1 #ifndef BOOST_DETAIL_LWM_WIN32_HPP_INCLUDED
2 #define BOOST_DETAIL_LWM_WIN32_HPP_INCLUDED
9 // boost/detail/lwm_win32.hpp
11 // Copyright (c) 2002 Peter Dimov and Multi Media Ltd.
13 // Permission to copy, use, modify, sell and distribute this software
14 // is granted provided this copyright notice appears in all copies.
15 // This software is provided "as is" without express or implied
16 // warranty, and with no claim as to its suitability for any purpose.
19 #include <boost/detail/winapi.hpp>
22 # pragma warn -8027 // Functions containing while are not expanded inline
31 class lightweight_mutex
37 lightweight_mutex(lightweight_mutex const &);
38 lightweight_mutex & operator=(lightweight_mutex const &);
42 lightweight_mutex(): l_(0)
47 friend class scoped_lock;
53 lightweight_mutex & m_;
55 scoped_lock(scoped_lock const &);
56 scoped_lock & operator=(scoped_lock const &);
60 explicit scoped_lock(lightweight_mutex & m): m_(m)
62 while( winapi::InterlockedExchange(&m_.l_, 1) )
64 // Note: changed to Sleep(1) from Sleep(0).
65 // According to MSDN, Sleep(0) will never yield
66 // to a lower-priority thread, whereas Sleep(1)
67 // will. Performance seems not to be affected.
75 winapi::InterlockedExchange(&m_.l_, 0);
77 // Note: adding a yield here will make
78 // the spinlock more fair and will increase the overall
79 // performance of some applications substantially in
80 // high contention situations, but will penalize the
81 // low contention / single thread case up to 5x
91 # pragma warn .8027 // Functions containing while are not expanded inline
94 #endif // #ifndef BOOST_DETAIL_LWM_WIN32_HPP_INCLUDED