From 7ef81e86c113af7176f64937f16a70bf04cc2d7a Mon Sep 17 00:00:00 2001
From: Andreas Stefl <stefl.andreas@gmail.com>
Date: Sun, 21 Apr 2024 14:20:42 +0200
Subject: [PATCH] perf: Benchmark `StraightLineStepper` (#3134)

Adds a benchmark for the `StraightLineStepper` similar as the benchmarks for `EigenStepper` and `AtlasStepper`.
---
 Tests/Benchmarks/CMakeLists.txt               |   5 +-
 .../StraightLineStepperBenchmark.cpp          | 123 ++++++++++++++++++
 2 files changed, 126 insertions(+), 2 deletions(-)
 create mode 100644 Tests/Benchmarks/StraightLineStepperBenchmark.cpp

diff --git a/Tests/Benchmarks/CMakeLists.txt b/Tests/Benchmarks/CMakeLists.txt
index e452add9ed2..3bd4a69f07e 100644
--- a/Tests/Benchmarks/CMakeLists.txt
+++ b/Tests/Benchmarks/CMakeLists.txt
@@ -26,5 +26,6 @@ add_benchmark(BinUtility BinUtilityBenchmark.cpp)
 add_benchmark(EigenStepper EigenStepperBenchmark.cpp)
 add_benchmark(SolenoidField SolenoidFieldBenchmark.cpp)
 add_benchmark(SurfaceIntersection SurfaceIntersectionBenchmark.cpp)
-add_benchmark(RayFrustumBenchmark RayFrustumBenchmark.cpp)
-add_benchmark(AnnulusBoundsBenchmark AnnulusBoundsBenchmark.cpp)
+add_benchmark(RayFrustum RayFrustumBenchmark.cpp)
+add_benchmark(AnnulusBounds AnnulusBoundsBenchmark.cpp)
+add_benchmark(StraightLineStepper StraightLineStepperBenchmark.cpp)
diff --git a/Tests/Benchmarks/StraightLineStepperBenchmark.cpp b/Tests/Benchmarks/StraightLineStepperBenchmark.cpp
new file mode 100644
index 00000000000..5d2262c6068
--- /dev/null
+++ b/Tests/Benchmarks/StraightLineStepperBenchmark.cpp
@@ -0,0 +1,123 @@
+// This file is part of the Acts project.
+//
+// Copyright (C) 2017-2019 CERN for the benefit of the Acts project
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#include "Acts/Definitions/Units.hpp"
+#include "Acts/EventData/ParticleHypothesis.hpp"
+#include "Acts/EventData/TrackParameters.hpp"
+#include "Acts/Geometry/GeometryContext.hpp"
+#include "Acts/MagneticField/MagneticFieldContext.hpp"
+#include "Acts/Propagator/Propagator.hpp"
+#include "Acts/Propagator/StraightLineStepper.hpp"
+#include "Acts/Tests/CommonHelpers/BenchmarkTools.hpp"
+#include "Acts/Utilities/Logger.hpp"
+
+#include <iostream>
+
+#include <boost/program_options.hpp>
+
+namespace po = boost::program_options;
+using namespace Acts;
+using namespace Acts::UnitLiterals;
+
+int main(int argc, char* argv[]) {
+  unsigned int toys = 1;
+  double ptInGeV = 1;
+  double BzInT = 1;
+  double maxPathInM = 1;
+  unsigned int lvl = Acts::Logging::INFO;
+  bool withCov = true;
+
+  // Create a test context
+  GeometryContext tgContext = GeometryContext();
+  MagneticFieldContext mfContext = MagneticFieldContext();
+
+  try {
+    po::options_description desc("Allowed options");
+    // clang-format off
+  desc.add_options()
+      ("help", "produce help message")
+      ("toys",po::value<unsigned int>(&toys)->default_value(20000),"number of tracks to propagate")
+      ("pT",po::value<double>(&ptInGeV)->default_value(1),"transverse momentum in GeV")
+      ("path",po::value<double>(&maxPathInM)->default_value(5),"maximum path length in m")
+      ("cov",po::value<bool>(&withCov)->default_value(true),"propagation with covariance matrix")
+      ("verbose",po::value<unsigned int>(&lvl)->default_value(Acts::Logging::INFO),"logging level");
+    // clang-format on
+    po::variables_map vm;
+    po::store(po::parse_command_line(argc, argv, desc), vm);
+    po::notify(vm);
+
+    if (vm.count("help") != 0u) {
+      std::cout << desc << std::endl;
+      return 0;
+    }
+  } catch (std::exception& e) {
+    std::cerr << "error: " << e.what() << std::endl;
+    return 1;
+  }
+
+  ACTS_LOCAL_LOGGER(
+      getDefaultLogger("ATLAS_Stepper", Acts::Logging::Level(lvl)));
+
+  // print information about profiling setup
+  ACTS_INFO("propagating " << toys << " tracks with pT = " << ptInGeV
+                           << "GeV in a " << BzInT << "T B-field");
+
+  using Stepper = StraightLineStepper;
+  using Propagator = Propagator<Stepper>;
+  using Covariance = BoundSquareMatrix;
+
+  Stepper stepper;
+  Propagator propagator(stepper);
+
+  PropagatorOptions<> options(tgContext, mfContext);
+  options.pathLimit = maxPathInM * UnitConstants::m;
+
+  Vector4 pos4(0, 0, 0, 0);
+  Vector3 dir(1, 0, 0);
+  Covariance cov;
+  // clang-format off
+  cov << 10_mm, 0, 0, 0, 0, 0,
+         0, 10_mm, 0, 0, 0, 0,
+         0, 0, 1, 0, 0, 0,
+         0, 0, 0, 1, 0, 0,
+         0, 0, 0, 0, 1_e / 10_GeV, 0,
+         0, 0, 0, 0, 0, 0;
+  // clang-format on
+
+  std::optional<Covariance> covOpt = std::nullopt;
+  if (withCov) {
+    covOpt = cov;
+  }
+  CurvilinearTrackParameters pars(pos4, dir, +1 / ptInGeV, covOpt,
+                                  ParticleHypothesis::pion());
+
+  double totalPathLength = 0;
+  std::size_t numSteps = 0;
+  std::size_t numIters = 0;
+  const auto propagationBenchResult = Acts::Test::microBenchmark(
+      [&] {
+        auto r = propagator.propagate(pars, options).value();
+        if (totalPathLength == 0.) {
+          ACTS_DEBUG("reached position "
+                     << r.endParameters->position(tgContext).transpose()
+                     << " in " << r.steps << " steps");
+        }
+        totalPathLength += r.pathLength;
+        numSteps += r.steps;
+        ++numIters;
+        return r;
+      },
+      1, toys);
+
+  ACTS_INFO("Execution stats: " << propagationBenchResult);
+  ACTS_INFO("average path length = " << totalPathLength / numIters / 1_mm
+                                     << "mm");
+  ACTS_INFO("average number of steps = " << 1.0 * numSteps / numIters);
+
+  return 0;
+}