1 // Copyright (c) 2013 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/pacing_sender.h"
6
7 namespace net {
8
PacingSender(SendAlgorithmInterface * sender,QuicTime::Delta alarm_granularity)9 PacingSender::PacingSender(SendAlgorithmInterface* sender,
10 QuicTime::Delta alarm_granularity)
11 : sender_(sender),
12 alarm_granularity_(alarm_granularity),
13 next_packet_send_time_(QuicTime::Zero()),
14 was_last_send_delayed_(false),
15 max_segment_size_(kDefaultMaxPacketSize) {
16 }
17
~PacingSender()18 PacingSender::~PacingSender() {}
19
SetMaxPacketSize(QuicByteCount max_packet_size)20 void PacingSender::SetMaxPacketSize(QuicByteCount max_packet_size) {
21 max_segment_size_ = max_packet_size;
22 sender_->SetMaxPacketSize(max_packet_size);
23 }
24
SetFromConfig(const QuicConfig & config,bool is_server)25 void PacingSender::SetFromConfig(const QuicConfig& config, bool is_server) {
26 sender_->SetFromConfig(config, is_server);
27 }
28
OnIncomingQuicCongestionFeedbackFrame(const QuicCongestionFeedbackFrame & feedback,QuicTime feedback_receive_time,const SendAlgorithmInterface::SentPacketsMap & sent_packets)29 void PacingSender::OnIncomingQuicCongestionFeedbackFrame(
30 const QuicCongestionFeedbackFrame& feedback,
31 QuicTime feedback_receive_time,
32 const SendAlgorithmInterface::SentPacketsMap& sent_packets) {
33 sender_->OnIncomingQuicCongestionFeedbackFrame(
34 feedback, feedback_receive_time, sent_packets);
35 }
36
OnPacketAcked(QuicPacketSequenceNumber acked_sequence_number,QuicByteCount acked_bytes,QuicTime::Delta rtt)37 void PacingSender::OnPacketAcked(
38 QuicPacketSequenceNumber acked_sequence_number,
39 QuicByteCount acked_bytes,
40 QuicTime::Delta rtt) {
41 sender_->OnPacketAcked(acked_sequence_number, acked_bytes, rtt);
42 }
43
OnPacketLost(QuicPacketSequenceNumber sequence_number,QuicTime ack_receive_time)44 void PacingSender::OnPacketLost(QuicPacketSequenceNumber sequence_number,
45 QuicTime ack_receive_time) {
46 sender_->OnPacketLost(sequence_number, ack_receive_time);
47 }
48
OnPacketSent(QuicTime sent_time,QuicPacketSequenceNumber sequence_number,QuicByteCount bytes,TransmissionType transmission_type,HasRetransmittableData has_retransmittable_data)49 bool PacingSender::OnPacketSent(
50 QuicTime sent_time,
51 QuicPacketSequenceNumber sequence_number,
52 QuicByteCount bytes,
53 TransmissionType transmission_type,
54 HasRetransmittableData has_retransmittable_data) {
55 // Only pace data packets.
56 if (has_retransmittable_data == HAS_RETRANSMITTABLE_DATA) {
57 // The next packet should be sent as soon as the current packets has
58 // been transferred. We pace at twice the rate of the underlying
59 // sender's bandwidth estimate to help ensure that pacing doesn't become
60 // a bottleneck.
61 const float kPacingAggression = 2;
62 QuicTime::Delta delay =
63 BandwidthEstimate().Scale(kPacingAggression).TransferTime(bytes);
64 next_packet_send_time_ = next_packet_send_time_.Add(delay);
65 }
66 return sender_->OnPacketSent(sent_time, sequence_number, bytes,
67 transmission_type, has_retransmittable_data);
68 }
69
OnRetransmissionTimeout()70 void PacingSender::OnRetransmissionTimeout() {
71 sender_->OnRetransmissionTimeout();
72 }
73
OnPacketAbandoned(QuicPacketSequenceNumber sequence_number,QuicByteCount abandoned_bytes)74 void PacingSender::OnPacketAbandoned(QuicPacketSequenceNumber sequence_number,
75 QuicByteCount abandoned_bytes) {
76 sender_->OnPacketAbandoned(sequence_number, abandoned_bytes);
77 }
78
TimeUntilSend(QuicTime now,TransmissionType transmission_type,HasRetransmittableData has_retransmittable_data,IsHandshake handshake)79 QuicTime::Delta PacingSender::TimeUntilSend(
80 QuicTime now,
81 TransmissionType transmission_type,
82 HasRetransmittableData has_retransmittable_data,
83 IsHandshake handshake) {
84 QuicTime::Delta time_until_send =
85 sender_->TimeUntilSend(now, transmission_type,
86 has_retransmittable_data, handshake);
87 if (!time_until_send.IsZero()) {
88 DCHECK(time_until_send.IsInfinite());
89 // The underlying sender prevents sending.
90 return time_until_send;
91 }
92
93 if (has_retransmittable_data == NO_RETRANSMITTABLE_DATA) {
94 // Don't pace ACK packets, since they do not count against CWND and do not
95 // cause CWND to grow.
96 return QuicTime::Delta::Zero();
97 }
98
99 if (!was_last_send_delayed_ &&
100 (!next_packet_send_time_.IsInitialized() ||
101 now > next_packet_send_time_.Add(alarm_granularity_))) {
102 // An alarm did not go off late, instead the application is "slow"
103 // delivering data. In this case, we restrict the amount of lost time
104 // that we can make up for.
105 next_packet_send_time_ = now.Subtract(alarm_granularity_);
106 }
107
108 // If the end of the epoch is far enough in the future, delay the send.
109 if (next_packet_send_time_ > now.Add(alarm_granularity_)) {
110 was_last_send_delayed_ = true;
111 DVLOG(1) << "Delaying packet: "
112 << next_packet_send_time_.Subtract(now).ToMicroseconds();
113 return next_packet_send_time_.Subtract(now);
114 }
115
116 // Sent it immediately. The epoch end will be adjusted in OnPacketSent.
117 was_last_send_delayed_ = false;
118 DVLOG(1) << "Sending packet now";
119 return QuicTime::Delta::Zero();
120 }
121
BandwidthEstimate() const122 QuicBandwidth PacingSender::BandwidthEstimate() const {
123 return sender_->BandwidthEstimate();
124 }
125
SmoothedRtt() const126 QuicTime::Delta PacingSender::SmoothedRtt() const {
127 return sender_->SmoothedRtt();
128 }
129
RetransmissionDelay() const130 QuicTime::Delta PacingSender::RetransmissionDelay() const {
131 return sender_->RetransmissionDelay();
132 }
133
GetCongestionWindow() const134 QuicByteCount PacingSender::GetCongestionWindow() const {
135 return sender_->GetCongestionWindow();
136 }
137
138 } // namespace net
139