Question

So I’m working on a windows 8 application with some asynchronous methods.
In one particular place I need the aplication to wait for the async method to finish, but it doesn’t seem it sends the EventHandle it’s state.

Here are the methods that need to work together:

public class Film : Page

private User loggedinUser = new User();
private EventWaitHandle handle = new AutoResetEvent(false);
private dynamic parameters;

protected override void OnNavigatedTo(NavigationEventArgs e)
{
    this.parameters = e.Parameter;
    LoadFacebookData(parameters);
    handle.WaitOne();
    LoadUserMovies(loggedinUser.UserName);

}

private async void LoadFacebookData(dynamic parameter)
{
    //async code that gets info from facebook whichs determines what user is logged in
    handle.Set();
}

private void LoadUserMovies(string username)
{
    // irrelevant code
} 

the moment the code hits the handle.WaitOne() bit, it stops working completely

Answer 1

In short you are not supposed to use async and wait on something. The standard mistake is to wait on the task returned (deadlock). You did a variation on this: You created an event and waited on it (also deadlock).

Solution: Either embrace async-await or don’t do async at all. Can’t do both in a mixed style (generally).

If await is available to you, this is a good start:

await LoadFacebookData(parameters);

Get rid of the event.