App Crash C++ Runtime Library

[onimusha]

I'm running this small app to read some sensors throughout an Arduino board, the problem is if i move too much the window around and play with it i get a C++ Runtime Library crash either using common Qt widgets or Qwt widgets as follows:
Microsoft Visual C++ Runtime Library
This application has requested the runtime to terminate it in a unsual way.
Please contact the application's support team for more information.
Plus it gets a little bit laggy when i open the port and start reading from the board, Why is that?
This are my files:
.pro

QT       += core gui serialport

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = EMS-ver2TEST
TEMPLATE = app


SOURCES += \
    main.cpp \
    puertoserie2.cpp \
    widget.cpp

HEADERS  += \
    puertoserie2.h \
    widget.h

QMAKE_CXXFLAGS += -std=gnu++14

Headers:
puertoserie2.h

#ifndef PUERTOSERIE2_H
#define PUERTOSERIE2_H

#include <QObject>
#include <QWidget>
#include <QSerialPort>
#include <QByteArray>
#include <QVector>
#include <QPushButton>

class PuertoSerie2 : public QWidget{
  Q_OBJECT

public:
  explicit PuertoSerie2(QWidget *parent = nullptr);

private Q_SLOTS:
  // Conecta con el dispositivo transmisor
  void conexion();

  // Lleva a cabo una lectura del vector de informacion entrante
  void leerPlaca();

Q_SIGNALS:
  void SENSOR_A(int);
  void SENSOR_B(int);
  void SENSOR_C(int);
  void SENSOR_D(int);

private:
  void emiteValor();

  char banderaEstado(QByteRef);

  void estado(char, char);

  void setValorSensores();

  int refactorizar(QByteArray);

  // Estado del boton
  int mPuertoEstado;

  // Numero del sensor a leer o modificar
  int mComa;

  QSerialPort *mPlaca;

  // Informacion de los sensores en arreglos para un  manejo mas compacto
  QVector<QByteArray> mSensorList;
  QVector <int> mSensorValor;

  // Buffer de entrada
  QByteArray mBuffer;

  // Puerto de la PC
  QString mPuerto;

  // Boton que establece la conexion
  QPushButton *mBoton;  
};

#endif // PUERTOSERIE2_H

widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QDial>

class Widget : public QWidget{
    Q_OBJECT
public:
    Widget(QWidget *parent = 0);
    ~Widget();
private:
    QWidget *crearDial(QDial *);
};

#endif // WIDGET_H

Sources:
puertoserie2.cpp

#include "puertoserie2.h"
#include <QMessageBox>
#include <QBoxLayout>
#include <QDebug>

PuertoSerie2::PuertoSerie2(QWidget *parent) : QWidget(parent){
  mComa = 0;
  mPuertoEstado = 0;
  mPuerto = "COM3";
  mBuffer = "";
  mSensorList.push_back(QByteArray());
  qDebug() << "Vector de QByteArray" << mSensorList.at(0);
  mSensorValor.push_back(0);
  qDebug() << "Vector de double" << mSensorValor.at(0);

  mBoton = new QPushButton("Abrir Puerto", this);

  QHBoxLayout *layout = new QHBoxLayout(this);
  layout->addWidget(mBoton);
  layout->addStretch();

  connect(mBoton, SIGNAL(clicked()), this, SLOT(conexion()));
 }

char PuertoSerie2::banderaEstado(QByteRef buffer){
  // 'a' = 42 (asterisco, inicio de cadena)
  // 'b' = 44 (coma, separador)
  // 'c' >= 48 (informacion, contenido)

  int var = (int)buffer;

  if(var == 42){
    return 'a';
  } else if(var == 44){
    return 'b';
  } else if(var >= 48){
    return 'c';
  }

  return 'd';
}

void PuertoSerie2::estado(char bandera, char byte){
  switch (bandera) {
    // El estado a se supone que limpia los valores enteriores del vector
    // para introducir las nuevas lecturas
    case 'a':
      qDebug() << "\n----------Caso 'a' disparado: " << byte;
      qDebug() << "\nTam de los vectores: " << mSensorList.size() <<
                  "| " << mSensorValor.size();
      qDebug() << "\nTam de coma: " << mComa;

      for(int i = 0; i < mSensorValor.size(); ++i){
        mSensorValor[i] = 0.0;
      }
      for(int i = 0; i < mSensorList.size(); ++i){
        mSensorList[i].clear();
      }

      mComa = 0;
    break;

