ceph/src/boost/libs/coroutine2/performance/clock.hpp

   1
   2 //          Copyright Oliver Kowalke 2014.
   3 // Distributed under the Boost Software License, Version 1.0.
   4 //    (See accompanying file LICENSE_1_0.txt or copy at
   5 //          http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7 #ifndef CLOCK_H
   8 #define CLOCK_H
   9
  10 #include <algorithm>
  11 #include <cstddef>
  12 #include <numeric>
  13 #include <vector>
  14
  15 #include <boost/assert.hpp>
  16 #include <boost/chrono.hpp>
  17 #include <boost/cstdint.hpp>
  18
  19 typedef boost::chrono::high_resolution_clock    clock_type;
  20 typedef clock_type::duration                    duration_type;
  21 typedef clock_type::time_point                  time_point_type;
  22
  23 struct clock_overhead
  24 {
  25     boost::uint64_t operator()()
  26     {
  27         time_point_type start( clock_type::now() );
  28         return ( clock_type::now() - start).count();
  29     }
  30 };
  31
  32 inline
  33 duration_type overhead_clock()
  34 {
  35     std::size_t iterations( 10);
  36     std::vector< boost::uint64_t >  overhead( iterations, 0);
  37     for ( std::size_t i = 0; i < iterations; ++i)
  38         std::generate(
  39             overhead.begin(), overhead.end(),
  40             clock_overhead() );
  41     BOOST_ASSERT( overhead.begin() != overhead.end() );
  42     return duration_type( std::accumulate( overhead.begin(), overhead.end(), 0) / iterations);
  43 }
  44
  45 #endif // CLOCK_H