Reduce the number of templates in Benchmarking

The basic idea was to reduce the number of things dependent on the `Clock`
type. To that end, I replaced `Duration<Clock>` with `IDuration` typedef
for `std::nanoseconds`, and `FloatDuration<Clock>` with `FDuration`
typedef for `Duration<double, std::nano>`. We can generally assume that
any clock's duration can be expressed in nanoseconds, as long as we insert
`duration_cast`s into the right places.

Note that we cannot remove all dependence on `Clock` as a template
arguments, because functions that actually measure the elapsed time have
to use the Clock.

We also changed some template function arguments to pass plain function
pointers, so that the actual implementation can be placed into a cpp file.

src/CMakeLists.txt

@@ -33,6 +33,7 @@ set(BENCHMARK_HEADERS
 )
 set(BENCHMARK_SOURCES
   ${SOURCES_DIR}/benchmark/catch_chronometer.cpp
+  ${SOURCES_DIR}/benchmark/detail/catch_analyse.cpp
   ${SOURCES_DIR}/benchmark/detail/catch_benchmark_function.cpp
   ${SOURCES_DIR}/benchmark/detail/catch_run_for_at_least.cpp
   ${SOURCES_DIR}/benchmark/detail/catch_stats.cpp

src/catch2/benchmark/catch_benchmark.hpp

@@ -45,16 +45,18 @@ namespace Catch {
                 : fun(CATCH_MOVE(func)), name(CATCH_MOVE(benchmarkName)) {}
 
             template <typename Clock>
-            ExecutionPlan<FloatDuration<Clock>> prepare(const IConfig &cfg, Environment<FloatDuration<Clock>> env) const {
+            ExecutionPlan prepare(const IConfig &cfg, Environment env) const {
                 auto min_time = env.clock_resolution.mean * Detail::minimum_ticks;
                 auto run_time = std::max(min_time, std::chrono::duration_cast<decltype(min_time)>(cfg.benchmarkWarmupTime()));
-                auto&& test = Detail::run_for_at_least<Clock>(std::chrono::duration_cast<ClockDuration<Clock>>(run_time), 1, fun);
+                auto&& test = Detail::run_for_at_least<Clock>(std::chrono::duration_cast<IDuration>(run_time), 1, fun);
                 int new_iters = static_cast<int>(std::ceil(min_time * test.iterations / test.elapsed));
-                return { new_iters, test.elapsed / test.iterations * new_iters * cfg.benchmarkSamples(), fun, std::chrono::duration_cast<FloatDuration<Clock>>(cfg.benchmarkWarmupTime()), Detail::warmup_iterations };
+                return { new_iters, test.elapsed / test.iterations * new_iters * cfg.benchmarkSamples(), fun, std::chrono::duration_cast<FDuration>(cfg.benchmarkWarmupTime()), Detail::warmup_iterations };
             }
 
             template <typename Clock = default_clock>
             void run() {
+                static_assert( Clock::is_steady,
+                               "Benchmarking clock should be steady" );
                 auto const* cfg = getCurrentContext().getConfig();
 
                 auto env = Detail::measure_environment<Clock>();
@@ -81,8 +83,8 @@ namespace Catch {
                         return plan.template run<Clock>(*cfg, env);
                     });
 
-                    auto analysis = Detail::analyse(*cfg, env, samples.begin(), samples.end());
-                    BenchmarkStats<FloatDuration<Clock>> stats{ CATCH_MOVE(info), CATCH_MOVE(analysis.samples), analysis.mean, analysis.standard_deviation, analysis.outliers, analysis.outlier_variance };
+                    auto analysis = Detail::analyse(*cfg, samples.data(), samples.data() + samples.size());
+                    BenchmarkStats<> stats{ CATCH_MOVE(info), CATCH_MOVE(analysis.samples), analysis.mean, analysis.standard_deviation, analysis.outliers, analysis.outlier_variance };
                     getResultCapture().benchmarkEnded(stats);
                 } CATCH_CATCH_ANON (TestFailureException const&) {
                     getResultCapture().benchmarkFailed("Benchmark failed due to failed assertion"_sr);

src/catch2/benchmark/catch_chronometer.hpp

@@ -32,7 +32,10 @@ namespace Catch {
                 void start() override { started = Clock::now(); }
                 void finish() override { finished = Clock::now(); }
 
