Add webrtc transport-cc feedback mechanism

worker/deps/libwebrtc/libwebrtc/rtc_base/numerics/mod_ops.h

@@ -0,0 +1,142 @@
+/*
+ *  Copyright (c) 2016 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.
+ */
+
+#ifndef RTC_BASE_NUMERICS_MOD_OPS_H_
+#define RTC_BASE_NUMERICS_MOD_OPS_H_
+
+#include <algorithm>
+#include <type_traits>
+
+// #include "rtc_base/checks.h"
+
+namespace webrtc {
+
+template <unsigned long M>                                    // NOLINT
+inline unsigned long Add(unsigned long a, unsigned long b) {  // NOLINT
+  // RTC_DCHECK_LT(a, M);
+  unsigned long t = M - b % M;  // NOLINT
+  unsigned long res = a - t;    // NOLINT
+  if (t > a)
+    return res + M;
+  return res;
+}
+
+template <unsigned long M>                                         // NOLINT
+inline unsigned long Subtract(unsigned long a, unsigned long b) {  // NOLINT
+  // RTC_DCHECK_LT(a, M);
+  unsigned long sub = b % M;  // NOLINT
+  if (a < sub)
+    return M - (sub - a);
+  return a - sub;
+}
+
+// Calculates the forward difference between two wrapping numbers.
+//
+// Example:
+// uint8_t x = 253;
+// uint8_t y = 2;
+//
+// ForwardDiff(x, y) == 5
+//
+//   252   253   254   255    0     1     2     3
+// #################################################
+// |     |  x  |     |     |     |     |  y  |     |
+// #################################################
+//          |----->----->----->----->----->
+//
+// ForwardDiff(y, x) == 251
+//
+//   252   253   254   255    0     1     2     3
+// #################################################
+// |     |  x  |     |     |     |     |  y  |     |
+// #################################################
+// -->----->                              |----->---
+//
+// If M > 0 then wrapping occurs at M, if M == 0 then wrapping occurs at the
+// largest value representable by T.
+template <typename T, T M>
+inline typename std::enable_if<(M > 0), T>::type ForwardDiff(T a, T b) {
+  static_assert(std::is_unsigned<T>::value,
+                "Type must be an unsigned integer.");
+  // RTC_DCHECK_LT(a, M);
+  // RTC_DCHECK_LT(b, M);
+  return a <= b ? b - a : M - (a - b);
+}
+
+template <typename T, T M>
+inline typename std::enable_if<(M == 0), T>::type ForwardDiff(T a, T b) {
+  static_assert(std::is_unsigned<T>::value,
+                "Type must be an unsigned integer.");
+  return b - a;
+}
+
+template <typename T>
+inline T ForwardDiff(T a, T b) {
+  return ForwardDiff<T, 0>(a, b);
+}
+
+// Calculates the reverse difference between two wrapping numbers.
+//
+// Example:
+// uint8_t x = 253;
+// uint8_t y = 2;
+//
+// ReverseDiff(y, x) == 5
+//
+//   252   253   254   255    0     1     2     3
+// #################################################
+// |     |  x  |     |     |     |     |  y  |     |
+// #################################################
+//          <-----<-----<-----<-----<-----|
+//
+// ReverseDiff(x, y) == 251
+//
+//   252   253   254   255    0     1     2     3
+// #################################################
+// |     |  x  |     |     |     |     |  y  |     |
+// #################################################
+// ---<-----|                             |<-----<--
+//
+// If M > 0 then wrapping occurs at M, if M == 0 then wrapping occurs at the
+// largest value representable by T.
+template <typename T, T M>
+inline typename std::enable_if<(M > 0), T>::type ReverseDiff(T a, T b) {
+  static_assert(std::is_unsigned<T>::value,
+                "Type must be an unsigned integer.");
+  // RTC_DCHECK_LT(a, M);
+  // RTC_DCHECK_LT(b, M);
+  return b <= a ? a - b : M - (b - a);
+}
+
+template <typename T, T M>
+inline typename std::enable_if<(M == 0), T>::type ReverseDiff(T a, T b) {
+  static_assert(std::is_unsigned<T>::value,
+                "Type must be an unsigned integer.");
+  return a - b;
+}
+
+template <typename T>
+inline T ReverseDiff(T a, T b) {
+  return ReverseDiff<T, 0>(a, b);
+}
+
+// Calculates the minimum distance between to wrapping numbers.
+//
+// The minimum distance is defined as min(ForwardDiff(a, b), ReverseDiff(a, b))
+template <typename T, T M = 0>
+inline T MinDiff(T a, T b) {
+  static_assert(std::is_unsigned<T>::value,
+                "Type must be an unsigned integer.");
+  return std::min(ForwardDiff<T, M>(a, b), ReverseDiff<T, M>(a, b));
+}
+
+}  // namespace webrtc
+
+#endif  // RTC_BASE_NUMERICS_MOD_OPS_H_

