| /* |
| * Copyright (c) 2018 The WebRTC project authors. All Rights Reserved. |
| * |
| * Use of this source code is governed by a BSD-style license |
| * that can be found in the LICENSE file in the root of the source |
| * tree. An additional intellectual property rights grant can be found |
| * in the file PATENTS. All contributing project authors may |
| * be found in the AUTHORS file in the root of the source tree. |
| */ |
| |
| #include "modules/congestion_controller/goog_cc/goog_cc_network_control.h" |
| |
| #include <stdio.h> |
| |
| #include <algorithm> |
| #include <cstdint> |
| #include <memory> |
| #include <numeric> |
| #include <optional> |
| #include <utility> |
| #include <vector> |
| |
| #include "absl/strings/string_view.h" |
| #include "api/environment/environment.h" |
| #include "api/field_trials_view.h" |
| #include "api/transport/bandwidth_usage.h" |
| #include "api/transport/network_control.h" |
| #include "api/transport/network_types.h" |
| #include "api/units/data_rate.h" |
| #include "api/units/data_size.h" |
| #include "api/units/time_delta.h" |
| #include "api/units/timestamp.h" |
| #include "logging/rtc_event_log/events/rtc_event_remote_estimate.h" |
| #include "modules/congestion_controller/goog_cc/acknowledged_bitrate_estimator_interface.h" |
| #include "modules/congestion_controller/goog_cc/alr_detector.h" |
| #include "modules/congestion_controller/goog_cc/congestion_window_pushback_controller.h" |
| #include "modules/congestion_controller/goog_cc/delay_based_bwe.h" |
| #include "modules/congestion_controller/goog_cc/loss_based_bwe_v2.h" |
| #include "modules/congestion_controller/goog_cc/probe_bitrate_estimator.h" |
| #include "modules/congestion_controller/goog_cc/probe_controller.h" |
| #include "modules/congestion_controller/goog_cc/send_side_bandwidth_estimation.h" |
| #include "modules/remote_bitrate_estimator/include/bwe_defines.h" |
| #include "rtc_base/checks.h" |
| #include "rtc_base/experiments/field_trial_parser.h" |
| #include "rtc_base/experiments/rate_control_settings.h" |
| #include "rtc_base/logging.h" |
| |
| namespace webrtc { |
| |
| namespace { |
| // From RTCPSender video report interval. |
| constexpr TimeDelta kLossUpdateInterval = TimeDelta::Millis(1000); |
| |
| // Pacing-rate relative to our target send rate. |
| // Multiplicative factor that is applied to the target bitrate to calculate |
| // the number of bytes that can be transmitted per interval. |
| // Increasing this factor will result in lower delays in cases of bitrate |
| // overshoots from the encoder. |
| constexpr float kDefaultPaceMultiplier = 2.5f; |
| |
| // If the probe result is far below the current throughput estimate |
| // it's unlikely that the probe is accurate, so we don't want to drop too far. |
| // However, if we actually are overusing, we want to drop to something slightly |
| // below the current throughput estimate to drain the network queues. |
| constexpr double kProbeDropThroughputFraction = 0.85; |
| |
| BandwidthLimitedCause GetBandwidthLimitedCause(LossBasedState loss_based_state, |
| bool is_rtt_above_limit, |
| BandwidthUsage bandwidth_usage) { |
| if (bandwidth_usage == BandwidthUsage::kBwOverusing || |
| bandwidth_usage == BandwidthUsage::kBwUnderusing) { |
| return BandwidthLimitedCause::kDelayBasedLimitedDelayIncreased; |
| } else if (is_rtt_above_limit) { |
| return BandwidthLimitedCause::kRttBasedBackOffHighRtt; |
| } |
| switch (loss_based_state) { |
| case LossBasedState::kDecreasing: |
| // Probes may not be sent in this state. |
| return BandwidthLimitedCause::kLossLimitedBwe; |
| case webrtc::LossBasedState::kIncreaseUsingPadding: |
| // Probes may not be sent in this state. |
| return BandwidthLimitedCause::kLossLimitedBwe; |
| case LossBasedState::kIncreasing: |
| // Probes may be sent in this state. |
| return BandwidthLimitedCause::kLossLimitedBweIncreasing; |
