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, 2003 Peter Dimov
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 #ifdef BOOST_USE_WINDOWS_H
24 # pragma warn -8027 // Functions containing while are not expanded inline
33 #ifndef BOOST_USE_WINDOWS_H
37 // Intel 6.0 on Win64 version, posted by Tim Fenders to [boost-users]
39 extern "C" long_type __cdecl _InterlockedExchange(long volatile *, long);
41 #pragma intrinsic(_InterlockedExchange)
43 inline long InterlockedExchange(long volatile* lp, long l)
45 return _InterlockedExchange(lp, l);
50 extern "C" __declspec(dllimport) long __stdcall InterlockedExchange(long volatile *, long);
54 extern "C" __declspec(dllimport) void __stdcall Sleep(unsigned long);
56 #endif // #ifndef BOOST_USE_WINDOWS_H
58 class lightweight_mutex
64 lightweight_mutex(lightweight_mutex const &);
65 lightweight_mutex & operator=(lightweight_mutex const &);
69 lightweight_mutex(): l_(0)
74 friend class scoped_lock;
80 lightweight_mutex & m_;
82 scoped_lock(scoped_lock const &);
83 scoped_lock & operator=(scoped_lock const &);
87 explicit scoped_lock(lightweight_mutex & m): m_(m)
89 while( InterlockedExchange(&m_.l_, 1) )
91 // Note: changed to Sleep(1) from Sleep(0).
92 // According to MSDN, Sleep(0) will never yield
93 // to a lower-priority thread, whereas Sleep(1)
94 // will. Performance seems not to be affected.
102 InterlockedExchange(&m_.l_, 0);
104 // Note: adding a yield here will make
105 // the spinlock more fair and will increase the overall
106 // performance of some applications substantially in
107 // high contention situations, but will penalize the
108 // low contention / single thread case up to 5x
113 } // namespace detail
118 # pragma warn .8027 // Functions containing while are not expanded inline
121 #endif // #ifndef BOOST_DETAIL_LWM_WIN32_HPP_INCLUDED