QAbstractListModel > call to endInsertRows() from NON Qt (GUI) thread results in crash

bkamps

Hi,

I have a derived class from QAbstractListModel and I want to add elements to this list. So I do the following:

@
void addElement()
beginInsertRows(QModelIndex(), myList.count(), myList.count());
myList.push_back(myElement);
endInsertRows();
@

This works when I call addElement() from the Qt main thread. When I call this function from a NON Qt thread (normal pthread) the application crashes on endInsertRows() method.

I have read that endInsertRows() emits a signal and this shouldn't be done from a NON Qt thread. For now I have "fixed" this by connecting addElement() to a signal that's used in the NON Qt thread and using Qt:QueuedConnection option.

Is there another way to do this?

ZapB

That seems a reasonable solution to me. If you know that you will always call this function from another thread then you can hide the use of signals/slots/queued connections within the class:

@
MyModel::MyModel( QObject* parent )
: QAbstractListModel( parent )
{
connet( this, SIGNAL( addElementRequested() ), this, SLOT( doAddElement() ) );
...
}

void MyModel::addElement()
{
emit addElementRequested();
}

void MyModel::doAddElement()
{
beginInsertRows(QModelIndex(), myList.count(), myList.count());
myList.push_back(myElement);
endInsertRows();
}
@

where doAddElement() is a private slot. WIth the above if you call addElement() from the main GUI thread it will be synchronous as it will use a direct connection. If you call it from a worker thread then it will use a queued connection and happen asynchronously.

HTH.