public async Task <IDisposable> WaitForReadiness(CancellationToken cancellationToken)
{
await _Semafore.WaitAsync(cancellationToken);
var count = 0;
var now = _Time.GetNow();
var target = now - _TimeSpan;
LinkedListNode <DateTime> element = _TimeStamps.First, last = null;
while ((element != null) && (element.Value > target))
{
last = element;
element = element.Next;
count++;
}
if (count < _Count)
{
return(new DisposeAction(OnEnded));
}
Debug.Assert(element == null);
Debug.Assert(last != null);
var timetoWait = last.Value.Add(_TimeSpan) - now;
try
{
await _Time.GetDelay(timetoWait, cancellationToken);
}
catch (Exception)
{
_Semafore.Release();
throw;
}
return(new DisposeAction(OnEnded));
}