src/thirdparty/boost_1_47_0/boost/smart_ptr/detail/yield_k.hpp

   1 #ifndef BOOST_SMART_PTR_DETAIL_YIELD_K_HPP_INCLUDED
   2 #define BOOST_SMART_PTR_DETAIL_YIELD_K_HPP_INCLUDED
   3
   4 // MS compatible compilers support #pragma once
   5
   6 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
   7 # pragma once
   8 #endif
   9
  10 //
  11 //  yield_k.hpp
  12 //
  13 //  Copyright (c) 2008 Peter Dimov
  14 //
  15 //  void yield( unsigned k );
  16 //
  17 //  Typical use:
  18 //
  19 //  for( unsigned k = 0; !try_lock(); ++k ) yield( k );
  20 //
  21 //  Distributed under the Boost Software License, Version 1.0.
  22 //  See accompanying file LICENSE_1_0.txt or copy at
  23 //  http://www.boost.org/LICENSE_1_0.txt
  24 //
  25
  26 #include <boost/config.hpp>
  27
  28 // BOOST_SMT_PAUSE
  29
  30 #if defined(_MSC_VER) && _MSC_VER >= 1310 && ( defined(_M_IX86) || defined(_M_X64) )
  31
  32 extern "C" void _mm_pause();
  33 #pragma intrinsic( _mm_pause )
  34
  35 #define BOOST_SMT_PAUSE _mm_pause();
  36
  37 #elif defined(__GNUC__) && ( defined(__i386__) || defined(__x86_64__) )
  38
  39 #define BOOST_SMT_PAUSE __asm__ __volatile__( "rep; nop" : : : "memory" );
  40
  41 #endif
  42
  43 //
  44
  45 #if defined( WIN32 ) || defined( _WIN32 ) || defined( __WIN32__ ) || defined( __CYGWIN__ )
  46
  47 #if defined( BOOST_USE_WINDOWS_H )
  48 # include <windows.h>
  49 #endif
  50
  51 namespace boost
  52 {
  53
  54 namespace detail
  55 {
  56
  57 #if !defined( BOOST_USE_WINDOWS_H )
  58   extern "C" void __stdcall Sleep( unsigned long ms );
  59 #endif
  60
  61 inline void yield( unsigned k )
  62 {
  63     if( k < 4 )
  64     {
  65     }
  66 #if defined( BOOST_SMT_PAUSE )
  67     else if( k < 16 )
  68     {
  69         BOOST_SMT_PAUSE
  70     }
  71 #endif
  72     else if( k < 32 )
  73     {
  74         Sleep( 0 );
  75     }
  76     else
  77     {
  78         Sleep( 1 );
  79     }
  80 }
  81
  82 } // namespace detail
  83
  84 } // namespace boost
  85
  86 #elif defined( BOOST_HAS_PTHREADS )
  87
  88 #include <sched.h>
  89 #include <time.h>
  90
  91 namespace boost
  92 {
  93
  94 namespace detail
  95 {
  96
  97 inline void yield( unsigned k )
  98 {
  99     if( k < 4 )
 100     {
 101     }
 102 #if defined( BOOST_SMT_PAUSE )
 103     else if( k < 16 )
 104     {
 105         BOOST_SMT_PAUSE
 106     }
 107 #endif
 108     else if( k < 32 || k & 1 )
 109     {
 110         sched_yield();
 111     }
 112     else
 113     {
 114         // g++ -Wextra warns on {} or {0}
 115         struct timespec rqtp = { 0, 0 };
 116
 117         // POSIX says that timespec has tv_sec and tv_nsec
 118         // But it doesn't guarantee order or placement
 119
 120         rqtp.tv_sec = 0;
 121         rqtp.tv_nsec = 1000;
 122
 123         nanosleep( &rqtp, 0 );
 124     }
 125 }
 126
 127 } // namespace detail
 128
 129 } // namespace boost
 130
 131 #else
 132
 133 namespace boost
 134 {
 135
 136 namespace detail
 137 {
 138
 139 inline void yield( unsigned )
 140 {
 141 }
 142
 143 } // namespace detail
 144
 145 } // namespace boost
 146
 147 #endif
 148
 149 #endif // #ifndef BOOST_SMART_PTR_DETAIL_YIELD_K_HPP_INCLUDED