| case LossBasedState::kDelayBasedEstimate: |
| return BandwidthLimitedCause::kDelayBasedLimited; |
| } |
| } |
| |
| } // namespace |
| |
| GoogCcNetworkController::GoogCcNetworkController(NetworkControllerConfig config, |
| GoogCcConfig goog_cc_config) |
| : env_(config.env), |
| packet_feedback_only_(goog_cc_config.feedback_only), |
| safe_reset_on_route_change_("Enabled"), |
| safe_reset_acknowledged_rate_("ack"), |
| use_min_allocatable_as_lower_bound_( |
| !env_.field_trials().IsDisabled("WebRTC-Bwe-MinAllocAsLowerBound")), |
| ignore_probes_lower_than_network_estimate_( |
| !env_.field_trials().IsDisabled( |
| "WebRTC-Bwe-IgnoreProbesLowerThanNetworkStateEstimate")), |
| limit_probes_lower_than_throughput_estimate_( |
| !env_.field_trials().IsDisabled( |
| "WebRTC-Bwe-LimitProbesLowerThanThroughputEstimate")), |
| rate_control_settings_(env_.field_trials()), |
| pace_at_max_of_bwe_and_lower_link_capacity_(env_.field_trials().IsEnabled( |
| "WebRTC-Bwe-PaceAtMaxOfBweAndLowerLinkCapacity")), |
| limit_pacingfactor_by_upper_link_capacity_estimate_( |
| env_.field_trials().IsEnabled( |
| "WebRTC-Bwe-LimitPacingFactorByUpperLinkCapacityEstimate")), |
| probe_controller_( |
| new ProbeController(&env_.field_trials(), &env_.event_log())), |
| congestion_window_pushback_controller_( |
| rate_control_settings_.UseCongestionWindowPushback() |
| ? std::make_unique<CongestionWindowPushbackController>( |
| env_.field_trials()) |
| : nullptr), |
| bandwidth_estimation_( |
| std::make_unique<SendSideBandwidthEstimation>(&env_.field_trials(), |
| &env_.event_log())), |
| alr_detector_(std::make_unique<AlrDetector>(&env_.field_trials(), |
| &env_.event_log())), |
| probe_bitrate_estimator_(new ProbeBitrateEstimator(&env_.event_log())), |
| network_estimator_(std::move(goog_cc_config.network_state_estimator)), |
| network_state_predictor_( |
| std::move(goog_cc_config.network_state_predictor)), |
| delay_based_bwe_(new DelayBasedBwe(&env_.field_trials(), |
| &env_.event_log(), |
| network_state_predictor_.get())), |
| acknowledged_bitrate_estimator_( |
| AcknowledgedBitrateEstimatorInterface::Create(&env_.field_trials())), |
| initial_config_(config), |
| last_loss_based_target_rate_(*config.constraints.starting_rate), |
| last_pushback_target_rate_(last_loss_based_target_rate_), |
| last_stable_target_rate_(last_loss_based_target_rate_), |
| last_loss_base_state_(LossBasedState::kDelayBasedEstimate), |
| pacing_factor_(config.stream_based_config.pacing_factor.value_or( |
| kDefaultPaceMultiplier)), |
| min_total_allocated_bitrate_( |
| config.stream_based_config.min_total_allocated_bitrate.value_or( |
| DataRate::Zero())), |
| max_padding_rate_(config.stream_based_config.max_padding_rate.value_or( |
| DataRate::Zero())) { |
| RTC_DCHECK(config.constraints.at_time.IsFinite()); |
| ParseFieldTrial( |
| {&safe_reset_on_route_change_, &safe_reset_acknowledged_rate_}, |
| env_.field_trials().Lookup("WebRTC-Bwe-SafeResetOnRouteChange")); |
| if (delay_based_bwe_) |
| delay_based_bwe_->SetMinBitrate(kCongestionControllerMinBitrate); |
| } |
| |
| GoogCcNetworkController::~GoogCcNetworkController() {} |
| |
| NetworkControlUpdate GoogCcNetworkController::OnNetworkAvailability( |
| NetworkAvailability msg) { |
| NetworkControlUpdate update; |
| update.probe_cluster_configs = probe_controller_->OnNetworkAvailability(msg); |
| return update; |
| } |
| |
| NetworkControlUpdate GoogCcNetworkController::OnNetworkRouteChange( |
| NetworkRouteChange msg) { |
| if (safe_reset_on_route_change_) { |
| std::optional<DataRate> estimated_bitrate; |
| if (safe_reset_acknowledged_rate_) { |
| estimated_bitrate = acknowledged_bitrate_estimator_->bitrate(); |
| if (!estimated_bitrate) |
| estimated_bitrate = acknowledged_bitrate_estimator_->PeekRate(); |
| } else { |
| estimated_bitrate = bandwidth_estimation_->target_rate(); |
