C#

Member 10291661 wrote:

Any Idea ?

// The task threw an exception
case TaskStatus.Faulted:
    _services.Remove(service);
    AddStatus(string.Format("Service '{0}' errored", service.ServiceId));
    AddStatus(task.Exception.ToString());
    break;

Task task = Task.Factory.StartNew(() =>
    {
        service.Start();
 
    }, TaskCreationOptions.LongRunning, service.CancellationTokenSource.Token);
task.ContinueWith(antecedent => { AddStatus(string.Format("Service '{0}' completed", service.ServiceId)) }, TaskContinuationOptions.OnlyOnRanToCompletion);
task.ContinueWith(antecedent => { AddStatus(string.Format("Service '{0}' cancelled", service.ServiceId)) }, TaskContinuationOptions.OnlyOnCanceled);
task.ContinueWith(antecedent => { 
  AddStatus(string.Format("Service '{0}' errored", service.ServiceId));
  AddStatus(task.Exception.ToString());
}, TaskContinuationOptions.OnlyOnFaulted);
task.ContinueWith(antecedent => {
  // Remove the service
  App.Current.Dispatcher.Invoke(() =>
  {
    // Remove the model from the UI
    Services.Remove(SelectedService);
    SelectedService = null;
    // If you haven't reached this point, then you don't have a current App Dispatcher...
    AddStatus("Removed from the dispatcher");
  });
  _services.Remove(service);
});

Pete O'Hanlon wrote:

For continuations, I find it best to use the explicit continuation that suits that particular status.

Kevin Marois wrote:

What benefit does it provide?

1. I can have my tasks attached to different schedulers - some of the stuff I deal with uses very complex scheduling.
2. I'm not mixing code. Each continuation has a single responsibility
3. This makes it very easy for me to provide general purpose continuation handlers - for instance, I could have a single OnlyOnFaulted handler that any Task calls.
4. This reduces the cyclomatic complexity of your code

public static class TaskExtensions
{
  public static void OnFaulted(this Task task)
  {
    task.ContinueWith(()=>{ /* do something here */ }, TaskContinuationOptions.OnlyOnFaulted);
  }
}

Task.Factory.StartNew(()=> { }).OnFaulted();

Task task = Task.Factory.StartNew(() =>
{
    service.Start();

}, TaskCreationOptions.LongRunning, service.CancellationTokenSource.Token);

Delegate 'Action<object>' does not take 0 arguments

Pete O'Hanlon wrote:

// If you haven't reached this point, then you don't have a current App Dispatcher...

    Task task = Task.Factory.StartNew(() =>
    {
        service.Start();

    }, service.CancellationTokenSource.Token);

    task.ContinueWith(antecedent => 
    {
        AddStatus(string.Format("Service '{0}' completed", service.ServiceId));

    }, TaskContinuationOptions.OnlyOnRanToCompletion);

    task.ContinueWith(antecedent => 
    {
        AddStatus(string.Format("Service '{0}' cancelled", service.ServiceId));

    }, TaskContinuationOptions.OnlyOnCanceled);

    task.ContinueWith(antecedent => 
    {
        AddStatus(string.Format("Service '{0}' errored", service.ServiceId));
        AddStatus(task.Exception.ToString());

    }, TaskContinuationOptions.OnlyOnFaulted);

    task.ContinueWith(antecedent => {

        // Remove the service
        App.Current.Dispatcher.Invoke(() =>
        {
            // Remove the model from the UI
            Services.Remove(SelectedService);
            SelectedService = null;
            // If you haven't reached this point, then you don't have a current App Dispatcher...
            AddStatus("Removed from the dispatcher");
        });

        _services.Remove(service);
    });
}

throw null;