comparison DEPENDENCIES/generic/include/boost/interprocess/sync/spin/wait.hpp @ 16:2665513ce2d3

Add boost headers

+//////////////////////////////////////////////////////////////////////////////
+//
+// (C) Copyright Peter Dimov 2008.
+// (C) Copyright Ion Gaztanaga 2013-2013. 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)
+//
+// See http://www.boost.org/libs/interprocess for documentation.
+//
+//////////////////////////////////////////////////////////////////////////////
+
+//Parts of this file come from boost/smart_ptr/detail/yield_k.hpp
+//Many thanks to Peter Dimov.
+
+#ifndef BOOST_INTERPROCESS_SYNC_WAIT_HPP_INCLUDED
+#define BOOST_INTERPROCESS_SYNC_WAIT_HPP_INCLUDED
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+#include <boost/interprocess/detail/config_begin.hpp>
+#include <boost/interprocess/detail/workaround.hpp>
+#include <boost/interprocess/detail/os_thread_functions.hpp>
+
+//#define BOOST_INTERPROCESS_SPIN_WAIT_DEBUG
+#ifdef BOOST_INTERPROCESS_SPIN_WAIT_DEBUG
+#include <iostream>
+#endif
+
+// BOOST_INTERPROCESS_SMT_PAUSE
+
+#if defined(_MSC_VER) && _MSC_VER >= 1310 && ( defined(_M_IX86) || defined(_M_X64) )
+
+extern "C" void _mm_pause();
+#pragma intrinsic( _mm_pause )
+
+#define BOOST_INTERPROCESS_SMT_PAUSE _mm_pause();
+
+#elif defined(__GNUC__) && ( defined(__i386__) || defined(__x86_64__) )
+
+#define BOOST_INTERPROCESS_SMT_PAUSE __asm__ __volatile__( "rep; nop" : : : "memory" );
+
+#endif
+
+namespace boost{
+namespace interprocess{
+namespace ipcdetail {
+
+template<int Dummy = 0>
+class num_core_holder
+{
+   public:
+   static unsigned int get()
+   {
+      if(!num_cores){
+         return ipcdetail::get_num_cores();
+      }
+      else{
+         return num_cores;
+      }
+   }
+
+   private:
+   static unsigned int num_cores;
+};
+
+template<int Dummy>
+unsigned int num_core_holder<Dummy>::num_cores = ipcdetail::get_num_cores();
+
+}  //namespace ipcdetail {
+
+class spin_wait
+{
+   public:
+
+   static const unsigned int nop_pause_limit = 32u;
+   spin_wait()
+      : m_count_start(), m_ul_yield_only_counts(), m_k()
+   {}
+
+   #ifdef BOOST_INTERPROCESS_SPIN_WAIT_DEBUG
+   ~spin_wait()
+   {
+      if(m_k){
+         std::cout << "final m_k: " << m_k
+                   << " system tick(us): " << ipcdetail::get_system_tick_us() << std::endl;
+      }
+   }
+   #endif
+
+   unsigned int count() const
+   {  return m_k;  }
+
+   void yield()
+   {
+      //Lazy initialization of limits
+      if( !m_k){
+         this->init_limits();
+      }
+      //Nop tries
+      if( m_k < (nop_pause_limit >> 2) ){
+
+      }
+      //Pause tries if the processor supports it
+      #if defined(BOOST_INTERPROCESS_SMT_PAUSE)
+      else if( m_k < nop_pause_limit ){
+         BOOST_INTERPROCESS_SMT_PAUSE
+      }
+      #endif
+      //Yield/Sleep strategy
+      else{
+         //Lazy initialization of tick information
+         if(m_k == nop_pause_limit){
+            this->init_tick_info();
+         }
+         else if( this->yield_or_sleep() ){
+            ipcdetail::thread_yield();
+         }
+         else{
+            ipcdetail::thread_sleep_tick();
+         }
+      }
+      ++m_k;
+   }
+
+   void reset()
+   {
+      m_k = 0u;
+   }
+
+   private:
+
+   void init_limits()
+   {
+      unsigned int num_cores = ipcdetail::num_core_holder<0>::get();
+      m_k = num_cores > 1u ? 0u : nop_pause_limit;
+   }
+
+   void init_tick_info()
+   {
+      m_ul_yield_only_counts = ipcdetail::get_system_tick_in_highres_counts();
+      m_count_start = ipcdetail::get_current_system_highres_count();
+   }
+
+   //Returns true if yield must be called, false is sleep must be called
+   bool yield_or_sleep()
+   {
+      if(!m_ul_yield_only_counts){  //If yield-only limit was reached then yield one in every two tries
+         return (m_k & 1u) != 0;
+      }
+      else{ //Try to see if we've reched yield-only time limit
+         const ipcdetail::OS_highres_count_t now = ipcdetail::get_current_system_highres_count();
+         const ipcdetail::OS_highres_count_t elapsed = ipcdetail::system_highres_count_subtract(now, m_count_start);
+         if(!ipcdetail::system_highres_count_less_ul(elapsed, m_ul_yield_only_counts)){
+            #ifdef BOOST_INTERPROCESS_SPIN_WAIT_DEBUG
+            std::cout << "elapsed!\n"
+                      << "  m_ul_yield_only_counts: " << m_ul_yield_only_counts
+                     << " system tick(us): " << ipcdetail::get_system_tick_us() << '\n'
+                      << "  m_k: " << m_k << " elapsed counts: ";
+                     ipcdetail::ostream_highres_count(std::cout, elapsed) << std::endl;
+            #endif
+            //Yield-only time reached, now it's time to sleep
+            m_ul_yield_only_counts = 0ul;
+            return false;
+         }
+      }
+      return true;   //Otherwise yield
+   }
+
+   ipcdetail::OS_highres_count_t m_count_start;
+   unsigned long m_ul_yield_only_counts;
+   unsigned int  m_k;
+};
+
+} // namespace interprocess
+} // namespace boost
+
+#include <boost/interprocess/detail/config_end.hpp>
+
+#endif // #ifndef BOOST_INTERPROCESS_SYNC_WAIT_HPP_INCLUDED