interthread signals and slots to update model

[ctarsoaga]

I have a custom item model: MyModel : public QAbstractItemModel
that holds a std::vector<MyStruct> as internal data.
I try to load a lot of items in that vector asynchronously, by using a worker thread.
I have two solutions:

A. - use the worker thread to load a std::vector<MyStruct>
- pass the loaded data, though a custom event to the main thread
- let the main thread update the model with the data copied inside the event

B. - use the worker thread to load the std::vector<MyStruct>
- connect a thread signal with loaded data as argument to a slot in the main thread (queued connection)
- let the main thread, update the model with the data received as argument in the slot


Both these solutions work, but they are updating the model inside the main thread.



My question is: is there any way to update the model inside the worker thread? If yes, how?

Let's say my model has a function

void MyModel::setData(const std::vector<MyStruct> & data)
{
    QMutexLocker locker(&m_mutex); //protect shared state, accessed from multiple threads
 
    beginResetModel(); //when will this be sent/received?
 
    ....update internal data
 
    endResetModel(); //when will this be sent/received?
}

void MyModel::setData(const std::vector<MyStruct> & data)
{
    QMutexLocker locker(&m_mutex); //protect shared state, accessed from multiple threads

    beginResetModel(); //when will this be sent/received?
    
    ....update internal data
    
    endResetModel(); //when will this be sent/received?
}

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and my worker thread does this:

void MyThread::run()
{
  std::vector<MyStruct> myVector;
  //load the data
  model->setData(myVector); //tricky: when will resetModel signals be emitted/received?
}

void MyThread::run()
{
  std::vector<MyStruct> myVector;
  //load the data
  model->setData(myVector); //tricky: when will resetModel signals be emitted/received?
}

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What will happen if I call

model->setData()

model->setData()

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from the worker thread? When will the

beginResetModel()

beginResetModel()

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and

endResetModel()

endResetModel()

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be handled?

I guess model will have to be mutexed, but I don't know if it will handle those beginResetModel() / endResetModel() properly.

I keep reading http://doc.qt.nokia.com/latest/threads-qobject.html
and I cannot figure this out.

I guess resetModel signals will be either ignored OR handled later, when main thread's event loop will receive them (e.g views observing model will be notified too late)

Thanks a lot,
Chris