如何在QCoreApplication析构函数中删除对象和线程实例

Question

  //my_class.h

  void My_class::My_Class(){

     my_ip=...
     my_port=...
  };

  void Data_Send_Func(){

 // send data over tcp;

 }

  void My_Class::~My_Class(){

   cout<<"Delete objects"<<endl;

  }

  void My_Class::process(){

     QTimer my_timer;
     my_timer->setInterval(30);
     connect(my_timer,SIGNAL(timeout()),this,SLOT(Data_Send_Func()));
     connect(this,SIGNAL(destroyed()),mytimer,SLOT(deleteLater));
  }


  //my_application.cpp
  My_application::My_application:QCoreApplication{

     my_class=new My_Class();

     QThread thread=new QThread();

     my_class->moveToThread(thread);

     connect(thread,SIGNAL(started()),my_class,SLOT(process())) ;

     connect(my_class,SIGNAL(finished()),thread,SLOT(quit())) ;

     connect(thread,SIGNAL(finished()),thread,SLOT(deletelater())) ;

     connect(my_class,SIGNAL(finished()),my_class,SLOT(deletelater())) ;        

 }

  //my_application.h

 struct Exit_App{

    Exit_App(){

     signal(SIGINT,&Exit_App::Exit_F); 
     signal(SIGTERM,&Exit_App::Exit_F); 
     signal(SIGBREAK,&Exit_App::Exit_F);  

   }
     static void Exit_F(int sig){

       cout<<"Exiting App"<<endl;

       QCoreApplication::exit(0);
     }
 }


 int main(argc,char* argv[]){

     Exit_App app;
     My_application a(arcg,argv);
     return a.exec();

 } 

So when I close my program I want to delete the objects in My_Class destructor.

I dont want to emit fnished signal in application so I want to delete the my_class object and thread in My_application destructor.

   My_application::~My_application{
   if (my_class->thread()) {

     connect(my_class, SIGNAL(destroyed()), thread, SLOT(quit());

     my_class->deleteLater();

  } else {

     delete my_class; // It's a threadless object, we can delete it
    thread->quit();
     }
    thread->wait();

 }

Answer 1

A QObject cannot be deleted from any thread but the one it's in, unless it is thread less (due to its thread having finished). The following must hold:

Q_ASSERT(!object->thread() || object->thread() == QThread::currentThread());
delete object;

In case of an object that has a thread, you need to invoke the object's deleteLater method. The deletion will be done within the thread's event loop. When the object is deleted, it's time to finish the thread. So:

if (my_class->thread()) {
  connect(my_class, SIGNAL(destroyed()), thread, SLOT(quit());
  my_class->deleteLater();
} else {
  delete my_class; // It's a threadless object, we can delete it
  thread->quit();
}
thread->wait();

Note that it's OK to call quit() and wait() on a thread that is finished. It is redundant to check for a running thread like you do.