-                ClockDuration<Clock> elapsed() const { return finished - started; }
+                IDuration elapsed() const {
+                    return std::chrono::duration_cast<std::chrono::nanoseconds>(
+                        finished - started );
+                }
 
                 TimePoint<Clock> started;
                 TimePoint<Clock> finished;

src/catch2/benchmark/catch_clock.hpp

@@ -11,28 +11,16 @@
 #define CATCH_CLOCK_HPP_INCLUDED
 
 #include <chrono>
-#include <ratio>
 
 namespace Catch {
     namespace Benchmark {
-        template <typename Clock>
-        using ClockDuration = typename Clock::duration;
-        template <typename Clock>
-        using FloatDuration = std::chrono::duration<double, typename Clock::period>;
+        using IDuration = std::chrono::nanoseconds;
+        using FDuration = std::chrono::duration<double, std::nano>;
 
         template <typename Clock>
         using TimePoint = typename Clock::time_point;
 
         using default_clock = std::chrono::steady_clock;
-
-        template <typename Clock>
-        struct now {
-            TimePoint<Clock> operator()() const {
-                return Clock::now();
-            }
-        };
-
-        using fp_seconds = std::chrono::duration<double, std::ratio<1>>;
     } // namespace Benchmark
 } // namespace Catch
 

src/catch2/benchmark/catch_environment.hpp

@@ -15,20 +15,13 @@
 
 namespace Catch {
     namespace Benchmark {
-        template <typename Duration>
         struct EnvironmentEstimate {
-            Duration mean;
+            FDuration mean;
             OutlierClassification outliers;
-
-            template <typename Duration2>
-            operator EnvironmentEstimate<Duration2>() const {
-                return { mean, outliers };
-            }
         };
-        template <typename Clock>
         struct Environment {
-            EnvironmentEstimate<FloatDuration<Clock>> clock_resolution;
-            EnvironmentEstimate<FloatDuration<Clock>> clock_cost;
+            EnvironmentEstimate clock_resolution;
+            EnvironmentEstimate clock_cost;
         };
     } // namespace Benchmark
 } // namespace Catch

src/catch2/benchmark/catch_estimate.hpp

@@ -12,17 +12,12 @@
 
 namespace Catch {
     namespace Benchmark {
-        template <typename Duration>
+        template <typename Type>
         struct Estimate {
-            Duration point;
-            Duration lower_bound;
-            Duration upper_bound;
+            Type point;
+            Type lower_bound;
+            Type upper_bound;
             double confidence_interval;
-
-            template <typename Duration2>
-            operator Estimate<Duration2>() const {
-                return { point, lower_bound, upper_bound, confidence_interval };
-            }
         };
     } // namespace Benchmark
 } // namespace Catch

src/catch2/benchmark/catch_execution_plan.hpp

@@ -21,33 +21,31 @@
 
 namespace Catch {
     namespace Benchmark {
-        template <typename Duration>
         struct ExecutionPlan {
             int iterations_per_sample;
-            Duration estimated_duration;
+            FDuration estimated_duration;
             Detail::BenchmarkFunction benchmark;
-            Duration warmup_time;
+            FDuration warmup_time;
             int warmup_iterations;
 
-            template <typename Duration2>
-            operator ExecutionPlan<Duration2>() const {
-                return { iterations_per_sample, estimated_duration, benchmark, warmup_time, warmup_iterations };
-            }
-
             template <typename Clock>
-            std::vector<FloatDuration<Clock>> run(const IConfig &cfg, Environment<FloatDuration<Clock>> env) const {
+            std::vector<FDuration> run(const IConfig &cfg, Environment env) const {
                 // warmup a bit
-                Detail::run_for_at_least<Clock>(std::chrono::duration_cast<ClockDuration<Clock>>(warmup_time), warmup_iterations, Detail::repeat(now<Clock>{}));
+                Detail::run_for_at_least<Clock>(
+                    std::chrono::duration_cast<IDuration>( warmup_time ),
+                    warmup_iterations,
+                    Detail::repeat( []() { return Clock::now(); } )
+                );
 
