Potential fix for #631

Author: sytelus

AirLib/include/vehicles/multirotor/controllers/RealMultirotorConnector.hpp

@@ -18,6 +18,7 @@ class RealMultirotorConnector : public VehicleConnectorBase
 
     virtual void updateRenderedState(float dt) override
     {
+        unused(dt);
     }
 
     virtual void updateRendering(float dt) override

PythonClient/PythonClient.pyproj

@@ -5,7 +5,7 @@
     <SchemaVersion>2.0</SchemaVersion>
     <ProjectGuid>e2049e20-b6dd-474e-8bca-1c8dc54725aa</ProjectGuid>
     <ProjectHome>.</ProjectHome>
-    <StartupFile>car_collision.py</StartupFile>
+    <StartupFile>hello_car.py</StartupFile>
     <SearchPath>
     </SearchPath>
     <WorkingDirectory>.</WorkingDirectory>

Unreal/Plugins/AirSim/Source/AirBlueprintLib.cpp

@@ -107,6 +107,10 @@ T* UAirBlueprintLib::FindActor(const UObject* context, FString name)
     return nullptr;
 }
 
+bool UAirBlueprintLib::IsInGameThread()
+{
+    return ::IsInGameThread();
+}
 
 void UAirBlueprintLib::RunCommandOnGameThread(TFunction<void()> InFunction, bool wait, const TStatId InStatId)
 {

Unreal/Plugins/AirSim/Source/AirBlueprintLib.h

@@ -53,6 +53,8 @@ class UAirBlueprintLib : public UBlueprintFunctionLibrary
     static int GetMeshStencilID(const std::string& mesh_name);
     static void InitializeMeshStencilIDs();
 
+    static bool IsInGameThread();
+    
     template<class T>
     static std::string GetMeshName(T* mesh);
     static std::string GetMeshName(ALandscapeProxy* mesh);

Unreal/Plugins/AirSim/Source/Multirotor/MultiRotorConnector.cpp

@@ -54,6 +54,7 @@ MultiRotorConnector::MultiRotorConnector(VehiclePawnWrapper* vehicle_pawn_wrappe
 
     last_pose_ = pending_pose_ = last_debug_pose_ = Pose::nanPose();
     pending_pose_status_ = PendingPoseStatus::NonePending;
+    reset_pending_ = false;
 
     std::string message;
     if (!vehicle_.getController()->isAvailable(message)) {
@@ -138,6 +139,12 @@ void MultiRotorConnector::updateRenderedState(float dt)
 {
     //Utils::log("------Render tick-------");
 
+    //if reset is pending then do it first, no need to do other things until next tick
+    if (reset_pending_) {
+        reset_task_();
+        return;
+    }
+
     //move collision info from rendering engine to vehicle
     const CollisionInfo& collision_info = vehicle_pawn_wrapper_->getCollisionInfo();
     vehicle_.setCollisionInfo(collision_info);
@@ -187,6 +194,12 @@ void MultiRotorConnector::updateRenderedState(float dt)
 
 void MultiRotorConnector::updateRendering(float dt)
 {
+    //if we did reset then don't worry about synchrnozing states for this tick
+    if (reset_pending_) {
+        reset_pending_ = false;
+        return;
+    }
+
     try {
         controller_->reportTelemetry(dt);
     }
@@ -296,16 +309,27 @@ bool MultiRotorConnector::isApiServerStarted()
 //*** Start: UpdatableState implementation ***//
 void MultiRotorConnector::reset()
 {
-    UAirBlueprintLib::RunCommandOnGameThread([this]() {
-        VehicleConnectorBase::reset();
+    if (UAirBlueprintLib::IsInGameThread())
+        resetPrivate();
+    else {
+        //schedule the task which we will execute in tick event when World object is locked
+        reset_task_ = std::packaged_task<void()>([this]() { resetPrivate(); });
+        std::future<void> reset_result = reset_task_.get_future();
+        reset_pending_ = true;
+        reset_result.wait();
+    }
+}
+
+void MultiRotorConnector::resetPrivate()
+{
+    VehicleConnectorBase::reset();
 
-        //TODO: should this be done in MultiRotor.hpp
-        //controller_->reset();
+    //TODO: should this be done in MultiRotor.hpp
+    //controller_->reset();
 
-        rc_data_ = RCData();
-        vehicle_pawn_wrapper_->reset();    //we do flier resetPose so that flier is placed back without collisions
-        vehicle_.reset();
-    }, true);
+    rc_data_ = RCData();
+    vehicle_pawn_wrapper_->reset();    //we do flier resetPose so that flier is placed back without collisions
+    vehicle_.reset();
 }
 
 void MultiRotorConnector::update()

Unreal/Plugins/AirSim/Source/Multirotor/MultiRotorConnector.h

@@ -15,6 +15,8 @@
 #include <chrono>
 #include "api/ControlServerBase.hpp"
 #include "SimJoyStick/SimJoyStick.h"
+#include <future>
+
 
 class MultiRotorConnector : public msr::airlib::VehicleConnectorBase
 {
@@ -65,8 +67,8 @@ class MultiRotorConnector : public msr::airlib::VehicleConnectorBase
 
 private:
     void detectUsbRc();
-    static float joyStickToRC(int16_t val);
-    const msr::airlib::RCData& getRCData();
+    const msr::airlib::RCData& getRCData();  
+    void resetPrivate();
 
 private:
     MultiRotor vehicle_;
@@ -104,6 +106,11 @@ class MultiRotorConnector : public msr::airlib::VehicleConnectorBase
         NonePending, RenderStatePending, RenderPending
     } pending_pose_status_;
     Pose pending_pose_; //force new pose through API
+
+    //reset must happen while World is locked so its async task initiated from API thread
+    bool reset_pending_;
+    std::packaged_task<void()> reset_task_;
+
     Pose last_pose_; //for trace lines showing vehicle path
     Pose last_debug_pose_; //for purposes such as comparing recorded trajectory
 };