private static Task CopyResultToCompletionSourceImplContinuation <TTask, TResult>(TTask task, TaskCompletionSource <TResult> tcs, Func <TTask, TResult> resultThunk)
where TTask : Task
{
return(task.ContinueWith(innerTask =>
{
switch (innerTask.Status)
{
case TaskStatus.Canceled:
case TaskStatus.Faulted:
TaskHelpers.TrySetFromTask(tcs, innerTask);
break;
case TaskStatus.RanToCompletion:
tcs.TrySetResult(resultThunk(task));
break;
}
}, TaskContinuationOptions.ExecuteSynchronously));
}
private static Task CopyResultToCompletionSourceImpl <TTask, TResult>(this TTask task, TaskCompletionSource <TResult> tcs, Func <TTask, TResult> resultThunk)
where TTask : Task
{
// Stay on the same thread if we can
if (task.IsCompleted)
{
switch (task.Status)
{
case TaskStatus.Canceled:
case TaskStatus.Faulted:
TaskHelpers.TrySetFromTask(tcs, task);
break;
case TaskStatus.RanToCompletion:
tcs.TrySetResult(resultThunk(task));
break;
}
return(TaskHelpers.Completed());
}
// Split into a continuation method so that we don't create a closure unnecessarily
return(CopyResultToCompletionSourceImplContinuation(task, tcs, resultThunk));
}