| // Copyright 2016 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef QUICHE_QUIC_CORE_CONGESTION_CONTROL_BANDWIDTH_SAMPLER_H_ |
| #define QUICHE_QUIC_CORE_CONGESTION_CONTROL_BANDWIDTH_SAMPLER_H_ |
| |
| #include "quic/core/congestion_control/send_algorithm_interface.h" |
| #include "quic/core/congestion_control/windowed_filter.h" |
| #include "quic/core/packet_number_indexed_queue.h" |
| #include "quic/core/quic_bandwidth.h" |
| #include "quic/core/quic_packet_number.h" |
| #include "quic/core/quic_packets.h" |
| #include "quic/core/quic_time.h" |
| #include "quic/core/quic_types.h" |
| #include "quic/core/quic_unacked_packet_map.h" |
| #include "quic/platform/api/quic_export.h" |
| #include "quic/platform/api/quic_flags.h" |
| #include "common/quiche_circular_deque.h" |
| |
| namespace quic { |
| |
| namespace test { |
| class BandwidthSamplerPeer; |
| } // namespace test |
| |
| // A subset of BandwidthSampler::ConnectionStateOnSentPacket which is returned |
| // to the caller when the packet is acked or lost. |
| struct QUIC_EXPORT_PRIVATE SendTimeState { |
| SendTimeState() |
| : is_valid(false), |
| is_app_limited(false), |
| total_bytes_sent(0), |
| total_bytes_acked(0), |
| total_bytes_lost(0), |
| bytes_in_flight(0) {} |
| |
| SendTimeState(bool is_app_limited, |
| QuicByteCount total_bytes_sent, |
| QuicByteCount total_bytes_acked, |
| QuicByteCount total_bytes_lost, |
| QuicByteCount bytes_in_flight) |
| : is_valid(true), |
| is_app_limited(is_app_limited), |
| total_bytes_sent(total_bytes_sent), |
| total_bytes_acked(total_bytes_acked), |
| total_bytes_lost(total_bytes_lost), |
| bytes_in_flight(bytes_in_flight) {} |
| |
| SendTimeState(const SendTimeState& other) = default; |
| SendTimeState& operator=(const SendTimeState& other) = default; |
| |
| friend QUIC_EXPORT_PRIVATE std::ostream& operator<<(std::ostream& os, |
| const SendTimeState& s); |
| |
| // Whether other states in this object is valid. |
| bool is_valid; |
| |
| // Whether the sender is app limited at the time the packet was sent. |
| // App limited bandwidth sample might be artificially low because the sender |
| // did not have enough data to send in order to saturate the link. |
| bool is_app_limited; |
| |
| // Total number of sent bytes at the time the packet was sent. |
| // Includes the packet itself. |
| QuicByteCount total_bytes_sent; |
| |
| // Total number of acked bytes at the time the packet was sent. |
| QuicByteCount total_bytes_acked; |
| |
| // Total number of lost bytes at the time the packet was sent. |
| QuicByteCount total_bytes_lost; |
| |
| // Total number of inflight bytes at the time the packet was sent. |
| // Includes the packet itself. |
| // It should be equal to |total_bytes_sent| minus the sum of |
| // |total_bytes_acked|, |total_bytes_lost| and total neutered bytes. |
| QuicByteCount bytes_in_flight; |
| }; |
| |
| struct QUIC_NO_EXPORT ExtraAckedEvent { |
| // The excess bytes acknowlwedged in the time delta for this event. |
| QuicByteCount extra_acked = 0; |
| |
| // The bytes acknowledged and time delta from the event. |
| QuicByteCount bytes_acked = 0; |
| QuicTime::Delta time_delta = QuicTime::Delta::Zero(); |
| // The round trip of the event. |
| QuicRoundTripCount round = 0; |
| |
| inline bool operator>=(const ExtraAckedEvent& other) const { |
| return extra_acked >= other.extra_acked; |
| } |
| inline bool operator==(const ExtraAckedEvent& other) const { |
| return extra_acked == other.extra_acked; |
| } |
| }; |
| |
| struct QUIC_EXPORT_PRIVATE BandwidthSample { |
| // The bandwidth at that particular sample. Zero if no valid bandwidth sample |
| // is available. |
| QuicBandwidth bandwidth = QuicBandwidth::Zero(); |
| |
| // The RTT measurement at this particular sample. Zero if no RTT sample is |
