#ifndef BOOST_DETAIL_LWM_WIN32_HPP_INCLUDED #define BOOST_DETAIL_LWM_WIN32_HPP_INCLUDED #if _MSC_VER >= 1020 #pragma once #endif // // boost/detail/lwm_win32.hpp // // Copyright (c) 2002 Peter Dimov and Multi Media Ltd. // // Permission to copy, use, modify, sell and distribute this software // is granted provided this copyright notice appears in all copies. // This software is provided "as is" without express or implied // warranty, and with no claim as to its suitability for any purpose. // #include #ifdef __BORLANDC__ # pragma warn -8027 // Functions containing while are not expanded inline #endif namespace boost { namespace detail { class lightweight_mutex { private: long l_; lightweight_mutex(lightweight_mutex const &); lightweight_mutex & operator=(lightweight_mutex const &); public: lightweight_mutex(): l_(0) { } class scoped_lock; friend class scoped_lock; class scoped_lock { private: lightweight_mutex & m_; scoped_lock(scoped_lock const &); scoped_lock & operator=(scoped_lock const &); public: explicit scoped_lock(lightweight_mutex & m): m_(m) { while( winapi::InterlockedExchange(&m_.l_, 1) ) { // Note: changed to Sleep(1) from Sleep(0). // According to MSDN, Sleep(0) will never yield // to a lower-priority thread, whereas Sleep(1) // will. Performance seems not to be affected. winapi::Sleep(1); } } ~scoped_lock() { winapi::InterlockedExchange(&m_.l_, 0); // Note: adding a yield here will make // the spinlock more fair and will increase the overall // performance of some applications substantially in // high contention situations, but will penalize the // low contention / single thread case up to 5x } }; }; } // namespace detail } // namespace boost #ifdef __BORLANDC__ # pragma warn .8027 // Functions containing while are not expanded inline #endif #endif // #ifndef BOOST_DETAIL_LWM_WIN32_HPP_INCLUDED