doc/v610/perf_8cxx.html

/*************************************************************************
 * Copyright (C) 1995-2015, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
#include "ROOT/THist.hxx"
#include "ROOT/TFit.hxx"
#include "ROOT/THistBufferedFill.hxx"
#include <chrono>
#include <iostream>
#include <type_traits>
long createNew(int count) {
  long ret = 1;
  for (int i = 0; i < count; ++i) {
    Experimental::TH2D hist({{{100, 0., 1.}, {{0., 1., 2., 3., 10.}}}});
    ret ^= (long)&hist;
  }
  return ret;
}
long fillNew(int count) {
  Experimental::TH2D hist({{{100, 0., 1.}, {{0., 1., 2., 3., 10.}}}});
  for (int i = 0; i < count; ++i)
    hist.Fill({0.611, 0.611});
  return hist.GetNDim();
}
long fillN(int count) {
  Experimental::TH2D hist({{{100, 0., 1.}, {{0., 1., 2., 3., 10.}}}});
  std::vector<std::array<double,2>> v(count);
  for (int i = 0; i < count; ++i)
    v[i] = {0.611, 0.611};
  hist.FillN(v);
  return hist.GetNDim();
}
long fillBufferedNew(int count) {
  Experimental::TH2D hist({{{100, 0., 1.}, {{0., 1., 2., 3., 10.}}}});
  Experimental::THistBufferedFill<Experimental::TH2D> filler(hist);
  for (int i = 0; i < count; ++i)
    filler.Fill({0.611, 0.611});
  return hist.GetNDim();
}
using timefunc_t = std::add_pointer_t<long(int)>;
void time1(timefunc_t run, int count, const std::string& name) {
  using namespace std::chrono;
  auto start = high_resolution_clock::now();
  run(count);
  auto end = high_resolution_clock::now();
  duration<double> time_span = duration_cast<duration<double>>(end - start);
  std::cout << count << " * " << name << ": " << time_span.count() << "seconds \n";
}
void time(timefunc_t r7, int count, const std::string& name) {
  time1(r7, count, name + " (ROOT7)");
}
void perf() {
  time(createOld, createNew, 1000000, "create 2D hists");
  time(fillNew, 100000000, "2D fills");
  time(fillBufferedNew, 100000000, "2D fills (buffered)");
}