| // available. Does not correct for delayed ack time. |
| QuicTime::Delta rtt = QuicTime::Delta::Zero(); |
| |
| // |send_rate| is computed from the current packet being acked('P') and an |
| // earlier packet that is acked before P was sent. |
| QuicBandwidth send_rate = QuicBandwidth::Infinite(); |
| |
| // States captured when the packet was sent. |
| SendTimeState state_at_send; |
| }; |
| |
| // MaxAckHeightTracker is part of the BandwidthSampler. It is called after every |
| // ack event to keep track the degree of ack aggregation(a.k.a "ack height"). |
| class QUIC_EXPORT_PRIVATE MaxAckHeightTracker { |
| public: |
| explicit MaxAckHeightTracker(QuicRoundTripCount initial_filter_window) |
| : max_ack_height_filter_(initial_filter_window, ExtraAckedEvent(), 0) {} |
| |
| QuicByteCount Get() const { |
| return max_ack_height_filter_.GetBest().extra_acked; |
| } |
| |
| QuicByteCount Update(QuicBandwidth bandwidth_estimate, |
| bool is_new_max_bandwidth, |
| QuicRoundTripCount round_trip_count, |
| QuicPacketNumber last_sent_packet_number, |
| QuicPacketNumber last_acked_packet_number, |
| QuicTime ack_time, QuicByteCount bytes_acked); |
| |
| void SetFilterWindowLength(QuicRoundTripCount length) { |
| max_ack_height_filter_.SetWindowLength(length); |
| } |
| |
| void Reset(QuicByteCount new_height, QuicRoundTripCount new_time) { |
| ExtraAckedEvent new_event; |
| new_event.extra_acked = new_height; |
| new_event.round = new_time; |
| max_ack_height_filter_.Reset(new_event, new_time); |
| } |
| |
| void SetAckAggregationBandwidthThreshold(double threshold) { |
| ack_aggregation_bandwidth_threshold_ = threshold; |
| } |
| |
| void SetStartNewAggregationEpochAfterFullRound(bool value) { |
| start_new_aggregation_epoch_after_full_round_ = value; |
| } |
| |
| void SetReduceExtraAckedOnBandwidthIncrease(bool value) { |
| reduce_extra_acked_on_bandwidth_increase_ = value; |
| } |
| |
| double ack_aggregation_bandwidth_threshold() const { |
| return ack_aggregation_bandwidth_threshold_; |
| } |
| |
| uint64_t num_ack_aggregation_epochs() const { |
| return num_ack_aggregation_epochs_; |
| } |
| |
| private: |
| // Tracks the maximum number of bytes acked faster than the estimated |
| // bandwidth. |
| using MaxAckHeightFilter = |
| WindowedFilter<ExtraAckedEvent, MaxFilter<ExtraAckedEvent>, |
| QuicRoundTripCount, QuicRoundTripCount>; |
| MaxAckHeightFilter max_ack_height_filter_; |
| |
| // The time this aggregation started and the number of bytes acked during it. |
| QuicTime aggregation_epoch_start_time_ = QuicTime::Zero(); |
| QuicByteCount aggregation_epoch_bytes_ = 0; |
| // The last sent packet number before the current aggregation epoch started. |
| QuicPacketNumber last_sent_packet_number_before_epoch_; |
| // The number of ack aggregation epochs ever started, including the ongoing |
| // one. Stats only. |
| uint64_t num_ack_aggregation_epochs_ = 0; |
| double ack_aggregation_bandwidth_threshold_ = |
| GetQuicFlag(FLAGS_quic_ack_aggregation_bandwidth_threshold); |
| bool start_new_aggregation_epoch_after_full_round_ = false; |
| bool reduce_extra_acked_on_bandwidth_increase_ = false; |
| }; |
| |
| // An interface common to any class that can provide bandwidth samples from the |
| // information per individual acknowledged packet. |
| class QUIC_EXPORT_PRIVATE BandwidthSamplerInterface { |
| public: |
| virtual ~BandwidthSamplerInterface() {} |
| |
| // Inputs the sent packet information into the sampler. Assumes that all |
| // packets are sent in order. The information about the packet will not be |
| // released from the sampler until it the packet is either acknowledged or |
| // declared lost. |
| virtual void OnPacketSent( |
| QuicTime sent_time, |
| QuicPacketNumber packet_number, |
| QuicByteCount bytes, |
