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 that adds pacing on top of an another send algorithm.
   6 // It uses the underlying sender's pacing rate to schedule packets.
   7 // It also takes into consideration the expected granularity of the underlying
   8 // alarm to ensure that alarms are not set too aggressively, and err towards
   9 // sending packets too early instead of too late.
  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/crypto/cached_network_parameters.h"
  20 #include "net/quic/quic_bandwidth.h"
  21 #include "net/quic/quic_config.h"
  22 #include "net/quic/quic_protocol.h"
  23 #include "net/quic/quic_time.h"
  24
  25 namespace net {
  26
  27 class NET_EXPORT_PRIVATE PacingSender : public SendAlgorithmInterface {
  28  public:
  29   // Create a PacingSender to wrap the specified sender.  |alarm_granularity|
  30   // indicates to the pacer to send that far into the future, since it should
  31   // not expect a callback before that time delta.  |initial_packet_burst| is
  32   // the number of packets sent without pacing after quiescence.
  33   PacingSender(SendAlgorithmInterface* sender,
  34                QuicTime::Delta alarm_granularity,
  35                uint32 initial_packet_burst);
  36   ~PacingSender() override;
  37
  38   // SendAlgorithmInterface methods.
  39   void SetFromConfig(const QuicConfig& config,
  40                      bool is_server,
  41                      bool using_pacing) override;
  42   bool ResumeConnectionState(
  43       const CachedNetworkParameters& cached_network_params) override;
  44   void SetNumEmulatedConnections(int num_connections) override;
  45   void OnCongestionEvent(bool rtt_updated,
  46                          QuicByteCount bytes_in_flight,
  47                          const CongestionVector& acked_packets,
  48                          const CongestionVector& lost_packets) override;
  49   bool OnPacketSent(QuicTime sent_time,
  50                     QuicByteCount bytes_in_flight,
  51                     QuicPacketSequenceNumber sequence_number,
  52                     QuicByteCount bytes,
  53                     HasRetransmittableData is_retransmittable) override;
  54   void OnRetransmissionTimeout(bool packets_retransmitted) override;
  55   void RevertRetransmissionTimeout() override;
  56   QuicTime::Delta TimeUntilSend(
  57       QuicTime now,
  58       QuicByteCount bytes_in_flight,
  59       HasRetransmittableData has_retransmittable_data) const override;
  60   QuicBandwidth PacingRate() const override;
  61   QuicBandwidth BandwidthEstimate() const override;
  62   bool HasReliableBandwidthEstimate() const override;
  63   QuicTime::Delta RetransmissionDelay() const override;
  64   QuicByteCount GetCongestionWindow() const override;
  65   bool InSlowStart() const override;
  66   bool InRecovery() const override;
  67   QuicByteCount GetSlowStartThreshold() const override;
  68   CongestionControlType GetCongestionControlType() const override;
  69   // End implementation of SendAlgorithmInterface.
  70
  71  private:
  72   scoped_ptr<SendAlgorithmInterface> sender_;  // Underlying sender.
  73   // The estimated system alarm granularity.
  74   const QuicTime::Delta alarm_granularity_;
  75   // Configured size of the burst coming out of quiescence.
  76   const uint32 initial_packet_burst_;
  77   // Number of unpaced packets to be sent before packets are delayed.
  78   uint32 burst_tokens_;
  79   // Send time of the last packet considered delayed.
  80   QuicTime last_delayed_packet_sent_time_;
  81   QuicTime ideal_next_packet_send_time_;  // When can the next packet be sent.
  82   mutable bool was_last_send_delayed_;  // True when the last send was delayed.
  83
  84   DISALLOW_COPY_AND_ASSIGN(PacingSender);
  85 };
  86
  87 }  // namespace net
  88
  89 #endif  // NET_QUIC_CONGESTION_CONTROL_PACING_SENDER_H_