tdesktop/Telegram/SourceFiles/base/task_queue.h

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/*
This file is part of Telegram Desktop,
the official desktop version of Telegram messaging app, see https://telegram.org
Telegram Desktop is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
It is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
In addition, as a special exception, the copyright holders give permission
to link the code of portions of this program with the OpenSSL library.
Full license: https://github.com/telegramdesktop/tdesktop/blob/master/LICENSE
Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
*/
#pragma once
#include <memory>
namespace base {
using Task = lambda_once<void()>;
// An attempt to create/use a TaskQueue or one of the default queues
// after the main() has returned leads to an undefined behaviour.
class TaskQueue {
enum class Type {
Main, // Unique queue for main thread tasks.
Serial,
Concurrent,
Special, // Unique special queue for thread pool lists terminal item.
};
public:
enum class Priority {
Normal,
Background,
};
// Creating custom serial queues.
TaskQueue(Priority priority) : TaskQueue(Type::Serial, priority) {
}
// Default main and two concurrent queues.
static TaskQueue &Main();
static TaskQueue &Normal();
static TaskQueue &Background();
void Put(Task &&task);
static void ProcessMainTasks();
static void ProcessMainTasks(TimeMs max_time_spent);
~TaskQueue();
private:
static bool ProcessOneMainTask();
TaskQueue(Type type, Priority priority);
bool IsMyThread() const;
bool SerialTaskInProcess() const {
return (destroyed_flag_ != nullptr);
}
const Type type_;
const Priority priority_;
std::deque<Task> tasks_;
QMutex tasks_mutex_; // Only for the main queue.
// Only for the other queues, not main.
class TaskThreadPool;
std::weak_ptr<TaskThreadPool> weak_thread_pool_;
class TaskQueueList;
struct TaskQueueListEntry {
TaskQueue *before = nullptr;
TaskQueue *after = nullptr;
};
// Thread pool queues linked list.
static constexpr int kAllQueuesList = 0;
// Thread pool queues linked list with excluded Background queues.
static constexpr int kOnlyNormalQueuesList = 1;
static constexpr int kQueuesListsCount = 2;
TaskQueueListEntry list_entries_[kQueuesListsCount];
// Only for Serial queues: non-null value means a task is currently processed.
bool *destroyed_flag_ = nullptr;
};
} // namespace base