catch2/include/internal/benchmark/detail/catch_estimate_clock.hpp

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/*
* Created by Joachim on 16/04/2019.
* Adapted from donated nonius code.
*
* 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)
*/
// Environment measurement
#ifndef TWOBLUECUBES_CATCH_DETAIL_ESTIMATE_CLOCK_HPP_INCLUDED
#define TWOBLUECUBES_CATCH_DETAIL_ESTIMATE_CLOCK_HPP_INCLUDED
#include "../catch_clock.hpp"
#include "../catch_environment.hpp"
#include "catch_stats.hpp"
#include "catch_measure.hpp"
#include "catch_run_for_at_least.hpp"
#include "../catch_clock.hpp"
#include <algorithm>
#include <iterator>
#include <tuple>
#include <vector>
#include <cmath>
namespace Catch {
namespace Benchmark {
namespace Detail {
template <typename Clock>
std::vector<double> resolution(int k) {
std::vector<TimePoint<Clock>> times;
times.reserve(k + 1);
std::generate_n(std::back_inserter(times), k + 1, now<Clock>{});
std::vector<double> deltas;
deltas.reserve(k);
std::transform(std::next(times.begin()), times.end(), times.begin(),
std::back_inserter(deltas),
[](TimePoint<Clock> a, TimePoint<Clock> b) { return static_cast<double>((a - b).count()); });
return deltas;
}
const auto warmup_iterations = 10000;
const auto warmup_time = std::chrono::milliseconds(100);
const auto minimum_ticks = 1000;
const auto warmup_seed = 10000;
const auto clock_resolution_estimation_time = std::chrono::milliseconds(500);
const auto clock_cost_estimation_time_limit = std::chrono::seconds(1);
const auto clock_cost_estimation_tick_limit = 100000;
const auto clock_cost_estimation_time = std::chrono::milliseconds(10);
const auto clock_cost_estimation_iterations = 10000;
template <typename Clock>
int warmup() {
return run_for_at_least<Clock>(std::chrono::duration_cast<ClockDuration<Clock>>(warmup_time), warmup_seed, &resolution<Clock>)
.iterations;
}
template <typename Clock>
EnvironmentEstimate<FloatDuration<Clock>> estimate_clock_resolution(int iterations) {
auto r = run_for_at_least<Clock>(std::chrono::duration_cast<ClockDuration<Clock>>(clock_resolution_estimation_time), iterations, &resolution<Clock>)
.result;
return {
FloatDuration<Clock>(mean(r.begin(), r.end())),
classify_outliers(r.begin(), r.end()),
};
}
template <typename Clock>
EnvironmentEstimate<FloatDuration<Clock>> estimate_clock_cost(FloatDuration<Clock> resolution) {
auto time_limit = (std::min)(
resolution * clock_cost_estimation_tick_limit,
FloatDuration<Clock>(clock_cost_estimation_time_limit));
auto time_clock = [](int k) {
return Detail::measure<Clock>([k] {
for (int i = 0; i < k; ++i) {
volatile auto ignored = Clock::now();
(void)ignored;
}
}).elapsed;
};
time_clock(1);
int iters = clock_cost_estimation_iterations;
auto&& r = run_for_at_least<Clock>(std::chrono::duration_cast<ClockDuration<Clock>>(clock_cost_estimation_time), iters, time_clock);
std::vector<double> times;
int nsamples = static_cast<int>(std::ceil(time_limit / r.elapsed));
times.reserve(nsamples);
std::generate_n(std::back_inserter(times), nsamples, [time_clock, &r] {
return static_cast<double>((time_clock(r.iterations) / r.iterations).count());
});
return {
FloatDuration<Clock>(mean(times.begin(), times.end())),
classify_outliers(times.begin(), times.end()),
};
}
template <typename Clock>
Environment<FloatDuration<Clock>> measure_environment() {
static Environment<FloatDuration<Clock>>* env = nullptr;
if (env) {
return *env;
}
auto iters = Detail::warmup<Clock>();
auto resolution = Detail::estimate_clock_resolution<Clock>(iters);
auto cost = Detail::estimate_clock_cost<Clock>(resolution.mean);
env = new Environment<FloatDuration<Clock>>{ resolution, cost };
return *env;
}
} // namespace Detail
} // namespace Benchmark
} // namespace Catch
#endif // TWOBLUECUBES_CATCH_DETAIL_ESTIMATE_CLOCK_HPP_INCLUDED