Initial Commit

include/asio/detail/win_global.hpp

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+//
+// detail/win_global.hpp
+// ~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2025 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef ASIO_DETAIL_WIN_GLOBAL_HPP
+#define ASIO_DETAIL_WIN_GLOBAL_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+#include "asio/detail/static_mutex.hpp"
+#include "asio/detail/tss_ptr.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+namespace detail {
+
+template <typename T>
+struct win_global_impl
+{
+  // Destructor automatically cleans up the global.
+  ~win_global_impl()
+  {
+    delete ptr_;
+  }
+
+  static win_global_impl instance_;
+  static static_mutex mutex_;
+  T* ptr_;
+  static tss_ptr<T> tss_ptr_;
+};
+
+template <typename T>
+win_global_impl<T> win_global_impl<T>::instance_ = { 0 };
+
+template <typename T>
+static_mutex win_global_impl<T>::mutex_ = ASIO_STATIC_MUTEX_INIT;
+
+template <typename T>
+tss_ptr<T> win_global_impl<T>::tss_ptr_;
+
+template <typename T>
+T& win_global()
+{
+  if (static_cast<T*>(win_global_impl<T>::tss_ptr_) == 0)
+  {
+    win_global_impl<T>::mutex_.init();
+    static_mutex::scoped_lock lock(win_global_impl<T>::mutex_);
+    if (win_global_impl<T>::instance_.ptr_ == 0)
+      win_global_impl<T>::instance_.ptr_ = new T;
+    win_global_impl<T>::tss_ptr_ = win_global_impl<T>::instance_.ptr_;
+  }
+
+  return *win_global_impl<T>::tss_ptr_;
+}
+
+} // namespace detail
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // ASIO_DETAIL_WIN_GLOBAL_HPP