public static Task FromCanceled(CancellationToken cancellationToken)
{
return(TaskEx.FromCanceled(cancellationToken));
}
public static Task <TResult> FromCanceled <TResult>(CancellationToken cancellationToken)
{
return(TaskEx.FromCanceled <TResult>(cancellationToken));
}
/// <summary>
/// Creates a Task that will complete after a time delay.
/// </summary>
/// <param name="millisecondsDelay">The number of milliseconds to wait before completing the returned Task</param>
/// <param name="cancellationToken">The cancellation token that will be checked prior to completing the returned Task</param>
/// <returns>A Task that represents the time delay</returns>
/// <exception cref="T:System.ArgumentOutOfRangeException">
/// The <paramref name="millisecondsDelay" /> is less than -1.
/// </exception>
/// <exception cref="T:System.ObjectDisposedException">
/// The provided <paramref name="cancellationToken" /> has already been disposed.
/// </exception>
/// <remarks>
/// If the cancellation token is signaled before the specified time delay, then the Task is completed in
/// Canceled state. Otherwise, the Task is completed in RanToCompletion state once the specified time
/// delay has expired.
/// </remarks>
public static Task Delay(int millisecondsDelay, CancellationToken cancellationToken)
{
// Throw on non-sensical time
if (millisecondsDelay < -1)
{
throw new ArgumentOutOfRangeException(nameof(millisecondsDelay), "The value needs to be either -1 (signifying an infinite timeout), 0 or a positive integer.");
}
Contract.EndContractBlock();
// some short-cuts in case quick completion is in order
if (cancellationToken.IsCancellationRequested)
{
// return a Task created as already-Canceled
return(TaskEx.FromCanceled(cancellationToken));
}
if (millisecondsDelay == 0)
{
// return a Task created as already-RanToCompletion
return(TaskEx.CompletedTask);
}
var source = new TaskCompletionSource <bool>();
if (millisecondsDelay > 0)
{
var timeout = RootedTimeout.Launch
(
() =>
{
try
{
source.SetResult(true);
}
catch (InvalidOperationException exception)
{
// Already canceled
No.Op(exception);
}
},
millisecondsDelay,
cancellationToken
);
source.Task.SetPromiseCheck(() => timeout.CheckRemaining());
}
if (cancellationToken.CanBeCanceled)
{
cancellationToken.Register
(
() =>
{
try
{
source.SetCanceled();
}
catch (InvalidOperationException exception)
{
// Already timed out
No.Op(exception);
}
}
);
}
return(source.Task);
}