/* * Copyright (c) 2012 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/include/send_side_congestion_controller.h" #include #include #include #include "modules/bitrate_controller/include/bitrate_controller.h" #include "modules/congestion_controller/acknowledged_bitrate_estimator.h" #include "modules/congestion_controller/probe_controller.h" #include "modules/pacing/alr_detector.h" #include "modules/remote_bitrate_estimator/include/bwe_defines.h" #include "rtc_base/checks.h" #include "rtc_base/format_macros.h" #include "rtc_base/logging.h" #include "rtc_base/ptr_util.h" #include "rtc_base/rate_limiter.h" #include "rtc_base/socket.h" #include "rtc_base/timeutils.h" #include "system_wrappers/include/field_trial.h" namespace webrtc { namespace { const char kCwndExperiment[] = "WebRTC-CwndExperiment"; const char kPacerPushbackExperiment[] = "WebRTC-PacerPushbackExperiment"; const int64_t kDefaultAcceptedQueueMs = 250; bool CwndExperimentEnabled() { std::string experiment_string = webrtc::field_trial::FindFullName(kCwndExperiment); // The experiment is enabled iff the field trial string begins with "Enabled". return experiment_string.find("Enabled") == 0; } bool ReadCwndExperimentParameter(int64_t* accepted_queue_ms) { RTC_DCHECK(accepted_queue_ms); std::string experiment_string = webrtc::field_trial::FindFullName(kCwndExperiment); int parsed_values = sscanf(experiment_string.c_str(), "Enabled-%" PRId64, accepted_queue_ms); if (parsed_values == 1) { RTC_CHECK_GE(*accepted_queue_ms, 0) << "Accepted must be greater than or equal to 0."; return true; } return false; } static const int64_t kRetransmitWindowSizeMs = 500; // Makes sure that the bitrate and the min, max values are in valid range. static void ClampBitrates(int* bitrate_bps, int* min_bitrate_bps, int* max_bitrate_bps) { // 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. if (*min_bitrate_bps < congestion_controller::GetMinBitrateBps()) *min_bitrate_bps = congestion_controller::GetMinBitrateBps(); if (*max_bitrate_bps > 0) *max_bitrate_bps = std::max(*min_bitrate_bps, *max_bitrate_bps); if (*bitrate_bps > 0) *bitrate_bps = std::max(*min_bitrate_bps, *bitrate_bps); } std::vector ReceivedPacketFeedbackVector( const std::vector& input) { std::vector received_packet_feedback_vector; auto is_received = [](const webrtc::PacketFeedback& packet_feedback) { return packet_feedback.arrival_time_ms != webrtc::PacketFeedback::kNotReceived; }; std::copy_if(input.begin(), input.end(), std::back_inserter(received_packet_feedback_vector), is_received); return received_packet_feedback_vector; } void SortPacketFeedbackVector( std::vector* const input) { RTC_DCHECK(input); std::sort(input->begin(), input->end(), PacketFeedbackComparator()); } } // namespace SendSideCongestionController::SendSideCongestionController( const Clock* clock, Observer* observer, RtcEventLog* event_log, PacketRouter* packet_router) : clock_(clock), observer_(observer), event_log_(event_log), owned_pacer_( rtc::MakeUnique(clock, packet_router, event_log)), pacer_(owned_pacer_.get()), bitrate_controller_( BitrateController::CreateBitrateController(clock_, event_log)), acknowledged_bitrate_estimator_( rtc::MakeUnique()), probe_controller_(new ProbeController(pacer_, clock_)), retransmission_rate_limiter_( new RateLimiter(clock, kRetransmitWindowSizeMs)), transport_feedback_adapter_(clock_), last_reported_bitrate_bps_(0), last_reported_fraction_loss_(0), last_reported_rtt_(0), network_state_(kNetworkUp), pause_pacer_(false), pacer_paused_(false), min_bitrate_bps_(congestion_controller::GetMinBitrateBps()), delay_based_bwe_(new DelayBasedBwe(event_log_, clock_)), in_cwnd_experiment_(CwndExperimentEnabled()), accepted_queue_ms_(kDefaultAcceptedQueueMs), was_in_alr_(false), pacer_pushback_experiment_( webrtc::field_trial::IsEnabled(kPacerPushbackExperiment)) { delay_based_bwe_->SetMinBitrate(min_bitrate_bps_); if (in_cwnd_experiment_ && !ReadCwndExperimentParameter(&accepted_queue_ms_)) { LOG(LS_WARNING) << "Failed to parse parameters for CwndExperiment " "from field trial string. Experiment disabled."; in_cwnd_experiment_ = false; } } SendSideCongestionController::SendSideCongestionController( const Clock* clock, Observer* observer, RtcEventLog* event_log, PacedSender* pacer) : clock_(clock), observer_(observer), event_log_(event_log), pacer_(pacer), bitrate_controller_( BitrateController::CreateBitrateController(clock_, event_log)), acknowledged_bitrate_estimator_( rtc::MakeUnique()), probe_controller_(new ProbeController(pacer_, clock_)), retransmission_rate_limiter_( new RateLimiter(clock, kRetransmitWindowSizeMs)), transport_feedback_adapter_(clock_), last_reported_bitrate_bps_(0), last_reported_fraction_loss_(0), last_reported_rtt_(0), network_state_(kNetworkUp), pause_pacer_(false), pacer_paused_(false), min_bitrate_bps_(congestion_controller::GetMinBitrateBps()), delay_based_bwe_(new DelayBasedBwe(event_log_, clock_)), in_cwnd_experiment_(CwndExperimentEnabled()), accepted_queue_ms_(kDefaultAcceptedQueueMs), was_in_alr_(false), pacer_pushback_experiment_( webrtc::field_trial::IsEnabled(kPacerPushbackExperiment)) { delay_based_bwe_->SetMinBitrate(min_bitrate_bps_); if (in_cwnd_experiment_ && !ReadCwndExperimentParameter(&accepted_queue_ms_)) { LOG(LS_WARNING) << "Failed to parse parameters for CwndExperiment " "from field trial string. Experiment disabled."; in_cwnd_experiment_ = false; } } SendSideCongestionController::~SendSideCongestionController() {} void SendSideCongestionController::RegisterPacketFeedbackObserver( PacketFeedbackObserver* observer) { transport_feedback_adapter_.RegisterPacketFeedbackObserver(observer); } void SendSideCongestionController::DeRegisterPacketFeedbackObserver( PacketFeedbackObserver* observer) { transport_feedback_adapter_.DeRegisterPacketFeedbackObserver(observer); } void SendSideCongestionController::RegisterNetworkObserver(Observer* observer) { rtc::CritScope cs(&observer_lock_); RTC_DCHECK(observer_ == nullptr); observer_ = observer; } void SendSideCongestionController::DeRegisterNetworkObserver( Observer* observer) { rtc::CritScope cs(&observer_lock_); RTC_DCHECK_EQ(observer_, observer); observer_ = nullptr; } void SendSideCongestionController::SetBweBitrates(int min_bitrate_bps, int start_bitrate_bps, int max_bitrate_bps) { ClampBitrates(&start_bitrate_bps, &min_bitrate_bps, &max_bitrate_bps); bitrate_controller_->SetBitrates(start_bitrate_bps, min_bitrate_bps, max_bitrate_bps); probe_controller_->SetBitrates(min_bitrate_bps, start_bitrate_bps, max_bitrate_bps); { rtc::CritScope cs(&bwe_lock_); if (start_bitrate_bps > 0) delay_based_bwe_->SetStartBitrate(start_bitrate_bps); min_bitrate_bps_ = min_bitrate_bps; delay_based_bwe_->SetMinBitrate(min_bitrate_bps_); } MaybeTriggerOnNetworkChanged(); } // TODO(holmer): Split this up and use SetBweBitrates in combination with // OnNetworkRouteChanged. void SendSideCongestionController::OnNetworkRouteChanged( const rtc::NetworkRoute& network_route, int bitrate_bps, int min_bitrate_bps, int max_bitrate_bps) { ClampBitrates(&bitrate_bps, &min_bitrate_bps, &max_bitrate_bps); // TODO(honghaiz): Recreate this object once the bitrate controller is // no longer exposed outside SendSideCongestionController. bitrate_controller_->ResetBitrates(bitrate_bps, min_bitrate_bps, max_bitrate_bps); transport_feedback_adapter_.SetNetworkIds(network_route.local_network_id, network_route.remote_network_id); { rtc::CritScope cs(&bwe_lock_); min_bitrate_bps_ = min_bitrate_bps; delay_based_bwe_.reset(new DelayBasedBwe(event_log_, clock_)); acknowledged_bitrate_estimator_.reset(new