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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 Lesser 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser 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{}
{
const std::lock_guard<std::mutex> lock{other.mutex};
data = other.data;
}
Atomic(self_type&& other)
: data{}
, mutex{}
{
const std::lock_guard<std::mutex> lock{other.mutex};
std::swap(data, other.data);
}
T operator=(T data)
{
const 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)
{
const std::lock_guard<std::mutex> lock{mutex};
this->data = std::move(data);
}
T load() const {
const std::lock_guard<std::mutex> lock{mutex};
return data;
}
T exchange(T data){
const std::lock_guard<std::mutex> lock{mutex};
std::swap(data, this->data);
return data;
}
bool operator==(const T& other) const
{
const std::lock_guard<std::mutex> lock{mutex};
return other == data;
}
bool operator!=(const T& other) const
{
const std::lock_guard<std::mutex> lock{mutex};
return !(other == data);
}
bool operator==(const Atomic<T>& other) const
{
const std::lock_guard<std::mutex> lock{mutex};
return other.load() == data;
}
bool operator!=(const Atomic<T>& other) const
{
const std::lock_guard<std::mutex> lock{mutex};
return !(other.load() == data);
}
private:
T data;
mutable std::mutex mutex;
};
//! Getter utility class.
template <typename T> class SettingRef
{
public:
SettingRef(Atomic<T>& value)
: value(value)
{
// string isn't lock free either
assert((std::is_same<T, std::string>::value || value.is_lock_free()));
}
bool hasChanged()
{
T tmp = cache;
cache.exchange(value);
if(firstAccess)
{
firstAccess = false;
return true;
}
return cache != tmp;
}
T getValue() const
{
return cache;
}
private:
bool firstAccess{true};
Atomic<T>& value;
Atomic<T> cache;
};
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