Let alr dectector use a budged to detect underuse.

webrtc/modules/pacing/alr_detector_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.
  */
 
@@ skipping 11 matching lines @@
 
 class AlrDetectorTest : public testing::Test {
  public:
   void SetUp() override {
     alr_detector_.SetEstimatedBitrate(kEstimatedBitrateBps);
   }
 
   void SimulateOutgoingTraffic(int interval_ms, int usage_percentage) {
     const int kTimeStepMs = 10;
     for (int t = 0; t < interval_ms; t += kTimeStepMs) {
-      now_ms += kTimeStepMs;
       alr_detector_.OnBytesSent(kEstimatedBitrateBps * usage_percentage *
                                     kTimeStepMs / (8 * 100 * 1000),
-                                now_ms);
+                                kTimeStepMs);
     }
-
     int remainder_ms = interval_ms % kTimeStepMs;
-    now_ms += remainder_ms;
     if (remainder_ms > 0) {
       alr_detector_.OnBytesSent(kEstimatedBitrateBps * usage_percentage *
                                     remainder_ms / (8 * 100 * 1000),
-                                remainder_ms);
+                                kTimeStepMs);
     }
   }
 
  protected:
   AlrDetector alr_detector_;
-  int64_t now_ms = 1;
 };
 
 TEST_F(AlrDetectorTest, AlrDetection) {
   // Start in non-ALR state.
   EXPECT_FALSE(alr_detector_.GetApplicationLimitedRegionStartTime());
 
   // Stay in non-ALR state when usage is close to 100%.
-  SimulateOutgoingTraffic(500, 90);
+  SimulateOutgoingTraffic(1000, 90);
   EXPECT_FALSE(alr_detector_.GetApplicationLimitedRegionStartTime());
 
   // Verify that we ALR starts when bitrate drops below 20%.
-  SimulateOutgoingTraffic(500, 20);
+  SimulateOutgoingTraffic(1000, 20);
   EXPECT_TRUE(alr_detector_.GetApplicationLimitedRegionStartTime());
 
-  // Verify that we remain in ALR state while usage is still below 70%.
-  SimulateOutgoingTraffic(500, 69);
-  EXPECT_TRUE(alr_detector_.GetApplicationLimitedRegionStartTime());
-
-  // Verify that ALR ends when usage is above 70%.
-  SimulateOutgoingTraffic(500, 75);
+  // Verify that ALR ends when usage is above 60%.

[stefan-webrtc, 2017/07/06 14:55:38]

Not clear how for instance 60% relates to 1000, 100 below. Can we express those
in terms of 60% instead, or in some way make it easier to read?

[tschumi, 2017/07/07 08:47:30]

Changed the impl a little so that the test code should be better understandable.

+  SimulateOutgoingTraffic(1000, 100);
   EXPECT_FALSE(alr_detector_.GetApplicationLimitedRegionStartTime());
 }
 
 TEST_F(AlrDetectorTest, ShortSpike) {
   // Start in non-ALR state.
   EXPECT_FALSE(alr_detector_.GetApplicationLimitedRegionStartTime());
 
   // Verify that we ALR starts when bitrate drops below 20%.
-  SimulateOutgoingTraffic(500, 20);
+  SimulateOutgoingTraffic(1000, 20);
   EXPECT_TRUE(alr_detector_.GetApplicationLimitedRegionStartTime());
 
   // Verify that we stay in ALR region even after a short bitrate spike.
-  SimulateOutgoingTraffic(100, 150);
+  SimulateOutgoingTraffic(200, 150);
   EXPECT_TRUE(alr_detector_.GetApplicationLimitedRegionStartTime());
 
-  SimulateOutgoingTraffic(200, 20);
-  EXPECT_TRUE(alr_detector_.GetApplicationLimitedRegionStartTime());
-
-  // ALR ends when usage is above 70%.
-  SimulateOutgoingTraffic(500, 75);
+  // ALR ends when usage is above 100%.

[stefan-webrtc, 2017/07/06 14:55:38]

Do we want to change from 70% to 100%?

[tschumi, 2017/07/07 08:47:30]

Yea my mistake => changed it to 65 % (new default for alr)

+  SimulateOutgoingTraffic(1000, 100);
   EXPECT_FALSE(alr_detector_.GetApplicationLimitedRegionStartTime());
 }
 
 TEST_F(AlrDetectorTest, BandwidthEstimateChanges) {
   // Start in non-ALR state.
   EXPECT_FALSE(alr_detector_.GetApplicationLimitedRegionStartTime());
 
   // ALR starts when bitrate drops below 20%.

[stefan-webrtc, 2017/07/06 14:55:37]

Is this comment still correct? Why did it change from 500 to 1000?

[tschumi, 2017/07/07 08:47:30]

Because of the new impl. it takes more time to detect alr.
The comment is still valid.

-  SimulateOutgoingTraffic(500, 20);
+  SimulateOutgoingTraffic(1000, 20);
   EXPECT_TRUE(alr_detector_.GetApplicationLimitedRegionStartTime());
 
   // When bandwidth estimate drops the detector should stay in ALR mode and quit
   // it shortly afterwards as the sender continues sending the same amount of
   // traffic. This is necessary to ensure that ProbeController can still react
   // to the BWE drop by initiating a new probe.
   alr_detector_.SetEstimatedBitrate(kEstimatedBitrateBps / 5);
   EXPECT_TRUE(alr_detector_.GetApplicationLimitedRegionStartTime());
-  SimulateOutgoingTraffic(10, 20);
+  SimulateOutgoingTraffic(1000, 50);
   EXPECT_FALSE(alr_detector_.GetApplicationLimitedRegionStartTime());
 }
 
 }  // namespace webrtc