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Add exponential backoff of retransmissions for a given packet

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Bug: webrtc:8624
Change-Id: I8900c54935bf1da11ac74665426b0d198bd6d814
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/30900
Reviewed-by: Sergey Silkin <ssilkin@webrtc.org>
Commit-Queue: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29625}
This commit is contained in:
Erik Språng
2019-10-25 09:24:45 +02:00
committed by Commit Bot
parent 632d57d3d0
commit 3eae7e4e3c
4 changed files with 145 additions and 41 deletions
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110
modules/video_coding/nack_module_unittest.cc
View File

@ -10,6 +10,7 @@
#include "modules/video_coding/nack_module.h"
#include <algorithm>
#include <cstdint>
#include <cstring>
#include <memory>
@ -19,15 +20,20 @@
#include "test/gtest.h"
namespace webrtc {
class TestNackModule : public ::testing::Test,
class TestNackModule : public ::testing::TestWithParam<bool>,
public NackSender,
public KeyFrameRequestSender {
protected:
TestNackModule()
: 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(),
@ -36,20 +42,22 @@ class TestNackModule : public ::testing::Test,
void RequestKeyFrame() override { ++keyframes_requested_; }
static constexpr int64_t kDefaultRttMs = 20;
std::unique_ptr<SimulatedClock> clock_;
test::ScopedFieldTrials field_trial_;
NackModule nack_module_;
std::vector<uint16_t> sent_nacks_;
int keyframes_requested_;
};
TEST_F(TestNackModule, NackOnePacket) {
TEST_P(TestNackModule, 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_F(TestNackModule, WrappingSeqNum) {
TEST_P(TestNackModule, WrappingSeqNum) {
nack_module_.OnReceivedPacket(0xfffe, false, false);
nack_module_.OnReceivedPacket(1, false, false);
EXPECT_EQ(2u, sent_nacks_.size());
@ -57,7 +65,7 @@ TEST_F(TestNackModule, WrappingSeqNum) {
EXPECT_EQ(0, sent_nacks_[1]);
}
TEST_F(TestNackModule, WrappingSeqNumClearToKeyframe) {
TEST_P(TestNackModule, WrappingSeqNumClearToKeyframe) {
nack_module_.OnReceivedPacket(0xfffe, false, false);
nack_module_.OnReceivedPacket(1, false, false);
EXPECT_EQ(2u, sent_nacks_.size());
@ -121,7 +129,7 @@ TEST_F(TestNackModule, WrappingSeqNumClearToKeyframe) {
EXPECT_EQ(1006, sent_nacks_[502]);
}
TEST_F(TestNackModule, DontBurstOnTimeSkip) {
TEST_P(TestNackModule, DontBurstOnTimeSkip) {
nack_module_.Process();
clock_->AdvanceTimeMilliseconds(20);
EXPECT_EQ(0, nack_module_.TimeUntilNextProcess());
@ -148,54 +156,80 @@ TEST_F(TestNackModule, DontBurstOnTimeSkip) {
EXPECT_EQ(19, nack_module_.TimeUntilNextProcess());
}
TEST_F(TestNackModule, ResendNack) {
TEST_P(TestNackModule, ResendNack) {
nack_module_.OnReceivedPacket(1, false, false);
nack_module_.OnReceivedPacket(3, false, false);
EXPECT_EQ(1u, sent_nacks_.size());
size_t expected_nacks_sent = 1;
EXPECT_EQ(expected_nacks_sent, sent_nacks_.size());
EXPECT_EQ(2, sent_nacks_[0]);
// Default RTT is 100
clock_->AdvanceTimeMilliseconds(99);
nack_module_.Process();
EXPECT_EQ(1u, sent_nacks_.size());
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();
EXPECT_EQ(2u, 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());
}
nack_module_.UpdateRtt(50);
clock_->AdvanceTimeMilliseconds(100);
nack_module_.Process();
EXPECT_EQ(3u, 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::ms(160); // + (i * 10 - 40)
nack_module_.UpdateRtt(rtt.ms());
clock_->AdvanceTimeMilliseconds(50);
nack_module_.Process();
EXPECT_EQ(4u, sent_nacks_.size());
// RTT gets capped at 160ms in backoff calculations.
