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a42055116d
Implemented behind the field trial "WebRTC-PacerPushbackExperiment/Enabled/" BUG=webrtc:8171, webrtc:8287 Review-Url: https://codereview.webrtc.org/3004783002 Cr-Commit-Position: refs/heads/master@{#19969}
489 lines
18 KiB
C++
489 lines
18 KiB
C++
/*
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* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "modules/congestion_controller/include/send_side_congestion_controller.h"
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#include <algorithm>
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#include <memory>
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#include <vector>
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#include "modules/bitrate_controller/include/bitrate_controller.h"
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#include "modules/congestion_controller/acknowledged_bitrate_estimator.h"
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#include "modules/congestion_controller/probe_controller.h"
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#include "modules/pacing/alr_detector.h"
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#include "modules/remote_bitrate_estimator/include/bwe_defines.h"
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#include "rtc_base/checks.h"
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#include "rtc_base/format_macros.h"
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#include "rtc_base/logging.h"
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#include "rtc_base/ptr_util.h"
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#include "rtc_base/rate_limiter.h"
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#include "rtc_base/socket.h"
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#include "rtc_base/timeutils.h"
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#include "system_wrappers/include/field_trial.h"
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namespace webrtc {
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namespace {
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const char kCwndExperiment[] = "WebRTC-CwndExperiment";
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const char kPacerPushbackExperiment[] = "WebRTC-PacerPushbackExperiment";
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const int64_t kDefaultAcceptedQueueMs = 250;
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bool CwndExperimentEnabled() {
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std::string experiment_string =
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webrtc::field_trial::FindFullName(kCwndExperiment);
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// The experiment is enabled iff the field trial string begins with "Enabled".
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return experiment_string.find("Enabled") == 0;
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}
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bool ReadCwndExperimentParameter(int64_t* accepted_queue_ms) {
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RTC_DCHECK(accepted_queue_ms);
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std::string experiment_string =
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webrtc::field_trial::FindFullName(kCwndExperiment);
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int parsed_values =
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sscanf(experiment_string.c_str(), "Enabled-%" PRId64, accepted_queue_ms);
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if (parsed_values == 1) {
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RTC_CHECK_GE(*accepted_queue_ms, 0)
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<< "Accepted must be greater than or equal to 0.";
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return true;
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}
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return false;
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}
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static const int64_t kRetransmitWindowSizeMs = 500;
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// Makes sure that the bitrate and the min, max values are in valid range.
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static void ClampBitrates(int* bitrate_bps,
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int* min_bitrate_bps,
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int* max_bitrate_bps) {
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// TODO(holmer): We should make sure the default bitrates are set to 10 kbps,
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// and that we don't try to set the min bitrate to 0 from any applications.
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// The congestion controller should allow a min bitrate of 0.
