Implement periodic bandwidth probing in application-limited region.

webrtc/modules/congestion_controller/probe_controller_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/base/logging.h"
 #include "webrtc/modules/congestion_controller/probe_controller.h"
 #include "webrtc/modules/pacing/mock/mock_paced_sender.h"
 #include "webrtc/system_wrappers/include/clock.h"
 #include "webrtc/test/gmock.h"
 #include "webrtc/test/gtest.h"
 
 using testing::_;
 using testing::AtLeast;
 using testing::NiceMock;
+using testing::Return;
 
 namespace webrtc {
 namespace test {
 
 namespace {
 
 constexpr int kMinBitrateBps = 100;
 constexpr int kStartBitrateBps = 300;
 constexpr int kMaxBitrateBps = 10000;
 
 constexpr int kExponentialProbingTimeoutMs = 5000;
 
+constexpr int kAlrProbeInterval = 5000;
+
 }  // namespace
 
 class ProbeControllerTest : public ::testing::Test {
  protected:
-  ProbeControllerTest() : clock_(0) {
+  ProbeControllerTest() : clock_(100000000L) {
     probe_controller_.reset(new ProbeController(&pacer_, &clock_));
   }
   ~ProbeControllerTest() override {}
 
   SimulatedClock clock_;
   NiceMock<MockPacedSender> pacer_;
   std::unique_ptr<ProbeController> probe_controller_;
 };
 
 TEST_F(ProbeControllerTest, InitiatesProbingAtStart) {
@@ skipping 23 matching lines @@
 
   EXPECT_CALL(pacer_, CreateProbeCluster(kMaxBitrateBps + 100, _));
   probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                  kMaxBitrateBps + 100);
 }
 
 TEST_F(ProbeControllerTest, TestExponentialProbing) {
   probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                  kMaxBitrateBps);
 
-
-
   EXPECT_CALL(pacer_, CreateProbeCluster(2 * 1800, _));
   probe_controller_->SetEstimatedBitrate(1800);
 }
 
 TEST_F(ProbeControllerTest, TestExponentialProbingTimeout) {
   probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                  kMaxBitrateBps);
 
   // Advance far enough to cause a time out in waiting for probing result.
   clock_.AdvanceTimeMilliseconds(kExponentialProbingTimeoutMs);
   EXPECT_CALL(pacer_, CreateProbeCluster(2 * 1800, _)).Times(0);
   probe_controller_->SetEstimatedBitrate(1800);
 }
 
+TEST_F(ProbeControllerTest, ProbeAfterEstimateDropInAlr) {
+  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_, GetApplicationLimitedRegionStartTime())
+      .WillRepeatedly(Return(clock_.TimeInMilliseconds()));
+  clock_.AdvanceTimeMilliseconds(kAlrProbeInterval + 1);
+  probe_controller_->SetEstimatedBitrate(50);
+}
+
+TEST_F(ProbeControllerTest, PeriodicProbing) {
+  EXPECT_CALL(pacer_, CreateProbeCluster(_, _)).Times(2);
+  probe_controller_->EnablePeriodicProbing(true);
+  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
+                                 kMaxBitrateBps);
+  probe_controller_->SetEstimatedBitrate(500);
+  testing::Mock::VerifyAndClearExpectations(&pacer_);
+
+  int64_t start_time = clock_.TimeInMilliseconds();
+
+  // Expect the controller to send a new probe after 5s has passed.
+  EXPECT_CALL(pacer_, CreateProbeCluster(1000, _)).Times(1);
+  EXPECT_CALL(pacer_, GetApplicationLimitedRegionStartTime())
+      .WillRepeatedly(Return(start_time));
+  clock_.AdvanceTimeMilliseconds(5000);
+  probe_controller_->Process();
+  probe_controller_->SetEstimatedBitrate(500);
+  testing::Mock::VerifyAndClearExpectations(&pacer_);
+
+  // The following probe should be sent at 10s into ALR.
+  EXPECT_CALL(pacer_, CreateProbeCluster(_, _)).Times(0);
+  EXPECT_CALL(pacer_, GetApplicationLimitedRegionStartTime())
+      .WillRepeatedly(Return(start_time));
+  clock_.AdvanceTimeMilliseconds(4000);
+  probe_controller_->Process();
+  probe_controller_->SetEstimatedBitrate(500);
+  testing::Mock::VerifyAndClearExpectations(&pacer_);
+
+  EXPECT_CALL(pacer_, CreateProbeCluster(_, _)).Times(1);
+  EXPECT_CALL(pacer_, GetApplicationLimitedRegionStartTime())
+      .WillRepeatedly(Return(start_time));
+  clock_.AdvanceTimeMilliseconds(1000);
+  probe_controller_->Process();
+  probe_controller_->SetEstimatedBitrate(500);
+  testing::Mock::VerifyAndClearExpectations(&pacer_);
+}
+
 }  // namespace test
 }  // namespace webrtc