Move BWE period calculation from ProbingIntervalEstimator to AimdRateControl.

webrtc/modules/remote_bitrate_estimator/aimd_rate_control_unittest.cc

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 #include <memory>
 
 #include "webrtc/modules/remote_bitrate_estimator/aimd_rate_control.h"
 #include "webrtc/system_wrappers/include/clock.h"
 #include "webrtc/test/gtest.h"
 
 namespace webrtc {
 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;
 };
 
 AimdRateControlStates CreateAimdRateControlStates() {
   AimdRateControlStates states;
   states.aimd_rate_control.reset(new AimdRateControl());
   states.simulated_clock.reset(new SimulatedClock(kClockInitialTime));
   return states;
@@ skipping 28 matching lines @@
 
 TEST(AimdRateControlTest, NearMaxIncreaseRateIs5kbpsOn60kbpsAnd100msRtt) {
   auto states = CreateAimdRateControlStates();
   constexpr int kBitrate = 60000;
   states.aimd_rate_control->SetEstimate(
       kBitrate, states.simulated_clock->TimeInMilliseconds());
   states.aimd_rate_control->SetRtt(100);
   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) {
   auto states = CreateAimdRateControlStates();
   constexpr int kAckedBitrate = 10000;
   states.aimd_rate_control->SetEstimate(
       kAckedBitrate, states.simulated_clock->TimeInMilliseconds());
   while (states.simulated_clock->TimeInMilliseconds() - kClockInitialTime <
          20000) {
     UpdateRateControl(states, BandwidthUsage::kBwNormal, kAckedBitrate,
@@ skipping 20 matching lines @@
   // If the acked bitrate decreases the BWE shouldn't be reduced to 1.5x
   // what's being acked, but also shouldn't get to increase more.
   uint32_t prev_estimate = states.aimd_rate_control->LatestEstimate();
   UpdateRateControl(states, BandwidthUsage::kBwNormal, kAckedBitrate / 2,
                     states.simulated_clock->TimeInMilliseconds());
   uint32_t new_estimate = states.aimd_rate_control->LatestEstimate();
   EXPECT_NEAR(new_estimate, static_cast<uint32_t>(1.5 * kAckedBitrate + 10000),
               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