pacing_sender.h revision a3f6a49ab37290eeeb8db0f41ec0f1cb74a68be7 
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// A send algorithm which adds pacing on top of an another send algorithm.
6// It uses the underlying sender's bandwidth estimate to determine the
7// pacing rate to be used.  It also takes into consideration the expected
8// resolution of the underlying alarm mechanism to ensure that alarms are
9// not set too aggressively, and to smooth out variations.
10
11#ifndef NET_QUIC_CONGESTION_CONTROL_PACING_SENDER_H_
12#define NET_QUIC_CONGESTION_CONTROL_PACING_SENDER_H_
13
14#include <map>
15
16#include "base/basictypes.h"
17#include "base/memory/scoped_ptr.h"
18#include "net/quic/congestion_control/send_algorithm_interface.h"
19#include "net/quic/quic_bandwidth.h"
20#include "net/quic/quic_clock.h"
21#include "net/quic/quic_config.h"
22#include "net/quic/quic_protocol.h"
23#include "net/quic/quic_time.h"
24
25namespace net {
26
27class NET_EXPORT_PRIVATE PacingSender : public SendAlgorithmInterface {
28 public:
29  PacingSender(SendAlgorithmInterface* sender,
30               QuicTime::Delta alarm_granularity);
31  virtual ~PacingSender();
32
33  // SendAlgorithmInterface methods.
34  virtual void SetFromConfig(const QuicConfig& config, bool is_server) OVERRIDE;
35  virtual void SetMaxPacketSize(QuicByteCount max_packet_size) OVERRIDE;
36  virtual void OnIncomingQuicCongestionFeedbackFrame(
37      const QuicCongestionFeedbackFrame& feedback,
38      QuicTime feedback_receive_time,
39      const SendAlgorithmInterface::SentPacketsMap& sent_packets) OVERRIDE;
40  virtual void OnPacketAcked(QuicPacketSequenceNumber acked_sequence_number,
41                             QuicByteCount acked_bytes,
42                             QuicTime::Delta rtt) OVERRIDE;
43  virtual void OnPacketLost(QuicPacketSequenceNumber sequence_number,
44                            QuicTime ack_receive_time) OVERRIDE;
45  virtual bool OnPacketSent(QuicTime sent_time,
46                            QuicPacketSequenceNumber sequence_number,
47                            QuicByteCount bytes,
48                            TransmissionType transmission_type,
49                            HasRetransmittableData is_retransmittable) OVERRIDE;
50  virtual void OnRetransmissionTimeout() OVERRIDE;
51  virtual void OnPacketAbandoned(QuicPacketSequenceNumber sequence_number,
52                                 QuicByteCount abandoned_bytes) OVERRIDE;
53  virtual QuicTime::Delta TimeUntilSend(
54      QuicTime now,
55      TransmissionType transmission_type,
56      HasRetransmittableData has_retransmittable_data,
57      IsHandshake handshake) OVERRIDE;
58  virtual QuicBandwidth BandwidthEstimate() const OVERRIDE;
59  virtual QuicTime::Delta SmoothedRtt() const OVERRIDE;
60  virtual QuicTime::Delta RetransmissionDelay() const OVERRIDE;
61  virtual QuicByteCount GetCongestionWindow() const OVERRIDE;
62
63 private:
64  QuicTime::Delta GetTransferTime(QuicByteCount bytes);
65
66  scoped_ptr<SendAlgorithmInterface> sender_;  // Underlying sender.
67  QuicTime::Delta alarm_granularity_;
68  QuicTime next_packet_send_time_;  // When can the next packet be sent.
69  bool was_last_send_delayed_;  // True when the last send was delayed.
70  QuicByteCount max_segment_size_;
71
72  DISALLOW_COPY_AND_ASSIGN(PacingSender);
73};
74
75}  // namespace net
76
77#endif  // NET_QUIC_CONGESTION_CONTROL_PACING_SENDER_H_
78