Clean-up of unused PacingBufferPushback feature.

Bug: webrtc:8171
Change-Id: I2804d6c87fe8b645e6c65784bbc525050c74a375
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/131387
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Commit-Queue: Christoffer Rodbro <crodbro@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27517}

modules/congestion_controller/include/send_side_congestion_controller.h

@@ -174,9 +174,6 @@ class DEPRECATED_SendSideCongestionController
 
   rtc::RaceChecker worker_race_;
 
-  bool pacer_pushback_experiment_ = false;
-  float encoding_rate_ = 1.0;
-
   std::unique_ptr<CongestionWindowPushbackController>
       congestion_window_pushback_controller_;
 

modules/congestion_controller/rtp/control_handler.cc

@@ -22,12 +22,6 @@
 namespace webrtc {
 namespace {
 
-// When PacerPushbackExperiment is enabled, build-up in the pacer due to
-// the congestion window and/or data spikes reduces encoder allocations.
-bool IsPacerPushbackExperimentEnabled() {
-  return field_trial::IsEnabled("WebRTC-PacerPushbackExperiment");
-}
-
 // By default, pacer emergency stops encoder when buffer reaches a high level.
 bool IsPacerEmergencyStopDisabled() {
   return field_trial::IsEnabled("WebRTC-DisablePacerEmergencyStop");
@@ -35,8 +29,7 @@ bool IsPacerEmergencyStopDisabled() {
 
 }  // namespace
 CongestionControlHandler::CongestionControlHandler()
-    : pacer_pushback_experiment_(IsPacerPushbackExperimentEnabled()),
+    : disable_pacer_emergency_stop_(IsPacerEmergencyStopDisabled()) {
-      disable_pacer_emergency_stop_(IsPacerEmergencyStopDisabled()) {
   sequenced_checker_.Detach();
 }
 
@@ -67,19 +60,6 @@ absl::optional<TargetTransferRate> CongestionControlHandler::GetUpdate() {
   bool pause_encoding = false;
   if (!network_available_) {
     pause_encoding = true;
-  } else if (pacer_pushback_experiment_) {
-    const int64_t queue_length_ms = pacer_expected_queue_ms_;
-    if (queue_length_ms == 0) {
-      encoding_rate_ratio_ = 1.0;
-    } else if (queue_length_ms > 50) {
-      double encoding_ratio = 1.0 - queue_length_ms / 1000.0;
-      encoding_rate_ratio_ = std::min(encoding_rate_ratio_, encoding_ratio);
-      encoding_rate_ratio_ = std::max(encoding_rate_ratio_, 0.0);
-    }
-    new_outgoing.target_rate = new_outgoing.target_rate * encoding_rate_ratio_;
-    log_target_rate = new_outgoing.target_rate;
-    if (new_outgoing.target_rate < DataRate::kbps(50))
-      pause_encoding = true;
   } else if (!disable_pacer_emergency_stop_ &&
              pacer_expected_queue_ms_ > PacedSender::kMaxQueueLengthMs) {
     pause_encoding = true;

modules/congestion_controller/rtp/control_handler.h

@@ -43,10 +43,8 @@ class CongestionControlHandler {
   bool network_available_ = true;
   bool encoder_paused_in_last_report_ = false;
 
-  const bool pacer_pushback_experiment_;
   const bool disable_pacer_emergency_stop_;
   int64_t pacer_expected_queue_ms_ = 0;
-  double encoding_rate_ratio_ = 1.0;
 
   rtc::SequencedTaskChecker sequenced_checker_;
   RTC_DISALLOW_COPY_AND_ASSIGN(CongestionControlHandler);

modules/congestion_controller/send_side_congestion_controller.cc

@@ -37,7 +37,6 @@
 namespace webrtc {
 namespace {
 
-const char kPacerPushbackExperiment[] = "WebRTC-PacerPushbackExperiment";
 static const int64_t kRetransmitWindowSizeMs = 500;
 
 // Makes sure that the bitrate and the min, max values are in valid range.
@@ -74,12 +73,6 @@ void SortPacketFeedbackVector(
   std::sort(input->begin(), input->end(), PacketFeedbackComparator());
 }
 
-bool IsPacerPushbackExperimentEnabled(
-    const WebRtcKeyValueConfig* const key_value_config) {
-  return key_value_config->Lookup(kPacerPushbackExperiment).find("Enabled") ==
-         0;
-}
-
 }  // namespace
 
