请帮我使用std :: thread

Question

I have a big query for SQLite and I want to make the query in another thread. Furthermore, I want to update a ProgressBar in another thread. Suffice it to say, I don't understand how to do this, but think that my main thread won't continue to run if I create std::thread t(func); t.join(); std::thread t(func); t.join(); .

I could instead send a single SQL query per frame update, but that would perform more slowly.

I have the following code:

//....pseudo code

int main()
{
    Game g;
    g->run();
    return 0;
}

//....code

class Game
{
private:
    ProgressBar *m_bar;  //have methods increase|decrease & draw for rendering
    SQLClass    *m_sql;

public:
    void handleEvents();
    void update()
    {
        if(/*when happened something*/)
        {
            m_sql->insertVeryBigQuery(); //20-30 seconds for writing
        }
    }
    void render()
    {
        m_bar->draw();
    }

    void run()
    {
        while(1)
        {
            handleEvents();
            update();
            render();
        }
    }
}

Answer 1

join() means you want to wait for the end of the thread right there. That's not what you want. You want it to run in parallel. Drop the join and find a way to signal your main loop when the thread is done.