From 67535428b467ee67beb1626d6b467a9144bcd31a Mon Sep 17 00:00:00 2001
From: Sebastian Jansson <srte@webrtc.org>
Date: Tue, 22 May 2018 12:25:45 +0200
Subject: [PATCH] Ensures that BBR always reports updated state.
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The BBR controller did not properly report updates to congestion
windows. This was due to a check to avoid the overhead of callbacks.
In the current design without callbacks in the controller, the check can
be removed. If helpful for performance, it should live outside of the
controller.

Bug: webrtc:8415
Change-Id: Idf6d6e76fe6d0450841e706019110307e559c11d
Reviewed-on: https://webrtc-review.googlesource.com/78181
Commit-Queue: Sebastian Jansson <srte@webrtc.org>
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23363}
---
 .../bbr/bbr_network_controller.cc             | 25 -------------------
 .../bbr/bbr_network_controller.h              | 14 -----------
 2 files changed, 39 deletions(-)

diff --git a/modules/congestion_controller/bbr/bbr_network_controller.cc b/modules/congestion_controller/bbr/bbr_network_controller.cc
index 33ba015584..bfb35cfbf4 100644
--- a/modules/congestion_controller/bbr/bbr_network_controller.cc
+++ b/modules/congestion_controller/bbr/bbr_network_controller.cc
@@ -84,11 +84,6 @@ constexpr int64_t kDefaultMaxCongestionWindowBytes =
     (kMaxRttMs * kMaxBandwidthKbps) / 8;
 }  // namespace
 
-BbrNetworkController::UpdateState::UpdateState() = default;
-BbrNetworkController::UpdateState::UpdateState(
-    const BbrNetworkController::UpdateState&) = default;
-BbrNetworkController::UpdateState::~UpdateState() = default;
-
 BbrNetworkController::BbrControllerConfig
 BbrNetworkController::BbrControllerConfig::DefaultConfig() {
   BbrControllerConfig config;
@@ -196,12 +191,6 @@ void BbrNetworkController::Reset() {
   round_trip_count_ = 0;
   rounds_without_bandwidth_gain_ = 0;
   is_at_full_bandwidth_ = false;
-  last_update_state_.mode = Mode::STARTUP;
-  last_update_state_.bandwidth.reset();
-  last_update_state_.rtt.reset();
-  last_update_state_.pacing_rate.reset();
-  last_update_state_.target_rate.reset();
-  last_update_state_.probing_for_bandwidth = false;
   EnterStartupMode();
 }
 
@@ -224,20 +213,6 @@ NetworkControlUpdate BbrNetworkController::CreateRateUpdate(Timestamp at_time) {
     if (constraints_->min_data_rate)
       target_rate = std::max(target_rate, *constraints_->min_data_rate);
   }
-  bool probing_for_bandwidth = IsProbingForMoreBandwidth();
-  if (last_update_state_.mode == mode_ &&
-      last_update_state_.bandwidth == bandwidth &&
-      last_update_state_.rtt == rtt &&
-      last_update_state_.pacing_rate == pacing_rate &&
-      last_update_state_.target_rate == target_rate &&
-      last_update_state_.probing_for_bandwidth == probing_for_bandwidth)
-    return NetworkControlUpdate();
-  last_update_state_.mode = mode_;
-  last_update_state_.bandwidth = bandwidth;
-  last_update_state_.rtt = rtt;
-  last_update_state_.pacing_rate = pacing_rate;
-  last_update_state_.target_rate = target_rate;
-  last_update_state_.probing_for_bandwidth = probing_for_bandwidth;
 
   NetworkControlUpdate update;
 
diff --git a/modules/congestion_controller/bbr/bbr_network_controller.h b/modules/congestion_controller/bbr/bbr_network_controller.h
index 34d76bbf30..2f842defab 100644
--- a/modules/congestion_controller/bbr/bbr_network_controller.h
+++ b/modules/congestion_controller/bbr/bbr_network_controller.h
@@ -157,19 +157,6 @@ class BbrNetworkController : public NetworkControllerInterface {
     // recently app limited.
     bool probe_rtt_disabled_if_app_limited;
   };
-  // Containing values that when changed should trigger an update.
-  struct UpdateState {
-    UpdateState();
-    UpdateState(const UpdateState&);
-    ~UpdateState();
-    Mode mode = Mode::STARTUP;
-    rtc::Optional<DataRate> bandwidth;
-    rtc::Optional<TimeDelta> rtt;
-    rtc::Optional<DataRate> pacing_rate;
-    rtc::Optional<DataRate> target_rate;
-    bool probing_for_bandwidth = false;
-  };
-
   void Reset();
   NetworkControlUpdate CreateRateUpdate(Timestamp at_time);
 
@@ -390,7 +377,6 @@ class BbrNetworkController : public NetworkControllerInterface {
 
   bool app_limited_since_last_probe_rtt_ = false;
   TimeDelta min_rtt_since_last_probe_rtt_ = TimeDelta::PlusInfinity();
-  UpdateState last_update_state_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(BbrNetworkController);
 };