modules/video_coding/nack_module2_unittest.cc - src - Git at Google

 /*
  *  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 "modules/video_coding/nack_module2.h"

 #include <algorithm>
 #include <cstdint>
 #include <cstring>
 #include <memory>

 #include "system_wrappers/include/clock.h"
 #include "test/field_trial.h"
 #include "test/gtest.h"

 namespace webrtc {
 class TestNackModule2 : public ::testing::TestWithParam<bool>,
                         public NackSender,
                         public KeyFrameRequestSender {
  protected:
   TestNackModule2()
       : clock_(new SimulatedClock(0)),
         field_trial_(GetParam()
                          ? "WebRTC-ExponentialNackBackoff/enabled:true/"
                          : "WebRTC-ExponentialNackBackoff/enabled:false/"),
         nack_module_(clock_.get(), this, this),
         keyframes_requested_(0) {}

   void SetUp() override { nack_module_.UpdateRtt(kDefaultRttMs); }

   void SendNack(const std::vector<uint16_t>& sequence_numbers,
                 bool buffering_allowed) override {
     sent_nacks_.insert(sent_nacks_.end(), sequence_numbers.begin(),
                        sequence_numbers.end());
   }

   void RequestKeyFrame() override { ++keyframes_requested_; }

   static constexpr int64_t kDefaultRttMs = 20;
   std::unique_ptr<SimulatedClock> clock_;
   test::ScopedFieldTrials field_trial_;
   NackModule2 nack_module_;
   std::vector<uint16_t> sent_nacks_;
   int keyframes_requested_;
 };

 TEST_P(TestNackModule2, NackOnePacket) {
   nack_module_.OnReceivedPacket(1, false, false);
   nack_module_.OnReceivedPacket(3, false, false);
   EXPECT_EQ(1u, sent_nacks_.size());
   EXPECT_EQ(2, sent_nacks_[0]);
 }

 TEST_P(TestNackModule2, WrappingSeqNum) {
   nack_module_.OnReceivedPacket(0xfffe, false, false);
   nack_module_.OnReceivedPacket(1, false, false);
   EXPECT_EQ(2u, sent_nacks_.size());
   EXPECT_EQ(0xffff, sent_nacks_[0]);
   EXPECT_EQ(0, sent_nacks_[1]);
 }

 TEST_P(TestNackModule2, WrappingSeqNumClearToKeyframe) {
   nack_module_.OnReceivedPacket(0xfffe, false, false);
   nack_module_.OnReceivedPacket(1, false, false);
   EXPECT_EQ(2u, sent_nacks_.size());
   EXPECT_EQ(0xffff, sent_nacks_[0]);
   EXPECT_EQ(0, sent_nacks_[1]);

   sent_nacks_.clear();
   nack_module_.OnReceivedPacket(2, true, false);
   EXPECT_EQ(0u, sent_nacks_.size());

   nack_module_.OnReceivedPacket(501, true, false);
   EXPECT_EQ(498u, sent_nacks_.size());
   for (int seq_num = 3; seq_num < 501; ++seq_num)
     EXPECT_EQ(seq_num, sent_nacks_[seq_num - 3]);

   sent_nacks_.clear();
   nack_module_.OnReceivedPacket(1001, false, false);
   EXPECT_EQ(499u, sent_nacks_.size());
   for (int seq_num = 502; seq_num < 1001; ++seq_num)
     EXPECT_EQ(seq_num, sent_nacks_[seq_num - 502]);

   sent_nacks_.clear();
   clock_->AdvanceTimeMilliseconds(100);
   nack_module_.Process();
   EXPECT_EQ(999u, sent_nacks_.size());
   EXPECT_EQ(0xffff, sent_nacks_[0]);
   EXPECT_EQ(0, sent_nacks_[1]);
   for (int seq_num = 3; seq_num < 501; ++seq_num)
     EXPECT_EQ(seq_num, sent_nacks_[seq_num - 1]);
   for (int seq_num = 502; seq_num < 1001; ++seq_num)
     EXPECT_EQ(seq_num, sent_nacks_[seq_num - 2]);

