Printing internal state of GoogCC.

This is useful for debugging and has minimal effect on production code.

Bug: webrtc:9510
Change-Id: I3a71f484a0d4e54999e376b7924b73230d86cd96
Reviewed-on: https://webrtc-review.googlesource.com/97607
Commit-Queue: Sebastian Jansson <srte@webrtc.org>
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24557}

modules/congestion_controller/goog_cc/BUILD.gn

@@ -147,6 +147,7 @@ if (rtc_include_tests) {
       "test/goog_cc_printer.h",
     ]
     deps = [
+      ":estimators",
       ":goog_cc",
       "..:test_controller_printer",
     ]

modules/congestion_controller/goog_cc/alr_detector.h

@@ -55,6 +55,7 @@ class AlrDetector {
   void UpdateBudgetWithBytesSent(size_t bytes_sent);
 
  private:
+  friend class GoogCcStatePrinter;
   int bandwidth_usage_percent_;
   int alr_start_budget_level_percent_;
   int alr_stop_budget_level_percent_;

modules/congestion_controller/goog_cc/delay_based_bwe.h

@@ -56,6 +56,7 @@ class DelayBasedBwe {
   int64_t GetExpectedBwePeriodMs() const;
 
  private:
+  friend class GoogCcStatePrinter;
   void IncomingPacketFeedback(const PacketFeedback& packet_feedback,
                               int64_t at_time_ms);
   Result OnLongFeedbackDelay(int64_t arrival_time_ms);

modules/congestion_controller/goog_cc/goog_cc_network_control.h

@@ -52,6 +52,7 @@ class GoogCcNetworkController : public NetworkControllerInterface {
   NetworkControlUpdate GetNetworkState(Timestamp at_time) const;
 
  private:
+  friend class GoogCcStatePrinter;
   std::vector<ProbeClusterConfig> UpdateBitrateConstraints(
       TargetRateConstraints constraints,
       absl::optional<DataRate> starting_rate);

modules/congestion_controller/goog_cc/test/goog_cc_printer.cc

@@ -8,6 +8,8 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 #include "modules/congestion_controller/goog_cc/test/goog_cc_printer.h"
+#include "modules/congestion_controller/goog_cc/trendline_estimator.h"
+
 namespace webrtc {
 
 GoogCcStatePrinter::GoogCcStatePrinter() = default;
@@ -21,10 +23,23 @@ bool GoogCcStatePrinter::Attached() const {
   return controller_ != nullptr;
 }
 
-void GoogCcStatePrinter::PrintHeaders(FILE* out) {}
+void GoogCcStatePrinter::PrintHeaders(FILE* out) {
+  fprintf(out,
+          "rate_control_state rate_control_region alr_state"
+          " trendline trendline_modified_offset trendline_offset_threshold");
+}
 
 void GoogCcStatePrinter::PrintValues(FILE* out) {
   RTC_CHECK(controller_);
+  auto* detector = controller_->delay_based_bwe_->delay_detector_.get();
+  auto* trendline_estimator = reinterpret_cast<TrendlineEstimator*>(detector);
+  fprintf(out, "%i %i %i %.6lf %.6lf %.6lf",
+          controller_->delay_based_bwe_->rate_control_.rate_control_state_,
+          controller_->delay_based_bwe_->rate_control_.rate_control_region_,
+          controller_->alr_detector_->alr_started_time_ms_.has_value(),
+          trendline_estimator->trendline_,
+          trendline_estimator->prev_modified_offset_,
+          trendline_estimator->threshold_);
 }
 
 NetworkControlUpdate GoogCcStatePrinter::GetState(Timestamp at_time) const {

modules/congestion_controller/goog_cc/trendline_estimator.cc

@@ -70,6 +70,7 @@ TrendlineEstimator::TrendlineEstimator(size_t window_size,
       k_down_(0.039),
       overusing_time_threshold_(kOverUsingTimeThreshold),
       threshold_(12.5),
+      prev_modified_offset_(NAN),
       last_update_ms_(-1),
       prev_offset_(0.0),
       time_over_using_(-1),
@@ -162,6 +163,7 @@ void TrendlineEstimator::Detect(double offset,
 
 void TrendlineEstimator::UpdateThreshold(double modified_offset,
                                          int64_t now_ms) {
+  prev_modified_offset_ = modified_offset;
   if (last_update_ms_ == -1)
     last_update_ms_ = now_ms;
 

modules/congestion_controller/goog_cc/trendline_estimator.h

@@ -53,6 +53,7 @@ class TrendlineEstimator : public DelayIncreaseDetectorInterface {
   unsigned int num_of_deltas() const { return num_of_deltas_; }
 
  private:
+  friend class GoogCcStatePrinter;
   void Detect(double offset,
               double ts_delta,
               int num_of_deltas,
@@ -79,6 +80,7 @@ class TrendlineEstimator : public DelayIncreaseDetectorInterface {
   const double k_down_;
   double overusing_time_threshold_;
   double threshold_;
+  double prev_modified_offset_;
   int64_t last_update_ms_;
   double prev_offset_;
   double time_over_using_;

modules/remote_bitrate_estimator/aimd_rate_control.h

@@ -54,6 +54,7 @@ class AimdRateControl {
   int GetExpectedBandwidthPeriodMs() const;
 
  private:
+  friend class GoogCcStatePrinter;
   // Update the target bitrate based on, among other things, the current rate
   // control state, the current target bitrate and the estimated throughput.
   // When in the "increase" state the bitrate will be increased either