forked from boostorg/smart_ptr
184 lines
3.3 KiB
C++
184 lines
3.3 KiB
C++
#ifndef BOOST_SMART_PTR_DETAIL_YIELD_K_HPP_INCLUDED
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#define BOOST_SMART_PTR_DETAIL_YIELD_K_HPP_INCLUDED
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// MS compatible compilers support #pragma once
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#if defined(_MSC_VER) && (_MSC_VER >= 1020)
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# pragma once
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#endif
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//
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// yield_k.hpp
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//
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// Copyright (c) 2008 Peter Dimov
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// Copyright (c) Microsoft Corporation 2014
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//
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// void yield( unsigned k );
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//
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// Typical use:
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//
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// for( unsigned k = 0; !try_lock(); ++k ) yield( k );
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//
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// Distributed under the Boost Software License, Version 1.0.
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// See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt
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//
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#include <boost/config.hpp>
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#include <boost/predef/platform/windows_runtime.h>
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#if BOOST_PLAT_WINDOWS_RUNTIME
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#include <thread>
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#endif
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// BOOST_SMT_PAUSE
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#if defined(_MSC_VER) && _MSC_VER >= 1310 && ( defined(_M_IX86) || defined(_M_X64) ) && !defined(__c2__)
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extern "C" void _mm_pause();
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#define BOOST_SMT_PAUSE _mm_pause();
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#elif defined(__GNUC__) && ( defined(__i386__) || defined(__x86_64__) )
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#define BOOST_SMT_PAUSE __asm__ __volatile__( "rep; nop" : : : "memory" );
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#endif
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//
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#if defined( WIN32 ) || defined( _WIN32 ) || defined( __WIN32__ ) || defined( __CYGWIN__ )
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#if defined( BOOST_USE_WINDOWS_H )
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# include <windows.h>
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#endif
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namespace boost
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{
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namespace detail
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{
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#if !defined( BOOST_USE_WINDOWS_H ) && !BOOST_PLAT_WINDOWS_RUNTIME
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#if defined(__clang__) && defined(__x86_64__)
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// clang x64 warns that __stdcall is ignored
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# define BOOST_SP_STDCALL
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#else
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# define BOOST_SP_STDCALL __stdcall
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#endif
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#if defined(__LP64__) // Cygwin 64
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extern "C" __declspec(dllimport) void BOOST_SP_STDCALL Sleep( unsigned int ms );
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#else
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extern "C" __declspec(dllimport) void BOOST_SP_STDCALL Sleep( unsigned long ms );
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#endif
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#undef BOOST_SP_STDCALL
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#endif // !defined( BOOST_USE_WINDOWS_H ) && !BOOST_PLAT_WINDOWS_RUNTIME
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inline void yield( unsigned k ) BOOST_NOEXCEPT
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{
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if( k < 4 )
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{
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}
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#if defined( BOOST_SMT_PAUSE )
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else if( k < 16 )
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{
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BOOST_SMT_PAUSE
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}
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#endif
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#if !BOOST_PLAT_WINDOWS_RUNTIME
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else if( k < 32 )
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{
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Sleep( 0 );
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}
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else
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{
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Sleep( 1 );
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}
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#else
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else
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{
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// Sleep isn't supported on the Windows Runtime.
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std::this_thread::yield();
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}
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#endif
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}
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} // namespace detail
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} // namespace boost
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#elif defined( BOOST_HAS_PTHREADS )
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#ifndef _AIX
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#include <sched.h>
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#else
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// AIX's sched.h defines ::var which sometimes conflicts with Lambda's var
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extern "C" int sched_yield(void);
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#endif
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#include <time.h>
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namespace boost
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{
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namespace detail
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{
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inline void yield( unsigned k )
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{
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if( k < 4 )
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{
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}
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#if defined( BOOST_SMT_PAUSE )
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else if( k < 16 )
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{
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BOOST_SMT_PAUSE
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}
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#endif
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else if( k < 32 || k & 1 )
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{
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sched_yield();
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}
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else
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{
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// g++ -Wextra warns on {} or {0}
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struct timespec rqtp = { 0, 0 };
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// POSIX says that timespec has tv_sec and tv_nsec
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// But it doesn't guarantee order or placement
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rqtp.tv_sec = 0;
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rqtp.tv_nsec = 1000;
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nanosleep( &rqtp, 0 );
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}
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}
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} // namespace detail
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} // namespace boost
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#else
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namespace boost
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{
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namespace detail
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{
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inline void yield( unsigned )
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{
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}
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} // namespace detail
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} // namespace boost
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#endif
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#endif // #ifndef BOOST_SMART_PTR_DETAIL_YIELD_K_HPP_INCLUDED
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