Fixing first ticks of a sensor (#5616)

* Stream is removed when the sensor is destroyed

* Changing log_info to log_debug

* changeslog

* Changes to return some non-const objects

* Changing from weak_ptr to shared_ptr for storing sessions

* Split long line

* Changing log priority of some messages

* Make sure sensor is active when an user wants to use it (before it connects to it)

* Change UE tasks to any task, and not from Game thread

LibCarla/source/carla/streaming/detail/Dispatcher.cpp

@@ -110,6 +110,7 @@ namespace detail {
     if (search != _stream_map.end()) {
       log_debug("Found sensor id: ", sensor_id);
       auto stream_state = search->second;
+      stream_state->ForceActive();
       log_debug("Getting token from stream ", sensor_id, " on port ", stream_state->token().get_port());
       return stream_state->token();
     } else {
@@ -118,6 +119,7 @@ namespace detail {
       temp_token.set_stream_id(sensor_id);
       auto ptr = std::make_shared<MultiStreamState>(temp_token);
       auto result = _stream_map.emplace(std::make_pair(temp_token.get_stream_id(), ptr));
+      ptr->ForceActive();
       if (!result.second) {
         log_debug("Failed to create multistream for stream ", sensor_id, " on port ", temp_token.get_port());
       }

LibCarla/source/carla/streaming/detail/MultiStreamState.h

@@ -58,8 +58,12 @@ namespace detail {
       }
     }
 
+    void ForceActive() {
+      _force_active = true;
+    }
+
     bool AreClientsListening() {
-      return (_sessions.size() > 0);
+      return (_sessions.size() > 0 || _force_active);
     }
 
     void ConnectSession(std::shared_ptr<Session> session) final {
@@ -84,6 +88,7 @@ namespace detail {
         DEBUG_ASSERT(session == _session.load());
         _session.store(nullptr);
         _sessions.clear();
+        _force_active = false;
         log_warning("Last session disconnected");
       } else {
         _sessions.erase(
@@ -107,6 +112,7 @@ namespace detail {
         }
       }
       _sessions.clear();
+      _force_active = false;
       _session.store(nullptr);
       log_debug("Disconnecting all multistream sessions");
     }
@@ -119,6 +125,7 @@ namespace detail {
     AtomicSharedPtr<Session> _session;
     // if there are more than one session, we use vector of sessions with mutex
     std::vector<std::shared_ptr<Session>> _sessions;
+    bool _force_active {false};
   };
 
 } // namespace detail

Unreal/CarlaUE4/Plugins/Carla/Source/Carla/Game/CarlaEngine.h

@@ -24,6 +24,7 @@
 #include <mutex>
 
 class UCarlaSettings;
+class FFrameData;
 struct FEpisodeSettings;
 
 class FCarlaEngine : private NonCopyable

Unreal/CarlaUE4/Plugins/Carla/Source/Carla/Sensor/AsyncDataStream.h

@@ -66,7 +66,7 @@ public:
     {
       if (HeaderStr->frame != FrameNumber)
       {
-        carla::log_info("Re-framing stream ", HeaderStr->sensor_type, " from ", HeaderStr->frame, " to ", FrameNumber);
+        carla::log_debug("Re-framing sensor type ", HeaderStr->sensor_type, " from ", HeaderStr->frame, " to ", FrameNumber);
         HeaderStr->frame = FrameNumber;
       }
     }

Unreal/CarlaUE4/Plugins/Carla/Source/Carla/Sensor/PixelReader.cpp

@@ -76,7 +76,7 @@ void FPixelReader::WritePixelsToBuffer(
     RHICmdList.GetRenderQueryResult(Query, OldAbsTime, true);
   }
 
-  AsyncTask(ENamedThreads::GameThread, [=, Readback=std::move(BackBufferReadback)]() mutable {
+  AsyncTask(ENamedThreads::AnyNormalThreadNormalTask, [=, Readback=std::move(BackBufferReadback)]() mutable {
     {
       TRACE_CPUPROFILER_EVENT_SCOPE_STR("Wait GPU transfer");
       while (!Readback->IsReady())

Unreal/CarlaUE4/Plugins/Carla/Source/Carla/Sensor/PixelReader.h

@@ -10,6 +10,8 @@
 #include "Engine/TextureRenderTarget2D.h"
 #include "Runtime/ImageWriteQueue/Public/ImagePixelData.h"
 
+#include "Carla/Game/CarlaEngine.h"
+
 #include <compiler/disable-ue4-macros.h>
 #include <carla/Logging.h>
 #include <carla/Buffer.h>
@@ -111,7 +113,7 @@ void FPixelReader::SendPixelsInRenderThread(TSensor &Sensor, bool use16BitFormat
       if (!Sensor.IsPendingKill())
       {
         FPixelReader::Payload FuncForSending = 
-          [&Sensor, Conversor = std::move(Conversor)](void *LockedData, uint32 Size, uint32 Offset)
+          [&Sensor, Frame = FCarlaEngine::GetFrameCounter(), Conversor = std::move(Conversor)](void *LockedData, uint32 Size, uint32 Offset)
           {
             if (Sensor.IsPendingKill()) return;
 
@@ -127,6 +129,7 @@ void FPixelReader::SendPixelsInRenderThread(TSensor &Sensor, bool use16BitFormat
             }
     
             auto Stream = Sensor.GetDataStream(Sensor);
+            Stream.SetFrameNumber(Frame);
             auto Buffer = Stream.PopBufferFromPool();
 
             {