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if (*min_bitrate_bps < congestion_controller::GetMinBitrateBps())
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*min_bitrate_bps = congestion_controller::GetMinBitrateBps();
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if (*max_bitrate_bps > 0)
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*max_bitrate_bps = std::max(*min_bitrate_bps, *max_bitrate_bps);
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if (*bitrate_bps > 0)
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*bitrate_bps = std::max(*min_bitrate_bps, *bitrate_bps);
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}
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std::vector<webrtc::PacketFeedback> ReceivedPacketFeedbackVector(
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const std::vector<webrtc::PacketFeedback>& input) {
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std::vector<PacketFeedback> received_packet_feedback_vector;
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auto is_received = [](const webrtc::PacketFeedback& packet_feedback) {
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return packet_feedback.arrival_time_ms !=
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webrtc::PacketFeedback::kNotReceived;
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};
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std::copy_if(input.begin(), input.end(),
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std::back_inserter(received_packet_feedback_vector),
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is_received);
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return received_packet_feedback_vector;
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}
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void SortPacketFeedbackVector(
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std::vector<webrtc::PacketFeedback>* const input) {
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RTC_DCHECK(input);
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std::sort(input->begin(), input->end(), PacketFeedbackComparator());
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}
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} // namespace
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SendSideCongestionController::SendSideCongestionController(
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const Clock* clock,
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Observer* observer,
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RtcEventLog* event_log,
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PacketRouter* packet_router)
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: clock_(clock),
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observer_(observer),
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event_log_(event_log),
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owned_pacer_(
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rtc::MakeUnique<PacedSender>(clock, packet_router, event_log)),
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pacer_(owned_pacer_.get()),
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bitrate_controller_(
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BitrateController::CreateBitrateController(clock_, event_log)),
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acknowledged_bitrate_estimator_(
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rtc::MakeUnique<AcknowledgedBitrateEstimator>()),
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probe_controller_(new ProbeController(pacer_, clock_)),
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retransmission_rate_limiter_(
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new RateLimiter(clock, kRetransmitWindowSizeMs)),
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transport_feedback_adapter_(clock_),
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last_reported_bitrate_bps_(0),
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last_reported_fraction_loss_(0),
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last_reported_rtt_(0),
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network_state_(kNetworkUp),
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pause_pacer_(false),
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pacer_paused_(false),
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min_bitrate_bps_(congestion_controller::GetMinBitrateBps()),
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delay_based_bwe_(new DelayBasedBwe(event_log_, clock_)),
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in_cwnd_experiment_(CwndExperimentEnabled()),
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accepted_queue_ms_(kDefaultAcceptedQueueMs),
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was_in_alr_(false),
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pacer_pushback_experiment_(
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webrtc::field_trial::IsEnabled(kPacerPushbackExperiment)) {
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delay_based_bwe_->SetMinBitrate(min_bitrate_bps_);
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if (in_cwnd_experiment_ &&
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!ReadCwndExperimentParameter(&accepted_queue_ms_)) {
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LOG(LS_WARNING) << "Failed to parse parameters for CwndExperiment "
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"from field trial string. Experiment disabled.";
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in_cwnd_experiment_ = false;
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}
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}
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SendSideCongestionController::SendSideCongestionController(
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const Clock* clock,
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Observer* observer,
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RtcEventLog* event_log,
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PacedSender* pacer)
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: clock_(clock),
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observer_(observer),
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event_log_(event_log),
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pacer_(pacer),
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bitrate_controller_(
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BitrateController::CreateBitrateController(clock_, event_log)),
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acknowledged_bitrate_estimator_(
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rtc::MakeUnique<AcknowledgedBitrateEstimator>()),
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probe_controller_(new ProbeController(pacer_, clock_)),
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retransmission_rate_limiter_(
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new RateLimiter(clock, kRetransmitWindowSizeMs)),
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transport_feedback_adapter_(clock_),
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last_reported_bitrate_bps_(0),
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last_reported_fraction_loss_(0),
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last_reported_rtt_(0),
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network_state_(kNetworkUp),
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pause_pacer_(false),
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pacer_paused_(false),
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min_bitrate_bps_(congestion_controller::GetMinBitrateBps()),
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delay_based_bwe_(new DelayBasedBwe(event_log_, clock_)),
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in_cwnd_experiment_(CwndExperimentEnabled()),
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accepted_queue_ms_(kDefaultAcceptedQueueMs),
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was_in_alr_(false),
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pacer_pushback_experiment_(
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webrtc::field_trial::IsEnabled(kPacerPushbackExperiment)) {
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delay_based_bwe_->SetMinBitrate(min_bitrate_bps_);
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if (in_cwnd_experiment_ &&
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!ReadCwndExperimentParameter(&accepted_queue_ms_)) {
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LOG(LS_WARNING) << "Failed to parse parameters for CwndExperiment "
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"from field trial string. Experiment disabled.";
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in_cwnd_experiment_ = false;
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}
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}
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SendSideCongestionController::~SendSideCongestionController() {}
