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// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "quic/core/congestion_control/uber_loss_algorithm.h"
#include <memory>
#include <utility>
#include "absl/types/optional.h"
#include "quic/core/congestion_control/rtt_stats.h"
#include "quic/core/crypto/crypto_protocol.h"
#include "quic/core/quic_types.h"
#include "quic/core/quic_utils.h"
#include "quic/platform/api/quic_test.h"
#include "quic/test_tools/mock_clock.h"
#include "quic/test_tools/quic_unacked_packet_map_peer.h"
namespace quic {
namespace test {
namespace {
// Default packet length.
const uint32_t kDefaultLength = 1000;
class UberLossAlgorithmTest : public QuicTest {
protected:
UberLossAlgorithmTest() {
unacked_packets_ =
std::make_unique<QuicUnackedPacketMap>(Perspective::IS_CLIENT);
rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(100),
QuicTime::Delta::Zero(), clock_.Now());
EXPECT_LT(0, rtt_stats_.smoothed_rtt().ToMicroseconds());
}
void SendPacket(uint64_t packet_number, EncryptionLevel encryption_level) {
QuicStreamFrame frame;
QuicTransportVersion version =
CurrentSupportedVersions()[0].transport_version;
frame.stream_id = QuicUtils::GetFirstBidirectionalStreamId(
version, Perspective::IS_CLIENT);
if (encryption_level == ENCRYPTION_INITIAL) {
if (QuicVersionUsesCryptoFrames(version)) {
frame.stream_id = QuicUtils::GetFirstBidirectionalStreamId(
version, Perspective::IS_CLIENT);
} else {
frame.stream_id = QuicUtils::GetCryptoStreamId(version);
}
}
SerializedPacket packet(QuicPacketNumber(packet_number),
PACKET_1BYTE_PACKET_NUMBER, nullptr, kDefaultLength,
false, false);
packet.encryption_level = encryption_level;
packet.retransmittable_frames.push_back(QuicFrame(frame));
unacked_packets_->AddSentPacket(&packet, NOT_RETRANSMISSION, clock_.Now(),
true, true);
}
void AckPackets(const std::vector<uint64_t>& packets_acked) {
packets_acked_.clear();
for (uint64_t acked : packets_acked) {
unacked_packets_->RemoveFromInFlight(QuicPacketNumber(acked));
packets_acked_.push_back(AckedPacket(
QuicPacketNumber(acked), kMaxOutgoingPacketSize, QuicTime::Zero()));
}
}
void VerifyLosses(uint64_t largest_newly_acked,
const AckedPacketVector& packets_acked,
const std::vector<uint64_t>& losses_expected) {
return VerifyLosses(largest_newly_acked, packets_acked, losses_expected,
absl::nullopt);
}
void VerifyLosses(
uint64_t largest_newly_acked,
const AckedPacketVector& packets_acked,
const std::vector<uint64_t>& losses_expected,
absl::optional<QuicPacketCount> max_sequence_reordering_expected) {
LostPacketVector lost_packets;
LossDetectionInterface::DetectionStats stats = loss_algorithm_.DetectLosses(
*unacked_packets_, clock_.Now(), rtt_stats_,
QuicPacketNumber(largest_newly_acked), packets_acked, &lost_packets);
if (max_sequence_reordering_expected.has_value()) {
EXPECT_EQ(stats.sent_packets_max_sequence_reordering,
max_sequence_reordering_expected.value());
}
ASSERT_EQ(losses_expected.size(), lost_packets.size());
for (size_t i = 0; i < losses_expected.size(); ++i) {
EXPECT_EQ(lost_packets[i].packet_number,
QuicPacketNumber(losses_expected[i]));
}
}
MockClock clock_;
std::unique_ptr<QuicUnackedPacketMap> unacked_packets_;
RttStats rtt_stats_;
UberLossAlgorithm loss_algorithm_;
AckedPacketVector packets_acked_;
};
TEST_F(UberLossAlgorithmTest, ScenarioA) {
// This test mimics a scenario: client sends 1-CHLO, 2-0RTT, 3-0RTT,
// timeout and retransmits 4-CHLO. Server acks packet 1 (ack gets lost).