    // El estado es un separador, aumenta el lugar del vector
    case 'b':
     qDebug() << "\n----------Caso 'b' disparado: " << byte;
     qDebug() << "\nTam de los vectores: " << mSensorList.size() <<
                 "| " << mSensorValor.size();
     qDebug() << "\nTam de coma: " << mComa;
     emiteValor();
     mSensorValor.push_back(0);
     mSensorList.push_back(QByteArray());
     ++mComa;
     qDebug() << "\nAcciones llevadas a cabo";
     qDebug() << "\nTam de los vectores: " << mSensorList.size() <<
                 "| " << mSensorValor.size();
     qDebug() << "\nTam de coma: " << mComa;
    break;

    // Tenemos informacion y la signamos al posicion actual de la coma
    case 'c':
     qDebug() << "\n----------Caso 'c' disparado: " << byte;
     qDebug() << "Coma actual: " << mComa;
     qDebug() << "\nTam de los vectores: " << mSensorList.size() <<
                 "| " << mSensorValor.size();
     mSensorList[mComa] += byte;
    break;

    default:
     qDebug() << "\n%%%%%%%%%%Final de la Cadena";
     qDebug() << "\nTam de los vectores: " << mSensorList.size() <<
                 "| " << mSensorValor.size();
     emiteValor();
     mBuffer.clear();

     while(mSensorList.size() > 1){
         mSensorList.pop_back();
     }

     while(mSensorValor.size() > 1){
         mSensorValor.pop_back();
     }
    break;
    }
}

void PuertoSerie2::conexion(){
  if (mPuertoEstado == 0){

    mPlaca = new QSerialPort(this);
    mPlaca->setPortName(mPuerto);
    mPlaca->open(QIODevice::ReadWrite);

    if(mPlaca->isOpen() == false){

	 QMessageBox::information(this, "Estado",
	 "Error al Abrir el puerto: " + mPuerto);

    } else {

	 mPlaca->setBaudRate(QSerialPort::Baud9600);
	 mPlaca->setStopBits(QSerialPort::OneStop);
	 mPlaca->setParity(QSerialPort::NoParity);
	 mPlaca->setDataBits(QSerialPort::Data8);
	 mPlaca->setFlowControl(QSerialPort::NoFlowControl);

	 connect(mPlaca, SIGNAL(readyRead()), this, SLOT(leerPlaca()));

	 mBoton->setText("Cerrar Puerto");
	 QMessageBox::information(this, "Estado",
	 "Puerto: " + mPuerto + " Abierto");
	 mPuertoEstado = 1;

    }
  } else if (mPuertoEstado == 1){

    mPlaca->close();
    mPlaca->destroyed();
    mPuertoEstado = 0;
    mBoton->setText("Abrir Puerto");
    QMessageBox::information(this, "Estado",
    "Puerto: " + mPuerto + " Cerrado");

  }
}

void PuertoSerie2::leerPlaca(){

  mBuffer = mPlaca->readAll();

  qDebug() << "\n>>>>>>>> Informacion de entrada: " << mBuffer;

  for(int i = 0; i < mBuffer.size(); ++i){
    estado(banderaEstado(mBuffer[i]), mBuffer.at(i));
  }
}

int PuertoSerie2::refactorizar(QByteArray byte){
  // Convierte el valor de binario a un doble usable
//  qDebug() << "\nRefactorizando: " << byte;

  QString cadena = byte;
  int i = cadena.toInt();
//  qDebug() << "\nRefactorizado: " << i;
  return i;

}

void PuertoSerie2::setValorSensores(){
  qDebug() << "\nSeteando Valores...";
  for(int i = 0; i < mSensorValor.size(); ++i){
    mSensorValor[i] = refactorizar(mSensorList.at(i));
  }
}

void PuertoSerie2::emiteValor(){
    setValorSensores();

    qDebug() <<"\nValores: " << mSensorValor.at(mComa);
    switch(mComa){

    case 0:
        emit SENSOR_A(mSensorValor.at(mComa));
    break;

    case 1:
        emit SENSOR_B(mSensorValor.at(mComa));
    break;

    case 2:
        emit SENSOR_C(mSensorValor.at(mComa));
    break;

    case 3:
        emit SENSOR_D(mSensorValor.at(mComa));
    break;
    }

}

widget.cpp

#include "widget.h"
#include "puertoserie2.h"
#include <QDial>
#include <QBoxLayout>
#include <QLabel>
#include <QFont>

Widget::Widget(QWidget *parent) : QWidget(parent){
    PuertoSerie2 *port = new PuertoSerie2;

    QDial *dial = new QDial;
    connect(port, SIGNAL(SENSOR_A(int)), dial, SLOT(setValue(int)));
    QWidget *dialWidget = crearDial(dial);

    QDial *dialA = new QDial;
    connect(port, SIGNAL(SENSOR_B(int)), dialA, SLOT(setValue(int)));
    QWidget *dialAWidget = crearDial(dialA);