AcknowledgedBitrateEstimator()); delay_based_bwe_->SetStartBitrate(bitrate_bps); delay_based_bwe_->SetMinBitrate(min_bitrate_bps); } probe_controller_->Reset(); probe_controller_->SetBitrates(min_bitrate_bps, bitrate_bps, max_bitrate_bps); MaybeTriggerOnNetworkChanged(); } BitrateController* SendSideCongestionController::GetBitrateController() const { return bitrate_controller_.get(); } RateLimiter* SendSideCongestionController::GetRetransmissionRateLimiter() { return retransmission_rate_limiter_.get(); } void SendSideCongestionController::EnablePeriodicAlrProbing(bool enable) { probe_controller_->EnablePeriodicAlrProbing(enable); } int64_t SendSideCongestionController::GetPacerQueuingDelayMs() const { return IsNetworkDown() ? 0 : pacer_->QueueInMs(); } int64_t SendSideCongestionController::GetFirstPacketTimeMs() const { return pacer_->FirstSentPacketTimeMs(); } TransportFeedbackObserver* SendSideCongestionController::GetTransportFeedbackObserver() { return this; } void SendSideCongestionController::SignalNetworkState(NetworkState state) { LOG(LS_INFO) << "SignalNetworkState " << (state == kNetworkUp ? "Up" : "Down"); { rtc::CritScope cs(&network_state_lock_); pause_pacer_ = state == kNetworkDown; network_state_ = state; } probe_controller_->OnNetworkStateChanged(state); MaybeTriggerOnNetworkChanged(); } void SendSideCongestionController::SetTransportOverhead( size_t transport_overhead_bytes_per_packet) { transport_feedback_adapter_.SetTransportOverhead( transport_overhead_bytes_per_packet); } void SendSideCongestionController::OnSentPacket( const rtc::SentPacket& sent_packet) { // We're not interested in packets without an id, which may be stun packets, // etc, sent on the same transport. if (sent_packet.packet_id == -1) return; transport_feedback_adapter_.OnSentPacket(sent_packet.packet_id, sent_packet.send_time_ms); if (in_cwnd_experiment_) LimitOutstandingBytes(transport_feedback_adapter_.GetOutstandingBytes()); } void SendSideCongestionController::OnRttUpdate(int64_t avg_rtt_ms, int64_t max_rtt_ms) { rtc::CritScope cs(&bwe_lock_); delay_based_bwe_->OnRttUpdate(avg_rtt_ms, max_rtt_ms); } int64_t SendSideCongestionController::TimeUntilNextProcess() { return bitrate_controller_->TimeUntilNextProcess(); } void SendSideCongestionController::Process() { bool pause_pacer; // TODO(holmer): Once this class is running on a task queue we should // replace this with a task instead. { rtc::CritScope lock(&network_state_lock_); pause_pacer = pause_pacer_; } if (pause_pacer && !pacer_paused_) { pacer_->Pause(); pacer_paused_ = true; } else if (!pause_pacer && pacer_paused_) { pacer_->Resume(); pacer_paused_ = false; } bitrate_controller_->Process(); probe_controller_->Process(); MaybeTriggerOnNetworkChanged(); } void SendSideCongestionController::AddPacket( uint32_t ssrc, uint16_t sequence_number, size_t length, const PacedPacketInfo& pacing_info) { transport_feedback_adapter_.AddPacket(ssrc, sequence_number, length, pacing_info); } void SendSideCongestionController::OnTransportFeedback( const rtcp::TransportFeedback& feedback) { RTC_DCHECK_RUNS_SERIALIZED(&worker_race_); transport_feedback_adapter_.OnTransportFeedback(feedback); std::vector feedback_vector = ReceivedPacketFeedbackVector( transport_feedback_adapter_.GetTransportFeedbackVector()); SortPacketFeedbackVector(&feedback_vector); bool currently_in_alr = pacer_->GetApplicationLimitedRegionStartTime().has_value(); if (was_in_alr_ && !currently_in_alr) { int64_t now_ms = rtc::TimeMillis(); acknowledged_bitrate_estimator_->SetAlrEndedTimeMs(now_ms); probe_controller_->SetAlrEndedTimeMs(now_ms); } was_in_alr_ = currently_in_alr; acknowledged_bitrate_estimator_->IncomingPacketFeedbackVector( feedback_vector); DelayBasedBwe::Result