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      1 // Copyright (c) 2012 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 // The pure virtual class for send side congestion control algorithm.
      6 
      7 #ifndef NET_QUIC_CONGESTION_CONTROL_SEND_ALGORITHM_INTERFACE_H_
      8 #define NET_QUIC_CONGESTION_CONTROL_SEND_ALGORITHM_INTERFACE_H_
      9 
     10 #include <algorithm>
     11 #include <map>
     12 
     13 #include "base/basictypes.h"
     14 #include "net/base/net_export.h"
     15 #include "net/quic/quic_bandwidth.h"
     16 #include "net/quic/quic_clock.h"
     17 #include "net/quic/quic_config.h"
     18 #include "net/quic/quic_connection_stats.h"
     19 #include "net/quic/quic_protocol.h"
     20 #include "net/quic/quic_time.h"
     21 
     22 namespace net {
     23 
     24 class RttStats;
     25 
     26 class NET_EXPORT_PRIVATE SendAlgorithmInterface {
     27  public:
     28   typedef std::map<QuicPacketSequenceNumber, TransmissionInfo> CongestionMap;
     29 
     30   static SendAlgorithmInterface* Create(const QuicClock* clock,
     31                                         const RttStats* rtt_stats,
     32                                         CongestionFeedbackType type,
     33                                         QuicConnectionStats* stats);
     34 
     35   virtual ~SendAlgorithmInterface() {}
     36 
     37   virtual void SetFromConfig(const QuicConfig& config, bool is_server) = 0;
     38 
     39   // Called when we receive congestion feedback from remote peer.
     40   virtual void OnIncomingQuicCongestionFeedbackFrame(
     41       const QuicCongestionFeedbackFrame& feedback,
     42       QuicTime feedback_receive_time) = 0;
     43 
     44   // Indicates an update to the congestion state, caused either by an incoming
     45   // ack or loss event timeout.  |rtt_updated| indicates whether a new
     46   // latest_rtt sample has been taken, |byte_in_flight| the bytes in flight
     47   // prior to the congestion event.  |acked_packets| and |lost_packets| are
     48   // any packets considered acked or lost as a result of the congestion event.
     49   virtual void OnCongestionEvent(bool rtt_updated,
     50                                  QuicByteCount bytes_in_flight,
     51                                  const CongestionMap& acked_packets,
     52                                  const CongestionMap& lost_packets) = 0;
     53 
     54   // Inform that we sent |bytes| to the wire, and if the packet is
     55   // retransmittable. Returns true if the packet should be tracked by the
     56   // congestion manager and included in bytes_in_flight, false otherwise.
     57   // |bytes_in_flight| is the number of bytes in flight before the packet was
     58   // sent.
     59   // Note: this function must be called for every packet sent to the wire.
     60   virtual bool OnPacketSent(QuicTime sent_time,
     61                             QuicByteCount bytes_in_flight,
     62                             QuicPacketSequenceNumber sequence_number,
     63                             QuicByteCount bytes,
     64                             HasRetransmittableData is_retransmittable) = 0;
     65 
     66   // Called when the retransmission timeout fires.  Neither OnPacketAbandoned
     67   // nor OnPacketLost will be called for these packets.
     68   virtual void OnRetransmissionTimeout(bool packets_retransmitted) = 0;
     69 
     70   // Calculate the time until we can send the next packet.
     71   virtual QuicTime::Delta TimeUntilSend(
     72       QuicTime now,
     73       QuicByteCount bytes_in_flight,
     74       HasRetransmittableData has_retransmittable_data) const = 0;
     75 
     76   // What's the current estimated bandwidth in bytes per second.
     77   // Returns 0 when it does not have an estimate.
     78   virtual QuicBandwidth BandwidthEstimate() const = 0;
     79 
     80   // Get the send algorithm specific retransmission delay, called RTO in TCP,
     81   // Note 1: the caller is responsible for sanity checking this value.
     82   // Note 2: this will return zero if we don't have enough data for an estimate.
     83   virtual QuicTime::Delta RetransmissionDelay() const = 0;
     84 
     85   // Returns the size of the current congestion window in bytes.  Note, this is
     86   // not the *available* window.  Some send algorithms may not use a congestion
     87   // window and will return 0.
     88   virtual QuicByteCount GetCongestionWindow() const = 0;
     89 };
     90 
     91 }  // namespace net
     92 
     93 #endif  // NET_QUIC_CONGESTION_CONTROL_SEND_ALGORITHM_INTERFACE_H_
     94