Link TBB task_scheduler lifetime with Engine scope

include/engine/engine.hpp

@@ -24,6 +24,8 @@
 #include "util/fingerprint.hpp"
 #include "util/json_container.hpp"
 
+#include <tbb/task_scheduler_init.h>
+
 #include <memory>
 #include <string>
 
@@ -53,7 +55,8 @@ template <typename Algorithm> class Engine final : public EngineInterface
 {
   public:
     explicit Engine(const EngineConfig &config)
-        : route_plugin(config.max_locations_viaroute, config.max_alternatives), //
+        : task_scheduler(config.use_threads_number),
+          route_plugin(config.max_locations_viaroute, config.max_alternatives), //
           table_plugin(config.max_locations_distance_table),                    //
           nearest_plugin(config.max_results_nearest),                           //
           trip_plugin(config.max_locations_trip),                               //
@@ -125,6 +128,7 @@ template <typename Algorithm> class Engine final : public EngineInterface
     }
     std::unique_ptr<DataFacadeProvider<Algorithm>> facade_provider;
     mutable SearchEngineData<Algorithm> heaps;
+    tbb::task_scheduler_init task_scheduler;
 
     const plugins::ViaRoutePlugin route_plugin;
     const plugins::TablePlugin table_plugin;

include/engine/engine_config.hpp

@@ -90,6 +90,8 @@ struct EngineConfig final
     int max_alternatives = 3; // set an arbitrary upper bound; can be adjusted by user
     bool use_shared_memory = true;
     Algorithm algorithm = Algorithm::CH;
+    int use_threads_number = 1;
+    std::string verbosity;
 };
 }
 }