asio/detail/win_global.hpp

0001 //
0002 // detail/win_global.hpp
0003 // ~~~~~~~~~~~~~~~~~~~~~
0004 //
0005 // Copyright (c) 2003-2023 Christopher M. Kohlhoff (chris at kohlhoff dot com)
0006 //
0007 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0008 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0009 //
0010
0011 #ifndef BOOST_ASIO_DETAIL_WIN_GLOBAL_HPP
0012 #define BOOST_ASIO_DETAIL_WIN_GLOBAL_HPP
0013
0014 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
0015 # pragma once
0016 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
0017
0018 #include <boost/asio/detail/config.hpp>
0019 #include <boost/asio/detail/static_mutex.hpp>
0020 #include <boost/asio/detail/tss_ptr.hpp>
0021
0022 #include <boost/asio/detail/push_options.hpp>
0023
0024 namespace boost {
0025 namespace asio {
0026 namespace detail {
0027
0028 template <typename T>
0029 struct win_global_impl
0030 {
0031   // Destructor automatically cleans up the global.
0032   ~win_global_impl()
0033   {
0034     delete ptr_;
0035   }
0036
0037   static win_global_impl instance_;
0038   static static_mutex mutex_;
0039   T* ptr_;
0040   static tss_ptr<T> tss_ptr_;
0041 };
0042
0043 template <typename T>
0044 win_global_impl<T> win_global_impl<T>::instance_ = { 0 };
0045
0046 template <typename T>
0047 static_mutex win_global_impl<T>::mutex_ = BOOST_ASIO_STATIC_MUTEX_INIT;
0048
0049 template <typename T>
0050 tss_ptr<T> win_global_impl<T>::tss_ptr_;
0051
0052 template <typename T>
0053 T& win_global()
0054 {
0055   if (static_cast<T*>(win_global_impl<T>::tss_ptr_) == 0)
0056   {
0057     win_global_impl<T>::mutex_.init();
0058     static_mutex::scoped_lock lock(win_global_impl<T>::mutex_);
0059     if (win_global_impl<T>::instance_.ptr_ == 0)
0060       win_global_impl<T>::instance_.ptr_ = new T;
0061     win_global_impl<T>::tss_ptr_ = win_global_impl<T>::instance_.ptr_;
0062   }
0063
0064   return *win_global_impl<T>::tss_ptr_;
0065 }
0066
0067 } // namespace detail
0068 } // namespace asio
0069 } // namespace boost
0070
0071 #include <boost/asio/detail/pop_options.hpp>
0072
0073 #endif // BOOST_ASIO_DETAIL_WIN_GLOBAL_HPP