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void SendSideCongestionController::RegisterPacketFeedbackObserver(
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PacketFeedbackObserver* observer) {
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transport_feedback_adapter_.RegisterPacketFeedbackObserver(observer);
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}
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void SendSideCongestionController::DeRegisterPacketFeedbackObserver(
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PacketFeedbackObserver* observer) {
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transport_feedback_adapter_.DeRegisterPacketFeedbackObserver(observer);
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}
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void SendSideCongestionController::RegisterNetworkObserver(Observer* observer) {
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rtc::CritScope cs(&observer_lock_);
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RTC_DCHECK(observer_ == nullptr);
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observer_ = observer;
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}
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void SendSideCongestionController::DeRegisterNetworkObserver(
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Observer* observer) {
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rtc::CritScope cs(&observer_lock_);
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RTC_DCHECK_EQ(observer_, observer);
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observer_ = nullptr;
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}
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void SendSideCongestionController::SetBweBitrates(int min_bitrate_bps,
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int start_bitrate_bps,
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int max_bitrate_bps) {
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ClampBitrates(&start_bitrate_bps, &min_bitrate_bps, &max_bitrate_bps);
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bitrate_controller_->SetBitrates(start_bitrate_bps, min_bitrate_bps,
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max_bitrate_bps);
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probe_controller_->SetBitrates(min_bitrate_bps, start_bitrate_bps,
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max_bitrate_bps);
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{
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rtc::CritScope cs(&bwe_lock_);
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if (start_bitrate_bps > 0)
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delay_based_bwe_->SetStartBitrate(start_bitrate_bps);
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min_bitrate_bps_ = min_bitrate_bps;
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delay_based_bwe_->SetMinBitrate(min_bitrate_bps_);
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}
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MaybeTriggerOnNetworkChanged();
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}
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// TODO(holmer): Split this up and use SetBweBitrates in combination with
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// OnNetworkRouteChanged.
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void SendSideCongestionController::OnNetworkRouteChanged(
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const rtc::NetworkRoute& network_route,
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int bitrate_bps,
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int min_bitrate_bps,
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int max_bitrate_bps) {
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ClampBitrates(&bitrate_bps, &min_bitrate_bps, &max_bitrate_bps);
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// TODO(honghaiz): Recreate this object once the bitrate controller is
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// no longer exposed outside SendSideCongestionController.
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bitrate_controller_->ResetBitrates(bitrate_bps, min_bitrate_bps,
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max_bitrate_bps);
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transport_feedback_adapter_.SetNetworkIds(network_route.local_network_id,
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network_route.remote_network_id);
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{
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rtc::CritScope cs(&bwe_lock_);
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min_bitrate_bps_ = min_bitrate_bps;
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delay_based_bwe_.reset(new DelayBasedBwe(event_log_, clock_));
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acknowledged_bitrate_estimator_.reset(new AcknowledgedBitrateEstimator());
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delay_based_bwe_->SetStartBitrate(bitrate_bps);
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delay_based_bwe_->SetMinBitrate(min_bitrate_bps);
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}
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probe_controller_->Reset();
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probe_controller_->SetBitrates(min_bitrate_bps, bitrate_bps, max_bitrate_bps);
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MaybeTriggerOnNetworkChanged();
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}
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BitrateController* SendSideCongestionController::GetBitrateController() const {
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return bitrate_controller_.get();
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}
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RateLimiter* SendSideCongestionController::GetRetransmissionRateLimiter() {
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return retransmission_rate_limiter_.get();
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}
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void SendSideCongestionController::EnablePeriodicAlrProbing(bool enable) {
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probe_controller_->EnablePeriodicAlrProbing(enable);
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}
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int64_t SendSideCongestionController::GetPacerQueuingDelayMs() const {
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return IsNetworkDown() ? 0 : pacer_->QueueInMs();
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}
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int64_t SendSideCongestionController::GetFirstPacketTimeMs() const {
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return pacer_->FirstSentPacketTimeMs();
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}
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TransportFeedbackObserver*
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SendSideCongestionController::GetTransportFeedbackObserver() {
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return this;
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}
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void SendSideCongestionController::SignalNetworkState(NetworkState state) {
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LOG(LS_INFO) << "SignalNetworkState "
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<< (state == kNetworkUp ? "Up" : "Down");
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{
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rtc::CritScope cs(&network_state_lock_);
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pause_pacer_ = state == kNetworkDown;
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network_state_ = state;
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}
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probe_controller_->OnNetworkStateChanged(state);
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MaybeTriggerOnNetworkChanged();
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}
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void SendSideCongestionController::SetTransportOverhead(
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size_t transport_overhead_bytes_per_packet) {
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transport_feedback_adapter_.SetTransportOverhead(
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transport_overhead_bytes_per_packet);
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}
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void SendSideCongestionController::OnSentPacket(
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const rtc::SentPacket& sent_packet) {
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// We're not interested in packets without an id, which may be stun packets,
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// etc, sent on the same transport.
