Almost full implementation of BBR's core.

webrtc/modules/remote_bitrate_estimator/test/estimators/bbr.h

Index: webrtc/modules/remote_bitrate_estimator/test/estimators/bbr.h
diff --git a/webrtc/modules/remote_bitrate_estimator/test/estimators/bbr.h b/webrtc/modules/remote_bitrate_estimator/test/estimators/bbr.h
index 2782f353d0bb7c4320b71e372c378d9c6d624104..ed17c84c0aa0938ea5aad1d767653f43971317f8 100644
--- a/webrtc/modules/remote_bitrate_estimator/test/estimators/bbr.h
+++ b/webrtc/modules/remote_bitrate_estimator/test/estimators/bbr.h
@@ -12,11 +12,13 @@
 #ifndef WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_TEST_ESTIMATORS_BBR_H_
 #define WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_TEST_ESTIMATORS_BBR_H_
 
+#include <list>
 #include <map>
 #include <memory>
 #include <vector>
 
 #include "webrtc/modules/remote_bitrate_estimator/test/bwe.h"
+#include "webrtc/modules/video_coding/sequence_number_util.h"
 #include "webrtc/rtc_base/optional.h"
 #include "webrtc/rtc_base/random.h"
 
@@ -39,15 +41,66 @@ class BbrBweSender : public BweSender {
     PROBE_BW,
     // Temporarily limiting congestion window size in order to measure
     // minimum RTT.
-    PROBE_RTT
+    PROBE_RTT,
+    // Temporarily reducing pacing rate and congestion window, in order to
+    // ensure no queues are built.
+    RECOVERY
   };
+
+  // For better understanding of what member variables stand for, let's name
+  // packets as follows:
+  // cur_packet - the packet for which PacketStats is stored.
+  // last_sent_packet - the last sent packet for the time when cur_packet was
+  // acked.
+  // last_acked_packet - the last acked packet for the time when cur_packet was
+  // sent.
   struct PacketStats {
     PacketStats() {}
-    PacketStats(int64_t send_time_, size_t payload_size_)
-        : send_time(send_time_), payload_size(payload_size_) {}
-
-    int64_t send_time;
-    size_t payload_size;
+    PacketStats(uint16_t sequence_number_,
+                int64_t last_sent_packet_send_time_ms_,

[philipel, 2017/08/08 11:54:54]

I would suggest |time_last_sent_packet_ms_| or just |last_sent_packet_ms_|.

[gnish1, 2017/08/08 13:19:56]

In that case it isn't clear whether we mean send time or akc time.

+                int64_t send_time_ms_,
+                int64_t ack_time_ms_,
+                int64_t last_acked_packet_ack_time_ms_,
+                size_t payload_size_bytes_,
+                size_t data_sent_bytes_,
+                size_t data_sent_before_last_sent_packet_bytes_,
+                size_t data_acked_bytes_,
+                size_t data_acked_before_last_acked_packet_bytes_)
+        : sequence_number(sequence_number_),
+          last_sent_packet_send_time_ms(last_sent_packet_send_time_ms_),
+          send_time_ms(send_time_ms_),
+          ack_time_ms(ack_time_ms_),
+          last_acked_packet_ack_time_ms(last_acked_packet_ack_time_ms_),
+          payload_size_bytes(payload_size_bytes_),
+          data_sent_bytes(data_sent_bytes_),
+          data_sent_before_last_sent_packet_bytes(
+              data_sent_before_last_sent_packet_bytes_),
+          data_acked_bytes(data_acked_bytes_),
+          data_acked_before_last_acked_packet_bytes(
+              data_acked_before_last_acked_packet_bytes_) {}
+    uint16_t sequence_number;

[philipel, 2017/08/08 11:54:54]

To me it's still not clear what these member variables represent.

[gnish1, 2017/08/08 13:19:56]

Done.

+    int64_t last_sent_packet_send_time_ms;
+    int64_t send_time_ms;
+    int64_t ack_time_ms;
+    int64_t last_acked_packet_ack_time_ms;
+    size_t payload_size_bytes;
+    size_t data_sent_bytes;
+    size_t data_sent_before_last_sent_packet_bytes;
+    size_t data_acked_bytes;
+    size_t data_acked_before_last_acked_packet_bytes;
+  };
+  struct AverageRtt {
+    AverageRtt() {}
+    AverageRtt(int64_t sum_of_rtts_ms_, int64_t num_samples_, uint64_t round_)
+        : sum_of_rtts_ms(sum_of_rtts_ms_),
+          num_samples(num_samples_),
+          round(round_) {}
+    // Sum of rtts over the round.
+    int64_t sum_of_rtts_ms;
+    // Number of rtt samples over the round.
+    int64_t num_samples;
+    // The number of the round average rtt is recorded for.
+    uint64_t round;
   };
   void OnPacketsSent(const Packets& packets) override;
   int GetFeedbackIntervalMs() const override;
@@ -57,14 +110,38 @@ class BbrBweSender : public BweSender {
 
