yield_k.hpp
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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) )
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
config.hpp
time.h
predef.h
boost
BOOST_MOVE_USE_STANDARD_LIBRARY_MOVE.
boost::detail::yield
void yield(unsigned)
Definition: yield_k.hpp:167
boost::detail::__declspec
__declspec(dllimport) void __stdcall InitializeCriticalSection(critical_section *)
windows.h

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autogenerated on Thu Feb 8 2024 03:56:19