| QuicByteCount bytes_in_flight, |
| HasRetransmittableData has_retransmittable_data) = 0; |
| |
| virtual void OnPacketNeutered(QuicPacketNumber packet_number) = 0; |
| |
| struct QUIC_NO_EXPORT CongestionEventSample { |
| // The maximum bandwidth sample from all acked packets. |
| // QuicBandwidth::Zero() if no samples are available. |
| QuicBandwidth sample_max_bandwidth = QuicBandwidth::Zero(); |
| // Whether |sample_max_bandwidth| is from a app-limited sample. |
| bool sample_is_app_limited = false; |
| // The minimum rtt sample from all acked packets. |
| // QuicTime::Delta::Infinite() if no samples are available. |
| QuicTime::Delta sample_rtt = QuicTime::Delta::Infinite(); |
| // For each packet p in acked packets, this is the max value of INFLIGHT(p), |
| // where INFLIGHT(p) is the number of bytes acked while p is inflight. |
| QuicByteCount sample_max_inflight = 0; |
| // The send state of the largest packet in acked_packets, unless it is |
| // empty. If acked_packets is empty, it's the send state of the largest |
| // packet in lost_packets. |
| SendTimeState last_packet_send_state; |
| // The number of extra bytes acked from this ack event, compared to what is |
| // expected from the flow's bandwidth. Larger value means more ack |
| // aggregation. |
| QuicByteCount extra_acked = 0; |
| }; |
| // Notifies the sampler that at |ack_time|, all packets in |acked_packets| |
| // have been acked, and all packets in |lost_packets| have been lost. |
| // See the comments in CongestionEventSample for the return value. |
| // |max_bandwidth| is the windowed maximum observed bandwidth. |
| // |est_bandwidth_upper_bound| is an upper bound of estimated bandwidth used |
| // to calculate extra_acked. |
| virtual CongestionEventSample OnCongestionEvent( |
| QuicTime ack_time, |
| const AckedPacketVector& acked_packets, |
| const LostPacketVector& lost_packets, |
| QuicBandwidth max_bandwidth, |
| QuicBandwidth est_bandwidth_upper_bound, |
| QuicRoundTripCount round_trip_count) = 0; |
| |
| // Informs the sampler that the connection is currently app-limited, causing |
| // the sampler to enter the app-limited phase. The phase will expire by |
| // itself. |
| virtual void OnAppLimited() = 0; |
| |
| // Remove all the packets lower than the specified packet number. |
| virtual void RemoveObsoletePackets(QuicPacketNumber least_unacked) = 0; |
| |
| // Total number of bytes sent/acked/lost/neutered in the connection. |
| virtual QuicByteCount total_bytes_sent() const = 0; |
| virtual QuicByteCount total_bytes_acked() const = 0; |
| virtual QuicByteCount total_bytes_lost() const = 0; |
| virtual QuicByteCount total_bytes_neutered() const = 0; |
| |
| // Application-limited information exported for debugging. |
| virtual bool is_app_limited() const = 0; |
| |
| virtual QuicPacketNumber end_of_app_limited_phase() const = 0; |
| }; |
| |
| // BandwidthSampler keeps track of sent and acknowledged packets and outputs a |
| // bandwidth sample for every packet acknowledged. The samples are taken for |
| // individual packets, and are not filtered; the consumer has to filter the |
| // bandwidth samples itself. In certain cases, the sampler will locally severely |
| // underestimate the bandwidth, hence a maximum filter with a size of at least |
| // one RTT is recommended. |
| // |
| // This class bases its samples on the slope of two curves: the number of bytes |
| // sent over time, and the number of bytes acknowledged as received over time. |
| // It produces a sample of both slopes for every packet that gets acknowledged, |
| // based on a slope between two points on each of the corresponding curves. Note |
| // that due to the packet loss, the number of bytes on each curve might get |
| // further and further away from each other, meaning that it is not feasible to |