result; { rtc::CritScope cs(&bwe_lock_); result = delay_based_bwe_->IncomingPacketFeedbackVector( feedback_vector, acknowledged_bitrate_estimator_->bitrate_bps()); } if (result.updated) { bitrate_controller_->OnDelayBasedBweResult(result); // Update the estimate in the ProbeController, in case we want to probe. MaybeTriggerOnNetworkChanged(); } if (result.recovered_from_overuse) probe_controller_->RequestProbe(); if (in_cwnd_experiment_) LimitOutstandingBytes(transport_feedback_adapter_.GetOutstandingBytes()); } void SendSideCongestionController::LimitOutstandingBytes( size_t num_outstanding_bytes) { RTC_DCHECK(in_cwnd_experiment_); rtc::CritScope lock(&network_state_lock_); rtc::Optional min_rtt_ms = transport_feedback_adapter_.GetMinFeedbackLoopRtt(); // 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 (!min_rtt_ms) return; const size_t kMinCwndBytes = 2 * 1500; size_t max_outstanding_bytes = std::max((*min_rtt_ms + accepted_queue_ms_) * last_reported_bitrate_bps_ / 1000 / 8, kMinCwndBytes); LOG(LS_INFO) << clock_->TimeInMilliseconds() << " Outstanding bytes: " << num_outstanding_bytes << " pacer queue: " << pacer_->QueueInMs() << " max outstanding: " << max_outstanding_bytes; LOG(LS_INFO) << "Feedback rtt: " << *min_rtt_ms << " Bitrate: " << last_reported_bitrate_bps_; pause_pacer_ = num_outstanding_bytes > max_outstanding_bytes; } std::vector SendSideCongestionController::GetTransportFeedbackVector() const { RTC_DCHECK_RUNS_SERIALIZED(&worker_race_); return transport_feedback_adapter_.GetTransportFeedbackVector(); } void SendSideCongestionController::MaybeTriggerOnNetworkChanged() { uint32_t bitrate_bps; uint8_t fraction_loss; int64_t rtt; bool estimate_changed = bitrate_controller_->GetNetworkParameters( &bitrate_bps, &fraction_loss, &rtt); if (estimate_changed) { pacer_->SetEstimatedBitrate(bitrate_bps); probe_controller_->SetEstimatedBitrate(bitrate_bps); retransmission_rate_limiter_->SetMaxRate(bitrate_bps); } if (!pacer_pushback_experiment_) { bitrate_bps = IsNetworkDown() || IsSendQueueFull() ? 0 : bitrate_bps; } else { if (IsNetworkDown()) { bitrate_bps = 0; } else { int64_t queue_length_ms = pacer_->ExpectedQueueTimeMs(); if (queue_length_ms == 0) { encoding_rate_ = 1.0; } else if (queue_length_ms > 50) { float encoding_rate = 1.0 - queue_length_ms / 1000.0; encoding_rate_ = std::min(encoding_rate_, encoding_rate); encoding_rate_ = std::max(encoding_rate_, 0.0f); } bitrate_bps *= encoding_rate_; bitrate_bps = bitrate_bps < 50000 ? 0 : bitrate_bps; } } if (HasNetworkParametersToReportChanged(bitrate_bps, fraction_loss, rtt)) { int64_t probing_interval_ms; { rtc::CritScope cs(&bwe_lock_); probing_interval_ms = delay_based_bwe_->GetExpectedBwePeriodMs(); } { rtc::CritScope cs(&observer_lock_); if (observer_) { observer_->OnNetworkChanged(bitrate_bps, fraction_loss, rtt, probing_interval_ms); } } } } bool SendSideCongestionController::HasNetworkParametersToReportChanged( uint32_t bitrate_bps, uint8_t fraction_loss, int64_t rtt) { rtc::CritScope cs(&network_state_lock_); bool changed = last_reported_bitrate_bps_ != bitrate_bps || (bitrate_bps > 0 && (last_reported_fraction_loss_ != fraction_loss || last_reported_rtt_ != rtt)); if (changed && (last_reported_bitrate_bps_ == 0 || bitrate_bps == 0)) { LOG(LS_INFO) << "Bitrate estimate state changed, BWE: " << bitrate_bps << " bps."; } last_reported_bitrate_bps_ = bitrate_bps; last_reported_fraction_loss_ = fraction_loss; last_reported_rtt_ = rtt; return changed; } bool SendSideCongestionController::IsSendQueueFull() const { return pacer_->ExpectedQueueTimeMs() > PacedSender::kMaxQueueLengthMs; } bool SendSideCongestionController::IsNetworkDown() const { rtc::CritScope cs(&network_state_lock_); return network_state_ == kNetworkDown; } } // namespace webrtc