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if (sent_packet.packet_id == -1)
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return;
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transport_feedback_adapter_.OnSentPacket(sent_packet.packet_id,
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sent_packet.send_time_ms);
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if (in_cwnd_experiment_)
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LimitOutstandingBytes(transport_feedback_adapter_.GetOutstandingBytes());
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}
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void SendSideCongestionController::OnRttUpdate(int64_t avg_rtt_ms,
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int64_t max_rtt_ms) {
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rtc::CritScope cs(&bwe_lock_);
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delay_based_bwe_->OnRttUpdate(avg_rtt_ms, max_rtt_ms);
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}
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int64_t SendSideCongestionController::TimeUntilNextProcess() {
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return bitrate_controller_->TimeUntilNextProcess();
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}
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void SendSideCongestionController::Process() {
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bool pause_pacer;
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// TODO(holmer): Once this class is running on a task queue we should
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// replace this with a task instead.
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{
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rtc::CritScope lock(&network_state_lock_);
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pause_pacer = pause_pacer_;
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}
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if (pause_pacer && !pacer_paused_) {
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pacer_->Pause();
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pacer_paused_ = true;
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} else if (!pause_pacer && pacer_paused_) {
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pacer_->Resume();
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pacer_paused_ = false;
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}
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bitrate_controller_->Process();
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probe_controller_->Process();
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MaybeTriggerOnNetworkChanged();
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}
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void SendSideCongestionController::AddPacket(
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uint32_t ssrc,
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uint16_t sequence_number,
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size_t length,
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const PacedPacketInfo& pacing_info) {
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transport_feedback_adapter_.AddPacket(ssrc, sequence_number, length,
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pacing_info);
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}
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void SendSideCongestionController::OnTransportFeedback(
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const rtcp::TransportFeedback& feedback) {
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RTC_DCHECK_RUNS_SERIALIZED(&worker_race_);
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transport_feedback_adapter_.OnTransportFeedback(feedback);
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std::vector<PacketFeedback> feedback_vector = ReceivedPacketFeedbackVector(
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transport_feedback_adapter_.GetTransportFeedbackVector());
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SortPacketFeedbackVector(&feedback_vector);
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bool currently_in_alr =
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pacer_->GetApplicationLimitedRegionStartTime().has_value();
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if (was_in_alr_ && !currently_in_alr) {
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int64_t now_ms = rtc::TimeMillis();
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acknowledged_bitrate_estimator_->SetAlrEndedTimeMs(now_ms);
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probe_controller_->SetAlrEndedTimeMs(now_ms);
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}
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was_in_alr_ = currently_in_alr;
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acknowledged_bitrate_estimator_->IncomingPacketFeedbackVector(
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feedback_vector);
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DelayBasedBwe::Result result;
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{
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rtc::CritScope cs(&bwe_lock_);
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result = delay_based_bwe_->IncomingPacketFeedbackVector(
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feedback_vector, acknowledged_bitrate_estimator_->bitrate_bps());
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}
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if (result.updated) {
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bitrate_controller_->OnDelayBasedBweResult(result);
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// Update the estimate in the ProbeController, in case we want to probe.
