commit 3376c84c90c26ad8daff030ca2205d88ad97ec4a
author terelius <terelius@webrtc.org> Mon Jul 31 04:23:25 2017 -0700
committer Commit Bot <commit-bot@chromium.org> Mon Jul 31 11:23:25 2017 +0000
tree 42b9ebb526c80a5fe8918410231f7429c6656c62
parent 8eab09c77b01783aef5323a0ed9d0200c76e1ade

Add probing to recover faster from large bitrate drops. A single probe at 85% of the original bitrate is sent when transitioning from underusing back to normal state. The actual sending of the probes is disabled by default, and enabled by the field trial string WebRTC-BweRapidRecoveryExperiment/Enabled/. Existing code that did probing after large drops in ALR have been restructured so that it also delays the probe until we are no longer overusing.

BUG=webrtc:8015

Review-Url: https://codereview.webrtc.org/2986563002
Cr-Commit-Position: refs/heads/master@{#19187}

webrtc/modules/congestion_controller/probe_controller_unittest.cc

diff --git a/webrtc/modules/congestion_controller/probe_controller_unittest.cc b/webrtc/modules/congestion_controller/probe_controller_unittest.cc
index 9fc0f55..e0a040f 100644
--- a/webrtc/modules/congestion_controller/probe_controller_unittest.cc
+++ b/webrtc/modules/congestion_controller/probe_controller_unittest.cc
@@ -33,6 +33,8 @@
 constexpr int kExponentialProbingTimeoutMs = 5000;
 
 constexpr int kAlrProbeInterval = 5000;
+constexpr int kAlrEndedTimeoutMs = 3000;
+constexpr int kBitrateDropTimeoutMs = 5000;
 
 }  // namespace
 
@@ -120,22 +122,71 @@
   probe_controller_->SetEstimatedBitrate(1800);
 }
 
-TEST_F(ProbeControllerTest, ProbeAfterEstimateDropInAlr) {
+TEST_F(ProbeControllerTest, RequestProbeInAlr) {
   EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(2);
   probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                  kMaxBitrateBps);
   probe_controller_->SetEstimatedBitrate(500);
   testing::Mock::VerifyAndClearExpectations(&pacer_);
-
-  // When bandwidth estimate drops the controller should send a probe at the
-  // previous bitrate.
-  EXPECT_CALL(pacer_, CreateProbeCluster(500)).Times(1);
+  EXPECT_CALL(pacer_, CreateProbeCluster(0.85 * 500)).Times(1);
   EXPECT_CALL(pacer_, GetApplicationLimitedRegionStartTime())
       .WillRepeatedly(
           Return(rtc::Optional<int64_t>(clock_.TimeInMilliseconds())));
   clock_.AdvanceTimeMilliseconds(kAlrProbeInterval + 1);
   probe_controller_->Process();
-  probe_controller_->SetEstimatedBitrate(50);
+  probe_controller_->SetEstimatedBitrate(250);
+  probe_controller_->RequestProbe();
+}
+
+TEST_F(ProbeControllerTest, RequestProbeWhenAlrEndedRecently) {
+  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(2);
+  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
+                                 kMaxBitrateBps);
+  probe_controller_->SetEstimatedBitrate(500);
+  testing::Mock::VerifyAndClearExpectations(&pacer_);
+  EXPECT_CALL(pacer_, CreateProbeCluster(0.85 * 500)).Times(1);
+  EXPECT_CALL(pacer_, GetApplicationLimitedRegionStartTime())
+      .WillRepeatedly(Return(rtc::Optional<int64_t>()));
+  clock_.AdvanceTimeMilliseconds(kAlrProbeInterval + 1);
+  probe_controller_->Process();
+  probe_controller_->SetEstimatedBitrate(250);
+  probe_controller_->SetAlrEndedTimeMs(clock_.TimeInMilliseconds());
+  clock_.AdvanceTimeMilliseconds(kAlrEndedTimeoutMs - 1);
+  probe_controller_->RequestProbe();
+}
+
+TEST_F(ProbeControllerTest, RequestProbeWhenAlrNotEndedRecently) {
+  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(2);
+  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
+                                 kMaxBitrateBps);
+  probe_controller_->SetEstimatedBitrate(500);
+  testing::Mock::VerifyAndClearExpectations(&pacer_);
+  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(0);
+  EXPECT_CALL(pacer_, GetApplicationLimitedRegionStartTime())
+      .WillRepeatedly(Return(rtc::Optional<int64_t>()));
+  clock_.AdvanceTimeMilliseconds(kAlrProbeInterval + 1);
+  probe_controller_->Process();
+  probe_controller_->SetEstimatedBitrate(250);
+  probe_controller_->SetAlrEndedTimeMs(clock_.TimeInMilliseconds());
+  clock_.AdvanceTimeMilliseconds(kAlrEndedTimeoutMs + 1);
+  probe_controller_->RequestProbe();
+}
+
+TEST_F(ProbeControllerTest, RequestProbeWhenBweDropNotRecent) {
+  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(2);
+  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
+                                 kMaxBitrateBps);
+  probe_controller_->SetEstimatedBitrate(500);
+  testing::Mock::VerifyAndClearExpectations(&pacer_);
+  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(0);
+  EXPECT_CALL(pacer_, GetApplicationLimitedRegionStartTime())
+      .WillRepeatedly(
+          Return(rtc::Optional<int64_t>(clock_.TimeInMilliseconds())));
+  clock_.AdvanceTimeMilliseconds(kAlrProbeInterval + 1);
+  probe_controller_->Process();
+  probe_controller_->SetEstimatedBitrate(250);
+  clock_.AdvanceTimeMilliseconds(kBitrateDropTimeoutMs + 1);
+  probe_controller_->RequestProbe();
 }
 
 TEST_F(ProbeControllerTest, PeriodicProbing) {