boost/libs/thread/example/perf_shared_mutex.cpp

//  (C) Copyright 2013 Andrey
//  (C) Copyright 2013 Vicente J. Botet Escriba
//
//  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)
//
// This performance test is based on the performance test provided by maxim.yegorushkin
// at https://svn.boost.org/trac/boost/ticket/7422

#define BOOST_THREAD_USES_CHRONO

#include <iostream>
#include <boost/thread/lock_types.hpp>
#include <boost/thread/thread_only.hpp>
#include <boost/chrono/chrono_io.hpp>

#include <boost/thread/shared_mutex.hpp>

using namespace boost;

shared_mutex mtx;
const int cycles = 10000;

void shared()
{
  int cycle(0);
  while (++cycle < cycles)
  {
    shared_lock<shared_mutex> lock(mtx);
  }
}

void unique()
{
  int cycle(0);
  while (++cycle < cycles)
  {
    unique_lock<shared_mutex> lock(mtx);
  }
}

int main()
{
  boost::chrono::high_resolution_clock::duration best_time(std::numeric_limits<boost::chrono::high_resolution_clock::duration::rep>::max BOOST_PREVENT_MACRO_SUBSTITUTION ());
  for (int i =100; i>0; --i) {
    boost::chrono::high_resolution_clock clock;
    boost::chrono::high_resolution_clock::time_point s1 = clock.now();
    thread t0(shared);
    thread t1(shared);
    thread t2(unique);
    //thread t11(shared);
    //thread t12(shared);
    //thread t13(shared);

    t0.join();
    t1.join();
    t2.join();
    //t11.join();
//    t12.join();
  //  t13.join();
    boost::chrono::high_resolution_clock::time_point f1 = clock.now();
    //std::cout << "     Time spent:" << (f1 - s1) << std::endl;
    best_time = std::min BOOST_PREVENT_MACRO_SUBSTITUTION (best_time, f1 - s1);

  }
  std::cout << "Best Time spent:" << best_time << std::endl;
  std::cout << "Time spent/cycle:" << best_time/cycles/3 << std::endl;

  return 1;
}