 DEPRECATED_SendSideCongestionController::
@@ -116,9 +109,7 @@ DEPRECATED_SendSideCongestionController::
       send_side_bwe_with_overhead_(
           key_value_config_->Lookup("WebRTC-SendSideBwe-WithOverhead")
               .find("Enabled") == 0),
-      transport_overhead_bytes_per_packet_(0),
+      transport_overhead_bytes_per_packet_(0) {
-      pacer_pushback_experiment_(
-          IsPacerPushbackExperimentEnabled(key_value_config_)) {
   RateControlSettings experiment_params =
       RateControlSettings::ParseFromKeyValueConfig(key_value_config);
   if (experiment_params.UseCongestionWindow()) {
@@ -500,21 +491,8 @@ void DEPRECATED_SendSideCongestionController::MaybeTriggerOnNetworkChanged() {
     rtc::CritScope lock(&network_state_lock_);
     bitrate_bps = congestion_window_pushback_controller_->UpdateTargetBitrate(
         bitrate_bps);
-  } else if (!pacer_pushback_experiment_) {
-    bitrate_bps = IsSendQueueFull() ? 0 : bitrate_bps;
   } else {
-    int64_t queue_length_ms = pacer_->ExpectedQueueTimeMs();
+    bitrate_bps = IsSendQueueFull() ? 0 : bitrate_bps;
-
-    if (queue_length_ms == 0) {
-      encoding_rate_ = 1.0;
-    } else if (queue_length_ms > 50) {
-      float encoding_rate = 1.0 - queue_length_ms / 1000.0;
-      encoding_rate_ = std::min(encoding_rate_, encoding_rate);
-      encoding_rate_ = std::max(encoding_rate_, 0.0f);
-    }
-
-    bitrate_bps *= encoding_rate_;
-    bitrate_bps = bitrate_bps < 50000 ? 0 : bitrate_bps;
   }
 
   if (HasNetworkParametersToReportChanged(bitrate_bps, fraction_loss, rtt)) {

modules/congestion_controller/send_side_congestion_controller_unittest.cc

@@ -365,43 +365,5 @@ TEST_F(LegacySendSideCongestionControllerTest, UpdatesDelayBasedEstimate) {
   EXPECT_LT(*target_bitrate_bps_, bitrate_before_delay);
 }
 
-TEST_F(LegacySendSideCongestionControllerTest, PacerQueueEncodeRatePushback) {
-  ScopedFieldTrials pushback_field_trial(
-      "WebRTC-PacerPushbackExperiment/Enabled/");
-  SetUp();
-
-  EXPECT_CALL(*pacer_, ExpectedQueueTimeMs()).WillOnce(Return(0));
-  controller_->Process();
-
-  EXPECT_CALL(*pacer_, ExpectedQueueTimeMs()).WillOnce(Return(100));
-  EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps * 0.9, _, _, _));
-  controller_->Process();
-
-  EXPECT_CALL(*pacer_, ExpectedQueueTimeMs()).WillOnce(Return(50));
-  controller_->Process();
-
-  EXPECT_CALL(*pacer_, ExpectedQueueTimeMs()).WillOnce(Return(0));
-  EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps, _, _, _));
-  controller_->Process();
-
-  const uint32_t kMinAdjustedBps = 50000;
-  int expected_queue_threshold =
-      1000 - kMinAdjustedBps * 1000.0 / kInitialBitrateBps;
-
-  EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
-      .WillOnce(Return(expected_queue_threshold));
-  EXPECT_CALL(observer_, OnNetworkChanged(Ge(kMinAdjustedBps), _, _, _));
-  controller_->Process();
-
-  EXPECT_CALL(*pacer_, ExpectedQueueTimeMs())
-      .WillOnce(Return(expected_queue_threshold + 1));
-  EXPECT_CALL(observer_, OnNetworkChanged(0, _, _, _));
-  controller_->Process();
-
-  EXPECT_CALL(*pacer_, ExpectedQueueTimeMs()).WillOnce(Return(0));
-  EXPECT_CALL(observer_, OnNetworkChanged(kInitialBitrateBps, _, _, _));
-  controller_->Process();
-}
-
 }  // namespace test
 }  // namespace webrtc

test/scenario/scenario_tests/bbr_performance.cc

@@ -101,7 +101,6 @@ struct CallTestConfig {
     if (tuning.use_bbr) {
       trials +=
           "WebRTC-BweCongestionController/Enabled,BBR/"
-          "WebRTC-PacerPushbackExperiment/Enabled/"
           "WebRTC-Pacer-DrainQueue/Disabled/"
           "WebRTC-Pacer-PadInSilence/Enabled/"
           "WebRTC-Pacer-BlockAudio/Disabled/"

video/full_stack_tests.cc

@@ -60,8 +60,6 @@ namespace webrtc {
 
 namespace {
 static const int kFullStackTestDurationSecs = 45;
-const char kPacerPushBackExperiment[] =
-    "WebRTC-PacerPushbackExperiment/Enabled/";
 const char kVp8TrustedRateControllerFieldTrial[] =
     "WebRTC-LibvpxVp8TrustedRateController/Enabled/";
 
@@ -1485,8 +1483,7 @@ class DualStreamsTest : public ::testing::TestWithParam<int> {};
 TEST_P(DualStreamsTest,
        ModeratelyRestricted_SlidesVp8_2TL_Simulcast_Video_Simulcast_High) {
   test::ScopedFieldTrials field_trial(
-      AppendFieldTrials(std::string(kPacerPushBackExperiment) +
+      AppendFieldTrials(std::string(kScreenshareSimulcastExperiment)));
-                        std::string(kScreenshareSimulcastExperiment)));
   const int first_stream = GetParam();
   ParamsWithLogging dual_streams;
 
@@ -1548,8 +1545,6 @@ TEST_P(DualStreamsTest,
         // !defined(WEBRTC_MAC)
 
 TEST_P(DualStreamsTest, Conference_Restricted) {
-  test::ScopedFieldTrials field_trial(
-      AppendFieldTrials(std::string(kPacerPushBackExperiment)));
   const int first_stream = GetParam();
   ParamsWithLogging dual_streams;