worker/deps/libwebrtc/libwebrtc/rtc_base/numerics/sequence_number_util.h

@@ -0,0 +1,117 @@
+/*
+ *  Copyright (c) 2016 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.
+ */
+
+#ifndef RTC_BASE_NUMERICS_SEQUENCE_NUMBER_UTIL_H_
+#define RTC_BASE_NUMERICS_SEQUENCE_NUMBER_UTIL_H_
+
+#include <stdint.h>
+#include <limits>
+#include <type_traits>
+
+#include "absl/types/optional.h"
+#include "rtc_base/numerics/mod_ops.h"
+
+namespace webrtc {
+
+// Test if the sequence number |a| is ahead or at sequence number |b|.
+//
+// If |M| is an even number and the two sequence numbers are at max distance
+// from each other, then the sequence number with the highest value is
+// considered to be ahead.
+template <typename T, T M>
+inline typename std::enable_if<(M > 0), bool>::type AheadOrAt(T a, T b) {
+  static_assert(std::is_unsigned<T>::value,
+                "Type must be an unsigned integer.");
+  const T maxDist = M / 2;
+  if (!(M & 1) && MinDiff<T, M>(a, b) == maxDist)
+    return b < a;
+  return ForwardDiff<T, M>(b, a) <= maxDist;
+}
+
+template <typename T, T M>
+inline typename std::enable_if<(M == 0), bool>::type AheadOrAt(T a, T b) {
+  static_assert(std::is_unsigned<T>::value,
+                "Type must be an unsigned integer.");
+  const T maxDist = std::numeric_limits<T>::max() / 2 + T(1);
+  if (a - b == maxDist)
+    return b < a;
+  return ForwardDiff(b, a) < maxDist;
+}
+
+template <typename T>
+inline bool AheadOrAt(T a, T b) {
+  return AheadOrAt<T, 0>(a, b);
+}
+
+// Test if the sequence number |a| is ahead of sequence number |b|.
+//
+// If |M| is an even number and the two sequence numbers are at max distance
+// from each other, then the sequence number with the highest value is
+// considered to be ahead.
+template <typename T, T M = 0>
+inline bool AheadOf(T a, T b) {
+  static_assert(std::is_unsigned<T>::value,
+                "Type must be an unsigned integer.");
+  return a != b && AheadOrAt<T, M>(a, b);
+}
+
+// Comparator used to compare sequence numbers in a continuous fashion.
+//
+// WARNING! If used to sort sequence numbers of length M then the interval
+//          covered by the sequence numbers may not be larger than floor(M/2).
+template <typename T, T M = 0>
+struct AscendingSeqNumComp {
+  bool operator()(T a, T b) const { return AheadOf<T, M>(a, b); }
+};
+
+// Comparator used to compare sequence numbers in a continuous fashion.
+//
+// WARNING! If used to sort sequence numbers of length M then the interval
+//          covered by the sequence numbers may not be larger than floor(M/2).
+template <typename T, T M = 0>
+struct DescendingSeqNumComp {
+  bool operator()(T a, T b) const { return AheadOf<T, M>(b, a); }
+};
+
+// A sequence number unwrapper where the first unwrapped value equals the
+// first value being unwrapped.
+template <typename T, T M = 0>
+class SeqNumUnwrapper {
+  static_assert(
+      std::is_unsigned<T>::value &&
+          std::numeric_limits<T>::max() < std::numeric_limits<int64_t>::max(),
+      "Type unwrapped must be an unsigned integer smaller than int64_t.");
+
+ public:
+  int64_t Unwrap(T value) {
+    if (!last_value_) {
+      last_unwrapped_ = {value};
+    } else {
+      last_unwrapped_ += ForwardDiff<T, M>(*last_value_, value);
+
+      if (!AheadOrAt<T, M>(value, *last_value_)) {
+        constexpr int64_t kBackwardAdjustment =
+            M == 0 ? int64_t{std::numeric_limits<T>::max()} + 1 : M;
+        last_unwrapped_ -= kBackwardAdjustment;
+      }
+    }
+
+    last_value_ = value;
+    return last_unwrapped_;
+  }
+
+ private:
+  int64_t last_unwrapped_ = 0;
+  absl::optional<T> last_value_;
+};
+
+}  // namespace webrtc
+
+#endif  // RTC_BASE_NUMERICS_SEQUENCE_NUMBER_UTIL_H_

worker/include/RTC/TransportCongestionControlServer.hpp

@@ -8,7 +8,9 @@
 #include "RTC/RtpPacket.hpp"
 #include "handles/Timer.hpp"
 #include <libwebrtc/modules/remote_bitrate_estimator/remote_bitrate_estimator_abs_send_time.h>
+#include <libwebrtc/rtc_base/numerics/sequence_number_util.h>
 #include <deque>
+using namespace webrtc;
 
 namespace RTC
 {
@@ -59,6 +61,13 @@ namespace RTC
 		void SendTransportCcFeedback();
 		void MaySendLimitationRembFeedback();
 		void UpdatePacketLoss(double packetLoss);
+		void OnPacketArrival(uint16_t sequence_number, uint64_t arrival_time);
+		void SendPeriodicFeedbacks();
+		int64_t BuildFeedbackPacket(
+		  int64_t base_sequence_number,
+		  std::map<int64_t, uint64_t>::const_iterator begin_iterator, // |begin_iterator| is inclusive.
+		  std::map<int64_t, uint64_t>::const_iterator end_iterator    // |end_iterator| is exclusive.
+		);
 
 		/* Pure virtual methods inherited from webrtc::RemoteBitrateEstimator::Listener. */
 	public:
@@ -89,6 +98,12 @@ namespace RTC
 		uint8_t unlimitedRembCounter{ 0u };
 		std::deque<double> packetLossHistory;
 		double packetLoss{ 0 };
+		SeqNumUnwrapper<uint16_t> unwrapper;
+		absl::optional<int64_t> periodicWindowStartSeq;
+		// Map unwrapped seq -> time.
+		std::map<int64_t, uint64_t> packetArrivalTimes;
+		// Use buffer policy similar to webrtc
+		bool useBufferPolicy{ true };
 	};
 } // namespace RTC