TrkVertexSeedFinderUtils/GaussianTrackDensity try to tidy a bit and use STLPool allocators

TrkVertexSeedFinderUtils/GaussianTrackDensity try to tidy a bit and use STLPool allocators

Tracking/TrkVertexFitter/TrkVertexSeedFinderUtils/TrkVertexSeedFinderUtils/GaussianTrackDensity.h

 /*
-  Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2023 CERN for the benefit of the ATLAS collaboration
 */
 
 #ifndef TRKVERTEXSEEDFINDERUTILIS_GAUSSIANTRACKDENSITY_H
@@ -10,6 +10,7 @@
 
 #include <map>
 
+#include "AthAllocators/ArenaPoolSTLAllocator.h"
 namespace Trk
 {
 
@@ -22,11 +23,9 @@ namespace Trk
    Implementation of IVertexTrackDensityEstimator modeling reconstructed tracks as
    two-dimensional Gaussian distributions in (d0, z0) space and sampling
    the aggregate density distribution at user-requested points along the beam axis.
-
    @author Dave Casper <dcasper@uci.edu>
 
-   ------------------------------------
-   Changes:
+   @author Christos Anastopoulos (Athena MT)
   */
 
   class GaussianTrackDensity final: public extends<AthAlgTool, IVertexTrackDensityEstimator>
@@ -35,7 +34,6 @@ namespace Trk
     /// Inherit constructor.
     using base_class::base_class;
 
-
     /**
      * @brief Find position of global maximum for density function.
      * @param vectorTrk List of input tracks.
@@ -43,7 +41,6 @@ namespace Trk
     virtual double
     globalMaximum (const std::vector<const Track*>& vectorTrk) const override final;
 
-
     /**
      * @brief Find position of global maximum for density function.
      * @param vectorTrk List of input tracks.
@@ -53,7 +50,6 @@ namespace Trk
     globalMaximum (const std::vector<const Track*>& vectorTrk,
                    std::unique_ptr<ITrackDensity>& density) const override final;
 
-
     /**
      * @brief Find position of global maximum for density function.
      * @param perigeeList List of input tracks.
@@ -61,7 +57,6 @@ namespace Trk
     virtual double
     globalMaximum (const std::vector<const TrackParameters*>& perigeeList) const override final;
 
-
     /**
      * @brief Find position of global maximum for density function.
      * @param perigeeList List of input tracks.
@@ -71,74 +66,33 @@ namespace Trk
     globalMaximum (const std::vector<const TrackParameters*>& perigeeList,
                    std::unique_ptr<ITrackDensity>& density) const override final;
 
-    virtual
-    std::pair<double,double> globalMaximumWithWidth (const std::vector<const TrackParameters*>& perigeeList/*,
-                                                  std::unique_ptr<ITrackDensity>& density*/) const override final;
-
-
-  private:
-    class TrackDensity;
-
-
-    /**
-     * @brief Find position of global maximum for density function.
-     * @param pergigeeList List of input tracks.
-     * @param density Helper density object.
-     */
-    double
-    globalMaximumImpl (const std::vector<const TrackParameters*>& perigeeList,
-                       TrackDensity& density) const;
-
-    /**
-     * @brief Find position of global maximum with Gaussian width for density function.
-     * @param pergigeeList List of input tracks.
-     * @param density Helper density object.
-     */
-    std::pair<double,double>
-    globalMaximumWithWidthImpl (const std::vector<const TrackParameters*>& perigeeList,
-                       TrackDensity& density) const;
-
-
-    /**
-     * @brief Add a set of tracks to a density object.
-     * @param perigeeList Set of track parameters to add.
-     * @param density Density object to which to add.
-     */
-    void addTracks(const std::vector<const TrackParameters*>& perigeeList,
-                   TrackDensity& density) const;
-
-
-    // functor to compare two Perigee values
-    struct pred_perigee {
-      bool operator()(const Perigee& left, const Perigee& right) const
-      {
-        return left.parameters()[Trk::z0] < right.parameters()[Trk::z0];
-      }
-    };
-
-    struct TrackEntry
-    {
-      TrackEntry() { c_0 = 0; c_1 = 0; c_2 = 0; lowerBound = 0; upperBound = 0; }
-      TrackEntry(double c0, double c1, double c2, double zMin, double zMax);
-      TrackEntry(double zProbe);
+    virtual std::pair<double, double> globalMaximumWithWidth(
+        const std::vector<const TrackParameters*>& perigeeList)
+        const override final;
+
+   private:
+    struct TrackEntry {
+      TrackEntry() = default;
+      TrackEntry(const TrackEntry&) = default;
+      TrackEntry(TrackEntry&&) = default;
+      TrackEntry& operator=(const TrackEntry&) = default;
+      TrackEntry& operator=(TrackEntry&&) = default;
+      ~TrackEntry() = default;
+
+      TrackEntry(double c0, double c1, double c2, double zMin, double zMax)
+          : c_0(c0), c_1(c1), c_2(c2), lowerBound(zMin), upperBound(zMax) {}
+      explicit TrackEntry(double z)
+          : c_0(0), c_1(0), c_2(0), lowerBound(z), upperBound(z) {}
       // Cached information for a single track
-      double c_0;      // z-independent term in exponent
-      double c_1;      // linear coefficient in exponent
-      double c_2;      // quadratic coefficient in exponent
-      double lowerBound;
-      double upperBound;
-    };
-
-    // functor to compare two TrackEntry values based on their upper limits (low to high)
-    struct pred_entry_by_max {
-      bool operator()(const TrackEntry& left, const TrackEntry& right) const
-      {
-        return left.upperBound < right.upperBound;
-      }
+      double c_0 = 0;  // z-independent term in exponent
+      double c_1 = 1;  // linear coefficient in exponent
+      double c_2 = 0;  // quadratic coefficient in exponent
+      double lowerBound = 0;
+      double upperBound = 0;
     };
 
