PythonInterface.cpp

Go to the documentation of this file.

/*
 * PythonSingleTon.h
 *
 *  Created on: Jan. 14, 2021
 *      Author: mathieu
 */

#include <rtabmap/core/PythonInterface.h>
#include <rtabmap/utilite/ULogger.h>
#include <rtabmap/utilite/UThread.h>

namespace rtabmap {

UMutex PythonInterface::mutex_;
int PythonInterface::refCount_ = 0;
PyThreadState * PythonInterface::mainThreadState_ = 0;
unsigned long PythonInterface::mainThreadID_ = 0;

PythonInterface::PythonInterface() :
                threadState_(0)
{
        UScopeMutex lockM(mutex_);
        if(refCount_ == 0)
        {
                UINFO("Py_Initialize() with thread = %d", UThread::currentThreadId());
                // initialize Python
                Py_Initialize();

                // initialize thread support
                PyEval_InitThreads();
                Py_DECREF(PyImport_ImportModule("threading"));

                //release the GIL, store thread state, set the current thread state to NULL
                mainThreadState_ = PyEval_SaveThread();
                UASSERT(mainThreadState_);
                mainThreadID_ = UThread::currentThreadId();
        }

        ++refCount_;
}

PythonInterface::~PythonInterface()
{
        UScopeMutex lock(mutex_);
        if(refCount_>0 && --refCount_==0)
        {
                // shut down the interpreter
                UINFO("Py_Finalize() with thread = %d", UThread::currentThreadId());
                PyEval_RestoreThread(mainThreadState_);
                Py_Finalize();
        }
}

void PythonInterface::lock()
{
        mutex_.lock();

        UDEBUG("Lock: Current thread=%d (main=%d)", UThread::currentThreadId(), mainThreadID_);
        if(UThread::currentThreadId() == mainThreadID_)
        {
                PyEval_RestoreThread(mainThreadState_);
        }
        else
        {
                // create a thread state object for this thread
                threadState_ = PyThreadState_New(mainThreadState_->interp);
                UASSERT(threadState_);
                PyEval_RestoreThread(threadState_);
        }
}

void PythonInterface::unlock()
{
        if(UThread::currentThreadId() == mainThreadID_)
        {
                mainThreadState_ = PyEval_SaveThread();
        }
        else
        {
                PyThreadState_Clear(threadState_);
                PyThreadState_DeleteCurrent();
        }
        UDEBUG("Unlock: Current thread=%d (main=%d)", UThread::currentThreadId(), mainThreadID_);
        mutex_.unlock();
}

std::string PythonInterface::getTraceback()
{
        // Author: https://stackoverflow.com/questions/41268061/c-c-python-exception-traceback-not-being-generated

        PyObject* type;
        PyObject* value;
        PyObject* traceback;

        PyErr_Fetch(&type, &value, &traceback);
        PyErr_NormalizeException(&type, &value, &traceback);

        std::string fcn = "";
        fcn += "def get_pretty_traceback(exc_type, exc_value, exc_tb):\n";
        fcn += "    import sys, traceback\n";
        fcn += "    lines = []\n";
        fcn += "    lines = traceback.format_exception(exc_type, exc_value, exc_tb)\n";
        fcn += "    output = '\\n'.join(lines)\n";
        fcn += "    return output\n";

        PyRun_SimpleString(fcn.c_str());
        PyObject* mod = PyImport_ImportModule("__main__");
        UASSERT(mod);
        PyObject* method = PyObject_GetAttrString(mod, "get_pretty_traceback");
        UASSERT(method);
        PyObject* outStr = PyObject_CallObject(method, Py_BuildValue("OOO", type, value, traceback));
        std::string pretty;
        if(outStr)
                pretty = PyBytes_AsString(PyUnicode_AsASCIIString(outStr));

        Py_DECREF(method);
        Py_DECREF(outStr);
        Py_DECREF(mod);

        return pretty;
}

}