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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>
+#include "mutex.h"
+
+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;
+ }
+
+ bool operator==(const T& other) const
+ {
+ std::lock_guard<std::mutex> lock{mutex};
+ return other == data;
+ }
+
+ bool operator!=(const T& other) const
+ {
+ std::lock_guard<std::mutex> lock{mutex};
+ return !(other == data);
+ }
+
+ bool operator==(const Atomic<T>& other) const
+ {
+ std::lock_guard<std::mutex> lock{mutex};
+ return other.load() == data;
+ }
+
+ bool operator!=(const Atomic<T>& other) 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;
+};