modules/congestion_controller/send_side_congestion_controller.cc - src.git - Git at Google

 /*
  *  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 <algorithm>
 #include <memory>
 #include <vector>

 #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<webrtc::PacketFeedback> ReceivedPacketFeedbackVector(
     const std::vector<webrtc::PacketFeedback>& input) {
   std::vector<PacketFeedback> 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<webrtc::PacketFeedback>* 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<PacedSender>(clock, packet_router, event_log)),
       pacer_(owned_pacer_.get()),
       bitrate_controller_(
           BitrateController::CreateBitrateController(clock_, event_log)),
       acknowledged_bitrate_estimator_(
           rtc::MakeUnique<AcknowledgedBitrateEstimator>()),
       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<AcknowledgedBitrateEstimator>()),
       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<PacketFeedback> 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<int64_t> 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<size_t>((*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<PacketFeedback>
 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
	/*
	* 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 <algorithm>
	#include <memory>
	#include <vector>

	#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<webrtc::PacketFeedback> ReceivedPacketFeedbackVector(
	const std::vector<webrtc::PacketFeedback>& input) {
	std::vector<PacketFeedback> 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<webrtc::PacketFeedback>* 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<PacedSender>(clock, packet_router, event_log)),
	pacer_(owned_pacer_.get()),
	bitrate_controller_(
	BitrateController::CreateBitrateController(clock_, event_log)),
	acknowledged_bitrate_estimator_(
	rtc::MakeUnique<AcknowledgedBitrateEstimator>()),
	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<AcknowledgedBitrateEstimator>()),
	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<PacketFeedback> 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<int64_t> 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<size_t>((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<PacketFeedback>
	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