| } |
| if (estimated_bitrate) { |
| if (msg.constraints.starting_rate) { |
| msg.constraints.starting_rate = |
| std::min(*msg.constraints.starting_rate, *estimated_bitrate); |
| } else { |
| msg.constraints.starting_rate = estimated_bitrate; |
| } |
| } |
| } |
| |
| acknowledged_bitrate_estimator_ = |
| AcknowledgedBitrateEstimatorInterface::Create(&env_.field_trials()); |
| probe_bitrate_estimator_.reset(new ProbeBitrateEstimator(&env_.event_log())); |
| if (network_estimator_) |
| network_estimator_->OnRouteChange(msg); |
| delay_based_bwe_.reset(new DelayBasedBwe( |
| &env_.field_trials(), &env_.event_log(), network_state_predictor_.get())); |
| bandwidth_estimation_->OnRouteChange(); |
| probe_controller_->Reset(msg.at_time); |
| NetworkControlUpdate update; |
| update.probe_cluster_configs = ResetConstraints(msg.constraints); |
| MaybeTriggerOnNetworkChanged(&update, msg.at_time); |
| return update; |
| } |
| |
| NetworkControlUpdate GoogCcNetworkController::OnProcessInterval( |
| ProcessInterval msg) { |
| NetworkControlUpdate update; |
| if (initial_config_) { |
| update.probe_cluster_configs = |
| ResetConstraints(initial_config_->constraints); |
| update.pacer_config = GetPacingRates(msg.at_time); |
| |
| if (initial_config_->stream_based_config.requests_alr_probing) { |
| probe_controller_->EnablePeriodicAlrProbing( |
| *initial_config_->stream_based_config.requests_alr_probing); |
| } |
| if (initial_config_->stream_based_config.enable_repeated_initial_probing) { |
| probe_controller_->EnableRepeatedInitialProbing( |
| *initial_config_->stream_based_config |
| .enable_repeated_initial_probing); |
| } |
| std::optional<DataRate> total_bitrate = |
| initial_config_->stream_based_config.max_total_allocated_bitrate; |
| if (total_bitrate) { |
| auto probes = probe_controller_->OnMaxTotalAllocatedBitrate( |
| *total_bitrate, msg.at_time); |
| update.probe_cluster_configs.insert(update.probe_cluster_configs.end(), |
| probes.begin(), probes.end()); |
| } |
| initial_config_.reset(); |
| } |
| if (congestion_window_pushback_controller_ && msg.pacer_queue) { |
| congestion_window_pushback_controller_->UpdatePacingQueue( |
| msg.pacer_queue->bytes()); |
| } |
| bandwidth_estimation_->UpdateEstimate(msg.at_time); |
| std::optional<int64_t> start_time_ms = |
| alr_detector_->GetApplicationLimitedRegionStartTime(); |
| probe_controller_->SetAlrStartTimeMs(start_time_ms); |
| |
| auto probes = probe_controller_->Process(msg.at_time); |
| update.probe_cluster_configs.insert(update.probe_cluster_configs.end(), |
| probes.begin(), probes.end()); |
| |
| if (rate_control_settings_.UseCongestionWindow() && |
| !feedback_max_rtts_.empty()) { |
| UpdateCongestionWindowSize(); |
| } |
| if (congestion_window_pushback_controller_ && current_data_window_) { |
| congestion_window_pushback_controller_->SetDataWindow( |
| *current_data_window_); |
| } else { |
| update.congestion_window = current_data_window_; |
| } |
| MaybeTriggerOnNetworkChanged(&update, msg.at_time); |
| return update; |
| } |
| |
| NetworkControlUpdate GoogCcNetworkController::OnRemoteBitrateReport( |
| RemoteBitrateReport msg) { |
| if (packet_feedback_only_) { |
| RTC_LOG(LS_ERROR) << "Received REMB for packet feedback only GoogCC"; |
| return NetworkControlUpdate(); |
| } |
| bandwidth_estimation_->UpdateReceiverEstimate(msg.receive_time, |
| msg.bandwidth); |
| return NetworkControlUpdate(); |
| } |
| |
| NetworkControlUpdate GoogCcNetworkController::OnRoundTripTimeUpdate( |
| RoundTripTimeUpdate msg) { |
| if (packet_feedback_only_ || msg.smoothed) |
| return NetworkControlUpdate(); |
| RTC_DCHECK(!msg.round_trip_time.IsZero()); |
| if (delay_based_bwe_) |
| delay_based_bwe_->OnRttUpdate(msg.round_trip_time); |
| bandwidth_estimation_->UpdateRtt(msg.round_trip_time, msg.receive_time); |
| return NetworkControlUpdate(); |
