Chris@16: //////////////////////////////////////////////////////////////////////////////
Chris@16: //
Chris@16: // (C) Copyright Peter Dimov 2008.
Chris@16: // (C) Copyright Ion Gaztanaga 2013-2013. Distributed under the Boost
Chris@16: // Software License, Version 1.0. (See accompanying file
Chris@16: // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: // See http://www.boost.org/libs/interprocess for documentation.
Chris@16: //
Chris@16: //////////////////////////////////////////////////////////////////////////////
Chris@16: 
Chris@16: //Parts of this file come from boost/smart_ptr/detail/yield_k.hpp
Chris@16: //Many thanks to Peter Dimov.
Chris@16: 
Chris@16: #ifndef BOOST_INTERPROCESS_SYNC_WAIT_HPP_INCLUDED
Chris@16: #define BOOST_INTERPROCESS_SYNC_WAIT_HPP_INCLUDED
Chris@16: 
Chris@101: #ifndef BOOST_CONFIG_HPP
Chris@101: #  include <boost/config.hpp>
Chris@101: #endif
Chris@101: #
Chris@101: #if defined(BOOST_HAS_PRAGMA_ONCE)
Chris@16: # pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/interprocess/detail/config_begin.hpp>
Chris@16: #include <boost/interprocess/detail/workaround.hpp>
Chris@16: #include <boost/interprocess/detail/os_thread_functions.hpp>
Chris@16: 
Chris@16: //#define BOOST_INTERPROCESS_SPIN_WAIT_DEBUG
Chris@16: #ifdef BOOST_INTERPROCESS_SPIN_WAIT_DEBUG
Chris@16: #include <iostream>
Chris@16: #endif
Chris@16: 
Chris@16: // BOOST_INTERPROCESS_SMT_PAUSE
Chris@16: 
Chris@101: #if defined(_MSC_VER) && ( defined(_M_IX86) || defined(_M_X64) )
Chris@16: 
Chris@16: extern "C" void _mm_pause();
Chris@16: #pragma intrinsic( _mm_pause )
Chris@16: 
Chris@16: #define BOOST_INTERPROCESS_SMT_PAUSE _mm_pause();
Chris@16: 
Chris@101: #elif defined(__GNUC__) && ( defined(__i386__) || defined(__x86_64__) ) && !defined(_CRAYC)
Chris@16: 
Chris@16: #define BOOST_INTERPROCESS_SMT_PAUSE __asm__ __volatile__( "rep; nop" : : : "memory" );
Chris@16: 
Chris@16: #endif
Chris@16: 
Chris@16: namespace boost{
Chris@16: namespace interprocess{
Chris@16: namespace ipcdetail {
Chris@16: 
Chris@16: template<int Dummy = 0>
Chris@16: class num_core_holder
Chris@16: {
Chris@16:    public:
Chris@16:    static unsigned int get()
Chris@16:    {
Chris@16:       if(!num_cores){
Chris@16:          return ipcdetail::get_num_cores();
Chris@16:       }
Chris@16:       else{
Chris@16:          return num_cores;
Chris@16:       }
Chris@16:    }
Chris@16: 
Chris@16:    private:
Chris@16:    static unsigned int num_cores;
Chris@16: };
Chris@16: 
Chris@16: template<int Dummy>
Chris@16: unsigned int num_core_holder<Dummy>::num_cores = ipcdetail::get_num_cores();
Chris@16: 
Chris@16: }  //namespace ipcdetail {
Chris@16: 
Chris@16: class spin_wait
Chris@16: {
Chris@16:    public:
Chris@16: 
Chris@16:    static const unsigned int nop_pause_limit = 32u;
Chris@16:    spin_wait()
Chris@16:       : m_count_start(), m_ul_yield_only_counts(), m_k()
Chris@16:    {}
Chris@16: 
Chris@16:    #ifdef BOOST_INTERPROCESS_SPIN_WAIT_DEBUG
Chris@16:    ~spin_wait()
Chris@16:    {
Chris@16:       if(m_k){
Chris@16:          std::cout << "final m_k: " << m_k
Chris@16:                    << " system tick(us): " << ipcdetail::get_system_tick_us() << std::endl;
Chris@16:       }
Chris@16:    }
Chris@16:    #endif
Chris@16: 
Chris@16:    unsigned int count() const
Chris@16:    {  return m_k;  }
Chris@16: 
Chris@16:    void yield()
Chris@16:    {
Chris@16:       //Lazy initialization of limits
Chris@16:       if( !m_k){
