chromium/components/offline_pages/task/task_queue.h

// Copyright 2016 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_OFFLINE_PAGES_TASK_TASK_QUEUE_H_
#define COMPONENTS_OFFLINE_PAGES_TASK_TASK_QUEUE_H_

#include <memory>
#include <vector>

#include "base/containers/circular_deque.h"
#include "base/functional/callback.h"
#include "base/location.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/sequence_checker.h"
#include "components/offline_pages/task/task.h"

namespace base {
class SingleThreadTaskRunner;
}  // namespace base

namespace offline_pages {

// Class for coordinating |Task|s in relation to access to a specific resource.
// As a task, we understand a set of asynchronous operations (possibly switching
// threads) that access a set of sensitive resource(s). Because the resource
// state is modified and individual steps of a task are asynchronous, allowing
// certain tasks to run in parallel may lead to incorrect results. This class
// allows for ordering of tasks in a FIFO manner, to ensure two tasks modifying
// a resources are not run at the same time.
//
// Consumers of this class should create an instance of TaskQueue and implement
// tasks that need to be run sequentially. New task will only be started when
// the previous one calls |Task::TaskComplete|.
//
// Methods on TaskQueue should be called from the same thread from which it
// is created.
class TaskQueue { … };

}  // namespace offline_pages

#endif  // COMPONENTS_OFFLINE_PAGES_TASK_TASK_QUEUE_H_