   // Adding packet 1004 will cause the nack list to reach it's max limit.
   // It will then clear all nacks up to the next keyframe (seq num 2),
   // thus removing 0xffff and 0 from the nack list.
   sent_nacks_.clear();
   nack_module_.OnReceivedPacket(1004, false, false);
   EXPECT_EQ(2u, sent_nacks_.size());
   EXPECT_EQ(1002, sent_nacks_[0]);
   EXPECT_EQ(1003, sent_nacks_[1]);

   sent_nacks_.clear();
   clock_->AdvanceTimeMilliseconds(100);
   nack_module_.Process();
   EXPECT_EQ(999u, sent_nacks_.size());
   for (int seq_num = 3; seq_num < 501; ++seq_num)
     EXPECT_EQ(seq_num, sent_nacks_[seq_num - 3]);
   for (int seq_num = 502; seq_num < 1001; ++seq_num)
     EXPECT_EQ(seq_num, sent_nacks_[seq_num - 4]);

   // Adding packet 1007 will cause the nack module to overflow again, thus
   // clearing everything up to 501 which is the next keyframe.
   nack_module_.OnReceivedPacket(1007, false, false);
   sent_nacks_.clear();
   clock_->AdvanceTimeMilliseconds(100);
   nack_module_.Process();
   EXPECT_EQ(503u, sent_nacks_.size());
   for (int seq_num = 502; seq_num < 1001; ++seq_num)
     EXPECT_EQ(seq_num, sent_nacks_[seq_num - 502]);
   EXPECT_EQ(1005, sent_nacks_[501]);
   EXPECT_EQ(1006, sent_nacks_[502]);
 }

 TEST_P(TestNackModule2, DontBurstOnTimeSkip) {
   nack_module_.Process();
   clock_->AdvanceTimeMilliseconds(20);
   EXPECT_EQ(0, nack_module_.TimeUntilNextProcess());
   nack_module_.Process();

   clock_->AdvanceTimeMilliseconds(100);
   EXPECT_EQ(0, nack_module_.TimeUntilNextProcess());
   nack_module_.Process();
   EXPECT_EQ(20, nack_module_.TimeUntilNextProcess());

   clock_->AdvanceTimeMilliseconds(19);
   EXPECT_EQ(1, nack_module_.TimeUntilNextProcess());
   clock_->AdvanceTimeMilliseconds(2);
   nack_module_.Process();
   EXPECT_EQ(19, nack_module_.TimeUntilNextProcess());

   clock_->AdvanceTimeMilliseconds(19);
   EXPECT_EQ(0, nack_module_.TimeUntilNextProcess());
   nack_module_.Process();

   clock_->AdvanceTimeMilliseconds(21);
   EXPECT_EQ(0, nack_module_.TimeUntilNextProcess());
   nack_module_.Process();
   EXPECT_EQ(19, nack_module_.TimeUntilNextProcess());
 }

 TEST_P(TestNackModule2, ResendNack) {
   nack_module_.OnReceivedPacket(1, false, false);
   nack_module_.OnReceivedPacket(3, false, false);
   size_t expected_nacks_sent = 1;
   EXPECT_EQ(expected_nacks_sent, sent_nacks_.size());
   EXPECT_EQ(2, sent_nacks_[0]);

   if (GetParam()) {
     // Retry has to wait at least 5ms by default.
     nack_module_.UpdateRtt(1);
     clock_->AdvanceTimeMilliseconds(4);
     nack_module_.Process();  // Too early.
     EXPECT_EQ(expected_nacks_sent, sent_nacks_.size());

     clock_->AdvanceTimeMilliseconds(1);
     nack_module_.Process();  // Now allowed.
     EXPECT_EQ(++expected_nacks_sent, sent_nacks_.size());
   } else {
     nack_module_.UpdateRtt(1);
     clock_->AdvanceTimeMilliseconds(1);
     nack_module_.Process();  // Fast retransmit allowed.
     EXPECT_EQ(++expected_nacks_sent, sent_nacks_.size());
   }

   // N:th try has to wait b^(N-1) * rtt by default.
   const double b = GetParam() ? 1.25 : 1.0;
   for (int i = 2; i < 10; ++i) {
     // Change RTT, above the 40ms max for exponential backoff.
     TimeDelta rtt = TimeDelta::Millis(160);  // + (i * 10 - 40)
     nack_module_.UpdateRtt(rtt.ms());