| // compare byte values coming from different curves with each other. |
| // |
| // The obvious points for measuring slope sample are the ones corresponding to |
| // the packet that was just acknowledged. Let us denote them as S_1 (point at |
| // which the current packet was sent) and A_1 (point at which the current packet |
| // was acknowledged). However, taking a slope requires two points on each line, |
| // so estimating bandwidth requires picking a packet in the past with respect to |
| // which the slope is measured. |
| // |
| // For that purpose, BandwidthSampler always keeps track of the most recently |
| // acknowledged packet, and records it together with every outgoing packet. |
| // When a packet gets acknowledged (A_1), it has not only information about when |
| // it itself was sent (S_1), but also the information about a previously |
| // acknowledged packet before it was sent (S_0 and A_0). |
| // |
| // Based on that data, send and ack rate are estimated as: |
| // send_rate = (bytes(S_1) - bytes(S_0)) / (time(S_1) - time(S_0)) |
| // ack_rate = (bytes(A_1) - bytes(A_0)) / (time(A_1) - time(A_0)) |
| // |
| // Here, the ack rate is intuitively the rate we want to treat as bandwidth. |
| // However, in certain cases (e.g. ack compression) the ack rate at a point may |
| // end up higher than the rate at which the data was originally sent, which is |
| // not indicative of the real bandwidth. Hence, we use the send rate as an upper |
| // bound, and the sample value is |
| // rate_sample = min(send_rate, ack_rate) |
| // |
| // An important edge case handled by the sampler is tracking the app-limited |
| // samples. There are multiple meaning of "app-limited" used interchangeably, |
| // hence it is important to understand and to be able to distinguish between |
| // them. |
| // |
| // Meaning 1: connection state. The connection is said to be app-limited when |
| // there is no outstanding data to send. This means that certain bandwidth |
| // samples in the future would not be an accurate indication of the link |
| // capacity, and it is important to inform consumer about that. Whenever |
| // connection becomes app-limited, the sampler is notified via OnAppLimited() |
| // method. |
| // |
| // Meaning 2: a phase in the bandwidth sampler. As soon as the bandwidth |
| // sampler becomes notified about the connection being app-limited, it enters |
| // app-limited phase. In that phase, all *sent* packets are marked as |
| // app-limited. Note that the connection itself does not have to be |
| // app-limited during the app-limited phase, and in fact it will not be |
| // (otherwise how would it send packets?). The boolean flag below indicates |
| // whether the sampler is in that phase. |
| // |
| // Meaning 3: a flag on the sent packet and on the sample. If a sent packet is |
| // sent during the app-limited phase, the resulting sample related to the |
| // packet will be marked as app-limited. |
| // |
| // With the terminology issue out of the way, let us consider the question of |
| // what kind of situation it addresses. |
| // |
| // Consider a scenario where we first send packets 1 to 20 at a regular |
| // bandwidth, and then immediately run out of data. After a few seconds, we send |
| // packets 21 to 60, and only receive ack for 21 between sending packets 40 and |
| // 41. In this case, when we sample bandwidth for packets 21 to 40, the S_0/A_0 |
| // we use to compute the slope is going to be packet 20, a few seconds apart |
| // from the current packet, hence the resulting estimate would be extremely low |
| // and not indicative of anything. Only at packet 41 the S_0/A_0 will become 21, |
| // meaning that the bandwidth sample would exclude the quiescence. |