| } |
| |
| NetworkControlUpdate GoogCcNetworkController::OnSentPacket( |
| SentPacket sent_packet) { |
| alr_detector_->OnBytesSent(sent_packet.size.bytes(), |
| sent_packet.send_time.ms()); |
| acknowledged_bitrate_estimator_->SetAlr( |
| alr_detector_->GetApplicationLimitedRegionStartTime().has_value()); |
| |
| if (!first_packet_sent_) { |
| first_packet_sent_ = true; |
| // Initialize feedback time to send time to allow estimation of RTT until |
| // first feedback is received. |
| bandwidth_estimation_->UpdatePropagationRtt(sent_packet.send_time, |
| TimeDelta::Zero()); |
| } |
| bandwidth_estimation_->OnSentPacket(sent_packet); |
| |
| if (congestion_window_pushback_controller_) { |
| congestion_window_pushback_controller_->UpdateOutstandingData( |
| sent_packet.data_in_flight.bytes()); |
| NetworkControlUpdate update; |
| MaybeTriggerOnNetworkChanged(&update, sent_packet.send_time); |
| return update; |
| } else { |
| return NetworkControlUpdate(); |
| } |
| } |
| |
| NetworkControlUpdate GoogCcNetworkController::OnReceivedPacket( |
| ReceivedPacket /* received_packet */) { |
| return NetworkControlUpdate(); |
| } |
| |
| NetworkControlUpdate GoogCcNetworkController::OnStreamsConfig( |
| StreamsConfig msg) { |
| NetworkControlUpdate update; |
| if (msg.requests_alr_probing) { |
| probe_controller_->EnablePeriodicAlrProbing(*msg.requests_alr_probing); |
| } |
| if (msg.max_total_allocated_bitrate) { |
| update.probe_cluster_configs = |
| probe_controller_->OnMaxTotalAllocatedBitrate( |
| *msg.max_total_allocated_bitrate, msg.at_time); |
| } |
| |
| bool pacing_changed = false; |
| if (msg.pacing_factor && *msg.pacing_factor != pacing_factor_) { |
| pacing_factor_ = *msg.pacing_factor; |
| pacing_changed = true; |
| } |
| if (msg.min_total_allocated_bitrate && |
| *msg.min_total_allocated_bitrate != min_total_allocated_bitrate_) { |
| min_total_allocated_bitrate_ = *msg.min_total_allocated_bitrate; |
| pacing_changed = true; |
| |
| if (use_min_allocatable_as_lower_bound_) { |
| ClampConstraints(); |
| delay_based_bwe_->SetMinBitrate(min_data_rate_); |
| bandwidth_estimation_->SetMinMaxBitrate(min_data_rate_, max_data_rate_); |
| } |
| } |
| if (msg.max_padding_rate && *msg.max_padding_rate != max_padding_rate_) { |
| max_padding_rate_ = *msg.max_padding_rate; |
| pacing_changed = true; |
| } |
| |
| if (pacing_changed) |
| update.pacer_config = GetPacingRates(msg.at_time); |
| return update; |
| } |
| |
| NetworkControlUpdate GoogCcNetworkController::OnTargetRateConstraints( |
| TargetRateConstraints constraints) { |
| NetworkControlUpdate update; |
| update.probe_cluster_configs = ResetConstraints(constraints); |
| MaybeTriggerOnNetworkChanged(&update, constraints.at_time); |
| return update; |
| } |
| |
| void GoogCcNetworkController::ClampConstraints() { |
| // TODO(holmer): We should make sure the default bitrates are set to 10 kbps, |
| // and that we don't try to set the min bitrate to 0 from any applications. |
| // The congestion controller should allow a min bitrate of 0. |
| min_data_rate_ = std::max(min_target_rate_, kCongestionControllerMinBitrate); |
| if (use_min_allocatable_as_lower_bound_) { |
| min_data_rate_ = std::max(min_data_rate_, min_total_allocated_bitrate_); |
| } |
| if (max_data_rate_ < min_data_rate_) { |
| RTC_LOG(LS_WARNING) << "max bitrate smaller than min bitrate"; |
| max_data_rate_ = min_data_rate_; |
| } |
| if (starting_rate_ && starting_rate_ < min_data_rate_) { |
| RTC_LOG(LS_WARNING) << "start bitrate smaller than min bitrate"; |
| starting_rate_ = min_data_rate_; |
| } |
| } |
| |
| std::vector<ProbeClusterConfig> GoogCcNetworkController::ResetConstraints( |
| TargetRateConstraints new_constraints) { |
| min_target_rate_ = new_constraints.min_data_rate.value_or(DataRate::Zero()); |
| max_data_rate_ = |
| new_constraints.max_data_rate.value_or(DataRate::PlusInfinity()); |
