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// Copyright Catch2 Authors
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE.txt or copy at
// https://www.boost.org/LICENSE_1_0.txt)
// SPDX-License-Identifier: BSL-1.0
// Adapted from donated nonius code.
#ifndef CATCH_ESTIMATE_CLOCK_HPP_INCLUDED
#define CATCH_ESTIMATE_CLOCK_HPP_INCLUDED
#include <catch2/benchmark/catch_clock.hpp>
#include <catch2/benchmark/catch_environment.hpp>
#include <catch2/benchmark/detail/catch_stats.hpp>
#include <catch2/benchmark/detail/catch_measure.hpp>
#include <catch2/benchmark/detail/catch_run_for_at_least.hpp>
#include <catch2/benchmark/catch_clock.hpp>
#include <catch2/internal/catch_unique_ptr.hpp>
#include <algorithm>
#include <vector>
#include <cmath>
namespace Catch {
namespace Benchmark {
namespace Detail {
template <typename Clock>
std::vector<double> resolution(int k) {
const size_t points = static_cast<size_t>( k + 1 );
// To avoid overhead from the branch inside vector::push_back,
// we allocate them all and then overwrite.
std::vector<TimePoint<Clock>> times(points);
for ( auto& time : times ) {
time = Clock::now();
}
std::vector<double> deltas;
deltas.reserve(static_cast<size_t>(k));
for ( size_t idx = 1; idx < points; ++idx ) {
deltas.push_back( static_cast<double>(
( times[idx] - times[idx - 1] ).count() ) );
}
return deltas;
}
constexpr auto warmup_iterations = 10000;
constexpr auto warmup_time = std::chrono::milliseconds(100);
constexpr auto minimum_ticks = 1000;
constexpr auto warmup_seed = 10000;
constexpr auto clock_resolution_estimation_time = std::chrono::milliseconds(500);
constexpr auto clock_cost_estimation_time_limit = std::chrono::seconds(1);
constexpr auto clock_cost_estimation_tick_limit = 100000;
constexpr auto clock_cost_estimation_time = std::chrono::milliseconds(10);
constexpr auto clock_cost_estimation_iterations = 10000;
template <typename Clock>
int warmup() {
return run_for_at_least<Clock>(warmup_time, warmup_seed, &resolution<Clock>)
.iterations;
}
template <typename Clock>
EnvironmentEstimate estimate_clock_resolution(int iterations) {
auto r = run_for_at_least<Clock>(clock_resolution_estimation_time, iterations, &resolution<Clock>)
.result;
return {
FDuration(mean(r.data(), r.data() + r.size())),
classify_outliers(r.data(), r.data() + r.size()),
};
}
template <typename Clock>
EnvironmentEstimate estimate_clock_cost(FDuration resolution) {
auto time_limit = (std::min)(
resolution * clock_cost_estimation_tick_limit,
FDuration(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>(clock_cost_estimation_time, iters, time_clock);
std::vector<double> times;
int nsamples = static_cast<int>(std::ceil(time_limit / r.elapsed));
times.reserve(static_cast<size_t>(nsamples));
for ( int s = 0; s < nsamples; ++s ) {
times.push_back( static_cast<double>(
( time_clock( r.iterations ) / r.iterations )
.count() ) );
}
return {
FDuration(mean(times.data(), times.data() + times.size())),
classify_outliers(times.data(), times.data() + times.size()),
};
}
template <typename Clock>
Environment measure_environment() {
#if defined(__clang__)
# pragma clang diagnostic push
# pragma clang diagnostic ignored "-Wexit-time-destructors"
#endif
static Catch::Detail::unique_ptr<Environment> env;
#if defined(__clang__)
# pragma clang diagnostic pop
#endif
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 = Catch::Detail::make_unique<Environment>( Environment{resolution, cost} );
return *env;
}
} // namespace Detail
} // namespace Benchmark
} // namespace Catch
#endif // CATCH_ESTIMATE_CLOCK_HPP_INCLUDED
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