Move BWE period calculation from ProbingIntervalEstimator to AimdRateControl.

webrtc/modules/remote_bitrate_estimator/aimd_rate_control_unittest.cc

Index: webrtc/modules/remote_bitrate_estimator/aimd_rate_control_unittest.cc
diff --git a/webrtc/modules/remote_bitrate_estimator/aimd_rate_control_unittest.cc b/webrtc/modules/remote_bitrate_estimator/aimd_rate_control_unittest.cc
index d15418ff093a34fd25ba216a2e34b5fe18da4b20..e90c5500b356b7b593910fce23be167560dd7ce2 100644
--- a/webrtc/modules/remote_bitrate_estimator/aimd_rate_control_unittest.cc
+++ b/webrtc/modules/remote_bitrate_estimator/aimd_rate_control_unittest.cc
@@ -18,6 +18,13 @@ namespace {
 
 constexpr int64_t kClockInitialTime = 123456;
 
+constexpr int kMinBwePeriodMs = 2000;
+constexpr int kMaxBwePeriodMs = 50000;
+constexpr int kDefaultPeriodMs = 3000;
+
+// After an overuse, we back off to 85% to the received bitrate.
+constexpr double kFractionAfterOveruse = 0.85;
+
 struct AimdRateControlStates {
   std::unique_ptr<AimdRateControl> aimd_rate_control;
   std::unique_ptr<SimulatedClock> simulated_clock;
@@ -66,21 +73,16 @@ TEST(AimdRateControlTest, NearMaxIncreaseRateIs5kbpsOn60kbpsAnd100msRtt) {
   EXPECT_EQ(5000, states.aimd_rate_control->GetNearMaxIncreaseRateBps());
 }
 
-TEST(AimdRateControlTest, UnknownBitrateDecreaseBeforeFirstOveruse) {
-  auto states = CreateAimdRateControlStates();
-  EXPECT_EQ(rtc::Optional<int>(),
-            states.aimd_rate_control->GetLastBitrateDecreaseBps());
-}
-
-TEST(AimdRateControlTest, GetLastBitrateDecrease) {
+TEST(AimdRateControlTest, GetIncreaseRateAndBandwidthPeriod) {
   auto states = CreateAimdRateControlStates();
   constexpr int kBitrate = 300000;
   states.aimd_rate_control->SetEstimate(
       kBitrate, states.simulated_clock->TimeInMilliseconds());
-  UpdateRateControl(states, BandwidthUsage::kBwOverusing, kBitrate - 2000,
+  UpdateRateControl(states, BandwidthUsage::kBwOverusing, kBitrate,
                     states.simulated_clock->TimeInMilliseconds());
-  EXPECT_EQ(rtc::Optional<int>(46700),
-            states.aimd_rate_control->GetLastBitrateDecreaseBps());
+  EXPECT_NEAR(14000, states.aimd_rate_control->GetNearMaxIncreaseRateBps(),
+              1000);
+  EXPECT_EQ(3000, states.aimd_rate_control->GetExpectedBandwidthPeriodMs());
 }
 
 TEST(AimdRateControlTest, BweLimitedByAckedBitrate) {
@@ -121,4 +123,60 @@ TEST(AimdRateControlTest, BweNotLimitedByDecreasingAckedBitrate) {
               2000);
   EXPECT_EQ(new_estimate, prev_estimate);
 }
+
+TEST(AimdRateControlTest, DefaultPeriodUntilFirstOveruse) {
+  auto states = CreateAimdRateControlStates();
+  states.aimd_rate_control->SetStartBitrate(300000);
+  EXPECT_EQ(kDefaultPeriodMs,
+            states.aimd_rate_control->GetExpectedBandwidthPeriodMs());
+  states.simulated_clock->AdvanceTimeMilliseconds(100);
+  UpdateRateControl(states, BandwidthUsage::kBwOverusing, 100000,
+                    states.simulated_clock->TimeInMilliseconds());
+  EXPECT_NE(kDefaultPeriodMs,
+            states.aimd_rate_control->GetExpectedBandwidthPeriodMs());
+}
+
+TEST(AimdRateControlTest, ExpectedPeriodAfter20kbpsDropAnd5kbpsIncrease) {
+  auto states = CreateAimdRateControlStates();
+  constexpr int kInitialBitrate = 110000;
+  states.aimd_rate_control->SetEstimate(
+      kInitialBitrate, states.simulated_clock->TimeInMilliseconds());
+  states.simulated_clock->AdvanceTimeMilliseconds(100);
+  // Make the bitrate drop by 20 kbps to get to 90 kbps.
+  // The rate increase at 90 kbps should be 5 kbps, so the period should be 4 s.
+  constexpr int kAckedBitrate =
+      (kInitialBitrate - 20000) / kFractionAfterOveruse;
+  UpdateRateControl(states, BandwidthUsage::kBwOverusing, kAckedBitrate,
+                    states.simulated_clock->TimeInMilliseconds());
+  EXPECT_EQ(5000, states.aimd_rate_control->GetNearMaxIncreaseRateBps());
+  EXPECT_EQ(4000, states.aimd_rate_control->GetExpectedBandwidthPeriodMs());
+}
+
+TEST(AimdRateControlTest, BandwidthPeriodIsNotBelowMin) {
+  auto states = CreateAimdRateControlStates();
+  constexpr int kInitialBitrate = 10000;
+  states.aimd_rate_control->SetEstimate(
+      kInitialBitrate, states.simulated_clock->TimeInMilliseconds());
+  states.simulated_clock->AdvanceTimeMilliseconds(100);
+  // Make a small (1.5 kbps) bitrate drop to 8.5 kbps.
+  UpdateRateControl(states, BandwidthUsage::kBwOverusing, kInitialBitrate - 1,
+                    states.simulated_clock->TimeInMilliseconds());
+  EXPECT_EQ(kMinBwePeriodMs,
+            states.aimd_rate_control->GetExpectedBandwidthPeriodMs());
+}
+
+TEST(AimdRateControlTest, BandwidthPeriodIsNotAboveMax) {
+  auto states = CreateAimdRateControlStates();
+  constexpr int kInitialBitrate = 10010000;
+  states.aimd_rate_control->SetEstimate(
+      kInitialBitrate, states.simulated_clock->TimeInMilliseconds());
+  states.simulated_clock->AdvanceTimeMilliseconds(100);
+  // Make a large (10 Mbps) bitrate drop to 10 kbps.
+  constexpr int kAckedBitrate = 10000 / kFractionAfterOveruse;
+  UpdateRateControl(states, BandwidthUsage::kBwOverusing, kAckedBitrate,
+                    states.simulated_clock->TimeInMilliseconds());
+  EXPECT_EQ(kMaxBwePeriodMs,
+            states.aimd_rate_control->GetExpectedBandwidthPeriodMs());
+}
+
 }  // namespace webrtc