     // RTT gets capped at 160ms in backoff calculations.
     TimeDelta expected_backoff_delay =
         std::pow(b, i - 1) * std::min(rtt, TimeDelta::Millis(160));

     // Move to one millisecond before next allowed NACK.
     clock_->AdvanceTimeMilliseconds(expected_backoff_delay.ms() - 1);
     nack_module_.Process();
     EXPECT_EQ(expected_nacks_sent, sent_nacks_.size());

     // Move to one millisecond after next allowed NACK.
     // After rather than on to avoid rounding errors.
     clock_->AdvanceTimeMilliseconds(2);
     nack_module_.Process();  // Now allowed.
     EXPECT_EQ(++expected_nacks_sent, sent_nacks_.size());
   }

   // Giving up after 10 tries.
   clock_->AdvanceTimeMilliseconds(3000);
   nack_module_.Process();
   EXPECT_EQ(expected_nacks_sent, sent_nacks_.size());
 }

 TEST_P(TestNackModule2, ResendPacketMaxRetries) {
   nack_module_.OnReceivedPacket(1, false, false);
   nack_module_.OnReceivedPacket(3, false, false);
   EXPECT_EQ(1u, sent_nacks_.size());
   EXPECT_EQ(2, sent_nacks_[0]);

   int backoff_factor = 1;
   for (size_t retries = 1; retries < 10; ++retries) {
     // Exponential backoff, so that we don't reject NACK because of time.
     clock_->AdvanceTimeMilliseconds(backoff_factor * kDefaultRttMs);
     backoff_factor *= 2;
     nack_module_.Process();
     EXPECT_EQ(retries + 1, sent_nacks_.size());
   }

   clock_->AdvanceTimeMilliseconds(backoff_factor * kDefaultRttMs);
   nack_module_.Process();
   EXPECT_EQ(10u, sent_nacks_.size());
 }

 TEST_P(TestNackModule2, TooLargeNackList) {
   nack_module_.OnReceivedPacket(0, false, false);
   nack_module_.OnReceivedPacket(1001, false, false);
   EXPECT_EQ(1000u, sent_nacks_.size());
   EXPECT_EQ(0, keyframes_requested_);
   nack_module_.OnReceivedPacket(1003, false, false);
   EXPECT_EQ(1000u, sent_nacks_.size());
   EXPECT_EQ(1, keyframes_requested_);
   nack_module_.OnReceivedPacket(1004, false, false);
   EXPECT_EQ(1000u, sent_nacks_.size());
   EXPECT_EQ(1, keyframes_requested_);
 }

 TEST_P(TestNackModule2, TooLargeNackListWithKeyFrame) {
   nack_module_.OnReceivedPacket(0, false, false);
   nack_module_.OnReceivedPacket(1, true, false);
   nack_module_.OnReceivedPacket(1001, false, false);
   EXPECT_EQ(999u, sent_nacks_.size());
   EXPECT_EQ(0, keyframes_requested_);
   nack_module_.OnReceivedPacket(1003, false, false);
   EXPECT_EQ(1000u, sent_nacks_.size());
   EXPECT_EQ(0, keyframes_requested_);
   nack_module_.OnReceivedPacket(1005, false, false);
   EXPECT_EQ(1000u, sent_nacks_.size());
   EXPECT_EQ(1, keyframes_requested_);
 }

 TEST_P(TestNackModule2, ClearUpTo) {
   nack_module_.OnReceivedPacket(0, false, false);
   nack_module_.OnReceivedPacket(100, false, false);
   EXPECT_EQ(99u, sent_nacks_.size());

   sent_nacks_.clear();
   clock_->AdvanceTimeMilliseconds(100);
   nack_module_.ClearUpTo(50);
   nack_module_.Process();
   EXPECT_EQ(50u, sent_nacks_.size());
   EXPECT_EQ(50, sent_nacks_[0]);
 }

 TEST_P(TestNackModule2, ClearUpToWrap) {
   nack_module_.OnReceivedPacket(0xfff0, false, false);
   nack_module_.OnReceivedPacket(0xf, false, false);
   EXPECT_EQ(30u, sent_nacks_.size());

   sent_nacks_.clear();
   clock_->AdvanceTimeMilliseconds(100);
   nack_module_.ClearUpTo(0);
   nack_module_.Process();
   EXPECT_EQ(15u, sent_nacks_.size());
   EXPECT_EQ(0, sent_nacks_[0]);
 }

