Only use 95% of the link capacity if the true link capacity is found by probing.

webrtc/modules/congestion_controller/probe_bitrate_estimator_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 "webrtc/modules/congestion_controller/probe_bitrate_estimator.h"
 
 #include <vector>
 #include <utility>
 
 #include "webrtc/modules/remote_bitrate_estimator/aimd_rate_control.h"
 #include "webrtc/test/gmock.h"
 #include "webrtc/test/gtest.h"
 
 namespace webrtc {
 
 namespace {
 constexpr int kInvalidBitrate = -1;
 constexpr int kDefaultMinProbes = 5;
 constexpr int kDefaultMinBytes = 5000;
+constexpr float kTargetUtilizationFraction = 0.95f;
 }  // anonymous namespace
 
 class TestProbeBitrateEstimator : public ::testing::Test {
  public:
   TestProbeBitrateEstimator() : probe_bitrate_estimator_(nullptr) {}
 
   // TODO(philipel): Use PacedPacketInfo when ProbeBitrateEstimator is rewritten
   //                 to use that information.
   void AddPacketFeedback(int probe_cluster_id,
                          size_t size_bytes,
@@ skipping 82 matching lines @@
   AddPacketFeedback(0, 1000, 40, 27);
 
   EXPECT_EQ(measured_bps_, kInvalidBitrate);
 }
 
 TEST_F(TestProbeBitrateEstimator, SlowReceive) {
   AddPacketFeedback(0, 1000, 0, 10);
   AddPacketFeedback(0, 1000, 10, 40);
   AddPacketFeedback(0, 1000, 20, 70);
   AddPacketFeedback(0, 1000, 30, 85);
+  // Expected send rate = 800 kbps, expected receive rate = 320 kbps.
 
-  EXPECT_NEAR(measured_bps_, 320000, 10);
+  EXPECT_NEAR(measured_bps_, kTargetUtilizationFraction * 320000, 10);
 }
 
 TEST_F(TestProbeBitrateEstimator, BurstReceive) {
   AddPacketFeedback(0, 1000, 0, 50);
   AddPacketFeedback(0, 1000, 10, 50);
   AddPacketFeedback(0, 1000, 20, 50);
   AddPacketFeedback(0, 1000, 40, 50);
 
   EXPECT_EQ(measured_bps_, kInvalidBitrate);
 }
 
 TEST_F(TestProbeBitrateEstimator, MultipleClusters) {
   AddPacketFeedback(0, 1000, 0, 10);
   AddPacketFeedback(0, 1000, 10, 20);
   AddPacketFeedback(0, 1000, 20, 30);
   AddPacketFeedback(0, 1000, 40, 60);
-  EXPECT_NEAR(measured_bps_, 480000, 10);
+  // Expected send rate = 600 kbps, expected receive rate = 480 kbps.
+  EXPECT_NEAR(measured_bps_, kTargetUtilizationFraction * 480000, 10);
 
   AddPacketFeedback(0, 1000, 50, 60);
+  // Expected send rate = 640 kbps, expected receive rate = 640 kbps.
   EXPECT_NEAR(measured_bps_, 640000, 10);
 
   AddPacketFeedback(1, 1000, 60, 70);
   AddPacketFeedback(1, 1000, 65, 77);
   AddPacketFeedback(1, 1000, 70, 84);
   AddPacketFeedback(1, 1000, 75, 90);
+  // Expected send rate = 1600 kbps, expected receive rate = 1200 kbps.
 
-  EXPECT_NEAR(measured_bps_, 1200000, 10);
+  EXPECT_NEAR(measured_bps_, kTargetUtilizationFraction * 1200000, 10);
 }
 
 TEST_F(TestProbeBitrateEstimator, IgnoreOldClusters) {
   AddPacketFeedback(0, 1000, 0, 10);
   AddPacketFeedback(0, 1000, 10, 20);
   AddPacketFeedback(0, 1000, 20, 30);
 
   AddPacketFeedback(1, 1000, 60, 70);
   AddPacketFeedback(1, 1000, 65, 77);
   AddPacketFeedback(1, 1000, 70, 84);
   AddPacketFeedback(1, 1000, 75, 90);
+  // Expected send rate = 1600 kbps, expected receive rate = 1200 kbps.
 
-  EXPECT_NEAR(measured_bps_, 1200000, 10);
+  EXPECT_NEAR(measured_bps_, kTargetUtilizationFraction * 1200000, 10);
 
   // Coming in 6s later
   AddPacketFeedback(0, 1000, 40 + 6000, 60 + 6000);
 
   EXPECT_EQ(measured_bps_, kInvalidBitrate);
 }
 
 TEST_F(TestProbeBitrateEstimator, IgnoreSizeLastSendPacket) {
   AddPacketFeedback(0, 1000, 0, 10);
   AddPacketFeedback(0, 1000, 10, 20);
   AddPacketFeedback(0, 1000, 20, 30);
   AddPacketFeedback(0, 1000, 30, 40);
   AddPacketFeedback(0, 1500, 40, 50);
+  // Expected send rate = 800 kbps, expected receive rate = 900 kbps.
 
   EXPECT_NEAR(measured_bps_, 800000, 10);
 }
 
 TEST_F(TestProbeBitrateEstimator, IgnoreSizeFirstReceivePacket) {
   AddPacketFeedback(0, 1500, 0, 10);
   AddPacketFeedback(0, 1000, 10, 20);
   AddPacketFeedback(0, 1000, 20, 30);
   AddPacketFeedback(0, 1000, 30, 40);
+  // Expected send rate = 933 kbps, expected receive rate = 800 kbps.
 
-  EXPECT_NEAR(measured_bps_, 800000, 10);
+  EXPECT_NEAR(measured_bps_, kTargetUtilizationFraction * 800000, 10);
 }
 
 TEST_F(TestProbeBitrateEstimator, NoLastEstimatedBitrateBps) {
   EXPECT_FALSE(probe_bitrate_estimator_.FetchAndResetLastEstimatedBitrateBps());
 }
 
 TEST_F(TestProbeBitrateEstimator, FetchLastEstimatedBitrateBps) {
   AddPacketFeedback(0, 1000, 0, 10);
   AddPacketFeedback(0, 1000, 10, 20);
   AddPacketFeedback(0, 1000, 20, 30);
   AddPacketFeedback(0, 1000, 30, 40);
 
   auto estimated_bitrate_bps =
       probe_bitrate_estimator_.FetchAndResetLastEstimatedBitrateBps();
   EXPECT_TRUE(estimated_bitrate_bps);
   EXPECT_NEAR(*estimated_bitrate_bps, 800000, 10);
   EXPECT_FALSE(probe_bitrate_estimator_.FetchAndResetLastEstimatedBitrateBps());
 }
 
 }  // namespace webrtc