From 8ac393623c214c8424912ef60374ed14a5ee07e4 Mon Sep 17 00:00:00 2001
From: Siarhei Fedartsou <siarhei.fedartsou@gmail.com>
Date: Sun, 12 May 2024 12:05:08 +0200
Subject: [PATCH] Optimise R-tree queries in the case if there is no need to
 limit maximum number of results

---
 include/util/coordinate_calculation.hpp |  7 +++++++
 include/util/rectangle.hpp              | 16 ++++------------
 include/util/static_rtree.hpp           | 18 +++---------------
 3 files changed, 14 insertions(+), 27 deletions(-)

diff --git a/include/util/coordinate_calculation.hpp b/include/util/coordinate_calculation.hpp
index 3ab8db076..6a716ffaf 100644
--- a/include/util/coordinate_calculation.hpp
+++ b/include/util/coordinate_calculation.hpp
@@ -36,6 +36,13 @@ inline double radToDeg(const double radian)
 }
 } // namespace detail
 
+const constexpr static double METERS_PER_DEGREE_LAT = 110567.0;
+
+inline double metersPerLngDegree(const FixedLatitude lat)
+{
+    return std::cos(detail::degToRad(static_cast<double>(toFloating(lat)))) * METERS_PER_DEGREE_LAT;
+}
+
 //! Takes the squared euclidean distance of the input coordinates. Does not return meters!
 std::uint64_t squaredEuclideanDistance(const Coordinate lhs, const Coordinate rhs);
 
diff --git a/include/util/rectangle.hpp b/include/util/rectangle.hpp
index ff4c2c6bc..2d4a45fc8 100644
--- a/include/util/rectangle.hpp
+++ b/include/util/rectangle.hpp
@@ -4,8 +4,8 @@
 #include "coordinate.hpp"
 #include "util/coordinate.hpp"
 #include "util/coordinate_calculation.hpp"
-
 #include <boost/assert.hpp>
+#include <boost/math/constants/constants.hpp>
 
 #include <limits>
 #include <utility>
@@ -170,19 +170,11 @@ struct RectangleInt2D
                max_lat != FixedLatitude{std::numeric_limits<std::int32_t>::min()};
     }
 
-    static double MetersPerLngDegree(const FixedLatitude lat)
-    {
-        constexpr static double kMetersPerDegreeLat = 110567.0f;
-
-        constexpr float kRadPerDeg = (3.14 /* TODO */ / 180.0f);
-
-        return std::cos(kRadPerDeg * static_cast<double>(toFloating(lat))) * kMetersPerDegreeLat;
-    }
     static RectangleInt2D ExpandMeters(const Coordinate &coordinate, const double meters)
     {
-        constexpr static double kMetersPerDegreeLat = 110567.0f;
-        const double lat_offset = meters / kMetersPerDegreeLat;
-        const double lon_offset = meters / MetersPerLngDegree(coordinate.lat);
+        const double lat_offset = meters / coordinate_calculation::METERS_PER_DEGREE_LAT;
+        const double lon_offset =
+            meters / coordinate_calculation::metersPerLngDegree(coordinate.lat);
 
         return RectangleInt2D{coordinate.lon - toFixed(FloatLongitude{lon_offset}),
                               coordinate.lon + toFixed(FloatLongitude{lon_offset}),
diff --git a/include/util/static_rtree.hpp b/include/util/static_rtree.hpp
index 0b562afe1..fb5c0a353 100644
--- a/include/util/static_rtree.hpp
+++ b/include/util/static_rtree.hpp
@@ -565,21 +565,9 @@ class StaticRTree
             { return num_results >= max_results; });
     }
 
-    inline double GetSegmentDistance(const Coordinate input_coordinate,
-                                     const CandidateSegment &segment) const
-    {
-        BOOST_ASSERT(segment.data.forward_segment_id.id != SPECIAL_SEGMENTID ||
-                     !segment.data.forward_segment_id.enabled);
-        BOOST_ASSERT(segment.data.reverse_segment_id.id != SPECIAL_SEGMENTID ||
-                     !segment.data.reverse_segment_id.enabled);
-
-        Coordinate wsg84_coordinate =
-            util::web_mercator::toWGS84(segment.fixed_projected_coordinate);
-
-        return util::coordinate_calculation::greatCircleDistance(input_coordinate,
-                                                                 wsg84_coordinate);
-    }
-
+    // NB 1: results are not guaranteed to be sorted by distance
+    // NB 2: maxDistanceMeters is not a hard limit, it's just a way to reduce the number of edges
+    // returned
     template <typename FilterT>
     std::vector<CandidateSegment> SearchInRange(const Coordinate input_coordinate,
                                                 double maxDistanceMeters,