 TEST_P(TestNackModule2, PacketNackCount) {
   EXPECT_EQ(0, nack_module_.OnReceivedPacket(0, false, false));
   EXPECT_EQ(0, nack_module_.OnReceivedPacket(2, false, false));
   EXPECT_EQ(1, nack_module_.OnReceivedPacket(1, false, false));

   sent_nacks_.clear();
   nack_module_.UpdateRtt(100);
   EXPECT_EQ(0, nack_module_.OnReceivedPacket(5, false, false));
   clock_->AdvanceTimeMilliseconds(100);
   nack_module_.Process();
   clock_->AdvanceTimeMilliseconds(125);
   nack_module_.Process();
   EXPECT_EQ(3, nack_module_.OnReceivedPacket(3, false, false));
   EXPECT_EQ(3, nack_module_.OnReceivedPacket(4, false, false));
   EXPECT_EQ(0, nack_module_.OnReceivedPacket(4, false, false));
 }

 TEST_P(TestNackModule2, NackListFullAndNoOverlapWithKeyframes) {
   const int kMaxNackPackets = 1000;
   const unsigned int kFirstGap = kMaxNackPackets - 20;
   const unsigned int kSecondGap = 200;
   uint16_t seq_num = 0;
   nack_module_.OnReceivedPacket(seq_num++, true, false);
   seq_num += kFirstGap;
   nack_module_.OnReceivedPacket(seq_num++, true, false);
   EXPECT_EQ(kFirstGap, sent_nacks_.size());
   sent_nacks_.clear();
   seq_num += kSecondGap;
   nack_module_.OnReceivedPacket(seq_num, true, false);
   EXPECT_EQ(kSecondGap, sent_nacks_.size());
 }

 TEST_P(TestNackModule2, HandleFecRecoveredPacket) {
   nack_module_.OnReceivedPacket(1, false, false);
   nack_module_.OnReceivedPacket(4, false, true);
   EXPECT_EQ(0u, sent_nacks_.size());
   nack_module_.OnReceivedPacket(5, false, false);
   EXPECT_EQ(2u, sent_nacks_.size());
 }

 TEST_P(TestNackModule2, SendNackWithoutDelay) {
   nack_module_.OnReceivedPacket(0, false, false);
   nack_module_.OnReceivedPacket(100, false, false);
   EXPECT_EQ(99u, sent_nacks_.size());
 }

 INSTANTIATE_TEST_SUITE_P(WithAndWithoutBackoff,
                          TestNackModule2,
                          ::testing::Values(true, false));

 class TestNackModule2WithFieldTrial : public ::testing::Test,
                                       public NackSender,
                                       public KeyFrameRequestSender {
  protected:
   TestNackModule2WithFieldTrial()
       : nack_delay_field_trial_("WebRTC-SendNackDelayMs/10/"),
         clock_(new SimulatedClock(0)),
         nack_module_(clock_.get(), this, this),
         keyframes_requested_(0) {}

   void SendNack(const std::vector<uint16_t>& sequence_numbers,
                 bool buffering_allowed) override {
     sent_nacks_.insert(sent_nacks_.end(), sequence_numbers.begin(),
                        sequence_numbers.end());
   }

   void RequestKeyFrame() override { ++keyframes_requested_; }

   test::ScopedFieldTrials nack_delay_field_trial_;
   std::unique_ptr<SimulatedClock> clock_;
   NackModule2 nack_module_;
   std::vector<uint16_t> sent_nacks_;
   int keyframes_requested_;
 };

 TEST_F(TestNackModule2WithFieldTrial, SendNackWithDelay) {
   nack_module_.OnReceivedPacket(0, false, false);
   nack_module_.OnReceivedPacket(100, false, false);
   EXPECT_EQ(0u, sent_nacks_.size());
   clock_->AdvanceTimeMilliseconds(10);
   nack_module_.OnReceivedPacket(106, false, false);
   EXPECT_EQ(99u, sent_nacks_.size());
   clock_->AdvanceTimeMilliseconds(10);
   nack_module_.OnReceivedPacket(109, false, false);
   EXPECT_EQ(104u, sent_nacks_.size());
 }
 }  // namespace webrtc
	/*
	* 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 "modules/video_coding/nack_module2.h"

