Sychronous mode bug resolution

LibCarla/source/carla/trafficmanager/BatchControlStage.cpp

@@ -65,28 +65,46 @@ void BatchControlStage::DataSender() {
   messenger->Pop();
   bool synch_mode = parameters.GetSynchronousMode();
 
-  if (commands != nullptr) {
-    // Run asynchronous mode commands.
-    episode_proxy_bcs.Lock()->ApplyBatch(*commands.get(), false);
-  }
-
-  // Limiting updates to 100 frames per second.
+  // Asynchronous mode.
   if (!synch_mode) {
+    // Apply batch command through an asynchronous RPC call.
+    if (commands != nullptr) {
+      episode_proxy_bcs.Lock()->ApplyBatch(*commands.get(), false);
+    }
+    // Limiting updates to 100 frames per second.
     std::this_thread::sleep_for(10ms);
-  } else {
+  }
+  // Synchronous mode.
+  else {
     std::unique_lock<std::mutex> lock(step_execution_mutex);
-    // Get timeout value in milliseconds.
-    double timeout = parameters.GetSynchronousModeTimeOutInMiliSecond();
-    // Wait for service to finish.
-    step_execution_notifier.wait_for(lock, timeout * 1ms, [this]() { return run_step.load(); });
+    // TODO: Re-introduce timeout while waiting for RunStep() call.
+    while (!run_step.load()) {
+      step_execution_notifier.wait_for(lock, 1ms, [this]() {return run_step.load();});
+    }
+    // Apply batch command in synchronous RPC call.
+    if (commands != nullptr) {
+      episode_proxy_bcs.Lock()->ApplyBatchSync(*commands.get(), false);
+    }
+    // Set flag to false, unblock RunStep() call and release mutex lock.
     run_step.store(false);
+    step_complete_notifier.notify_one();
+    lock.unlock();
   }
 }
 
 
 bool BatchControlStage::RunStep() {
-  // Set run set flag.
-  run_step.store(true);
+
+  bool synch_mode = parameters.GetSynchronousMode();
+  if (synch_mode) {
+    std::unique_lock<std::mutex> lock(step_execution_mutex);
+    // Set flag to true, notify DataSender and wait for a return notification
+    run_step.store(true);
+    step_execution_notifier.notify_one();
+    while (run_step.load()) {
+      step_complete_notifier.wait_for(lock, 1ms, [this]() {return !run_step.load();});
+    }
+  }
 
   return true;
 }

LibCarla/source/carla/trafficmanager/BatchControlStage.h

@@ -47,11 +47,12 @@ private:
   /// Parameter object for changing synchronous behaviour.
   Parameters &parameters;
   /// Step runner flag.
-  std::atomic<bool> run_step;
+  std::atomic<bool> run_step {false};
   /// Mutex for progressing synchronous execution.
   std::mutex step_execution_mutex;
   /// Condition variables for progressing synchronous execution.
   std::condition_variable step_execution_notifier;
+  std::condition_variable step_complete_notifier;
 
 public:
 

LibCarla/source/carla/trafficmanager/Parameters.cpp

@@ -13,9 +13,6 @@ namespace traffic_manager {
 
 Parameters::Parameters() {
 
-  /// Set default synchronous mode to false.
-  synchronous_mode.store(false);
-
   /// Set default synchronous mode time out.
   synchronous_time_out = std::chrono::duration<int, std::milli>(10);
 }

LibCarla/source/carla/trafficmanager/Parameters.h

@@ -57,7 +57,7 @@ namespace traffic_manager {
     /// Map containing % of keep right rule.
     AtomicMap<ActorId, float> perc_keep_right;
     /// Synchronous mode switch.
-    std::atomic<bool> synchronous_mode;
+    std::atomic<bool> synchronous_mode {false};
     /// Distance Margin
     std::atomic<float> distance_margin {2.0};
 

PythonAPI/carla/source/libcarla/TrafficManager.cpp

@@ -29,5 +29,6 @@ void export_trafficmanager() {
       .def("ignore_lights_percentage", &carla::traffic_manager::TrafficManager::SetPercentageRunningLight)
       .def("ignore_signs_percentage", &carla::traffic_manager::TrafficManager::SetPercentageRunningSign)
       .def("set_global_distance_to_leading_vehicle", &carla::traffic_manager::TrafficManager::SetGlobalDistanceToLeadingVehicle)
-      .def("set_percentage_keep_right_rule", &carla::traffic_manager::TrafficManager::SetKeepRightPercentage);
+      .def("set_percentage_keep_right_rule", &carla::traffic_manager::TrafficManager::SetKeepRightPercentage)
+      .def("set_synchronous_mode", &carla::traffic_manager::TrafficManager::SetSynchronousMode);
 }

PythonAPI/examples/spawn_npc.py

@@ -98,6 +98,7 @@ def main():
 
         if args.sync:
             settings = world.get_settings()
+            traffic_manager.set_synchronous_mode(True)
             if not settings.synchronous_mode:
                 synchronous_master = True
                 settings.synchronous_mode = True