| starting_rate_ = new_constraints.starting_rate; |
| ClampConstraints(); |
| |
| bandwidth_estimation_->SetBitrates(starting_rate_, min_data_rate_, |
| max_data_rate_, new_constraints.at_time); |
| |
| if (starting_rate_) |
| delay_based_bwe_->SetStartBitrate(*starting_rate_); |
| delay_based_bwe_->SetMinBitrate(min_data_rate_); |
| |
| return probe_controller_->SetBitrates( |
| min_data_rate_, starting_rate_.value_or(DataRate::Zero()), max_data_rate_, |
| new_constraints.at_time); |
| } |
| |
| NetworkControlUpdate GoogCcNetworkController::OnTransportLossReport( |
| TransportLossReport msg) { |
| if (packet_feedback_only_) |
| return NetworkControlUpdate(); |
| int64_t total_packets_delta = |
| msg.packets_received_delta + msg.packets_lost_delta; |
| bandwidth_estimation_->UpdatePacketsLost( |
| msg.packets_lost_delta, total_packets_delta, msg.receive_time); |
| return NetworkControlUpdate(); |
| } |
| |
| void GoogCcNetworkController::UpdateCongestionWindowSize() { |
| TimeDelta min_feedback_max_rtt = TimeDelta::Millis( |
| *std::min_element(feedback_max_rtts_.begin(), feedback_max_rtts_.end())); |
| |
| const DataSize kMinCwnd = DataSize::Bytes(2 * 1500); |
| TimeDelta time_window = |
| min_feedback_max_rtt + |
| TimeDelta::Millis( |
| rate_control_settings_.GetCongestionWindowAdditionalTimeMs()); |
| |
| DataSize data_window = last_loss_based_target_rate_ * time_window; |
| if (current_data_window_) { |
| data_window = |
| std::max(kMinCwnd, (data_window + current_data_window_.value()) / 2); |
| } else { |
| data_window = std::max(kMinCwnd, data_window); |
| } |
| current_data_window_ = data_window; |
| } |
| |
| NetworkControlUpdate GoogCcNetworkController::OnTransportPacketsFeedback( |
| TransportPacketsFeedback report) { |
| if (report.packet_feedbacks.empty()) { |
| // TODO(bugs.webrtc.org/10125): Design a better mechanism to safe-guard |
| // against building very large network queues. |
| return NetworkControlUpdate(); |
| } |
| |
| if (congestion_window_pushback_controller_) { |
| congestion_window_pushback_controller_->UpdateOutstandingData( |
| report.data_in_flight.bytes()); |
| } |
| TimeDelta max_feedback_rtt = TimeDelta::MinusInfinity(); |
| TimeDelta min_propagation_rtt = TimeDelta::PlusInfinity(); |
| Timestamp max_recv_time = Timestamp::MinusInfinity(); |
| |
| std::vector<PacketResult> feedbacks = report.ReceivedWithSendInfo(); |
| for (const auto& feedback : feedbacks) |
| max_recv_time = std::max(max_recv_time, feedback.receive_time); |
| |
| for (const auto& feedback : feedbacks) { |
| TimeDelta feedback_rtt = |
| report.feedback_time - feedback.sent_packet.send_time; |
| TimeDelta min_pending_time = max_recv_time - feedback.receive_time; |
| TimeDelta propagation_rtt = feedback_rtt - min_pending_time; |
| max_feedback_rtt = std::max(max_feedback_rtt, feedback_rtt); |
| min_propagation_rtt = std::min(min_propagation_rtt, propagation_rtt); |
| } |
| |
| if (max_feedback_rtt.IsFinite()) { |
| feedback_max_rtts_.push_back(max_feedback_rtt.ms()); |
| const size_t kMaxFeedbackRttWindow = 32; |
| if (feedback_max_rtts_.size() > kMaxFeedbackRttWindow) |
| feedback_max_rtts_.pop_front(); |
| // TODO(srte): Use time since last unacknowledged packet. |
| bandwidth_estimation_->UpdatePropagationRtt(report.feedback_time, |
| min_propagation_rtt); |
| } |
| if (packet_feedback_only_) { |
| if (!feedback_max_rtts_.empty()) { |
| int64_t sum_rtt_ms = |
| std::accumulate(feedback_max_rtts_.begin(), feedback_max_rtts_.end(), |
| static_cast<int64_t>(0)); |
| int64_t mean_rtt_ms = sum_rtt_ms / feedback_max_rtts_.size(); |
| if (delay_based_bwe_) |
| delay_based_bwe_->OnRttUpdate(TimeDelta::Millis(mean_rtt_ms)); |
| } |
| |
| TimeDelta feedback_min_rtt = TimeDelta::PlusInfinity(); |
| for (const auto& packet_feedback : feedbacks) { |
