[fix] fix congestion control module

src/qos/congestion_control_feedback_generator.cc

@@ -0,0 +1,125 @@
+/*
+ *  Copyright (c) 2024 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 "congestion_control_feedback_generator.h"
+
+#include <algorithm>
+#include <chrono>
+#include <cstdint>
+#include <memory>
+#include <optional>
+#include <utility>
+#include <vector>
+
+#include "api/units/data_rate.h"
+#include "api/units/data_size.h"
+#include "api/units/time_delta.h"
+#include "api/units/timestamp.h"
+#include "clock.h"
+#include "congestion_control_feedback.h"
+#include "ntp_time_util.h"
+#include "rtcp_packet.h"
+#include "rtp_packet_received.h"
+
+namespace webrtc {
+
+CongestionControlFeedbackGenerator::CongestionControlFeedbackGenerator(
+    std::shared_ptr<SimulatedClock> clock, RtcpSender rtcp_sender)
+    : clock_(clock),
+      rtcp_sender_(std::move(rtcp_sender)),
+      min_time_between_feedback_(TimeDelta::Millis(25)),
+      max_time_to_wait_for_packet_with_marker_(TimeDelta::Millis(25)),
+      max_time_between_feedback_(TimeDelta::Millis(250)) {}
+
+void CongestionControlFeedbackGenerator::OnReceivedPacket(
+    const RtpPacketReceived& packet) {
+  marker_bit_seen_ |= packet.Marker();
+  if (!first_arrival_time_since_feedback_) {
+    first_arrival_time_since_feedback_ = packet.arrival_time();
+  }
+  feedback_trackers_[packet.Ssrc()].ReceivedPacket(packet);
+  if (NextFeedbackTime() < packet.arrival_time()) {
+    SendFeedback(Timestamp::Micros(
+        std::chrono::duration_cast<std::chrono::microseconds>(
+            std::chrono::system_clock::now().time_since_epoch())
+            .count()));
+  }
+}
+
+Timestamp CongestionControlFeedbackGenerator::NextFeedbackTime() const {
+  if (!first_arrival_time_since_feedback_) {
+    return std::max(Timestamp::Micros(
+                        std::chrono::duration_cast<std::chrono::microseconds>(
+                            std::chrono::system_clock::now().time_since_epoch())
+                            .count()) +
+                        min_time_between_feedback_,
+                    next_possible_feedback_send_time_);
+  }
+
+  if (!marker_bit_seen_) {
+    return std::max(next_possible_feedback_send_time_,
+                    *first_arrival_time_since_feedback_ +
+                        max_time_to_wait_for_packet_with_marker_);
+  }
+  return next_possible_feedback_send_time_;
+}
+
+TimeDelta CongestionControlFeedbackGenerator::Process(Timestamp now) {
+  if (NextFeedbackTime() <= now) {
+    SendFeedback(now);
+  }
+  return NextFeedbackTime() - now;
+}
+
+void CongestionControlFeedbackGenerator::OnSendBandwidthEstimateChanged(
+    DataRate estimate) {
+  // Feedback reports should max occupy 5% of total bandwidth.
+  max_feedback_rate_ = estimate * 0.05;
+}
+
+void CongestionControlFeedbackGenerator::SetTransportOverhead(
+    DataSize overhead_per_packet) {
+  packet_overhead_ = overhead_per_packet;
+}
+
+void CongestionControlFeedbackGenerator::SendFeedback(Timestamp now) {
+  SimulatedClock clock(now);
+  uint32_t compact_ntp = CompactNtp(clock.ConvertTimestampToNtpTime(now));
+  std::vector<rtcp::CongestionControlFeedback::PacketInfo> rtcp_packet_info;
+  for (auto& [unused, tracker] : feedback_trackers_) {
+    tracker.AddPacketsToFeedback(now, rtcp_packet_info);
+  }
+  marker_bit_seen_ = false;
+  first_arrival_time_since_feedback_ = std::nullopt;
+
+  auto feedback = std::make_unique<rtcp::CongestionControlFeedback>(
+      std::move(rtcp_packet_info), compact_ntp);
+  CalculateNextPossibleSendTime(DataSize::Bytes(feedback->BlockLength()), now);
+
+  std::vector<std::unique_ptr<RtcpPacket>> rtcp_packets;
+  rtcp_packets.push_back(std::move(feedback));
+  rtcp_sender_(std::move(rtcp_packets));
+}
+
+void CongestionControlFeedbackGenerator::CalculateNextPossibleSendTime(
+    DataSize feedback_size, Timestamp now) {
+  TimeDelta time_since_last_sent = now - last_feedback_sent_time_;
+  DataSize debt_payed = time_since_last_sent * max_feedback_rate_;
+  send_rate_debt_ = debt_payed > send_rate_debt_ ? DataSize::Zero()
+                                                 : send_rate_debt_ - debt_payed;
+  send_rate_debt_ += feedback_size + packet_overhead_;
+  last_feedback_sent_time_ = now;
+  next_possible_feedback_send_time_ =
+      now + std::clamp(max_feedback_rate_.IsZero()
+                           ? TimeDelta::PlusInfinity()
+                           : send_rate_debt_ / max_feedback_rate_,
+                       min_time_between_feedback_, max_time_between_feedback_);
+}
+
+}  // namespace webrtc