	#include <algorithm>
	#include <cstdint>
	#include <cstring>
	#include <memory>

	#include "system_wrappers/include/clock.h"
	#include "test/field_trial.h"
	#include "test/gtest.h"

	namespace webrtc {
	class TestNackModule2 : public ::testing::TestWithParam<bool>,
	public NackSender,
	public KeyFrameRequestSender {
	protected:
	TestNackModule2()
	: clock_(new SimulatedClock(0)),
	field_trial_(GetParam()
	? "WebRTC-ExponentialNackBackoff/enabled:true/"
	: "WebRTC-ExponentialNackBackoff/enabled:false/"),
	nack_module_(clock_.get(), this, this),
	keyframes_requested_(0) {}

	void SetUp() override { nack_module_.UpdateRtt(kDefaultRttMs); }

	void SendNack(const std::vector<uint16_t>& sequence_numbers,
	bool buffering_allowed) override {
	sent_nacks_.insert(sent_nacks_.end(), sequence_numbers.begin(),
	sequence_numbers.end());
	}

	void RequestKeyFrame() override { ++keyframes_requested_; }

	static constexpr int64_t kDefaultRttMs = 20;
	std::unique_ptr<SimulatedClock> clock_;
	test::ScopedFieldTrials field_trial_;
	NackModule2 nack_module_;
	std::vector<uint16_t> sent_nacks_;
	int keyframes_requested_;
	};

	TEST_P(TestNackModule2, NackOnePacket) {
	nack_module_.OnReceivedPacket(1, false, false);
	nack_module_.OnReceivedPacket(3, false, false);
	EXPECT_EQ(1u, sent_nacks_.size());
	EXPECT_EQ(2, sent_nacks_[0]);
	}

	TEST_P(TestNackModule2, WrappingSeqNum) {
	nack_module_.OnReceivedPacket(0xfffe, false, false);
	nack_module_.OnReceivedPacket(1, false, false);
	EXPECT_EQ(2u, sent_nacks_.size());
	EXPECT_EQ(0xffff, sent_nacks_[0]);
	EXPECT_EQ(0, sent_nacks_[1]);
	}

	TEST_P(TestNackModule2, WrappingSeqNumClearToKeyframe) {
	nack_module_.OnReceivedPacket(0xfffe, false, false);
	nack_module_.OnReceivedPacket(1, false, false);
	EXPECT_EQ(2u, sent_nacks_.size());
	EXPECT_EQ(0xffff, sent_nacks_[0]);
	EXPECT_EQ(0, sent_nacks_[1]);

	sent_nacks_.clear();
	nack_module_.OnReceivedPacket(2, true, false);
	EXPECT_EQ(0u, sent_nacks_.size());

	nack_module_.OnReceivedPacket(501, true, false);
	EXPECT_EQ(498u, sent_nacks_.size());
	for (int seq_num = 3; seq_num < 501; ++seq_num)
	EXPECT_EQ(seq_num, sent_nacks_[seq_num - 3]);

	sent_nacks_.clear();
	nack_module_.OnReceivedPacket(1001, false, false);
	EXPECT_EQ(499u, sent_nacks_.size());
	for (int seq_num = 502; seq_num < 1001; ++seq_num)
	EXPECT_EQ(seq_num, sent_nacks_[seq_num - 502]);

	sent_nacks_.clear();
	clock_->AdvanceTimeMilliseconds(100);
	nack_module_.Process();
	EXPECT_EQ(999u, sent_nacks_.size());
	EXPECT_EQ(0xffff, sent_nacks_[0]);
	EXPECT_EQ(0, sent_nacks_[1]);
	for (int seq_num = 3; seq_num < 501; ++seq_num)
	EXPECT_EQ(seq_num, sent_nacks_[seq_num - 1]);
	for (int seq_num = 502; seq_num < 1001; ++seq_num)
	EXPECT_EQ(seq_num, sent_nacks_[seq_num - 2]);