| TimeDelta pending_time = max_recv_time - packet_feedback.receive_time; |
| TimeDelta rtt = report.feedback_time - |
| packet_feedback.sent_packet.send_time - pending_time; |
| // Value used for predicting NACK round trip time in FEC controller. |
| feedback_min_rtt = std::min(rtt, feedback_min_rtt); |
| } |
| if (feedback_min_rtt.IsFinite()) { |
| bandwidth_estimation_->UpdateRtt(feedback_min_rtt, report.feedback_time); |
| } |
| |
| expected_packets_since_last_loss_update_ += |
| report.PacketsWithFeedback().size(); |
| for (const auto& packet_feedback : report.PacketsWithFeedback()) { |
| if (!packet_feedback.IsReceived()) |
| lost_packets_since_last_loss_update_ += 1; |
| } |
| if (report.feedback_time > next_loss_update_) { |
| next_loss_update_ = report.feedback_time + kLossUpdateInterval; |
| bandwidth_estimation_->UpdatePacketsLost( |
| lost_packets_since_last_loss_update_, |
| expected_packets_since_last_loss_update_, report.feedback_time); |
| expected_packets_since_last_loss_update_ = 0; |
| lost_packets_since_last_loss_update_ = 0; |
| } |
| } |
| std::optional<int64_t> alr_start_time = |
| alr_detector_->GetApplicationLimitedRegionStartTime(); |
| |
| if (previously_in_alr_ && !alr_start_time.has_value()) { |
| int64_t now_ms = report.feedback_time.ms(); |
| acknowledged_bitrate_estimator_->SetAlrEndedTime(report.feedback_time); |
| probe_controller_->SetAlrEndedTimeMs(now_ms); |
| } |
| previously_in_alr_ = alr_start_time.has_value(); |
| acknowledged_bitrate_estimator_->IncomingPacketFeedbackVector( |
| report.SortedByReceiveTime()); |
| auto acknowledged_bitrate = acknowledged_bitrate_estimator_->bitrate(); |
| bandwidth_estimation_->SetAcknowledgedRate(acknowledged_bitrate, |
| report.feedback_time); |
| for (const auto& feedback : report.SortedByReceiveTime()) { |
| if (feedback.sent_packet.pacing_info.probe_cluster_id != |
| PacedPacketInfo::kNotAProbe) { |
| probe_bitrate_estimator_->HandleProbeAndEstimateBitrate(feedback); |
| } |
| } |
| |
| if (network_estimator_) { |
| network_estimator_->OnTransportPacketsFeedback(report); |
| SetNetworkStateEstimate(network_estimator_->GetCurrentEstimate()); |
| } |
| std::optional<DataRate> probe_bitrate = |
| probe_bitrate_estimator_->FetchAndResetLastEstimatedBitrate(); |
| if (ignore_probes_lower_than_network_estimate_ && probe_bitrate && |
| estimate_ && *probe_bitrate < delay_based_bwe_->last_estimate() && |
| *probe_bitrate < estimate_->link_capacity_lower) { |
| probe_bitrate.reset(); |
| } |
| if (limit_probes_lower_than_throughput_estimate_ && probe_bitrate && |
| acknowledged_bitrate) { |
| // Limit the backoff to something slightly below the acknowledged |
| // bitrate. ("Slightly below" because we want to drain the queues |
| // if we are actually overusing.) |
| // The acknowledged bitrate shouldn't normally be higher than the delay |
| // based estimate, but it could happen e.g. due to packet bursts or |
| // encoder overshoot. We use std::min to ensure that a probe result |
| // below the current BWE never causes an increase. |
| DataRate limit = |
| std::min(delay_based_bwe_->last_estimate(), |
| *acknowledged_bitrate * kProbeDropThroughputFraction); |
| probe_bitrate = std::max(*probe_bitrate, limit); |
| } |
| |
| NetworkControlUpdate update; |
| bool recovered_from_overuse = false; |
| |
| DelayBasedBwe::Result result; |
| result = delay_based_bwe_->IncomingPacketFeedbackVector( |
| report, acknowledged_bitrate, probe_bitrate, estimate_, |
| alr_start_time.has_value()); |
| |
| if (result.updated) { |
| if (result.probe) { |
| bandwidth_estimation_->SetSendBitrate(result.target_bitrate, |
| report.feedback_time); |
| } |
| // Since SetSendBitrate now resets the delay-based estimate, we have to |
| // call UpdateDelayBasedEstimate after SetSendBitrate. |
| bandwidth_estimation_->UpdateDelayBasedEstimate(report.feedback_time, |
| result.target_bitrate); |
