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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/***************************************************************************
 *            atomic.h
 *
 *  Wed Mar 23 09:15:05 CET 2016
 *  Copyright 2016 Christian Glöckner
 *  cgloeckner@freenet.de
 ****************************************************************************/

/*
 *  This file is part of DrumGizmo.
 *
 *  DrumGizmo 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.
 *
 *  DrumGizmo 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.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with DrumGizmo; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 */
#pragma once

#include <type_traits>
#include <atomic>
#include <mutex>

template <typename T, typename = void>
class Atomic;

// use std::atomic if possible
template <typename T>
class Atomic<T, typename std::enable_if<std::is_pod<T>::value>::type>
	: public std::atomic<T> {
	
	public:
		// inherit methods
		using std::atomic<T>::atomic;
		using std::atomic<T>::operator=;
};

// else work around it using a mutex
template <typename T>
class Atomic<T, typename std::enable_if<!std::is_pod<T>::value>::type> {
	public:
		using self_type = Atomic<T, typename std::enable_if<!std::is_pod<T>::value>::type>;

		Atomic()
			: data{}
			, mutex{} {
		}

		Atomic(T data)
			: data{std::move(data)}
			, mutex{} {
		}

		Atomic(self_type const & other)
			: data{}
			, mutex{} {
			std::lock_guard<std::mutex> lock{other.mutex};
			data = other.data;
		}

		Atomic(self_type&& other)
			: data{}
			, mutex{} {
			std::lock_guard<std::mutex> lock{other.mutex};
			std::swap(data, other.data);
		}

		T operator=(T data) {
			std::lock_guard<std::mutex> lock{mutex};
			this->data = std::move(data);
			return this->data;
		}

		operator T() const {
			return load();
		}

		bool is_lock_free() const {
			return false;
		}

		void store(T data) {
			std::lock_guard<std::mutex> lock{mutex};
			this->data = std::move(data);
		}

		T load() const {
			std::lock_guard<std::mutex> lock{mutex};
			return data;
		}

		T exchange(T data){
			std::lock_guard<std::mutex> lock{mutex};
			std::swap(data, this->data);
			return data;
		}

	private:
		T data;
		mutable std::mutex mutex;
};