-                std::vector<FloatDuration<Clock>> times;
+                std::vector<FDuration> times;
                 const auto num_samples = cfg.benchmarkSamples();
                 times.reserve( num_samples );
                 for ( size_t i = 0; i < num_samples; ++i ) {
                     Detail::ChronometerModel<Clock> model;
                     this->benchmark( Chronometer( model, iterations_per_sample ) );
                     auto sample_time = model.elapsed() - env.clock_cost.mean;
-                    if ( sample_time < FloatDuration<Clock>::zero() ) {
-                        sample_time = FloatDuration<Clock>::zero();
+                    if ( sample_time < FDuration::zero() ) {
+                        sample_time = FDuration::zero();
                     }
                     times.push_back(sample_time / iterations_per_sample);
                 }

src/catch2/benchmark/catch_sample_analysis.hpp

@@ -12,35 +12,18 @@
 
 #include <catch2/benchmark/catch_estimate.hpp>
 #include <catch2/benchmark/catch_outlier_classification.hpp>
-#include <catch2/internal/catch_move_and_forward.hpp>
+#include <catch2/benchmark/catch_clock.hpp>
 
 #include <vector>
 
 namespace Catch {
     namespace Benchmark {
-        template <typename Duration>
         struct SampleAnalysis {
-            std::vector<Duration> samples;
-            Estimate<Duration> mean;
-            Estimate<Duration> standard_deviation;
+            std::vector<FDuration> samples;
+            Estimate<FDuration> mean;
+            Estimate<FDuration> standard_deviation;
             OutlierClassification outliers;
             double outlier_variance;
-
-            template <typename Duration2>
-            operator SampleAnalysis<Duration2>() const {
-                std::vector<Duration2> samples2;
-                samples2.reserve(samples.size());
-                for (auto const& d : samples) {
-                    samples2.push_back(Duration2(d));
-                }
-                return {
-                    CATCH_MOVE(samples2),
-                    mean,
-                    standard_deviation,
-                    outliers,
-                    outlier_variance,
-                };
-            }
         };
     } // namespace Benchmark
 } // namespace Catch

src/catch2/benchmark/detail/catch_analyse.cpp

@@ -0,0 +1,85 @@
+
+//              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.
+
+#include <catch2/benchmark/detail/catch_analyse.hpp>
+#include <catch2/benchmark/catch_clock.hpp>
+#include <catch2/benchmark/catch_sample_analysis.hpp>
+#include <catch2/benchmark/detail/catch_stats.hpp>
+#include <catch2/interfaces/catch_interfaces_config.hpp>
+#include <catch2/internal/catch_move_and_forward.hpp>
+
+#include <vector>
+
+namespace Catch {
+    namespace Benchmark {
+        namespace Detail {
+            SampleAnalysis analyse(const IConfig &cfg, FDuration* first, FDuration* last) {
+                if (!cfg.benchmarkNoAnalysis()) {
+                    std::vector<double> samples;
+                    samples.reserve(static_cast<size_t>(last - first));
+                    for (auto current = first; current != last; ++current) {
+                        samples.push_back( current->count() );
+                    }
+
+                    auto analysis = Catch::Benchmark::Detail::analyse_samples(
+                        cfg.benchmarkConfidenceInterval(),
+                        cfg.benchmarkResamples(),
+                        samples.data(),
+                        samples.data() + samples.size() );
+                    auto outliers = Catch::Benchmark::Detail::classify_outliers(
+                        samples.data(), samples.data() + samples.size() );
+
+                    auto wrap_estimate = [](Estimate<double> e) {
+                        return Estimate<FDuration> {
+                            FDuration(e.point),
+                                FDuration(e.lower_bound),
+                                FDuration(e.upper_bound),
+                                e.confidence_interval,
+                        };
+                    };
+                    std::vector<FDuration> samples2;
+                    samples2.reserve(samples.size());
+                    for (auto s : samples) {
+                        samples2.push_back( FDuration( s ) );
+                    }
+
+                    return {
+                        CATCH_MOVE(samples2),
+                        wrap_estimate(analysis.mean),
+                        wrap_estimate(analysis.standard_deviation),
+                        outliers,
+                        analysis.outlier_variance,
+                    };
+                } else {
+                    std::vector<FDuration> samples;
+                    samples.reserve(static_cast<size_t>(last - first));
+
+                    FDuration mean = FDuration(0);
+                    int i = 0;
+                    for (auto it = first; it < last; ++it, ++i) {
+                        samples.push_back(FDuration(*it));
+                        mean += FDuration(*it);
+                    }
+                    mean /= i;
+
+                    return SampleAnalysis{
+                        CATCH_MOVE(samples),
+                        Estimate<FDuration>{ mean, mean, mean, 0.0 },
+                        Estimate<FDuration>{ FDuration( 0 ),
+                                             FDuration( 0 ),
+                                             FDuration( 0 ),
+                                             0.0 },
+                        OutlierClassification{},
+                        0.0
+                    };
+                }
+            }
+        } // namespace Detail
+    } // namespace Benchmark
+} // namespace Catch

