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// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_LANGUAGE_DETECTION_CORE_BACKGROUND_FILE_H_
#define COMPONENTS_LANGUAGE_DETECTION_CORE_BACKGROUND_FILE_H_
#include "base/component_export.h"
#include "base/files/file.h"
#include "base/functional/callback_forward.h"
#include "base/task/sequenced_task_runner.h"
namespace language_detection {
// Holds a `base::File`, and provides and API that pushes the user to perform
// opens and closes on a background task runner.
class COMPONENT_EXPORT(LANGUAGE_DETECTION) BackgroundFile {
public:
using ReplacedCallback = base::OnceCallback<void()>;
using FileOpener = base::OnceCallback<base::File()>;
explicit BackgroundFile(
scoped_refptr<base::SequencedTaskRunner> background_task_runner);
~BackgroundFile();
// Replaces the current file with the invalid `base::File()`. It closes the
// previous file on the background task runner.
void InvalidateFile();
// Replaces the current file with the return value of running `file_opener` on
// the background thread then calls `callback` on the default task runner. It
// closes the previous file on the background task runner.
void ReplaceFile(FileOpener file_opener, ReplacedCallback replaced_callback);
base::File& GetFile() { return file_.GetFile(); }
private:
// A wrapper of `base::File` that always closes the file on the provided
// task runner. See https://crbug.com/366698727.
class TaskRunnerBoundFile {
public:
explicit TaskRunnerBoundFile(
base::File file,
scoped_refptr<base::SequencedTaskRunner> background_task_runner);
~TaskRunnerBoundFile();
TaskRunnerBoundFile(TaskRunnerBoundFile&& other);
// Runs the `file_opener` callback and created a `TaskRunnerBoundFile` from
// the result.
static TaskRunnerBoundFile Create(
BackgroundFile::FileOpener file_opener,
scoped_refptr<base::SequencedTaskRunner> background_task_runner);
base::File& GetFile() { return file_; }
TaskRunnerBoundFile& operator=(TaskRunnerBoundFile&& other);
private:
void Invalidate();
base::File file_;
scoped_refptr<base::SequencedTaskRunner> background_task_runner_;
};
void SwapFile(ReplacedCallback callback, TaskRunnerBoundFile new_file);
TaskRunnerBoundFile file_;
// Used for blocking IO calls.
scoped_refptr<base::SequencedTaskRunner> background_task_runner_;
// All calls that mutate state in the object should be on the same sequence
// that created it.
SEQUENCE_CHECKER(sequence_checker_);
base::WeakPtrFactory<BackgroundFile> weak_ptr_factory_{this};
};
} // namespace language_detection
#endif // COMPONENTS_LANGUAGE_DETECTION_CORE_BACKGROUND_FILE_H_
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