How to merge/append/add two models for threading ?

[Dogukan]

Hey Guys !!!
I am kinda newbie so if this post is in wrong place just inform me please.

I am trying to use threads for "for loops" in my program but according to my research "model->setData" is not compatible with threading.

So my solutions is :
-> I am gonna use different models in each thread and at the and I am gonna merge them into one to show in tableview.

But I am not familiar with qt so I kinda stuck here could you please check my code ?

t2 = std::thread{[&]{

                                for(unsigned int i = 0 ; i < ((RegexOperations_.indexed_arranged_file.size()+1) / 2)  ; i++)
                                {

                                    for(unsigned int j = 0 ; j < RegexOperations_.indexed_arranged_file[0].size();j++)
                                    {
                                        std::string temp = RegexOperations_.indexed_arranged_file[i][j];
                                        QModelIndex index = model ->index(i,j,QModelIndex());
                                        model->setData(index,temp.c_str());
                                    }

                                }

                            }
                        };

//                        t3 = std::thread{[&]{

//                                for(unsigned int i = ((RegexOperations_.indexed_arranged_file.size()+1) / 2) ; i < RegexOperations_.indexed_arranged_file.size();i++)
//                                {
//                                    for(unsigned int j = 0 ; j < RegexOperations_.indexed_arranged_file[0].size();j++)
//                                    {
//                                        std::string temp = RegexOperations_.indexed_arranged_file[i][j];
//                                        QModelIndex index = model ->index(i,j,QModelIndex());
//                                        model->setData(index,temp.c_str());
//                                    }
//                                }
//                            }
//                        };
                    }



            t2.join();
            //t3.join();

            ui->tableView_results->setModel(model);
            ui->tableView_results->horizontalHeader()->setSectionResizeMode(QHeaderView::ResizeToContents);
            ui->tableView_results->setEditTriggers(QAbstractItemView::NoEditTriggers);
            }

Thank you for your help ...

[SGaist]

Hi and welcome to devnet,

Why not use Qt's Signal and Slots ? That way you can have only one model that's updated by two threads.

[Dogukan]

I did a little research about signals and slots but could not figure out how to implement into my code. Could you give me a little detailed explanation ?

[VRonin]

The big question is: is the model flat? i.e. is it a list/table or a tree?

If so it's easy:

class ModelUpdateNotify : public QObject{
Q_OBJECT
Q_DISABLE_COPY(ModelUpdateNotify)
public:
explicit ModelUpdateNotify(QObject* parent = Q_NULLPTR) : QObject(parent){}
Q_SIGNAL void updateData(int row, int column, const QVariant& data);
};

ModelUpdateNotify* notifier2 = new  ModelUpdateNotify;
QObject::connect(notifier2, &ModelUpdateNotify::updateData,model,[=](int row, int column, const QVariant& data){
model->setData(model ->index(i,j),data);
},Qt::QueuedConnection);
t2 = std::thread{[&,notifier2]{
    for(unsigned int i = 0 ; i < ((RegexOperations_.indexed_arranged_file.size()+1) / 2)  ; i++){
        for(unsigned int j = 0 ; j < RegexOperations_.indexed_arranged_file[0].size();j++)
            notifier2->updateData(i,j,QString::fromStdString(RegexOperations_.indexed_arranged_file[i][j]));
    }
delete notifier2;
};

[Dogukan]

my model is QTableViewModel

[JonB]

@Dogukan
There is no such Qt class as "QTableViewModel"... ?

[VRonin]

@Dogukan said in How to merge/append/add two models for threading ?:

my model is QTableViewModel

It's not really relevant, any flat QAbstractItemModel would work with the method above