TimeDelta expected_backoff_delay =
std::pow(b, i - 1) * std::min(rtt, TimeDelta::ms(160));
nack_module_.OnReceivedPacket(2, false, false);
clock_->AdvanceTimeMilliseconds(50);
// 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(4u, sent_nacks_.size());
EXPECT_EQ(expected_nacks_sent, sent_nacks_.size());
}
TEST_F(TestNackModule, ResendPacketMaxRetries) {
TEST_P(TestNackModule, 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) {
clock_->AdvanceTimeMilliseconds(100);
// 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(100);
clock_->AdvanceTimeMilliseconds(backoff_factor * kDefaultRttMs);
nack_module_.Process();
EXPECT_EQ(10u, sent_nacks_.size());
}
TEST_F(TestNackModule, TooLargeNackList) {
TEST_P(TestNackModule, TooLargeNackList) {
nack_module_.OnReceivedPacket(0, false, false);
nack_module_.OnReceivedPacket(1001, false, false);
EXPECT_EQ(1000u, sent_nacks_.size());
@ -208,7 +242,7 @@ TEST_F(TestNackModule, TooLargeNackList) {
EXPECT_EQ(1, keyframes_requested_);
}
TEST_F(TestNackModule, TooLargeNackListWithKeyFrame) {
TEST_P(TestNackModule, TooLargeNackListWithKeyFrame) {
nack_module_.OnReceivedPacket(0, false, false);
nack_module_.OnReceivedPacket(1, true, false);
nack_module_.OnReceivedPacket(1001, false, false);
@ -222,7 +256,7 @@ TEST_F(TestNackModule, TooLargeNackListWithKeyFrame) {
EXPECT_EQ(1, keyframes_requested_);
}
TEST_F(TestNackModule, ClearUpTo) {
TEST_P(TestNackModule, ClearUpTo) {
nack_module_.OnReceivedPacket(0, false, false);
nack_module_.OnReceivedPacket(100, false, false);
EXPECT_EQ(99u, sent_nacks_.size());
@ -235,7 +269,7 @@ TEST_F(TestNackModule, ClearUpTo) {
EXPECT_EQ(50, sent_nacks_[0]);
}
TEST_F(TestNackModule, ClearUpToWrap) {
TEST_P(TestNackModule, ClearUpToWrap) {
nack_module_.OnReceivedPacket(0xfff0, false, false);
nack_module_.OnReceivedPacket(0xf, false, false);
EXPECT_EQ(30u, sent_nacks_.size());
@ -248,7 +282,7 @@ TEST_F(TestNackModule, ClearUpToWrap) {
EXPECT_EQ(0, sent_nacks_[0]);
}
TEST_F(TestNackModule, PacketNackCount) {
TEST_P(TestNackModule, 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));
@ -258,14 +292,14 @@ TEST_F(TestNackModule, PacketNackCount) {
EXPECT_EQ(0, nack_module_.OnReceivedPacket(5, false, false));
clock_->AdvanceTimeMilliseconds(100);
nack_module_.Process();
clock_->AdvanceTimeMilliseconds(100);
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_F(TestNackModule, NackListFullAndNoOverlapWithKeyframes) {
TEST_P(TestNackModule, NackListFullAndNoOverlapWithKeyframes) {
const int kMaxNackPackets = 1000;
const unsigned int kFirstGap = kMaxNackPackets - 20;
const unsigned int kSecondGap = 200;
@ -280,7 +314,7 @@ TEST_F(TestNackModule, NackListFullAndNoOverlapWithKeyframes) {
EXPECT_EQ(kSecondGap, sent_nacks_.size());
}
TEST_F(TestNackModule, HandleFecRecoveredPacket) {
TEST_P(TestNackModule, HandleFecRecoveredPacket) {
nack_module_.OnReceivedPacket(1, false, false);
nack_module_.OnReceivedPacket(4, false, true);
EXPECT_EQ(0u, sent_nacks_.size());
@ -288,12 +322,16 @@ TEST_F(TestNackModule, HandleFecRecoveredPacket) {
EXPECT_EQ(2u, sent_nacks_.size());
}
TEST_F(TestNackModule, SendNackWithoutDelay) {
TEST_P(TestNackModule, SendNackWithoutDelay) {
nack_module_.OnReceivedPacket(0, false, false);
nack_module_.OnReceivedPacket(100, false, false);
EXPECT_EQ(99u, sent_nacks_.size());
}
INSTANTIATE_TEST_SUITE_P(WithAndWithoutBackoff,
TestNackModule,
::testing::Values(true, false));
class TestNackModuleWithFieldTrial : public ::testing::Test,
public NackSender,
public KeyFrameRequestSender {