    QDial *dialB = new QDial;
    connect(port, SIGNAL(SENSOR_C(int)), dialB, SLOT(setValue(int)));
    QWidget *dialBWidget = crearDial(dialB);

    QDial *dialC = new QDial;
    connect(port, SIGNAL(SENSOR_D(int)), dialC, SLOT(setValue(int)));
    QWidget *dialCWidget = crearDial(dialC);

    QHBoxLayout *mainLayout = new QHBoxLayout(this);
    mainLayout->addWidget(dialWidget);
    mainLayout->addWidget(dialAWidget);
    mainLayout->addWidget(dialBWidget);
    mainLayout->addWidget(dialCWidget);
    mainLayout->addWidget(port);

    this->setLayout(mainLayout);
}

Widget::~Widget(){

}

QWidget *Widget::crearDial(QDial* dial){
    int min = 0;
    int max = 100;

    dial->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
    dial->setMinimum(min);
    dial->setMaximum(max);

    QFont font;
    font.setBold(true);

    QLabel *label = new QLabel;
    label->setAlignment(Qt::AlignHCenter);
    label->setFont(font);

    connect(dial, SIGNAL(valueChanged(int)), label, SLOT(setNum(int)));
    label->setNum(dial->value());

    QVBoxLayout *dialLayout = new QVBoxLayout;
    dialLayout->addWidget(dial);
    dialLayout->addWidget(label);

    QWidget *box = new QWidget;
    box->setLayout(dialLayout);
    return box;
}

main.cpp

#include "widget.h"
#include <QApplication>

int main(int argc, char *argv[]){
    QApplication a(argc, argv);
    Widget w;
    w.show();

    return a.exec();
}

[Paul Colby]

Hi @onimusha,

There's a few suspicious things that could be causing your problems. Let's start with a couple of the ones that stand out to me.

It seems that PuertoSerie2::leerPlaca is not checking the validity of the PuertoSerie2::mPlaca member before dereferencing it. I can see that your code logic would normally never expect it to be called without being initialised first, but as its connected to a signal, you can't guarantee the order of the events that destroy and use mPlaca (a quick validity check is always advisable anyway).

Also, the way PuertoSerie2::conexion destroys mPlaca looks risky to me... specifically, the mPlaca->destroyed(); call is (probably) bad - QObject::destroyed is a signal, and probably should not be called this way (at best, it will be ignored, at worst, it will put the object in a very unintended state).

A better approach might be something like:

void PuertoSerie2::conexion(){
    ...
    mPlaca->close();
    mPlaca->deleteLater();
    mPlaca = nullptr;
    ...
}

Then in PuertoSerie2::leerPlaca, check if mPlace is null or not (and/or disconnect the slot prior to the deleteLater call above). As the code stands currently, leerPlace could be calling readAll on a QSerialPort object on which you have invoked QObject::destroyed (which may well have corrupted the object).

So try fixing up the management of your PuertoSerie2::mPlace pointer's lifecycle, and see if that helps.

Cheers.

[onimusha]

Hi @Paul-Colby,
Changing a few lines:

else if (mPuertoEstado == 1){

    mPlaca->close();
    mPlaca->deleteLater();
    mPlaca = nullptr;
    mPuertoEstado = 0;
    mBoton->setText("Abrir Puerto");
    QMessageBox::information(this, "Estado",
    "Puerto: " + mPuerto + " Cerrado");

  }

and:

if(mPlaca != nullptr){

    mBuffer = mPlaca->readAll();

    qDebug() << "\n>>>>>>>> Informacion de entrada: " << mBuffer;

    for(int i = 0; i < mBuffer.size(); ++i){
      estado(banderaEstado(mBuffer[i]), mBuffer.at(i));
    }
  }

as you said makes thinks even worse. the whole thing crashes in 2 sec, i cannot think how to manage that king of menber life cicle because this reaches my level of understanding about C++ / Qt / System platform

[onimusha]

@Paul-Colby
One thing to notice is that the same code runs smoother on my IBM thinkpad Z60t under Lubuntu 14.04. Just wonder why....

[jsulm]

You should run a debug build through the debugger to see where it crashes

[onimusha]

Hello @jsulm i did that alrdy and nothing pops up when the crash happens

[onimusha]

@jsulm I just want to know if there is something wrong in my code that could cause the crash besides my fuzzy logic to write code and algorithms. Other than that i think its my windows 7 machine.

[onimusha]

I think the problem lies in windows asynchronous tasks...... not being able to read the buffer properly while taking care of other tasks like repainting the window i'm currently moving, as a result my QVector goes out of index.