1 files changed, 147 insertions, 0 deletions
diff --git a/libtransport/src/protocols/rtc/trendline_estimator.h b/libtransport/src/protocols/rtc/trendline_estimator.h
new file mode 100644
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--- /dev/null
+++ b/libtransport/src/protocols/rtc/trendline_estimator.h
@@ -0,0 +1,147 @@
+/*
+ *  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.
+ */
+
+// FROM
+// https://source.chromium.org/chromium/chromium/src/+/master:third_party/webrtc/modules/congestion_controller/goog_cc/trendline_estimator.h
+
+#ifndef MODULES_CONGESTION_CONTROLLER_GOOG_CC_TRENDLINE_ESTIMATOR_H_
+#define MODULES_CONGESTION_CONTROLLER_GOOG_CC_TRENDLINE_ESTIMATOR_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <algorithm>
+#include <deque>
+#include <memory>
+#include <utility>
+
+namespace transport {
+
+namespace protocol {
+
+namespace rtc {
+
+class OptionalDouble {
+ public:
+  OptionalDouble() : val(0), has_val(false){};
+  OptionalDouble(double val) : val(val), has_val(true){};
+
+  double value() { return val; }
+  bool has_value() { return has_val; }
+
+ private:
+  double val;
+  bool has_val;
+};
+
+enum class BandwidthUsage {
+  kBwNormal = 0,
+  kBwUnderusing = 1,
+  kBwOverusing = 2,
+  kLast
+};
+
+struct TrendlineEstimatorSettings {
+  static constexpr char kKey[] = "WebRTC-Bwe-TrendlineEstimatorSettings";
+  static constexpr unsigned kDefaultTrendlineWindowSize = 20;
+
+  // TrendlineEstimatorSettings() = delete;
+  TrendlineEstimatorSettings(
+      /*const WebRtcKeyValueConfig* key_value_config*/);
+
+  // Sort the packets in the window. Should be redundant,
+  // but then almost no cost.
+  bool enable_sort = false;
+
+  // Cap the trendline slope based on the minimum delay seen
+  // in the beginning_packets and end_packets respectively.
+  bool enable_cap = false;
+  unsigned beginning_packets = 7;
+  unsigned end_packets = 7;
+  double cap_uncertainty = 0.0;
+
+  // Size (in packets) of the window.
+  unsigned window_size = kDefaultTrendlineWindowSize;
+
+  // std::unique_ptr<StructParametersParser> Parser();
+};
+
+class TrendlineEstimator /*: public DelayIncreaseDetectorInterface */ {
+ public:
+  TrendlineEstimator(/*const WebRtcKeyValueConfig* key_value_config,
+                     NetworkStatePredictor* network_state_predictor*/);
+
+  ~TrendlineEstimator();
+
+  // Update the estimator with a new sample. The deltas should represent deltas
+  // between timestamp groups as defined by the InterArrival class.
+  void Update(double recv_delta_ms, double send_delta_ms, int64_t send_time_ms,
+              int64_t arrival_time_ms, size_t packet_size,
+              bool calculated_deltas);
+
+  void UpdateTrendline(double recv_delta_ms, double send_delta_ms,
+                       int64_t send_time_ms, int64_t arrival_time_ms,
+                       size_t packet_size);
+
+  BandwidthUsage State() const;
+
+  struct PacketTiming {
+    PacketTiming(double arrival_time_ms, double smoothed_delay_ms,
+                 double raw_delay_ms)
+        : arrival_time_ms(arrival_time_ms),
+          smoothed_delay_ms(smoothed_delay_ms),
+          raw_delay_ms(raw_delay_ms) {}
+    double arrival_time_ms;
+    double smoothed_delay_ms;
+    double raw_delay_ms;
+  };
+
+ private:
+  // friend class GoogCcStatePrinter;
+  void Detect(double trend, double ts_delta, int64_t now_ms);
+
+  void UpdateThreshold(double modified_offset, int64_t now_ms);
+
+  // Parameters.
+  TrendlineEstimatorSettings settings_;
+  const double smoothing_coef_;
+  const double threshold_gain_;
+  // Used by the existing threshold.
+  int num_of_deltas_;
+  // Keep the arrival times small by using the change from the first packet.
+  int64_t first_arrival_time_ms_;
+  // Exponential backoff filtering.
+  double accumulated_delay_;
+  double smoothed_delay_;
+  // Linear least squares regression.
+  std::deque<PacketTiming> delay_hist_;
+
+  const double k_up_;
+  const double k_down_;
+  double overusing_time_threshold_;
+  double threshold_;
+  double prev_modified_trend_;
+  int64_t last_update_ms_;
+  double prev_trend_;
+  double time_over_using_;
+  int overuse_counter_;
+  BandwidthUsage hypothesis_;
+  // BandwidthUsage hypothesis_predicted_;
+  // NetworkStatePredictor* network_state_predictor_;
+
+  // RTC_DISALLOW_COPY_AND_ASSIGN(TrendlineEstimator);
+};
+
+}  // namespace rtc
+
+}  // end namespace protocol
+
+}  // end namespace transport
+#endif  // MODULES_CONGESTION_CONTROLLER_GOOG_CC_TRENDLINE_ESTIMATOR_H_