// Server receives and buffers packets 2 and 3. Server receives packet 4 and
// processes handshake asynchronously, so server acks 4 and cannot process
// packets 2 and 3.
SendPacket(1, ENCRYPTION_INITIAL);
SendPacket(2, ENCRYPTION_ZERO_RTT);
SendPacket(3, ENCRYPTION_ZERO_RTT);
unacked_packets_->RemoveFromInFlight(QuicPacketNumber(1));
SendPacket(4, ENCRYPTION_INITIAL);
AckPackets({1, 4});
unacked_packets_->MaybeUpdateLargestAckedOfPacketNumberSpace(
HANDSHAKE_DATA, QuicPacketNumber(4));
// Verify no packet is detected lost.
VerifyLosses(4, packets_acked_, std::vector<uint64_t>{}, 0);
EXPECT_EQ(QuicTime::Zero(), loss_algorithm_.GetLossTimeout());
}
TEST_F(UberLossAlgorithmTest, ScenarioB) {
// This test mimics a scenario: client sends 3-0RTT, 4-0RTT, receives SHLO,
// sends 5-1RTT, 6-1RTT.
SendPacket(3, ENCRYPTION_ZERO_RTT);
SendPacket(4, ENCRYPTION_ZERO_RTT);
SendPacket(5, ENCRYPTION_FORWARD_SECURE);
SendPacket(6, ENCRYPTION_FORWARD_SECURE);
AckPackets({4});
unacked_packets_->MaybeUpdateLargestAckedOfPacketNumberSpace(
APPLICATION_DATA, QuicPacketNumber(4));
// No packet loss by acking 4.
VerifyLosses(4, packets_acked_, std::vector<uint64_t>{}, 1);
EXPECT_EQ(clock_.Now() + 1.25 * rtt_stats_.smoothed_rtt(),
loss_algorithm_.GetLossTimeout());
// Acking 6 causes 3 to be detected loss.
AckPackets({6});
unacked_packets_->MaybeUpdateLargestAckedOfPacketNumberSpace(
APPLICATION_DATA, QuicPacketNumber(6));
VerifyLosses(6, packets_acked_, std::vector<uint64_t>{3}, 3);
EXPECT_EQ(clock_.Now() + 1.25 * rtt_stats_.smoothed_rtt(),
loss_algorithm_.GetLossTimeout());
packets_acked_.clear();
clock_.AdvanceTime(1.25 * rtt_stats_.latest_rtt());
// Verify 5 will be early retransmitted.
VerifyLosses(6, packets_acked_, {5}, 1);
}
TEST_F(UberLossAlgorithmTest, ScenarioC) {
// This test mimics a scenario: server sends 1-SHLO, 2-1RTT, 3-1RTT, 4-1RTT
// and retransmit 4-SHLO. Client receives and buffers packet 4. Client
// receives packet 5 and processes 4.
QuicUnackedPacketMapPeer::SetPerspective(unacked_packets_.get(),
Perspective::IS_SERVER);
SendPacket(1, ENCRYPTION_ZERO_RTT);
SendPacket(2, ENCRYPTION_FORWARD_SECURE);
SendPacket(3, ENCRYPTION_FORWARD_SECURE);
SendPacket(4, ENCRYPTION_FORWARD_SECURE);
unacked_packets_->RemoveFromInFlight(QuicPacketNumber(1));
SendPacket(5, ENCRYPTION_ZERO_RTT);
AckPackets({4, 5});
unacked_packets_->MaybeUpdateLargestAckedOfPacketNumberSpace(
APPLICATION_DATA, QuicPacketNumber(4));
unacked_packets_->MaybeUpdateLargestAckedOfPacketNumberSpace(
HANDSHAKE_DATA, QuicPacketNumber(5));
// No packet loss by acking 5.
VerifyLosses(5, packets_acked_, std::vector<uint64_t>{}, 2);
EXPECT_EQ(clock_.Now() + 1.25 * rtt_stats_.smoothed_rtt(),
loss_algorithm_.GetLossTimeout());
packets_acked_.clear();
clock_.AdvanceTime(1.25 * rtt_stats_.latest_rtt());
// Verify 2 and 3 will be early retransmitted.
