fix(ros2): move ROS2 unregistration before actor deregistration

Move ROS2 UnregisterSensor/UnregisterVehicle calls inside the
CarlaActor null check, before Registry.Deregister. This prevents
a potential null pointer dereference in multi-GPU setups where
CarlaActor may be null when OnActorDestroyed fires.

Also add "actor" prefix to auto-generated ROS names for clarity.

Port of ue4-dev commit 201d375.

Signed-off-by: Yutaka Kondo <yutaka.kondo@youtalk.jp>

Author: youtalk

Unreal/CarlaUnreal/Plugins/Carla/Source/Carla/Actor/ActorDispatcher.cpp

@@ -180,7 +180,7 @@ FCarlaActor* UActorDispatcher::RegisterActor(
       // If not specified by the user, set the ActorId as the actor name
       if (RosName.empty())
       {
-        RosName = std::to_string(View->GetActorId());
+        RosName = "actor" + std::to_string(View->GetActorId());
       }
 
       std::string FrameId = std::string(TCHAR_TO_UTF8(*Description.GetAttribute("ros_frame_id").Value));
@@ -231,26 +231,27 @@ void UActorDispatcher::OnActorDestroyed(AActor *Actor)
   FCarlaActor* CarlaActor = Registry.FindCarlaActor(Actor);
   if (CarlaActor)
   {
-    if (CarlaActor->IsActive())
+    #if defined(WITH_ROS2)
+    auto ROS2 = carla::ros2::ROS2::GetInstance();
+    if (ROS2->IsEnabled())
     {
-      Registry.Deregister(CarlaActor->GetActorId());
-    }
-  }
+      auto Description = CarlaActor->GetActorInfo()->Description;
 
-  #if defined(WITH_ROS2)
-  auto ROS2 = carla::ros2::ROS2::GetInstance();
-  if (ROS2->IsEnabled())
-  {
-    auto *Sensor = Cast<ASensor>(Actor);
-    auto *Vehicle = Cast<ACarlaWheeledVehicle>(Actor);
-    if (Sensor != nullptr)
-    {
-      ROS2->UnregisterSensor(static_cast<void*>(Actor));
+      auto *Sensor = Cast<ASensor>(Actor);
+      auto *Vehicle = Cast<ACarlaWheeledVehicle>(Actor);
+      if (Sensor != nullptr)
+      {
+        ROS2->UnregisterSensor(static_cast<void*>(Actor));
+      }
+      else if (Vehicle != nullptr && Description.GetAttribute("role_name").Value == "hero") {
+        ROS2->UnregisterVehicle(static_cast<void*>(Actor));
+      }
     }
-    else if (Vehicle != nullptr)
+    #endif
+
+    if (CarlaActor->IsActive())
     {
-      ROS2->UnregisterVehicle(static_cast<void*>(Actor));
+      Registry.Deregister(CarlaActor->GetActorId());
     }
   }
-  #endif
 }