src/net/quic/congestion_control/pacing_sender.h

   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_config.h"
  21 #include "net/quic/quic_protocol.h"
  22 #include "net/quic/quic_time.h"
  23
  24 namespace net {
  25
  26 class NET_EXPORT_PRIVATE PacingSender : public SendAlgorithmInterface {
  27  public:
  28   // Create a PacingSender to wrap the specified sender.  |alarm_granularity|
  29   // indicates to the pacer to send that far into the future, since it should
  30   // not expect a callback before that time delta.  |initial_packet_burst| is
  31   // the number of packets sent without pacing after quiescence.
  32   PacingSender(SendAlgorithmInterface* sender,
  33                QuicTime::Delta alarm_granularity,
  34                uint32 initial_packet_burst);
  35   virtual ~PacingSender();
  36
  37   // SendAlgorithmInterface methods.
  38   virtual void SetFromConfig(const QuicConfig& config, bool is_server) OVERRIDE;
  39   virtual void OnIncomingQuicCongestionFeedbackFrame(
  40       const QuicCongestionFeedbackFrame& feedback,
  41       QuicTime feedback_receive_time) OVERRIDE;
  42   virtual void OnCongestionEvent(bool rtt_updated,
  43                                  QuicByteCount bytes_in_flight,
  44                                  const CongestionVector& acked_packets,
  45                                  const CongestionVector& lost_packets) OVERRIDE;
  46   virtual bool OnPacketSent(QuicTime sent_time,
  47                             QuicByteCount bytes_in_flight,
  48                             QuicPacketSequenceNumber sequence_number,
  49                             QuicByteCount bytes,
  50                             HasRetransmittableData is_retransmittable) OVERRIDE;
  51   virtual void OnRetransmissionTimeout(bool packets_retransmitted) OVERRIDE;
  52   virtual void RevertRetransmissionTimeout() OVERRIDE;
  53   virtual QuicTime::Delta TimeUntilSend(
  54       QuicTime now,
  55       QuicByteCount bytes_in_flight,
  56       HasRetransmittableData has_retransmittable_data) const OVERRIDE;
  57   virtual QuicBandwidth BandwidthEstimate() const OVERRIDE;
  58   virtual bool HasReliableBandwidthEstimate() const OVERRIDE;
  59   virtual QuicTime::Delta RetransmissionDelay() const OVERRIDE;
  60   virtual QuicByteCount GetCongestionWindow() const OVERRIDE;
  61   virtual bool InSlowStart() const OVERRIDE;
  62   virtual bool InRecovery() const OVERRIDE;
  63   virtual QuicByteCount GetSlowStartThreshold() const OVERRIDE;
  64   virtual CongestionControlType GetCongestionControlType() const OVERRIDE;
  65
  66  private:
  67   scoped_ptr<SendAlgorithmInterface> sender_;  // Underlying sender.
  68   QuicTime::Delta alarm_granularity_;
  69   uint32 initial_packet_burst_;
  70   mutable uint32 burst_tokens_;
  71   // Send time of the last packet considered delayed.
  72   QuicTime last_delayed_packet_sent_time_;
  73   QuicTime next_packet_send_time_;  // When can the next packet be sent.
  74   mutable bool was_last_send_delayed_;  // True when the last send was delayed.
  75   bool has_valid_rtt_;  // True if we have at least one RTT update.
  76
  77   DISALLOW_COPY_AND_ASSIGN(PacingSender);
  78 };
  79
  80 }  // namespace net
  81
  82 #endif  // NET_QUIC_CONGESTION_CONTROL_PACING_SENDER_H_