Added API for accessing structs in a thread-safe way

1 files changed, 112 insertions, 0 deletions

diff --git a/src/syncedsettings.h b/src/syncedsettings.h
new file mode 100644
index 0000000..f83847c
--- /dev/null
+++ b/src/syncedsettings.h
@@ -0,0 +1,112 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/***************************************************************************
+ *            syncedsettings.h
+ *
+ *  Thu Mar 31 09:23:27 CEST 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 <mutex>
+
+// type trait helper
+
+template <typename T, typename... Types>
+struct pack_contains;
+
+template <typename T, typename... Types>
+struct pack_contains<T, T, Types...>
+	: std::true_type {
+};
+
+template <typename T, typename Head, typename... Types>
+struct pack_contains<T, Head, Types...>
+	: pack_contains<T, Types...> {
+};
+
+template <typename T>
+struct pack_contains<T>
+	: std::false_type {
+};
+
+// --------------------------------------------------------------------
+
+template <typename T>
+class Group;
+
+template <typename T>
+class Accessor {
+	private:
+		std::lock_guard<std::mutex> lock;
+		
+	public:
+		Accessor(Group<T>& parent)
+			: lock{parent.mutex}
+			, data{parent.data} {
+		}
+		
+		T& data;
+};
+
+template <typename T>
+class Group {
+	private:
+		friend class Accessor<T>;
+		
+		mutable std::mutex mutex;
+		T data;
+		
+	public:
+		Group()
+			: mutex{}
+			,  data{} {
+		}
+		
+		Group(T const & data)
+			: mutex{}
+			, data{data} {
+		}
+		
+		Group(T&& data)
+			: mutex{}
+			, data{std::move(data)} {
+		}
+		
+		Group(Group<T> const & other)
+			: mutex{}
+			, data{} {
+			std::lock_guard<std::mutex> lock{other.mutex};
+			data = other.data;
+		}
+		
+		Group(Group<T>&& other)
+			: mutex{}
+			, data{} {
+			std::lock_guard<std::mutex> lock{other.mutex};
+			std::swap(data, other.data);
+		}
+		
+		operator T() const {
+			std::lock_guard<std::mutex> lock{mutex};
+			return data;
+		}
+};