     // helper to handle the evaluation of the parametrised track density 
-    class TrackDensityEval{
+    struct TrackDensityEval{
       public:
         // initialise with the z coordinate at which the density is to be evaluated 
         TrackDensityEval(double z_coordinate): m_z(z_coordinate){} 
@@ -155,104 +109,121 @@ namespace Trk
         double m_density{0};
         double m_firstDerivative{0};
         double m_secondDerivative{0}; 
-    }; 
-
-    typedef std::map< Perigee, 
-                      GaussianTrackDensity::TrackEntry, 
-                      GaussianTrackDensity::pred_perigee > trackMap;
-
-    typedef std::map< Perigee, 
-                      GaussianTrackDensity::TrackEntry, 
-                      GaussianTrackDensity::pred_perigee >::const_iterator trackMapIterator;
-
-    typedef std::map< GaussianTrackDensity::TrackEntry,
-                      Perigee,
-                      GaussianTrackDensity::pred_entry_by_max > lowerMap;
-
-    typedef std::map< GaussianTrackDensity::TrackEntry,
-                      Perigee,
-                      GaussianTrackDensity::pred_entry_by_max >::const_iterator lowerMapIterator;
-
-
-    class TrackDensity final: public ITrackDensity
-    {
-    public:
-      TrackDensity (bool gaussStep) : m_gaussStep (gaussStep) {}
-      virtual ~TrackDensity() = default;
-
-
-      /**
-       *  Evaluate the density function at the specified coordinate
-       *  along the beamline.
-       */
-      virtual double trackDensity (double z) const override final;
-
-
-      /**
-       *  Evaluate the density and its first two derivatives
-       *  at the specified coordinate.
-       */
-      virtual void trackDensity (double z,
-                                 double& density,
-                                 double& firstDerivative,
-                                 double& secondDerivative) const override final;
-
-
-      /**
-       * @brief Return position of global maximum for density function.
-       * @param msg Message stream.
-       */
-      double globalMaximum (MsgStream& msg) const;
-
-      /**
-       * @brief Return position of global maximum with Gaussian width for density function.
-       * @param msg Message stream.
-       */
-      std::pair<double,double> globalMaximumWithWidth (MsgStream& msg) const;
-
-
-      /**
-       * @brief Add a track to the set being considered.
-       * @param itrk Track parameters.
-       * @param d0SignificanceCut Significance cut on d0.
-       * @param z0SignificanceCut Significance cut on z0.
-       */
-      void addTrack (const Perigee& itrk,
-                     const double d0SignificanceCut,
-                     const double z0SignificanceCut);
-
-
-
+    };
 
