Hardcode search radius parameters

include/engine/api/match_parameters.hpp

@@ -28,13 +28,6 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #ifndef ENGINE_API_MATCH_PARAMETERS_HPP
 #define ENGINE_API_MATCH_PARAMETERS_HPP
 
-#define SEARCH_RADIUS_BASE_DEFAULT 45
-#define SEARCH_RADIUS_BASE_LIMIT 100
-#define SEARCH_RADIUS_MULTIPLIER_DEFAULT 3.5
-#define SEARCH_RADIUS_MULTIPLIER_LIMIT 10
-#define SEARCH_RADIUS_MAX_DEFAULT 200
-#define SEARCH_RADIUS_MAX_LIMIT 500
-
 #include "engine/api/route_parameters.hpp"
 
 #include <vector>
@@ -74,20 +67,10 @@ struct MatchParameters : public RouteParameters
     }
 
     std::vector<unsigned> timestamps;
-
-    double search_radius_base = SEARCH_RADIUS_BASE_DEFAULT;
-    double search_radius_multiplier = SEARCH_RADIUS_MULTIPLIER_DEFAULT;
-    double search_radius_max = SEARCH_RADIUS_MAX_DEFAULT;
-
     bool IsValid() const
     {
         return RouteParameters::IsValid() &&
-               (timestamps.empty() || timestamps.size() == coordinates.size()) &&
+               (timestamps.empty() || timestamps.size() == coordinates.size());
-               search_radius_base >= 0 && search_radius_multiplier >= 0 && search_radius_max > 0 &&
-               // limit the search_radius parameters to sane values to prevent overloading the server
-               search_radius_base <= SEARCH_RADIUS_BASE_LIMIT &&
-               search_radius_multiplier <= SEARCH_RADIUS_MULTIPLIER_LIMIT &&
-               search_radius_max <= SEARCH_RADIUS_MAX_LIMIT;
     }
 };
 }

include/server/api/match_parameter_grammar.hpp

@@ -33,33 +33,13 @@ struct MatchParametersGrammar final : public RouteParametersGrammar<Iterator, Si
             (qi::uint_ %
              ';')[ph::bind(&engine::api::MatchParameters::timestamps, qi::_r1) = qi::_1];
 
-        search_radius_base_rule =
-            qi::lit("search_radius_base=") > qi::double_[
-                ph::bind(&engine::api::MatchParameters::search_radius_base, qi::_r1) = qi::_1];
-
-        search_radius_multiplier_rule =
-            qi::lit("search_radius_multiplier=") > qi::double_[
-                ph::bind(&engine::api::MatchParameters::search_radius_multiplier, qi::_r1) = qi::_1];
-
-        search_radius_max_rule =
-            qi::lit("search_radius_max=") > qi::double_[
-                ph::bind(&engine::api::MatchParameters::search_radius_max, qi::_r1) = qi::_1];
-
         root_rule = BaseGrammar::query_rule(qi::_r1) > -qi::lit(".json") >
-                    -('?' > (timestamps_rule(qi::_r1) |
+                    -('?' > (timestamps_rule(qi::_r1) | BaseGrammar::base_rule(qi::_r1)) % '&');
-                             search_radius_base_rule(qi::_r1) |
-                             search_radius_multiplier_rule(qi::_r1) |
-                             search_radius_max_rule(qi::_r1) |
-                             BaseGrammar::base_rule(qi::_r1))
-                            % '&');
     }
 
   private:
     qi::rule<Iterator, Signature> root_rule;
     qi::rule<Iterator, Signature> timestamps_rule;
-    qi::rule<Iterator, Signature> search_radius_base_rule;
-    qi::rule<Iterator, Signature> search_radius_multiplier_rule;
-    qi::rule<Iterator, Signature> search_radius_max_rule;
 };
 }
 }

src/engine/plugins/match.cpp

@@ -19,6 +19,13 @@
 #include <string>
 #include <vector>
 
+static double search_radius_for_gps_radius(double gps_radius) {
+    // For a given GPS radius, determine the radius we need to search for candidate street segments
+    // to have a 99.9% chance of finding the correct segment.
+    // For more detail, see the analysis at https://github.com/Project-OSRM/osrm-backend/pull/3184
+    return std::min(gps_radius * 3.5  + 45, 200);
+}
+
 namespace osrm
 {
 namespace engine
@@ -153,11 +160,8 @@ Status MatchPlugin::HandleRequest(const std::shared_ptr<datafacade::BaseDataFaca
                        parameters.radiuses.end(),
                        search_radiuses.begin(),
                        [&](const boost::optional<double> &maybe_radius) {
-                           double in_radius = maybe_radius ? *maybe_radius : DEFAULT_GPS_PRECISION;
+                           double gps_radius = maybe_radius ? *maybe_radius : DEFAULT_GPS_PRECISION;
-
+                           return search_radius_for_gps_radius(gps_radius);
-                           return std::min(
-                               in_radius * parameters.search_radius_multiplier + parameters.search_radius_base,
-                               parameters.search_radius_max);
                        });
     }