1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "net/quic/congestion_control/paced_sender.h" 6 7 #include <algorithm> 8 9 #include "net/quic/quic_protocol.h" 10 11 namespace net { 12 13 // To prevent too aggressive pacing we allow the following packet burst size. 14 const int64 kMinPacketBurstSize = 2; 15 // Max estimated time between calls to TimeUntilSend and 16 // AvailableCongestionWindow. 17 const int64 kMaxSchedulingDelayUs = 2000; 18 19 PacedSender::PacedSender(QuicBandwidth estimate, QuicByteCount max_segment_size) 20 : leaky_bucket_(estimate), 21 pace_(estimate), 22 max_segment_size_(kDefaultMaxPacketSize) { 23 } 24 25 void PacedSender::set_max_segment_size(QuicByteCount max_segment_size) { 26 max_segment_size_ = max_segment_size; 27 } 28 29 void PacedSender::UpdateBandwidthEstimate(QuicTime now, 30 QuicBandwidth estimate) { 31 leaky_bucket_.SetDrainingRate(now, estimate); 32 pace_ = estimate; 33 } 34 35 void PacedSender::OnPacketSent(QuicTime now, QuicByteCount bytes) { 36 leaky_bucket_.Add(now, bytes); 37 } 38 39 QuicTime::Delta PacedSender::TimeUntilSend(QuicTime now, 40 QuicTime::Delta time_until_send) { 41 if (time_until_send.ToMicroseconds() >= kMaxSchedulingDelayUs) { 42 return time_until_send; 43 } 44 // Pace the data. 45 QuicByteCount pacing_window = pace_.ToBytesPerPeriod( 46 QuicTime::Delta::FromMicroseconds(kMaxSchedulingDelayUs)); 47 QuicByteCount min_window_size = kMinPacketBurstSize * max_segment_size_; 48 pacing_window = std::max(pacing_window, min_window_size); 49 50 if (pacing_window > leaky_bucket_.BytesPending(now)) { 51 // We have not filled our pacing window yet. 52 return time_until_send; 53 } 54 return leaky_bucket_.TimeRemaining(now); 55 } 56 57 } // namespace net 58