-    private:
-      inline void updateMaximum(double trialZ,
-                                double trialValue,
-                                double secondDerivative,
-                                double& maxZ,
-                                double& maxValue,
-                                double& maxSecondDerivative) const
-      {
+    class TrackDensity final : public ITrackDensity {
+       public:
+        explicit TrackDensity(bool gaussStep) : m_gaussStep(gaussStep) {}
+        virtual ~TrackDensity() = default;
+
+        /**
+         *  Evaluate the density function at the specified coordinate
+         *  along the beamline.
+         */
+        virtual double trackDensity(double z) const override final;
+
+        /**
+         *  Evaluate the density and its first two derivatives
+         *  at the specified coordinate.
+         */
+        virtual void trackDensity(
+            double z, double& density, double& firstDerivative,
+            double& secondDerivative) const override final;
+        /**
+         * @brief Return position of global maximum for density function.
+         */
+        double globalMaximum() const;
+        /**
+         * @brief Return position of global maximum with Gaussian width for
+         * density function.
+         */
+        std::pair<double, double> globalMaximumWithWidth() const;
+        /**
+         * @brief Add a track to the set being considered.
+         * @param itrk Track parameters.
+         * @param d0SignificanceCut Significance cut on d0.
+         * @param z0SignificanceCut Significance cut on z0.
+         */
+        void addTrack(const Perigee& itrk, const double d0SignificanceCut,
+                      const double z0SignificanceCut);
+
+       private:
+        inline void updateMaximum(double trialZ, double trialValue,
+                                  double secondDerivative, double& maxZ,
+                                  double& maxValue,
+                                  double& maxSecondDerivative) const {
         if (trialValue > maxValue) {
           maxZ = trialZ;
           maxValue = trialValue;
           maxSecondDerivative = secondDerivative;
         }
-      }
+        }
 
-      inline double stepSize(double y, double dy, double ddy) const
-      {
+        inline double stepSize(double y, double dy, double ddy) const {
         return (m_gaussStep ? (y * dy) / (dy * dy - y * ddy) : -dy / ddy);
-      }
+        }
+        bool m_gaussStep;
+        double m_maxRange = 0;
+        //  Cache for track information
+        // functor to compare two Perigee values
+        struct pred_perigee {
+        inline bool operator()(const Perigee& left,
+                               const Perigee& right) const {
+          return left.parameters()[Trk::z0] < right.parameters()[Trk::z0];
+        }
+        };
+        // functor to compare two TrackEntry values based on their upper limits (low
+        // to high)
+        struct pred_entry_by_max {
+        inline bool operator()(const TrackEntry& left,
+                               const TrackEntry& right) const {
+          return left.upperBound < right.upperBound;
+        }
+        };
 
-      bool m_gaussStep;
+        using trackMap =
+            std::map<Perigee, GaussianTrackDensity::TrackEntry, pred_perigee,
+                     SG::ArenaPoolSTLAllocator<std::pair<
+                         const Perigee, GaussianTrackDensity::TrackEntry>>>;
 
-      //  Cache for track information
-      trackMap m_trackMap;
-      lowerMap m_lowerMap;
+        using lowerMap = std::map<
+            GaussianTrackDensity::TrackEntry, Perigee, pred_entry_by_max,
+            SG::ArenaPoolSTLAllocator<
+                std::pair<const GaussianTrackDensity::TrackEntry, Perigee>>>;
 
-      double m_maxRange = 0;
+        trackMap m_trackMap;
+        lowerMap m_lowerMap;
     };
 
+    /**
+     * @brief Find position of global maximum for density function.
+     * @param pergigeeList List of input tracks.
+     * @param density Helper density object.
+     */
+    double
+    globalMaximumImpl (const std::vector<const TrackParameters*>& perigeeList,
+                       TrackDensity& density) const;
+
+    /**
+     * @brief Find position of global maximum with Gaussian width for density function.
+     * @param pergigeeList List of input tracks.
+     * @param density Helper density object.
+     */
+    std::pair<double,double>
+    globalMaximumWithWidthImpl (const std::vector<const TrackParameters*>& perigeeList,
+                       TrackDensity& density) const;
+
+
+    /**
+     * @brief Add a set of tracks to a density object.
+     * @param perigeeList Set of track parameters to add.
+     * @param density Density object to which to add.
+     */
+    void addTracks(const std::vector<const TrackParameters*>& perigeeList,
+                   TrackDensity& density) const;
+
+
+ 
     //  Cuts set by configurable properties
     
     //  Maximum allowed d0 significance to use (in sigma)