Chris@16:          this->init_limits();
Chris@16:       }
Chris@16:       //Nop tries
Chris@16:       if( m_k < (nop_pause_limit >> 2) ){
Chris@16: 
Chris@16:       }
Chris@16:       //Pause tries if the processor supports it
Chris@16:       #if defined(BOOST_INTERPROCESS_SMT_PAUSE)
Chris@16:       else if( m_k < nop_pause_limit ){
Chris@16:          BOOST_INTERPROCESS_SMT_PAUSE
Chris@16:       }
Chris@16:       #endif
Chris@16:       //Yield/Sleep strategy
Chris@16:       else{
Chris@16:          //Lazy initialization of tick information
Chris@16:          if(m_k == nop_pause_limit){
Chris@16:             this->init_tick_info();
Chris@16:          }
Chris@16:          else if( this->yield_or_sleep() ){
Chris@16:             ipcdetail::thread_yield();
Chris@16:          }
Chris@16:          else{
Chris@16:             ipcdetail::thread_sleep_tick();
Chris@16:          }
Chris@16:       }
Chris@16:       ++m_k;
Chris@16:    }
Chris@16: 
Chris@16:    void reset()
Chris@16:    {
Chris@16:       m_k = 0u;
Chris@16:    }
Chris@16: 
Chris@16:    private:
Chris@16: 
Chris@16:    void init_limits()
Chris@16:    {
Chris@16:       unsigned int num_cores = ipcdetail::num_core_holder<0>::get();
Chris@16:       m_k = num_cores > 1u ? 0u : nop_pause_limit;
Chris@16:    }
Chris@16: 
Chris@16:    void init_tick_info()
Chris@16:    {
Chris@16:       m_ul_yield_only_counts = ipcdetail::get_system_tick_in_highres_counts();
Chris@16:       m_count_start = ipcdetail::get_current_system_highres_count();
Chris@16:    }
Chris@16: 
Chris@16:    //Returns true if yield must be called, false is sleep must be called
Chris@16:    bool yield_or_sleep()
Chris@16:    {
Chris@16:       if(!m_ul_yield_only_counts){  //If yield-only limit was reached then yield one in every two tries
Chris@16:          return (m_k & 1u) != 0;
Chris@16:       }
Chris@16:       else{ //Try to see if we've reched yield-only time limit
Chris@16:          const ipcdetail::OS_highres_count_t now = ipcdetail::get_current_system_highres_count();
Chris@16:          const ipcdetail::OS_highres_count_t elapsed = ipcdetail::system_highres_count_subtract(now, m_count_start);
Chris@16:          if(!ipcdetail::system_highres_count_less_ul(elapsed, m_ul_yield_only_counts)){
Chris@16:             #ifdef BOOST_INTERPROCESS_SPIN_WAIT_DEBUG
Chris@16:             std::cout << "elapsed!\n"
Chris@16:                       << "  m_ul_yield_only_counts: " << m_ul_yield_only_counts
Chris@16:                      << " system tick(us): " << ipcdetail::get_system_tick_us() << '\n'
Chris@16:                       << "  m_k: " << m_k << " elapsed counts: ";
Chris@16:                      ipcdetail::ostream_highres_count(std::cout, elapsed) << std::endl;
Chris@16:             #endif
Chris@16:             //Yield-only time reached, now it's time to sleep
Chris@16:             m_ul_yield_only_counts = 0ul;
Chris@16:             return false;
Chris@16:          }
Chris@16:       }
Chris@16:       return true;   //Otherwise yield
Chris@16:    }
Chris@16: 
Chris@16:    ipcdetail::OS_highres_count_t m_count_start;
Chris@16:    unsigned long m_ul_yield_only_counts;
Chris@16:    unsigned int  m_k;
Chris@16: };
Chris@16: 
Chris@16: } // namespace interprocess
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #include <boost/interprocess/detail/config_end.hpp>
Chris@16: 
Chris@16: #endif // #ifndef BOOST_INTERPROCESS_SYNC_WAIT_HPP_INCLUDED