	// Adding packet 1004 will cause the nack list to reach it's max limit.
	// It will then clear all nacks up to the next keyframe (seq num 2),
	// thus removing 0xffff and 0 from the nack list.
	sent_nacks_.clear();
	nack_module_.OnReceivedPacket(1004, false, false);
	EXPECT_EQ(2u, sent_nacks_.size());
	EXPECT_EQ(1002, sent_nacks_[0]);
	EXPECT_EQ(1003, sent_nacks_[1]);

	sent_nacks_.clear();
	clock_->AdvanceTimeMilliseconds(100);
	nack_module_.Process();
	EXPECT_EQ(999u, sent_nacks_.size());
	for (int seq_num = 3; seq_num < 501; ++seq_num)
	EXPECT_EQ(seq_num, sent_nacks_[seq_num - 3]);
	for (int seq_num = 502; seq_num < 1001; ++seq_num)
	EXPECT_EQ(seq_num, sent_nacks_[seq_num - 4]);

	// Adding packet 1007 will cause the nack module to overflow again, thus
	// clearing everything up to 501 which is the next keyframe.
	nack_module_.OnReceivedPacket(1007, false, false);
	sent_nacks_.clear();
	clock_->AdvanceTimeMilliseconds(100);
	nack_module_.Process();
	EXPECT_EQ(503u, sent_nacks_.size());
	for (int seq_num = 502; seq_num < 1001; ++seq_num)
	EXPECT_EQ(seq_num, sent_nacks_[seq_num - 502]);
	EXPECT_EQ(1005, sent_nacks_[501]);
	EXPECT_EQ(1006, sent_nacks_[502]);
	}

	TEST_P(TestNackModule2, DontBurstOnTimeSkip) {
	nack_module_.Process();
	clock_->AdvanceTimeMilliseconds(20);
	EXPECT_EQ(0, nack_module_.TimeUntilNextProcess());
	nack_module_.Process();

	clock_->AdvanceTimeMilliseconds(100);
	EXPECT_EQ(0, nack_module_.TimeUntilNextProcess());
	nack_module_.Process();
	EXPECT_EQ(20, nack_module_.TimeUntilNextProcess());

	clock_->AdvanceTimeMilliseconds(19);
	EXPECT_EQ(1, nack_module_.TimeUntilNextProcess());
	clock_->AdvanceTimeMilliseconds(2);
	nack_module_.Process();
	EXPECT_EQ(19, nack_module_.TimeUntilNextProcess());

	clock_->AdvanceTimeMilliseconds(19);
	EXPECT_EQ(0, nack_module_.TimeUntilNextProcess());
	nack_module_.Process();

	clock_->AdvanceTimeMilliseconds(21);
	EXPECT_EQ(0, nack_module_.TimeUntilNextProcess());
	nack_module_.Process();
	EXPECT_EQ(19, nack_module_.TimeUntilNextProcess());
	}

	TEST_P(TestNackModule2, ResendNack) {
	nack_module_.OnReceivedPacket(1, false, false);
	nack_module_.OnReceivedPacket(3, false, false);
	size_t expected_nacks_sent = 1;
	EXPECT_EQ(expected_nacks_sent, sent_nacks_.size());
	EXPECT_EQ(2, sent_nacks_[0]);

	if (GetParam()) {
	// Retry has to wait at least 5ms by default.
	nack_module_.UpdateRtt(1);
	clock_->AdvanceTimeMilliseconds(4);
	nack_module_.Process(); // Too early.
	EXPECT_EQ(expected_nacks_sent, sent_nacks_.size());

	clock_->AdvanceTimeMilliseconds(1);
	nack_module_.Process(); // Now allowed.
	EXPECT_EQ(++expected_nacks_sent, sent_nacks_.size());
	} else {
	nack_module_.UpdateRtt(1);
	clock_->AdvanceTimeMilliseconds(1);
	nack_module_.Process(); // Fast retransmit allowed.
	EXPECT_EQ(++expected_nacks_sent, sent_nacks_.size());
	}

	// N:th try has to wait b^(N-1) * rtt by default.
	const double b = GetParam() ? 1.25 : 1.0;
	for (int i = 2; i < 10; ++i) {
	// Change RTT, above the 40ms max for exponential backoff.
	TimeDelta rtt = TimeDelta::Millis(160); // + (i * 10 - 40)
	nack_module_.UpdateRtt(rtt.ms());