| // |
| // Based on the analysis of that scenario, we implement the following rule: once |
| // OnAppLimited() is called, all sent packets will produce app-limited samples |
| // up until an ack for a packet that was sent after OnAppLimited() was called. |
| // Note that while the scenario above is not the only scenario when the |
| // connection is app-limited, the approach works in other cases too. |
| class QUIC_EXPORT_PRIVATE BandwidthSampler : public BandwidthSamplerInterface { |
| public: |
| BandwidthSampler(const QuicUnackedPacketMap* unacked_packet_map, |
| QuicRoundTripCount max_height_tracker_window_length); |
| |
| // Copy states from |other|. This is useful when changing send algorithms in |
| // the middle of a connection. |
| BandwidthSampler(const BandwidthSampler& other); |
| ~BandwidthSampler() override; |
| |
| void OnPacketSent(QuicTime sent_time, |
| QuicPacketNumber packet_number, |
| QuicByteCount bytes, |
| QuicByteCount bytes_in_flight, |
| HasRetransmittableData has_retransmittable_data) override; |
| void OnPacketNeutered(QuicPacketNumber packet_number) override; |
| |
| CongestionEventSample OnCongestionEvent( |
| QuicTime ack_time, |
| const AckedPacketVector& acked_packets, |
| const LostPacketVector& lost_packets, |
| QuicBandwidth max_bandwidth, |
| QuicBandwidth est_bandwidth_upper_bound, |
| QuicRoundTripCount round_trip_count) override; |
| QuicByteCount OnAckEventEnd(QuicBandwidth bandwidth_estimate, |
| bool is_new_max_bandwidth, |
| QuicRoundTripCount round_trip_count); |
| |
| void OnAppLimited() override; |
| |
| void RemoveObsoletePackets(QuicPacketNumber least_unacked) override; |
| |
| QuicByteCount total_bytes_sent() const override; |
| QuicByteCount total_bytes_acked() const override; |
| QuicByteCount total_bytes_lost() const override; |
| QuicByteCount total_bytes_neutered() const override; |
| |
| bool is_app_limited() const override; |
| |
| QuicPacketNumber end_of_app_limited_phase() const override; |
| |
| QuicByteCount max_ack_height() const { return max_ack_height_tracker_.Get(); } |
| |
| uint64_t num_ack_aggregation_epochs() const { |
| return max_ack_height_tracker_.num_ack_aggregation_epochs(); |
| } |
| |
| void SetMaxAckHeightTrackerWindowLength(QuicRoundTripCount length) { |
| max_ack_height_tracker_.SetFilterWindowLength(length); |
| } |
| |
| void ResetMaxAckHeightTracker(QuicByteCount new_height, |
| QuicRoundTripCount new_time) { |
| max_ack_height_tracker_.Reset(new_height, new_time); |
| } |
| |
| void SetStartNewAggregationEpochAfterFullRound(bool value) { |
| max_ack_height_tracker_.SetStartNewAggregationEpochAfterFullRound(value); |
| } |
| |
| void SetLimitMaxAckHeightTrackerBySendRate(bool value) { |
| limit_max_ack_height_tracker_by_send_rate_ = value; |
| } |
| |
| void SetReduceExtraAckedOnBandwidthIncrease(bool value) { |
| max_ack_height_tracker_.SetReduceExtraAckedOnBandwidthIncrease(value); |
| } |
| |
| // AckPoint represents a point on the ack line. |
| struct QUIC_NO_EXPORT AckPoint { |
| QuicTime ack_time = QuicTime::Zero(); |
| QuicByteCount total_bytes_acked = 0; |
| |
| friend QUIC_NO_EXPORT std::ostream& operator<<(std::ostream& os, |
| const AckPoint& ack_point) { |
| return os << ack_point.ack_time << ":" << ack_point.total_bytes_acked; |
| } |
| }; |
| |
| // RecentAckPoints maintains the most recent 2 ack points at distinct times. |
| class QUIC_NO_EXPORT RecentAckPoints { |
| public: |
| void Update(QuicTime ack_time, QuicByteCount total_bytes_acked) { |
| QUICHE_DCHECK_GE(total_bytes_acked, ack_points_[1].total_bytes_acked); |
| |
| if (ack_time < ack_points_[1].ack_time) { |
| // This can only happen when time goes backwards, we use the smaller |
| // timestamp for the most recent ack point in that case. |
