantFileWriter { … };

}  // namespace base

#endif  // BASE_FILES_IMPORTANT_FILE_WRITER_H_