src/catch2/benchmark/detail/catch_analyse.hpp

@@ -10,76 +10,16 @@
 #ifndef CATCH_ANALYSE_HPP_INCLUDED
 #define CATCH_ANALYSE_HPP_INCLUDED
 
-#include <catch2/benchmark/catch_environment.hpp>
+#include <catch2/benchmark/catch_clock.hpp>
 #include <catch2/benchmark/catch_sample_analysis.hpp>
-#include <catch2/benchmark/detail/catch_stats.hpp>
-#include <catch2/interfaces/catch_interfaces_config.hpp>
-#include <catch2/internal/catch_move_and_forward.hpp>
 
-#include <vector>
 
 namespace Catch {
+    class IConfig;
+
     namespace Benchmark {
         namespace Detail {
-            template <typename Duration, typename Iterator>
-            SampleAnalysis<Duration> analyse(const IConfig &cfg, Environment<Duration>, Iterator first, Iterator last) {
-                if (!cfg.benchmarkNoAnalysis()) {
-                    std::vector<double> samples;
-                    samples.reserve(static_cast<size_t>(last - first));
-                    for (auto current = first; current != last; ++current) {
-                        samples.push_back( current->count() );
-                    }
-
-                    auto analysis = Catch::Benchmark::Detail::analyse_samples(
-                        cfg.benchmarkConfidenceInterval(),
-                        cfg.benchmarkResamples(),
-                        samples.data(),
-                        samples.data() + samples.size() );
-                    auto outliers = Catch::Benchmark::Detail::classify_outliers(
-                        samples.data(), samples.data() + samples.size() );
-
-                    auto wrap_estimate = [](Estimate<double> e) {
-                        return Estimate<Duration> {
-                            Duration(e.point),
-                                Duration(e.lower_bound),
-                                Duration(e.upper_bound),
-                                e.confidence_interval,
-                        };
-                    };
-                    std::vector<Duration> samples2;
-                    samples2.reserve(samples.size());
-                    for (auto s : samples) {
-                        samples2.push_back( Duration( s ) );
-                    }
-
-                    return {
-                        CATCH_MOVE(samples2),
-                        wrap_estimate(analysis.mean),
-                        wrap_estimate(analysis.standard_deviation),
-                        outliers,
-                        analysis.outlier_variance,
-                    };
-                } else {
-                    std::vector<Duration> samples;
-                    samples.reserve(static_cast<size_t>(last - first));
-
-                    Duration mean = Duration(0);
-                    int i = 0;
-                    for (auto it = first; it < last; ++it, ++i) {
-                        samples.push_back(Duration(*it));
-                        mean += Duration(*it);
-                    }
-                    mean /= i;
-
-                    return {
-                        CATCH_MOVE(samples),
-                        Estimate<Duration>{mean, mean, mean, 0.0},
-                        Estimate<Duration>{Duration(0), Duration(0), Duration(0), 0.0},
-                        OutlierClassification{},
-                        0.0
-                    };
-                }
-            }
+            SampleAnalysis analyse(const IConfig &cfg, FDuration* first, FDuration* last);
         } // namespace Detail
     } // namespace Benchmark
 } // namespace Catch