ceph/src/boost/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 //  Copyright (c) Microsoft Corporation 2014
  15 //
  16 //  void yield( unsigned k );
  17 //
  18 //  Typical use:
  19 //
  20 //  for( unsigned k = 0; !try_lock(); ++k ) yield( k );
  21 //
  22 //  Distributed under the Boost Software License, Version 1.0.
  23 //  See accompanying file LICENSE_1_0.txt or copy at
  24 //  http://www.boost.org/LICENSE_1_0.txt
  25 //
  26
  27 #include <boost/config.hpp>
  28 #include <boost/predef.h>
  29
  30 #if BOOST_PLAT_WINDOWS_RUNTIME
  31 #include <thread>
  32 #endif
  33
  34 // BOOST_SMT_PAUSE
  35
  36 #if defined(_MSC_VER) && _MSC_VER >= 1310 && ( defined(_M_IX86) || defined(_M_X64) ) && !defined(__c2__)
  37
  38 extern "C" void _mm_pause();
  39
  40 #define BOOST_SMT_PAUSE _mm_pause();
  41
  42 #elif defined(__GNUC__) && ( defined(__i386__) || defined(__x86_64__) )
  43
  44 #define BOOST_SMT_PAUSE __asm__ __volatile__( "rep; nop" : : : "memory" );
  45
  46 #endif
  47
  48 //
  49
  50 #if defined( WIN32 ) || defined( _WIN32 ) || defined( __WIN32__ ) || defined( __CYGWIN__ )
  51
  52 #if defined( BOOST_USE_WINDOWS_H )
  53 # include <windows.h>
  54 #endif
  55
  56 namespace boost
  57 {
  58
  59 namespace detail
  60 {
  61
  62 #if !defined( BOOST_USE_WINDOWS_H ) && !BOOST_PLAT_WINDOWS_RUNTIME
  63 #if !BOOST_COMP_CLANG || !defined __MINGW32__
  64   extern "C" void __stdcall Sleep( unsigned long ms );
  65 #else
  66 #include <_mingw.h>
  67 #if !defined __MINGW64_VERSION_MAJOR
  68   extern "C" void __stdcall Sleep( unsigned long ms );
  69 #else
  70   extern "C" __declspec(dllimport) void __stdcall Sleep( unsigned long ms );
  71 #endif
  72 #endif
  73 #endif
  74
  75 inline void yield( unsigned k )
  76 {
  77     if( k < 4 )
  78     {
  79     }
  80 #if defined( BOOST_SMT_PAUSE )
  81     else if( k < 16 )
  82     {
  83         BOOST_SMT_PAUSE
  84     }
  85 #endif
  86 #if !BOOST_PLAT_WINDOWS_RUNTIME
  87     else if( k < 32 )
  88     {
  89         Sleep( 0 );
  90     }
  91     else
  92     {
  93         Sleep( 1 );
  94     }
  95 #else
  96     else
  97     {
  98         // Sleep isn't supported on the Windows Runtime.
  99         std::this_thread::yield();
 100     }
 101 #endif
 102 }
 103
 104 } // namespace detail
 105
 106 } // namespace boost
 107
 108 #elif defined( BOOST_HAS_PTHREADS )
 109
 110 #ifndef _AIX
 111 #include <sched.h>
 112 #else
 113    // AIX's sched.h defines ::var which sometimes conflicts with Lambda's var
 114        extern "C" int sched_yield(void);
 115 #endif
 116
 117 #include <time.h>
 118
 119 namespace boost
 120 {
 121
 122 namespace detail
 123 {
 124
 125 inline void yield( unsigned k )
 126 {
 127     if( k < 4 )
 128     {
 129     }
 130 #if defined( BOOST_SMT_PAUSE )
 131     else if( k < 16 )
 132     {
 133         BOOST_SMT_PAUSE
 134     }
 135 #endif
 136     else if( k < 32 || k & 1 )
 137     {
 138         sched_yield();
 139     }
 140     else
 141     {
 142         // g++ -Wextra warns on {} or {0}
 143         struct timespec rqtp = { 0, 0 };
 144
 145         // POSIX says that timespec has tv_sec and tv_nsec
 146         // But it doesn't guarantee order or placement
 147
 148         rqtp.tv_sec = 0;
 149         rqtp.tv_nsec = 1000;
 150
 151         nanosleep( &rqtp, 0 );
 152     }
 153 }
 154
 155 } // namespace detail
 156
 157 } // namespace boost
 158
 159 #else
 160
 161 namespace boost
 162 {
 163
 164 namespace detail
 165 {
 166
 167 inline void yield( unsigned )
 168 {
 169 }
 170
 171 } // namespace detail
 172
 173 } // namespace boost
 174
 175 #endif
 176
 177 #endif // #ifndef BOOST_SMART_PTR_DETAIL_YIELD_K_HPP_INCLUDED