Question

Background: I used to call a stored procedure during my Form Load. However, since this resulted in a suboptimal UI experience, I put my SP call in a task of its own inside the Shown event. Since this is typically the last event in the form display process, it resulted in a much better experience than putting stuff in the Form load event. I have:

private void MainForm_Shown(object sender, EventArgs e)
{
   dbCheckTask = Task<bool>.Factory.StartNew(RunSPAndCheckStuff());

  // both of below run on the GUI thread.

  // if I print the thread ID in mycallback it is the GUI thread id
  dbCheckTask.ContinueWith(mycallback());  

  // I also tried below. But obviously, that too runs on the GUI thread
  mycallback(dbCheckTask.Result)

}

Because they fire on the GUI thread, my startup form paint is still neither instantaneous nor smooth. How can I get my task complete callback on a non-GUI thread without resorting to events? Whenever the task completes and if something is wrong and only if something is wrong (bool result returned false) then the user gets a message box pop. Until then he could go ahead and do other non database related stuff on the form. Please advise how I can get a task completion callback with task result in a non gui thread. Thank you

Answer 1

I’d use a BackgroundWorker for this, personally. One way to get your callback to run on the task thread would be to modify your method call and task creation as follows:

private void MainForm_Shown(object sender, EventArgs e)
{
    dbCheckTask = Task<bool>.Factory.StartNew(() => RunSPAndCheckStuff(mycallback));
    ...
}

private bool RunSPAndCheckStuff(Action<bool> callback)
{
    bool result = false;
    // Do stuff
    callback(result);
    return result;
}