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