VerifyLosses(5, packets_acked_, std::vector<uint64_t>{2, 3}, 2);
}
// Regression test for b/133771183.
TEST_F(UberLossAlgorithmTest, PacketInLimbo) {
// This test mimics a scenario: server sends 1-SHLO, 2-1RTT, 3-1RTT,
// 4-retransmit SHLO. Client receives and ACKs packets 1, 3 and 4.
QuicUnackedPacketMapPeer::SetPerspective(unacked_packets_.get(),
Perspective::IS_SERVER);
SendPacket(1, ENCRYPTION_ZERO_RTT);
SendPacket(2, ENCRYPTION_FORWARD_SECURE);
SendPacket(3, ENCRYPTION_FORWARD_SECURE);
SendPacket(4, ENCRYPTION_ZERO_RTT);
SendPacket(5, ENCRYPTION_FORWARD_SECURE);
AckPackets({1, 3, 4});
unacked_packets_->MaybeUpdateLargestAckedOfPacketNumberSpace(
APPLICATION_DATA, QuicPacketNumber(3));
unacked_packets_->MaybeUpdateLargestAckedOfPacketNumberSpace(
HANDSHAKE_DATA, QuicPacketNumber(4));
// No packet loss detected.
VerifyLosses(4, packets_acked_, std::vector<uint64_t>{});
SendPacket(6, ENCRYPTION_FORWARD_SECURE);
AckPackets({5, 6});
unacked_packets_->MaybeUpdateLargestAckedOfPacketNumberSpace(
APPLICATION_DATA, QuicPacketNumber(6));
// Verify packet 2 is detected lost.
VerifyLosses(6, packets_acked_, std::vector<uint64_t>{2});
}
class TestLossTuner : public LossDetectionTunerInterface {
public:
TestLossTuner(bool forced_start_result,
LossDetectionParameters forced_parameters)
: forced_start_result_(forced_start_result),
forced_parameters_(std::move(forced_parameters)) {}
~TestLossTuner() override = default;
bool Start(LossDetectionParameters* params) override {
start_called_ = true;
*params = forced_parameters_;
return forced_start_result_;
}
void Finish(const LossDetectionParameters& /*params*/) override {}
bool start_called() const { return start_called_; }
private:
bool forced_start_result_;
LossDetectionParameters forced_parameters_;
bool start_called_ = false;
};
// Verify the parameters are changed if first call SetFromConfig(), then call
// OnMinRttAvailable().
TEST_F(UberLossAlgorithmTest, LossDetectionTuning_SetFromConfigFirst) {
const int old_reordering_shift = loss_algorithm_.GetPacketReorderingShift();
const QuicPacketCount old_reordering_threshold =
loss_algorithm_.GetPacketReorderingThreshold();
loss_algorithm_.OnUserAgentIdKnown();
// Not owned.
TestLossTuner* test_tuner = new TestLossTuner(
/*forced_start_result=*/true,
LossDetectionParameters{
/*reordering_shift=*/old_reordering_shift + 1,
/*reordering_threshold=*/old_reordering_threshold * 2});
loss_algorithm_.SetLossDetectionTuner(
std::unique_ptr<LossDetectionTunerInterface>(test_tuner));
QuicConfig config;
QuicTagVector connection_options;
connection_options.push_back(kELDT);
config.SetInitialReceivedConnectionOptions(connection_options);
loss_algorithm_.SetFromConfig(config, Perspective::IS_SERVER);
// MinRtt was not available when SetFromConfig was called.
EXPECT_FALSE(test_tuner->start_called());
EXPECT_EQ(old_reordering_shift, loss_algorithm_.GetPacketReorderingShift());
EXPECT_EQ(old_reordering_threshold,
loss_algorithm_.GetPacketReorderingThreshold());
// MinRtt available. Tuner should not start yet because no reordering yet.
loss_algorithm_.OnMinRttAvailable();
EXPECT_FALSE(test_tuner->start_called());
// Reordering happened. Tuner should start now.
loss_algorithm_.OnReorderingDetected();
EXPECT_TRUE(test_tuner->start_called());
EXPECT_NE(old_reordering_shift, loss_algorithm_.GetPacketReorderingShift());
EXPECT_NE(old_reordering_threshold,
loss_algorithm_.GetPacketReorderingThreshold());
}
// Verify the parameters are changed if first call OnMinRttAvailable(), then
// call SetFromConfig().
