protected async Task WaitForIdleAsync(IExpeditableDelaySource expeditableDelaySource)
{
while (true)
{
if (CancellationToken.IsCancellationRequested)
{
return;
}
var diffInMS = Environment.TickCount - _lastAccessTimeInMS;
if (diffInMS >= BackOffTimeSpanInMS)
{
return;
}
// TODO: will safestart/unwarp capture cancellation exception?
var timeLeft = BackOffTimeSpanInMS - diffInMS;
if (!await expeditableDelaySource.Delay(TimeSpan.FromMilliseconds(Math.Max(MinimumDelayInMS, timeLeft)), CancellationToken).ConfigureAwait(false))
{
// The delay terminated early to accommodate a blocking operation. Make sure to delay long
// enough that low priority (on idle) operations get a chance to be triggered.
//
// 📝 At the time this was discovered, it was not clear exactly why the delay was needed in order
// to avoid live-lock scenarios.
await Task.Delay(TimeSpan.FromMilliseconds(10), CancellationToken).ConfigureAwait(false);
return;
}
}
}
protected async Task WaitForIdleAsync(IExpeditableDelaySource expeditableDelaySource)
{
while (true)
{
if (CancellationToken.IsCancellationRequested)
{
return;
}
var diff = _timeSinceLastAccess.Elapsed;
if (diff >= BackOffTimeSpan)
{
return;
}
// TODO: will safestart/unwarp capture cancellation exception?
var timeLeft = BackOffTimeSpan - diff;
if (!await expeditableDelaySource.Delay(TimeSpan.FromMilliseconds(Math.Max(s_minimumDelay.TotalMilliseconds, timeLeft.TotalMilliseconds)), CancellationToken).ConfigureAwait(false))
{
// The delay terminated early to accommodate a blocking operation. Make sure to yield so low
// priority (on idle) operations get a chance to be triggered.
//
// 📝 At the time this was discovered, it was not clear exactly why the yield (previously delay)
// was needed in order to avoid live-lock scenarios.
await Task.Yield().ConfigureAwait(false);
return;
}
}
}
private async Task StartTimerAsync(bool continueOnCapturedContext)
{
do
{
// Keep delaying until at least delayInMilliseconds has elapsed since lastSetTime
if (!await _expeditableDelaySource.Delay(TimeSpan.FromMilliseconds(_delayInMilliseconds), CancellationToken.None).ConfigureAwait(continueOnCapturedContext))
{
// The operation is being expedited.
break;
}
}while (Environment.TickCount - _lastSetTime < _delayInMilliseconds);
_taskCompletionSource.SetResult(null);
}
