Adds a limit for number of results returned in Nearest service, resolves #2872

include/engine/engine_config.hpp

@@ -51,6 +51,7 @@ namespace engine
  *  - Route
  *  - Table
  *  - Match
+ *  - Nearest
  *
  * In addition, shared memory can be used for datasets loaded with osrm-datastore.
  *
@@ -65,6 +66,7 @@ struct EngineConfig final
     int max_locations_viaroute = -1;
     int max_locations_distance_table = -1;
     int max_locations_map_matching = -1;
+    int max_results_nearest = -1;
     bool use_shared_memory = true;
 };
 }

include/engine/plugins/nearest.hpp

@@ -15,9 +15,12 @@ namespace plugins
 class NearestPlugin final : public BasePlugin
 {
   public:
-    explicit NearestPlugin(datafacade::BaseDataFacade &facade);
+    explicit NearestPlugin(datafacade::BaseDataFacade &facade, const int max_results);
 
     Status HandleRequest(const api::NearestParameters &params, util::json::Object &result);
+
+  private:
+    const int max_results;
 };
 }
 }