TEST_F(UberLossAlgorithmTest, LossDetectionTuning_OnMinRttAvailableFirst) {
const int old_reordering_shift = loss_algorithm_.GetPacketReorderingShift();
const QuicPacketCount old_reordering_threshold =
loss_algorithm_.GetPacketReorderingThreshold();
loss_algorithm_.OnUserAgentIdKnown();
// Not owned.
TestLossTuner* test_tuner = new TestLossTuner(
/*forced_start_result=*/true,
LossDetectionParameters{
/*reordering_shift=*/old_reordering_shift + 1,
/*reordering_threshold=*/old_reordering_threshold * 2});
loss_algorithm_.SetLossDetectionTuner(
std::unique_ptr<LossDetectionTunerInterface>(test_tuner));
loss_algorithm_.OnMinRttAvailable();
EXPECT_FALSE(test_tuner->start_called());
EXPECT_EQ(old_reordering_shift, loss_algorithm_.GetPacketReorderingShift());
EXPECT_EQ(old_reordering_threshold,
loss_algorithm_.GetPacketReorderingThreshold());
// Pretend a reodering has happened.
loss_algorithm_.OnReorderingDetected();
EXPECT_FALSE(test_tuner->start_called());
QuicConfig config;
QuicTagVector connection_options;
connection_options.push_back(kELDT);
config.SetInitialReceivedConnectionOptions(connection_options);
// Should start tuning since MinRtt is available.
loss_algorithm_.SetFromConfig(config, Perspective::IS_SERVER);
EXPECT_TRUE(test_tuner->start_called());
EXPECT_NE(old_reordering_shift, loss_algorithm_.GetPacketReorderingShift());
EXPECT_NE(old_reordering_threshold,
loss_algorithm_.GetPacketReorderingThreshold());
}
// Verify the parameters are not changed if Tuner.Start() returns false.
TEST_F(UberLossAlgorithmTest, LossDetectionTuning_StartFailed) {
const int old_reordering_shift = loss_algorithm_.GetPacketReorderingShift();
const QuicPacketCount old_reordering_threshold =
loss_algorithm_.GetPacketReorderingThreshold();
loss_algorithm_.OnUserAgentIdKnown();
// Not owned.
TestLossTuner* test_tuner = new TestLossTuner(
/*forced_start_result=*/false,
LossDetectionParameters{
/*reordering_shift=*/old_reordering_shift + 1,
/*reordering_threshold=*/old_reordering_threshold * 2});
loss_algorithm_.SetLossDetectionTuner(
std::unique_ptr<LossDetectionTunerInterface>(test_tuner));
QuicConfig config;
QuicTagVector connection_options;
connection_options.push_back(kELDT);
config.SetInitialReceivedConnectionOptions(connection_options);
loss_algorithm_.SetFromConfig(config, Perspective::IS_SERVER);
// MinRtt was not available when SetFromConfig was called.
EXPECT_FALSE(test_tuner->start_called());
EXPECT_EQ(old_reordering_shift, loss_algorithm_.GetPacketReorderingShift());
EXPECT_EQ(old_reordering_threshold,
loss_algorithm_.GetPacketReorderingThreshold());
// Pretend a reodering has happened.
loss_algorithm_.OnReorderingDetected();
EXPECT_FALSE(test_tuner->start_called());
// Parameters should not change since test_tuner->Start() returns false.
loss_algorithm_.OnMinRttAvailable();
EXPECT_TRUE(test_tuner->start_called());
EXPECT_EQ(old_reordering_shift, loss_algorithm_.GetPacketReorderingShift());
EXPECT_EQ(old_reordering_threshold,
loss_algorithm_.GetPacketReorderingThreshold());
}
} // namespace
} // namespace test
} // namespace quic