	// RTT gets capped at 160ms in backoff calculations.
	TimeDelta expected_backoff_delay =
	std::pow(b, i - 1) * std::min(rtt, TimeDelta::Millis(160));

	// Move to one millisecond before next allowed NACK.
	clock_->AdvanceTimeMilliseconds(expected_backoff_delay.ms() - 1);
	nack_module_.Process();
	EXPECT_EQ(expected_nacks_sent, sent_nacks_.size());

	// Move to one millisecond after next allowed NACK.
	// After rather than on to avoid rounding errors.
	clock_->AdvanceTimeMilliseconds(2);
	nack_module_.Process(); // Now allowed.
	EXPECT_EQ(++expected_nacks_sent, sent_nacks_.size());
	}

	// Giving up after 10 tries.
	clock_->AdvanceTimeMilliseconds(3000);
	nack_module_.Process();
	EXPECT_EQ(expected_nacks_sent, sent_nacks_.size());
	}

	TEST_P(TestNackModule2, ResendPacketMaxRetries) {
	nack_module_.OnReceivedPacket(1, false, false);
	nack_module_.OnReceivedPacket(3, false, false);
	EXPECT_EQ(1u, sent_nacks_.size());
	EXPECT_EQ(2, sent_nacks_[0]);

	int backoff_factor = 1;
	for (size_t retries = 1; retries < 10; ++retries) {
	// Exponential backoff, so that we don't reject NACK because of time.
	clock_->AdvanceTimeMilliseconds(backoff_factor * kDefaultRttMs);
	backoff_factor *= 2;
	nack_module_.Process();
	EXPECT_EQ(retries + 1, sent_nacks_.size());
	}

	clock_->AdvanceTimeMilliseconds(backoff_factor * kDefaultRttMs);
	nack_module_.Process();
	EXPECT_EQ(10u, sent_nacks_.size());
	}

	TEST_P(TestNackModule2, TooLargeNackList) {
	nack_module_.OnReceivedPacket(0, false, false);
	nack_module_.OnReceivedPacket(1001, false, false);
	EXPECT_EQ(1000u, sent_nacks_.size());
	EXPECT_EQ(0, keyframes_requested_);
	nack_module_.OnReceivedPacket(1003, false, false);
	EXPECT_EQ(1000u, sent_nacks_.size());
	EXPECT_EQ(1, keyframes_requested_);
	nack_module_.OnReceivedPacket(1004, false, false);
	EXPECT_EQ(1000u, sent_nacks_.size());
	EXPECT_EQ(1, keyframes_requested_);
	}

	TEST_P(TestNackModule2, TooLargeNackListWithKeyFrame) {
	nack_module_.OnReceivedPacket(0, false, false);
	nack_module_.OnReceivedPacket(1, true, false);
	nack_module_.OnReceivedPacket(1001, false, false);
	EXPECT_EQ(999u, sent_nacks_.size());
	EXPECT_EQ(0, keyframes_requested_);
	nack_module_.OnReceivedPacket(1003, false, false);
	EXPECT_EQ(1000u, sent_nacks_.size());
	EXPECT_EQ(0, keyframes_requested_);
	nack_module_.OnReceivedPacket(1005, false, false);
	EXPECT_EQ(1000u, sent_nacks_.size());
	EXPECT_EQ(1, keyframes_requested_);
	}

	TEST_P(TestNackModule2, ClearUpTo) {
	nack_module_.OnReceivedPacket(0, false, false);
	nack_module_.OnReceivedPacket(100, false, false);
	EXPECT_EQ(99u, sent_nacks_.size());

	sent_nacks_.clear();
	clock_->AdvanceTimeMilliseconds(100);
	nack_module_.ClearUpTo(50);
	nack_module_.Process();
	EXPECT_EQ(50u, sent_nacks_.size());
	EXPECT_EQ(50, sent_nacks_[0]);
	}

	TEST_P(TestNackModule2, ClearUpToWrap) {
	nack_module_.OnReceivedPacket(0xfff0, false, false);
	nack_module_.OnReceivedPacket(0xf, false, false);
	EXPECT_EQ(30u, sent_nacks_.size());

	sent_nacks_.clear();
	clock_->AdvanceTimeMilliseconds(100);
	nack_module_.ClearUpTo(0);
	nack_module_.Process();
	EXPECT_EQ(15u, sent_nacks_.size());
	EXPECT_EQ(0, sent_nacks_[0]);
	}

