private void AdjustWindowDynamic(int bytesConsumed, Http2Stream stream)
{
_deliveredBytes += bytesConsumed;
if (_deliveredBytes < StreamWindowThreshold)
{
return;
}
int windowUpdateIncrement = _deliveredBytes;
long currentTime = Stopwatch.GetTimestamp();
Http2Connection connection = stream.Connection;
TimeSpan rtt = connection._rttEstimator.MinRtt;
if (rtt > TimeSpan.Zero && _streamWindowSize < MaxStreamWindowSize)
{
TimeSpan dt = Stopwatch.GetElapsedTime(_lastWindowUpdate, currentTime);
// We are detecting bursts in the amount of data consumed within a single 'dt' window update period.
// The value "_deliveredBytes / dt" correlates with the bandwidth of the connection.
// We need to extend the window, if the bandwidth-delay product grows over the current window size.
// To enable empirical fine tuning, we apply a configurable multiplier (_windowScaleThresholdMultiplier) to the window size, which defaults to 1.0
//
// The condition to extend the window is:
// (_deliveredBytes / dt) * rtt > _streamWindowSize * _windowScaleThresholdMultiplier
//
// Which is reordered into the form below, to avoid the division:
if (_deliveredBytes * (double)rtt.Ticks > _streamWindowSize * dt.Ticks * WindowScaleThresholdMultiplier)
{
int extendedWindowSize = Math.Min(MaxStreamWindowSize, _streamWindowSize * 2);
windowUpdateIncrement += extendedWindowSize - _streamWindowSize;
_streamWindowSize = extendedWindowSize;
if (NetEventSource.Log.IsEnabled())
{
stream.Trace($"[FlowControl] Updated Stream Window. StreamWindowSize: {StreamWindowSize}, StreamWindowThreshold: {StreamWindowThreshold}");
}
Debug.Assert(_streamWindowSize <= MaxStreamWindowSize);
if (_streamWindowSize == MaxStreamWindowSize)
{
if (NetEventSource.Log.IsEnabled())
{
stream.Trace($"[FlowControl] StreamWindowSize reached the configured maximum of {MaxStreamWindowSize}.");
}
}
}
}
_deliveredBytes = 0;
Task sendWindowUpdateTask = connection.SendWindowUpdateAsync(stream.StreamId, windowUpdateIncrement);
connection.LogExceptions(sendWindowUpdateTask);
_lastWindowUpdate = currentTime;
}
private void AjdustWindowStatic(int bytesConsumed, Http2Stream stream)
{
_deliveredBytes += bytesConsumed;
if (_deliveredBytes < StreamWindowThreshold)
{
return;
}
int windowUpdateIncrement = _deliveredBytes;
_deliveredBytes = 0;
Http2Connection connection = stream.Connection;
Task sendWindowUpdateTask = connection.SendWindowUpdateAsync(stream.StreamId, windowUpdateIncrement);
connection.LogExceptions(sendWindowUpdateTask);
}
private void ExtendWindow(int amount)
{
Debug.Assert(amount > 0);
Debug.Assert(_pendingWindowUpdate < StreamWindowThreshold);
if (_state != StreamState.ExpectingData)
{
// We are not expecting any more data (because we've either completed or aborted).
// So no need to send any more WINDOW_UPDATEs.
return;
}
_pendingWindowUpdate += amount;
if (_pendingWindowUpdate < StreamWindowThreshold)
{
return;
}
int windowUpdateSize = _pendingWindowUpdate;
_pendingWindowUpdate = 0;
_connection.LogExceptions(_connection.SendWindowUpdateAsync(_streamId, windowUpdateSize));
}