| // TODO(wub): Add a QUIC_BUG if ack time stops going backwards. |
| ack_points_[1].ack_time = ack_time; |
| } else if (ack_time > ack_points_[1].ack_time) { |
| ack_points_[0] = ack_points_[1]; |
| ack_points_[1].ack_time = ack_time; |
| } |
| |
| ack_points_[1].total_bytes_acked = total_bytes_acked; |
| } |
| |
| void Clear() { ack_points_[0] = ack_points_[1] = AckPoint(); } |
| |
| const AckPoint& MostRecentPoint() const { return ack_points_[1]; } |
| |
| const AckPoint& LessRecentPoint() const { |
| if (ack_points_[0].total_bytes_acked != 0) { |
| return ack_points_[0]; |
| } |
| |
| return ack_points_[1]; |
| } |
| |
| private: |
| AckPoint ack_points_[2]; |
| }; |
| |
| void EnableOverestimateAvoidance(); |
| bool IsOverestimateAvoidanceEnabled() const { |
| return overestimate_avoidance_; |
| } |
| |
| private: |
| friend class test::BandwidthSamplerPeer; |
| |
| // ConnectionStateOnSentPacket represents the information about a sent packet |
| // and the state of the connection at the moment the packet was sent, |
| // specifically the information about the most recently acknowledged packet at |
| // that moment. |
| struct QUIC_EXPORT_PRIVATE ConnectionStateOnSentPacket { |
| // Time at which the packet is sent. |
| QuicTime sent_time; |
| |
| // Size of the packet. |
| QuicByteCount size; |
| |
| // The value of |total_bytes_sent_at_last_acked_packet_| at the time the |
| // packet was sent. |
| QuicByteCount total_bytes_sent_at_last_acked_packet; |
| |
| // The value of |last_acked_packet_sent_time_| at the time the packet was |
| // sent. |
| QuicTime last_acked_packet_sent_time; |
| |
| // The value of |last_acked_packet_ack_time_| at the time the packet was |
| // sent. |
| QuicTime last_acked_packet_ack_time; |
| |
| // Send time states that are returned to the congestion controller when the |
| // packet is acked or lost. |
| SendTimeState send_time_state; |
| |
| // Snapshot constructor. Records the current state of the bandwidth |
| // sampler. |
| // |bytes_in_flight| is the bytes in flight right after the packet is sent. |
| ConnectionStateOnSentPacket(QuicTime sent_time, |
| QuicByteCount size, |
| QuicByteCount bytes_in_flight, |
| const BandwidthSampler& sampler) |
| : sent_time(sent_time), |
| size(size), |
| total_bytes_sent_at_last_acked_packet( |
| sampler.total_bytes_sent_at_last_acked_packet_), |
| last_acked_packet_sent_time(sampler.last_acked_packet_sent_time_), |
| last_acked_packet_ack_time(sampler.last_acked_packet_ack_time_), |
| send_time_state(sampler.is_app_limited_, |
| sampler.total_bytes_sent_, |
| sampler.total_bytes_acked_, |
| sampler.total_bytes_lost_, |
| bytes_in_flight) {} |
| |
| // Default constructor. Required to put this structure into |
| // PacketNumberIndexedQueue. |
| ConnectionStateOnSentPacket() |
| : sent_time(QuicTime::Zero()), |
| size(0), |
| total_bytes_sent_at_last_acked_packet(0), |
| last_acked_packet_sent_time(QuicTime::Zero()), |
| last_acked_packet_ack_time(QuicTime::Zero()) {} |
| |
| friend QUIC_EXPORT_PRIVATE std::ostream& operator<<( |
| std::ostream& os, |
| const ConnectionStateOnSentPacket& p) { |
| os << "{sent_time:" << p.sent_time << ", size:" << p.size |
| << ", total_bytes_sent_at_last_acked_packet:" |
| << p.total_bytes_sent_at_last_acked_packet |
| << ", last_acked_packet_sent_time:" << p.last_acked_packet_sent_time |
| << ", last_acked_packet_ack_time:" << p.last_acked_packet_ack_time |
| << ", send_time_state:" << p.send_time_state << "}"; |
| return os; |
| } |
| }; |
| |
| BandwidthSample OnPacketAcknowledged(QuicTime ack_time, |
| QuicPacketNumber packet_number); |
| |
| SendTimeState OnPacketLost(QuicPacketNumber packet_number, |
| QuicPacketLength bytes_lost); |
| |
| // Copy a subset of the (private) ConnectionStateOnSentPacket to the (public) |