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MaybeTriggerOnNetworkChanged();
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}
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if (result.recovered_from_overuse)
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probe_controller_->RequestProbe();
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if (in_cwnd_experiment_)
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LimitOutstandingBytes(transport_feedback_adapter_.GetOutstandingBytes());
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}
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void SendSideCongestionController::LimitOutstandingBytes(
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size_t num_outstanding_bytes) {
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RTC_DCHECK(in_cwnd_experiment_);
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rtc::CritScope lock(&network_state_lock_);
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rtc::Optional<int64_t> min_rtt_ms =
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transport_feedback_adapter_.GetMinFeedbackLoopRtt();
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// No valid RTT. Could be because send-side BWE isn't used, in which case
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// we don't try to limit the outstanding packets.
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if (!min_rtt_ms)
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return;
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const size_t kMinCwndBytes = 2 * 1500;
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size_t max_outstanding_bytes =
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std::max<size_t>((*min_rtt_ms + accepted_queue_ms_) *
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last_reported_bitrate_bps_ / 1000 / 8,
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kMinCwndBytes);
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LOG(LS_INFO) << clock_->TimeInMilliseconds()
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<< " Outstanding bytes: " << num_outstanding_bytes
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<< " pacer queue: " << pacer_->QueueInMs()
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<< " max outstanding: " << max_outstanding_bytes;
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LOG(LS_INFO) << "Feedback rtt: " << *min_rtt_ms
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<< " Bitrate: " << last_reported_bitrate_bps_;
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pause_pacer_ = num_outstanding_bytes > max_outstanding_bytes;
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}
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std::vector<PacketFeedback>
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SendSideCongestionController::GetTransportFeedbackVector() const {
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RTC_DCHECK_RUNS_SERIALIZED(&worker_race_);
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return transport_feedback_adapter_.GetTransportFeedbackVector();
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}
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void SendSideCongestionController::MaybeTriggerOnNetworkChanged() {
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uint32_t bitrate_bps;
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uint8_t fraction_loss;
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int64_t rtt;
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bool estimate_changed = bitrate_controller_->GetNetworkParameters(
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&bitrate_bps, &fraction_loss, &rtt);
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if (estimate_changed) {
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pacer_->SetEstimatedBitrate(bitrate_bps);
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probe_controller_->SetEstimatedBitrate(bitrate_bps);
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retransmission_rate_limiter_->SetMaxRate(bitrate_bps);
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}
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if (!pacer_pushback_experiment_) {
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bitrate_bps = IsNetworkDown() || IsSendQueueFull() ? 0 : bitrate_bps;
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} else {
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if (IsNetworkDown()) {
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bitrate_bps = 0;
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} else {
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int64_t queue_length_ms = pacer_->ExpectedQueueTimeMs();
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if (queue_length_ms == 0) {
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encoding_rate_ = 1.0;
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} else if (queue_length_ms > 50) {
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float encoding_rate = 1.0 - queue_length_ms / 1000.0;
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encoding_rate_ = std::min(encoding_rate_, encoding_rate);
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encoding_rate_ = std::max(encoding_rate_, 0.0f);
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}
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bitrate_bps *= encoding_rate_;
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bitrate_bps = bitrate_bps < 50000 ? 0 : bitrate_bps;
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}
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}
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if (HasNetworkParametersToReportChanged(bitrate_bps, fraction_loss, rtt)) {
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int64_t probing_interval_ms;
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{
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rtc::CritScope cs(&bwe_lock_);
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probing_interval_ms = delay_based_bwe_->GetExpectedBwePeriodMs();
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}
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{
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rtc::CritScope cs(&observer_lock_);
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if (observer_) {
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observer_->OnNetworkChanged(bitrate_bps, fraction_loss, rtt,
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probing_interval_ms);
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}
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}
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}
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}
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|
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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
|