| } |
| bandwidth_estimation_->UpdateLossBasedEstimator( |
| report, result.delay_detector_state, probe_bitrate, |
| alr_start_time.has_value()); |
| if (result.updated) { |
| // Update the estimate in the ProbeController, in case we want to probe. |
| MaybeTriggerOnNetworkChanged(&update, report.feedback_time); |
| } |
| |
| recovered_from_overuse = result.recovered_from_overuse; |
| |
| if (recovered_from_overuse) { |
| probe_controller_->SetAlrStartTimeMs(alr_start_time); |
| auto probes = probe_controller_->RequestProbe(report.feedback_time); |
| update.probe_cluster_configs.insert(update.probe_cluster_configs.end(), |
| probes.begin(), probes.end()); |
| } |
| |
| // No valid RTT could be because send-side BWE isn't used, in which case |
| // we don't try to limit the outstanding packets. |
| if (rate_control_settings_.UseCongestionWindow() && |
| max_feedback_rtt.IsFinite()) { |
| UpdateCongestionWindowSize(); |
| } |
| if (congestion_window_pushback_controller_ && current_data_window_) { |
| congestion_window_pushback_controller_->SetDataWindow( |
| *current_data_window_); |
| } else { |
| update.congestion_window = current_data_window_; |
| } |
| |
| return update; |
| } |
| |
| NetworkControlUpdate GoogCcNetworkController::OnNetworkStateEstimate( |
| NetworkStateEstimate msg) { |
| if (!network_estimator_) { |
| SetNetworkStateEstimate(msg); |
| } |
| return NetworkControlUpdate(); |
| } |
| |
| void GoogCcNetworkController::SetNetworkStateEstimate( |
| std::optional<NetworkStateEstimate> estimate) { |
| auto prev_estimate = estimate_; |
| estimate_ = estimate; |
| if (estimate_ && (!prev_estimate || |
| estimate_->update_time != prev_estimate->update_time)) { |
| env_.event_log().Log(std::make_unique<RtcEventRemoteEstimate>( |
| estimate_->link_capacity_lower, estimate_->link_capacity_upper)); |
| probe_controller_->SetNetworkStateEstimate(*estimate_); |
| } |
| } |
| |
| NetworkControlUpdate GoogCcNetworkController::GetNetworkState( |
| Timestamp at_time) const { |
| NetworkControlUpdate update; |
| update.target_rate = TargetTransferRate(); |
| update.target_rate->network_estimate.at_time = at_time; |
| update.target_rate->network_estimate.loss_rate_ratio = |
| last_estimated_fraction_loss_.value_or(0) / 255.0; |
| update.target_rate->network_estimate.round_trip_time = |
| last_estimated_round_trip_time_; |
| update.target_rate->network_estimate.bwe_period = |
| delay_based_bwe_->GetExpectedBwePeriod(); |
| |
| update.target_rate->at_time = at_time; |
| update.target_rate->target_rate = last_pushback_target_rate_; |
| update.target_rate->stable_target_rate = |
| bandwidth_estimation_->GetEstimatedLinkCapacity(); |
| update.pacer_config = GetPacingRates(at_time); |
| update.congestion_window = current_data_window_; |
| return update; |
| } |
| |
| void GoogCcNetworkController::MaybeTriggerOnNetworkChanged( |
| NetworkControlUpdate* update, |
| Timestamp at_time) { |
| uint8_t fraction_loss = bandwidth_estimation_->fraction_loss(); |
| TimeDelta round_trip_time = bandwidth_estimation_->round_trip_time(); |
| DataRate loss_based_target_rate = bandwidth_estimation_->target_rate(); |
| LossBasedState loss_based_state = bandwidth_estimation_->loss_based_state(); |
| DataRate pushback_target_rate = loss_based_target_rate; |
| |
| double cwnd_reduce_ratio = 0.0; |
| if (congestion_window_pushback_controller_) { |
| int64_t pushback_rate = |
| congestion_window_pushback_controller_->UpdateTargetBitrate( |
| loss_based_target_rate.bps()); |
| pushback_rate = std::max<int64_t>(bandwidth_estimation_->GetMinBitrate(), |
| pushback_rate); |
| pushback_target_rate = DataRate::BitsPerSec(pushback_rate); |
| if (rate_control_settings_.UseCongestionWindowDropFrameOnly()) { |
| cwnd_reduce_ratio = static_cast<double>(loss_based_target_rate.bps() - |
| pushback_target_rate.bps()) / |
