[SOLVED] Load a Python scene from a C++ unit test

[Ant0nin]

Hi guys,

I wrote a simple unit test in C++ using GUnit as recommanded in the documentation. In the code example given in https://www.sofa-framework.org/community/doc/programming-with-sofa/contribute-to-sofa/writing-tests/ there is a function called sceneLoad() which is able to load an existing XML scene. However, when I try to load a valid Python scene in the same way, an error occurs at the instruction PythonEnvironment::gil lock(__func__); located at the beginning of the method SceneLoaderPY::loadSceneWithArguments. So the error seems to be related to the Python GIL (Global Interpreter Lock), and it says: Fatal Python error: PyEval_SaveThread: NULL tstate. Maybe I missed an initialization or something about the SofaPython plugin. I had a look in the file applications/projects/runSofa/Main.cpp to try to understand what is wrong in my code but I still struggle to figure it out. I also looked for another examples in some SOFA plugins but I have only seen XML file scene loading at the moment. Is someone has already encounters this issue? What is the correct way to load a Python scene in C++?

Here is my C++ code:

#include <SofaTest/Sofa_test.h>
#include <SofaTest/TestMessageHandler.h>

#include <SofaPython/SceneLoaderPY.h>
#include <SofaSimulationGraph/init.h>
#include <SofaSimulationGraph/DAGSimulation.h>

#include <string>
#include <chrono>

namespace sofa {

using namespace defaulttype;
using namespace sofa::helper::testing;
using namespace simulation;
using namespace sofa::gui;

    template< typename DataTypes >
    struct SuctionCup_benchmark :public BaseSimulationTest
    {
        /// Root of the scene graph
        Node::SPtr root;

        Simulation* simulation;

        void onSetUp()
        {
            sofa::simulation::graph::init();
            sofa::simulation::setSimulation(simulation = new sofa::simulation::graph::DAGSimulation());
        }

        void sceneLoad()
        {
            std::string sceneFilename = std::string("/home/abernard/Workspace/suction_cup/examples/scene_08.py");
            root = sofa::simulation::getSimulation()->load(sceneFilename.c_str());
        }

        void onTearDown()
        {
            if (root!=NULL)
                sofa::simulation::getSimulation()->unload(root);
        }

        void initScene()
        {
            sofa::simulation::getSimulation()->init(root.get());
        }

        bool simpleBenchmark()
        {
            using namespace std::chrono;

            high_resolution_clock::time_point t0 = high_resolution_clock::now();

            // Run the simulation
            this->runSimulationSteps();

            high_resolution_clock::time_point t1 = high_resolution_clock::now();
            duration<double> time_span = duration_cast<duration<double>>(t1 - t0);

            EXPECT_LT(time_span.count(), 10.0);
        }

        void runSimulationSteps()
        {            
            float timeStep = 0.1;
            float timeEvaluation = 10.0;

            //Animate simulation
            unsigned int nbSteps = timeEvaluation/timeStep;
            unsigned int stepId;
            for (stepId = 0; stepId < nbSteps; ++stepId)
                sofa::simulation::getSimulation()->animate(root.get(),timeStep);
        }
    };

    using testing::Types;
    typedef Types< Vec3Types > DataTypes;

    TYPED_TEST_CASE(SuctionCup_benchmark, DataTypes);

    TYPED_TEST( SuctionCup_benchmark, benchmark_1)
    {
        this->onSetUp();
        this->sceneLoad();
        this->initScene();

        ASSERT_TRUE( this->simpleBenchmark() );

        this->onTearDown();
    }

} // namespace sofa

My operating system is Fedora 26.

[Hugo]

Hey @ant0nin

I never did such a full-python test scene. I would rather 1) create a usual simulation, as you are doing with
sofa::simulation::setSimulation(simulation = new sofa::simulation::graph::DAGSimulation());
2) add a RequiredPlugin component loading the SofaPython.so library in your root node and 3) add a PythonScriptController loading your python script.

Have you tried this?
Cheers,

Hugo

[Ant0nin]

Thank you @hugo (and sorry for the late answer). I tried your solution but the problem is the same (I obtained the same error about GIL). But, I created a classical XML file scene (.scn) containing a PythonScriptController component which is configured to load my python controller. With this setup, when I try to load the XML file scene on C++ side, it works well!

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