Land Recent QUIC Changes.

net/quic/congestion_control/pacing_sender.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/congestion_control/pacing_sender.h"
 
 namespace net {
 
 PacingSender::PacingSender(SendAlgorithmInterface* sender,
                            QuicTime::Delta alarm_granularity,
@@ skipping 23 matching lines @@
       feedback, feedback_receive_time);
 }
 
 void PacingSender::OnCongestionEvent(bool rtt_updated,
                                      QuicByteCount bytes_in_flight,
                                      const CongestionMap& acked_packets,
                                      const CongestionMap& lost_packets) {
   if (rtt_updated) {
     has_valid_rtt_ = true;
   }
-  if (bytes_in_flight == 0) {
-    // Add more burst tokens anytime the connection is entering quiescence.
-    burst_tokens_ = initial_packet_burst_;
-  }
   sender_->OnCongestionEvent(
       rtt_updated, bytes_in_flight, acked_packets, lost_packets);
 }
 
 bool PacingSender::OnPacketSent(
     QuicTime sent_time,
     QuicByteCount bytes_in_flight,
     QuicPacketSequenceNumber sequence_number,
     QuicByteCount bytes,
     HasRetransmittableData has_retransmittable_data) {
   // Only pace data packets once we have an updated RTT.
   const bool in_flight =
       sender_->OnPacketSent(sent_time, bytes_in_flight, sequence_number,
                             bytes, has_retransmittable_data);
   if (has_retransmittable_data != HAS_RETRANSMITTABLE_DATA || !has_valid_rtt_) {
     return in_flight;
   }
   if (burst_tokens_ > 0) {
     --burst_tokens_;
     was_last_send_delayed_ = false;
     last_delayed_packet_sent_time_ = QuicTime::Zero();
     next_packet_send_time_ = QuicTime::Zero();
     return in_flight;
   }
   // The next packet should be sent as soon as the current packets has
   // been transferred.  We pace at twice the rate of the underlying
-  // sender's bandwidth estimate to help ensure that pacing doesn't become
-  // a bottleneck.
-  const float kPacingAggression = 2;
+  // sender's bandwidth estimate during slow start and 1.25x during congestion
+  // avoidance to ensure pacing doesn't prevent us from filling the window.
+  const float kPacingAggression = sender_->InSlowStart() ? 2 : 1.25;
   QuicTime::Delta delay =
       BandwidthEstimate().Scale(kPacingAggression).TransferTime(bytes);
   // If the last send was delayed, and the alarm took a long time to get
   // invoked, allow the connection to make up for lost time.
   if (was_last_send_delayed_) {
     next_packet_send_time_ = next_packet_send_time_.Add(delay);
     // The send was application limited if it takes longer than the
     // pacing delay between sent packets.
     const bool application_limited =
         last_delayed_packet_sent_time_.IsInitialized() &&
@@ skipping 27 matching lines @@
 QuicTime::Delta PacingSender::TimeUntilSend(
       QuicTime now,
       QuicByteCount bytes_in_flight,
       HasRetransmittableData has_retransmittable_data) const {
   QuicTime::Delta time_until_send =
       sender_->TimeUntilSend(now, bytes_in_flight, has_retransmittable_data);
   if (!has_valid_rtt_) {
     // Don't pace if we don't have an updated RTT estimate.
     return time_until_send;
   }
+  if (bytes_in_flight == 0) {
+    // Add more burst tokens anytime the connection is entering quiescence.
+    burst_tokens_ = initial_packet_burst_;
+  }
   if (burst_tokens_ > 0) {
     // Don't pace if we have burst tokens available.
     return time_until_send;
   }
 
   if (!time_until_send.IsZero()) {
     DCHECK(time_until_send.IsInfinite());
     // The underlying sender prevents sending.
     return time_until_send;
   }
@@ skipping 25 matching lines @@
 }
 
 QuicTime::Delta PacingSender::RetransmissionDelay() const {
   return sender_->RetransmissionDelay();
 }
 
 QuicByteCount PacingSender::GetCongestionWindow() const {
   return sender_->GetCongestionWindow();
 }
 
+bool PacingSender::InSlowStart() const {
+  return sender_->InSlowStart();
+}
+
+QuicByteCount PacingSender::GetSlowStartThreshold() const {
+  return sender_->GetSlowStartThreshold();
+}
+
 }  // namespace net