| loss_based_target_rate.bps(); |
| } |
| } |
| DataRate stable_target_rate = |
| bandwidth_estimation_->GetEstimatedLinkCapacity(); |
| stable_target_rate = std::min(stable_target_rate, pushback_target_rate); |
| |
| if ((loss_based_target_rate != last_loss_based_target_rate_) || |
| (loss_based_state != last_loss_base_state_) || |
| (fraction_loss != last_estimated_fraction_loss_) || |
| (round_trip_time != last_estimated_round_trip_time_) || |
| (pushback_target_rate != last_pushback_target_rate_) || |
| (stable_target_rate != last_stable_target_rate_)) { |
| last_loss_based_target_rate_ = loss_based_target_rate; |
| last_pushback_target_rate_ = pushback_target_rate; |
| last_estimated_fraction_loss_ = fraction_loss; |
| last_estimated_round_trip_time_ = round_trip_time; |
| last_stable_target_rate_ = stable_target_rate; |
| last_loss_base_state_ = loss_based_state; |
| |
| alr_detector_->SetEstimatedBitrate(loss_based_target_rate.bps()); |
| |
| TimeDelta bwe_period = delay_based_bwe_->GetExpectedBwePeriod(); |
| |
| TargetTransferRate target_rate_msg; |
| target_rate_msg.at_time = at_time; |
| if (rate_control_settings_.UseCongestionWindowDropFrameOnly()) { |
| target_rate_msg.target_rate = loss_based_target_rate; |
| target_rate_msg.cwnd_reduce_ratio = cwnd_reduce_ratio; |
| } else { |
| target_rate_msg.target_rate = pushback_target_rate; |
| } |
| target_rate_msg.stable_target_rate = stable_target_rate; |
| target_rate_msg.network_estimate.at_time = at_time; |
| target_rate_msg.network_estimate.round_trip_time = round_trip_time; |
| target_rate_msg.network_estimate.loss_rate_ratio = fraction_loss / 255.0f; |
| target_rate_msg.network_estimate.bwe_period = bwe_period; |
| |
| update->target_rate = target_rate_msg; |
| |
| auto probes = probe_controller_->SetEstimatedBitrate( |
| loss_based_target_rate, |
| GetBandwidthLimitedCause(bandwidth_estimation_->loss_based_state(), |
| bandwidth_estimation_->IsRttAboveLimit(), |
| delay_based_bwe_->last_state()), |
| at_time); |
| update->probe_cluster_configs.insert(update->probe_cluster_configs.end(), |
| probes.begin(), probes.end()); |
| update->pacer_config = GetPacingRates(at_time); |
| RTC_LOG(LS_VERBOSE) << "bwe " << at_time.ms() << " pushback_target_bps=" |
| << last_pushback_target_rate_.bps() |
| << " estimate_bps=" << loss_based_target_rate.bps(); |
| } |
| } |
| |
| PacerConfig GoogCcNetworkController::GetPacingRates(Timestamp at_time) const { |
| // Pacing rate is based on target rate before congestion window pushback, |
| // because we don't want to build queues in the pacer when pushback occurs. |
| DataRate pacing_rate = DataRate::Zero(); |
| if (pace_at_max_of_bwe_and_lower_link_capacity_ && estimate_ && |
| !bandwidth_estimation_->PaceAtLossBasedEstimate()) { |
| pacing_rate = |
| std::max({min_total_allocated_bitrate_, estimate_->link_capacity_lower, |
| last_loss_based_target_rate_}) * |
| pacing_factor_; |
| } else { |
| pacing_rate = |
| std::max(min_total_allocated_bitrate_, last_loss_based_target_rate_) * |
| pacing_factor_; |
| } |
| if (limit_pacingfactor_by_upper_link_capacity_estimate_ && estimate_ && |
| estimate_->link_capacity_upper.IsFinite() && |
| pacing_rate > estimate_->link_capacity_upper) { |
| pacing_rate = |
| std::max({estimate_->link_capacity_upper, min_total_allocated_bitrate_, |
| last_loss_based_target_rate_}); |
| } |
| |
| DataRate padding_rate = |
| (last_loss_base_state_ == LossBasedState::kIncreaseUsingPadding) |
| ? std::max(max_padding_rate_, last_loss_based_target_rate_) |
| : max_padding_rate_; |
| padding_rate = std::min(padding_rate, last_pushback_target_rate_); |
| PacerConfig msg; |
| msg.at_time = at_time; |
| msg.time_window = TimeDelta::Seconds(1); |
| msg.data_window = pacing_rate * msg.time_window; |
| msg.pad_window = padding_rate * msg.time_window; |
| return msg; |
| } |
| |
| } // namespace webrtc |
