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   ~PacingSender() override;
  36
  37   // SendAlgorithmInterface methods.
  38   void SetFromConfig(const QuicConfig& config, bool is_server) override;
  39   void SetNumEmulatedConnections(int num_connections) override;
  40   void OnCongestionEvent(bool rtt_updated,
  41                          QuicByteCount bytes_in_flight,
  42                          const CongestionVector& acked_packets,
  43                          const CongestionVector& lost_packets) override;
  44   bool OnPacketSent(QuicTime sent_time,
  45                     QuicByteCount bytes_in_flight,
  46                     QuicPacketSequenceNumber sequence_number,
  47                     QuicByteCount bytes,
  48                     HasRetransmittableData is_retransmittable) override;
  49   void OnRetransmissionTimeout(bool packets_retransmitted) override;
  50   void RevertRetransmissionTimeout() override;
  51   QuicTime::Delta TimeUntilSend(
  52       QuicTime now,
  53       QuicByteCount bytes_in_flight,
  54       HasRetransmittableData has_retransmittable_data) const override;
  55   QuicBandwidth PacingRate() const override;
  56   QuicBandwidth BandwidthEstimate() const override;
  57   bool HasReliableBandwidthEstimate() const override;
  58   QuicTime::Delta RetransmissionDelay() const override;
  59   QuicByteCount GetCongestionWindow() const override;
  60   bool InSlowStart() const override;
  61   bool InRecovery() const override;
  62   QuicByteCount GetSlowStartThreshold() const override;
  63   CongestionControlType GetCongestionControlType() const override;
  64
  65  private:
  66   scoped_ptr<SendAlgorithmInterface> sender_;  // Underlying sender.
  67   QuicTime::Delta alarm_granularity_;
  68   uint32 initial_packet_burst_;
  69   mutable uint32 burst_tokens_;
  70   // Send time of the last packet considered delayed.
  71   QuicTime last_delayed_packet_sent_time_;
  72   QuicTime next_packet_send_time_;  // When can the next packet be sent.
  73   mutable bool was_last_send_delayed_;  // True when the last send was delayed.
  74
  75   DISALLOW_COPY_AND_ASSIGN(PacingSender);
  76 };
  77
  78 }  // namespace net
  79
  80 #endif  // NET_QUIC_CONGESTION_CONTROL_PACING_SENDER_H_