| // SendTimeState. Always set send_time_state->is_valid to true. |
| void SentPacketToSendTimeState(const ConnectionStateOnSentPacket& sent_packet, |
| SendTimeState* send_time_state) const; |
| |
| // Choose the best a0 from |a0_candidates_| to calculate the ack rate. |
| // |total_bytes_acked| is the total bytes acked when the packet being acked is |
| // sent. The best a0 is chosen as follows: |
| // - If there's only one candidate, use it. |
| // - If there are multiple candidates, let a[n] be the nth candidate, and |
| // a[n-1].total_bytes_acked <= |total_bytes_acked| < a[n].total_bytes_acked, |
| // use a[n-1]. |
| // - If all candidates's total_bytes_acked is > |total_bytes_acked|, use a[0]. |
| // This may happen when acks are received out of order, and ack[n] caused |
| // some candidates of ack[n-x] to be removed. |
| // - If all candidates's total_bytes_acked is <= |total_bytes_acked|, use |
| // a[a.size()-1]. |
| bool ChooseA0Point(QuicByteCount total_bytes_acked, AckPoint* a0); |
| |
| // The total number of congestion controlled bytes sent during the connection. |
| QuicByteCount total_bytes_sent_; |
| |
| // The total number of congestion controlled bytes which were acknowledged. |
| QuicByteCount total_bytes_acked_; |
| |
| // The total number of congestion controlled bytes which were lost. |
| QuicByteCount total_bytes_lost_; |
| |
| // The total number of congestion controlled bytes which have been neutered. |
| QuicByteCount total_bytes_neutered_; |
| |
| // The value of |total_bytes_sent_| at the time the last acknowledged packet |
| // was sent. Valid only when |last_acked_packet_sent_time_| is valid. |
| QuicByteCount total_bytes_sent_at_last_acked_packet_; |
| |
| // The time at which the last acknowledged packet was sent. Set to |
| // QuicTime::Zero() if no valid timestamp is available. |
| QuicTime last_acked_packet_sent_time_; |
| |
| // The time at which the most recent packet was acknowledged. |
| QuicTime last_acked_packet_ack_time_; |
| |
| // The most recently sent packet. |
| QuicPacketNumber last_sent_packet_; |
| |
| // The most recently acked packet. |
| QuicPacketNumber last_acked_packet_; |
| |
| // Indicates whether the bandwidth sampler is currently in an app-limited |
| // phase. |
| bool is_app_limited_; |
| |
| // The packet that will be acknowledged after this one will cause the sampler |
| // to exit the app-limited phase. |
| QuicPacketNumber end_of_app_limited_phase_; |
| |
| // Record of the connection state at the point where each packet in flight was |
| // sent, indexed by the packet number. |
| PacketNumberIndexedQueue<ConnectionStateOnSentPacket> connection_state_map_; |
| |
| RecentAckPoints recent_ack_points_; |
| quiche::QuicheCircularDeque<AckPoint> a0_candidates_; |
| |
| // Maximum number of tracked packets. |
| const QuicPacketCount max_tracked_packets_; |
| |
| // The main unacked packet map. Used for outputting extra debugging details. |
| // May be null. |
| // TODO(vasilvv): remove this once it's no longer useful for debugging. |
| const QuicUnackedPacketMap* unacked_packet_map_; |
| |
| // Handles the actual bandwidth calculations, whereas the outer method handles |
| // retrieving and removing |sent_packet|. |
| BandwidthSample OnPacketAcknowledgedInner( |
| QuicTime ack_time, |
| QuicPacketNumber packet_number, |
| const ConnectionStateOnSentPacket& sent_packet); |
| |
| MaxAckHeightTracker max_ack_height_tracker_; |
| QuicByteCount total_bytes_acked_after_last_ack_event_; |
| |
| // True if connection option 'BSAO' is set. |
| bool overestimate_avoidance_; |
| |
| // True if connection option 'BBRB' is set. |
| bool limit_max_ack_height_tracker_by_send_rate_; |
| }; |
| |
| } // namespace quic |
| |
| #endif // QUICHE_QUIC_CORE_CONGESTION_CONTROL_BANDWIDTH_SAMPLER_H_ |