feat(Core/Common): add Asio network threading (#6063)

src/common/Asio/Strand.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2016+ AzerothCore <www.azerothcore.org>, released under GNU AGPL v3 license: https://github.com/azerothcore/azerothcore-wotlk/blob/master/LICENSE-AGPL3
+ * Copyright (C) 2021+ WarheadCore <https://github.com/WarheadCore>
+ */
+
+#ifndef Strand_h__
+#define Strand_h__
+
+#include "IoContext.h"
+#include <boost/asio/strand.hpp>
+
+#if BOOST_VERSION >= 106600
+#include <boost/asio/bind_executor.hpp>
+#endif
+
+namespace acore::Asio
+{
+    /**
+        Hack to make it possible to forward declare strand (which is a inner class)
+    */
+    class Strand : public IoContextBaseNamespace::IoContextBase::strand
+    {
+    public:
+        Strand(IoContext& ioContext) : IoContextBaseNamespace::IoContextBase::strand(ioContext) { }
+    };
+
+#if BOOST_VERSION >= 106600
+    using boost::asio::bind_executor;
+#else
+    template<typename T>
+    inline decltype(auto) bind_executor(Strand& strand, T&& t)
+    {
+        return strand.wrap(std::forward<T>(t));
+    }
+#endif
+}
+
+#endif // Strand_h__