	TEST_P(TestNackModule2, PacketNackCount) {
	EXPECT_EQ(0, nack_module_.OnReceivedPacket(0, false, false));
	EXPECT_EQ(0, nack_module_.OnReceivedPacket(2, false, false));
	EXPECT_EQ(1, nack_module_.OnReceivedPacket(1, false, false));

	sent_nacks_.clear();
	nack_module_.UpdateRtt(100);
	EXPECT_EQ(0, nack_module_.OnReceivedPacket(5, false, false));
	clock_->AdvanceTimeMilliseconds(100);
	nack_module_.Process();
	clock_->AdvanceTimeMilliseconds(125);
	nack_module_.Process();
	EXPECT_EQ(3, nack_module_.OnReceivedPacket(3, false, false));
	EXPECT_EQ(3, nack_module_.OnReceivedPacket(4, false, false));
	EXPECT_EQ(0, nack_module_.OnReceivedPacket(4, false, false));
	}

	TEST_P(TestNackModule2, NackListFullAndNoOverlapWithKeyframes) {
	const int kMaxNackPackets = 1000;
	const unsigned int kFirstGap = kMaxNackPackets - 20;
	const unsigned int kSecondGap = 200;
	uint16_t seq_num = 0;
	nack_module_.OnReceivedPacket(seq_num++, true, false);
	seq_num += kFirstGap;
	nack_module_.OnReceivedPacket(seq_num++, true, false);
	EXPECT_EQ(kFirstGap, sent_nacks_.size());
	sent_nacks_.clear();
	seq_num += kSecondGap;
	nack_module_.OnReceivedPacket(seq_num, true, false);
	EXPECT_EQ(kSecondGap, sent_nacks_.size());
	}

	TEST_P(TestNackModule2, HandleFecRecoveredPacket) {
	nack_module_.OnReceivedPacket(1, false, false);
	nack_module_.OnReceivedPacket(4, false, true);
	EXPECT_EQ(0u, sent_nacks_.size());
	nack_module_.OnReceivedPacket(5, false, false);
	EXPECT_EQ(2u, sent_nacks_.size());
	}

	TEST_P(TestNackModule2, SendNackWithoutDelay) {
	nack_module_.OnReceivedPacket(0, false, false);
	nack_module_.OnReceivedPacket(100, false, false);
	EXPECT_EQ(99u, sent_nacks_.size());
	}

	INSTANTIATE_TEST_SUITE_P(WithAndWithoutBackoff,
	TestNackModule2,
	::testing::Values(true, false));

	class TestNackModule2WithFieldTrial : public ::testing::Test,
	public NackSender,
	public KeyFrameRequestSender {
	protected:
	TestNackModule2WithFieldTrial()
	: nack_delay_field_trial_("WebRTC-SendNackDelayMs/10/"),
	clock_(new SimulatedClock(0)),
	nack_module_(clock_.get(), this, this),
	keyframes_requested_(0) {}

	void SendNack(const std::vector<uint16_t>& sequence_numbers,
	bool buffering_allowed) override {
	sent_nacks_.insert(sent_nacks_.end(), sequence_numbers.begin(),
	sequence_numbers.end());
	}

	void RequestKeyFrame() override { ++keyframes_requested_; }

	test::ScopedFieldTrials nack_delay_field_trial_;
	std::unique_ptr<SimulatedClock> clock_;
	NackModule2 nack_module_;
	std::vector<uint16_t> sent_nacks_;
	int keyframes_requested_;
	};

	TEST_F(TestNackModule2WithFieldTrial, SendNackWithDelay) {
	nack_module_.OnReceivedPacket(0, false, false);
	nack_module_.OnReceivedPacket(100, false, false);
	EXPECT_EQ(0u, sent_nacks_.size());
	clock_->AdvanceTimeMilliseconds(10);
	nack_module_.OnReceivedPacket(106, false, false);
	EXPECT_EQ(99u, sent_nacks_.size());
	clock_->AdvanceTimeMilliseconds(10);
	nack_module_.OnReceivedPacket(109, false, false);
	EXPECT_EQ(104u, sent_nacks_.size());
	}
	} // namespace webrtc