/// <summary>
/// This will "seems" that is working, but taking deeper look, we can see that actually an error was thrown (use the debugger).
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void MakeTeaAsyncUsingTPLNoDispatcher_OnClick(object sender, RoutedEventArgs e)
{
BeforeMakingTea();
Task.Run(async() =>
{
_finalMessage = new StringBuilder();
_finalMessage.AppendLine("Making tea started.");
_finalMessage.AppendLine(await MakeTeaAsync.MakeMeTeaAsync());
Notes.Text = _finalMessage.ToString();
});
AfterMakingTea();
}
/// <summary>
/// Will make the tea in a async way.
/// The UI thread is available again and we can perform any actions while the code is been executed somewhere else.
/// This will introduce a state machine and a continuation.
/// Once the job is done, the UI thread will update the finalMessasge text
/// And carry on with the following piece of code.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private async void MakeTeaAsynchronous_OnClick(object sender, RoutedEventArgs e)
{
// UI Thread
BeforeMakingTea();
_finalMessage = new StringBuilder();
_finalMessage.AppendLine("Making tea started.");
// Will spin a new thread and the UI thread is released from the work.
_finalMessage.AppendLine(await MakeTeaAsync.MakeMeTeaAsync());
Notes.Text = _finalMessage.ToString();
AfterMakingTea();
}
/// <summary>
/// This will crash the application
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private async void MakeTeaAsynchronousConfigureAwaitFalse_OnClick(object sender, RoutedEventArgs e)
{
BeforeMakingTea();
_finalMessage = new StringBuilder();
_finalMessage.AppendLine("Making tea started.");
// Adding ConfigureAwait false, will indicate that we don't care that the continuation been executed in a different thread.
// Because this is a UI component, we can see that we are trying to update the UI with something, and because we are
// in a different thread in the continuation, the application will crash.
_finalMessage.AppendLine(await MakeTeaAsync.MakeMeTeaAsync().ConfigureAwait(false));
Notes.Text = _finalMessage.ToString();
AfterMakingTea();
}
/// <summary>
/// This scenario will cause a Deadlock. See GiveMeStringFromAnInt() for a more info.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private async void MakeTeaAsyncDeadlock_OnClick(object sender, RoutedEventArgs e)
{
BeforeMakingTea();
try
{
_finalMessage = new StringBuilder();
_finalMessage.AppendLine("Making tea started.");
MakeTeaAsync.MakeMeTeaAsync().Wait();
// Now comment the above Wait() and try the below line instead.
// var result = MakeTeaAsync.MakeMeTeaAsync().Result;
_finalMessage.AppendLine("After calling the method async");
Notes.Text = _finalMessage.ToString();
}
catch (Exception exception)
{
Notes.Text = exception.Message;
}
AfterMakingTea();
}
/// <summary>
/// This example will achieve the same as above but without adding any async and await keyword.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void MakeTeaAsyncUsingTPLDispatcherContinuation_OnClick(object sender, RoutedEventArgs e)
{
BeforeMakingTea();
var makeTeaTask = Task.Run(async() =>
{
_finalMessage = new StringBuilder();
_finalMessage.AppendLine("Making tea started.");
_finalMessage.AppendLine(await MakeTeaAsync.MakeMeTeaAsync());
Dispatcher.Invoke(() =>
{
Notes.Text = _finalMessage.ToString();
});
});
makeTeaTask.ContinueWith(_ =>
{
Dispatcher.Invoke(AfterMakingTea);
});
}
private void MakeTeaAsyncUsingTPLCancellationSecondAttempt_OnClick(object sender, RoutedEventArgs e)
{
if (cancellationTokenSource != null)
{
// Already have an instance of the cancellation token source?
// This means the button has already been pressed!
cancellationTokenSource.Cancel();
cancellationTokenSource = null;
TplCancellationSecondButton.Content = "TPL - Cancellation 2";
return;
}
cancellationTokenSource = new CancellationTokenSource();
TplCancellationSecondButton.Content = "Cancel";
BeforeMakingTea();
var makeTeaTask = Task.Run(async() =>
{
_finalMessage = new StringBuilder();
_finalMessage.AppendLine("Making tea started.");
_finalMessage.AppendLine(await MakeTeaAsync.MakeMeTeaAsync());
Dispatcher.Invoke(() =>
{
Notes.Text = _finalMessage.ToString();
});
}, cancellationTokenSource.Token);
makeTeaTask.ContinueWith(_ =>
{
Dispatcher.Invoke(AfterMakingTea);
cancellationTokenSource = null;
TplCancellationSecondButton.Content = "TPL - Cancellation 2";
});
}