  private:
   void EnterStartup();
-  bool UpdateBandwidthAndMinRtt();
+  bool UpdateBandwidthAndMinRtt(int64_t now_ms,
+                                const std::vector<uint64_t>& feedback_vector,
+                                int64_t bytes_acked);
   void TryExitingStartup();
   void TryExitingDrain(int64_t now_ms);
   void EnterProbeBw(int64_t now_ms);
   void TryUpdatingCyclePhase(int64_t now_ms);
   void TryEnteringProbeRtt(int64_t now_ms);
   void TryExitingProbeRtt(int64_t now_ms, int64_t round);
+  void TryEnteringRecovery(bool new_round_started);
+  void TryExitingRecovery(bool new_round_started);
   size_t TargetCongestionWindow(float gain);
+  void CalculatePacingRate();
+
+  // Calculates and returns bandwidth sample as minimum between send rate and
+  // ack rate, returns nothing if sample cannot be calculated.
+  rtc::Optional<int64_t> CalculateBandwidthSample(size_t data_sent,
+                                                  int64_t send_time_delta_ms,
+                                                  size_t data_acked,
+                                                  int64_t ack_time_delta_ms);
+
+  // Calculate and add bandwidth sample only for packets' sent during high gain
+  // phase. Motivation of having a seperate bucket for high gain phase is to
+  // achieve quicker ramp up. Slight overestimations may happen due to window
+  // not being as large as usual.
+  void AddSampleForHighGain();
+
+  // Declares lost packets as acked. Implements simple logic by looking at the
+  // gap between sequence numbers. If there is a gap between sequence numbers we
+  // declare those packets as lost immediately.
+  void HandleLoss(uint64_t last_acked_packet, uint64_t recently_acked_packet);
+  void AddToPastRtts(int64_t rtt_sample_ms);
   Clock* const clock_;
   Mode mode_;
   std::unique_ptr<MaxBandwidthFilter> max_bandwidth_filter_;
@@ -72,7 +149,6 @@ class BbrBweSender : public BweSender {
   std::unique_ptr<CongestionWindow> congestion_window_;
   std::unique_ptr<Random> rand_;
   uint64_t round_count_;
-  uint64_t last_packet_sent_;
   uint64_t round_trip_end_;
   float pacing_gain_;
   float congestion_window_gain_;
@@ -87,8 +163,7 @@ class BbrBweSender : public BweSender {
   // Index number of the currently used gain value in PROBE_BW mode, from 0 to
   // kGainCycleLength - 1.
   int64_t cycle_index_;
-
-  // Data inflight prior to the moment when last feedback was received.
+  size_t bytes_acked_;
   size_t prior_in_flight_;
 
   // Time we entered PROBE_RTT mode.
@@ -101,6 +176,48 @@ class BbrBweSender : public BweSender {
   // First round when data inflight decreased below kMinimumCongestionWindow in
   // PROBE_RTT mode.
   int64_t minimum_congestion_window_start_round_;
+  size_t bytes_sent_;
+  uint16_t last_packet_sent_sequence_number_;
+  uint16_t last_packet_acked_sequence_number_;
+  int64_t last_packet_ack_time_;
+  int64_t last_packet_send_time_;
+  int64_t pacing_rate_bps_;
+
+  // Send time of a packet sent first during high gain phase. Also serves as a
+  // flag, holding value means that we are already in high gain.
+  rtc::Optional<int64_t> first_packet_send_time_during_high_gain_ms_;
+
+  // Send time of a packet sent last during high gain phase.
+  int64_t last_packet_send_time_during_high_gain_ms_;
+
+  // Amount of data sent, before first packet was sent during high gain phase.
+  int64_t data_sent_before_high_gain_started_bytes_;
+
+  // Amount of data sent, before last packet was sent during high gain phase.
+  int64_t data_sent_before_high_gain_ended_bytes_;
+
+  // Ack time of a packet acked first during high gain phase.
+  int64_t first_packet_ack_time_during_high_gain_ms_;
+
+  // Ack time of a packet acked last during high gain phase.
+  int64_t last_packet_ack_time_during_high_gain_ms_;
+
+  // Amount of data acked, before the first packet was acked during high gain
+  // phase.
+  int64_t data_acked_before_high_gain_started_bytes_;
+
+  // Amount of data acked, before the last packet was acked during high gain
+  // phase.
+  int64_t data_acked_before_high_gain_ended_bytes_;
+
+  // Sequence number of the first packet sent during high gain phase.
+  uint16_t first_packet_seq_num_during_high_gain_;
+
+  // Sequence number of the last packet sent during high gain phase.
+  uint16_t last_packet_seq_num_during_high_gain_;
+  bool high_gain_over_;
+  std::map<int64_t, PacketStats> packet_stats_;
+  std::list<AverageRtt> past_rtts_;
 };
 
 class BbrBweReceiver : public BweReceiver {
@@ -113,6 +230,7 @@ class BbrBweReceiver : public BweReceiver {
 
  private:
   SimulatedClock clock_;
+  std::vector<uint64_t> packet_feedbacks_;
 };
 }  // namespace bwe
 }  // namespace testing