Add wx headers and ext

wxheaders/wx/private/refcountermt.h

@@ -0,0 +1,42 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        wx/private/refcountermt.h
+// Purpose:     wxRefCounterMT class: MT-safe version of wxRefCounter
+// Author:      Vadim Zeitlin
+// Created:     2021-01-11
+// Copyright:   (c) 2021 Vadim Zeitlin <vadim@wxwidgets.org>
+// Licence:     wxWindows licence
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_PRIVATE_REFCOUNTERMT_H_
+#define _WX_PRIVATE_REFCOUNTERMT_H_
+
+#include "wx/atomic.h"
+
+// ----------------------------------------------------------------------------
+// Version of wxRefCounter with MT-safe count
+// ----------------------------------------------------------------------------
+
+class wxRefCounterMT
+{
+public:
+    wxRefCounterMT() { m_count = 1; }
+
+    void IncRef() { wxAtomicInc(m_count); }
+    void DecRef()
+    {
+        if ( wxAtomicDec(m_count) == 0 )
+            delete this;
+    }
+
+protected:
+    virtual ~wxRefCounterMT() { }
+
+private:
+    // Ref count is atomic to allow IncRef() and DecRef() to be concurrently
+    // called from different threads.
+    wxAtomicInt m_count;
+
+    wxDECLARE_NO_COPY_CLASS(wxRefCounterMT);
+};
+
+#endif // _WX_PRIVATE_REFCOUNTERMT_H_