blob: 7206b4cb5f4dfbe79a4f12271cabcdd785e8c83b [file] [log] [blame]
// Copyright (c) 2013 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 "quiche/quic/core/congestion_control/pacing_sender.h"
#include <memory>
#include <utility>
#include "quiche/quic/core/quic_constants.h"
#include "quiche/quic/core/quic_packets.h"
#include "quiche/quic/platform/api/quic_flag_utils.h"
#include "quiche/quic/platform/api/quic_flags.h"
#include "quiche/quic/platform/api/quic_logging.h"
#include "quiche/quic/platform/api/quic_test.h"
#include "quiche/quic/test_tools/mock_clock.h"
#include "quiche/quic/test_tools/quic_test_utils.h"
using testing::_;
using testing::AtMost;
using testing::Return;
using testing::StrictMock;
namespace quic {
namespace test {
const QuicByteCount kBytesInFlight = 1024;
const int kInitialBurstPackets = 10;
class TestPacingSender : public PacingSender {
public:
using PacingSender::lumpy_tokens;
using PacingSender::PacingSender;
QuicTime ideal_next_packet_send_time() const {
return GetNextReleaseTime().release_time;
}
};
class PacingSenderTest : public QuicTest {
protected:
PacingSenderTest()
: zero_time_(QuicTime::Delta::Zero()),
infinite_time_(QuicTime::Delta::Infinite()),
packet_number_(1),
mock_sender_(new StrictMock<MockSendAlgorithm>()),
pacing_sender_(new TestPacingSender) {
pacing_sender_->set_sender(mock_sender_.get());
// Pick arbitrary time.
clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(9));
}
~PacingSenderTest() override {}
void InitPacingRate(QuicPacketCount burst_size, QuicBandwidth bandwidth) {
mock_sender_ = std::make_unique<StrictMock<MockSendAlgorithm>>();
pacing_sender_ = std::make_unique<TestPacingSender>();
pacing_sender_->set_sender(mock_sender_.get());
EXPECT_CALL(*mock_sender_, PacingRate(_)).WillRepeatedly(Return(bandwidth));
EXPECT_CALL(*mock_sender_, BandwidthEstimate())
.WillRepeatedly(Return(bandwidth));
if (burst_size == 0) {
EXPECT_CALL(*mock_sender_, OnCongestionEvent(_, _, _, _, _));
LostPacketVector lost_packets;
lost_packets.push_back(
LostPacket(QuicPacketNumber(1), kMaxOutgoingPacketSize));
AckedPacketVector empty;
pacing_sender_->OnCongestionEvent(true, 1234, clock_.Now(), empty,
lost_packets);
} else if (burst_size != kInitialBurstPackets) {
QUIC_LOG(FATAL) << "Unsupported burst_size " << burst_size
<< " specificied, only 0 and " << kInitialBurstPackets
<< " are supported.";
}
}
void CheckPacketIsSentImmediately(HasRetransmittableData retransmittable_data,
QuicByteCount prior_in_flight,
bool in_recovery, QuicPacketCount cwnd) {
// In order for the packet to be sendable, the underlying sender must
// permit it to be sent immediately.
for (int i = 0; i < 2; ++i) {
EXPECT_CALL(*mock_sender_, CanSend(prior_in_flight))
.WillOnce(Return(true));
// Verify that the packet can be sent immediately.
EXPECT_EQ(zero_time_,
pacing_sender_->TimeUntilSend(clock_.Now(), prior_in_flight));
}
// Actually send the packet.
if (prior_in_flight == 0) {
EXPECT_CALL(*mock_sender_, InRecovery()).WillOnce(Return(in_recovery));
}
EXPECT_CALL(*mock_sender_,
OnPacketSent(clock_.Now(), prior_in_flight, packet_number_,
kMaxOutgoingPacketSize, retransmittable_data));
EXPECT_CALL(*mock_sender_, GetCongestionWindow())
.WillRepeatedly(Return(cwnd * kDefaultTCPMSS));
EXPECT_CALL(*mock_sender_,
CanSend(prior_in_flight + kMaxOutgoingPacketSize))
.Times(AtMost(1))
.WillRepeatedly(Return((prior_in_flight + kMaxOutgoingPacketSize) <
(cwnd * kDefaultTCPMSS)));
pacing_sender_->OnPacketSent(clock_.Now(), prior_in_flight,
packet_number_++, kMaxOutgoingPacketSize,
retransmittable_data);
}
void CheckPacketIsSentImmediately() {
CheckPacketIsSentImmediately(HAS_RETRANSMITTABLE_DATA, kBytesInFlight,
false, 10);
}
void CheckPacketIsDelayed(QuicTime::Delta delay) {
// In order for the packet to be sendable, the underlying sender must
// permit it to be sent immediately.
for (int i = 0; i < 2; ++i) {
EXPECT_CALL(*mock_sender_, CanSend(kBytesInFlight))
.WillOnce(Return(true));
// Verify that the packet is delayed.
EXPECT_EQ(delay.ToMicroseconds(),
pacing_sender_->TimeUntilSend(clock_.Now(), kBytesInFlight)
.ToMicroseconds());
}
}
void UpdateRtt() {
EXPECT_CALL(*mock_sender_,
OnCongestionEvent(true, kBytesInFlight, _, _, _));
AckedPacketVector empty_acked;
LostPacketVector empty_lost;
pacing_sender_->OnCongestionEvent(true, kBytesInFlight, clock_.Now(),
empty_acked, empty_lost);
}
void OnApplicationLimited() { pacing_sender_->OnApplicationLimited(); }
const QuicTime::Delta zero_time_;
const QuicTime::Delta infinite_time_;
MockClock clock_;
QuicPacketNumber packet_number_;
std::unique_ptr<StrictMock<MockSendAlgorithm>> mock_sender_;
std::unique_ptr<TestPacingSender> pacing_sender_;
};
TEST_F(PacingSenderTest, NoSend) {
for (int i = 0; i < 2; ++i) {
EXPECT_CALL(*mock_sender_, CanSend(kBytesInFlight)).WillOnce(Return(false));
EXPECT_EQ(infinite_time_,
pacing_sender_->TimeUntilSend(clock_.Now(), kBytesInFlight));
}
}
TEST_F(PacingSenderTest, SendNow) {
for (int i = 0; i < 2; ++i) {
EXPECT_CALL(*mock_sender_, CanSend(kBytesInFlight)).WillOnce(Return(true));
EXPECT_EQ(zero_time_,
pacing_sender_->TimeUntilSend(clock_.Now(), kBytesInFlight));
}
}
TEST_F(PacingSenderTest, VariousSending) {
// Configure pacing rate of 1 packet per 1 ms, no initial burst.
InitPacingRate(
0, QuicBandwidth::FromBytesAndTimeDelta(
kMaxOutgoingPacketSize, QuicTime::Delta::FromMilliseconds(1)));
// Now update the RTT and verify that packets are actually paced.
UpdateRtt();
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
// The first packet was a "make up", then we sent two packets "into the
// future", so the delay should be 2.
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
// Wake up on time.
clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(2));
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
// Wake up late.
clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(4));
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
// Wake up really late.
clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(8));
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
// Wake up really late again, but application pause partway through.
clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(8));
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
OnApplicationLimited();
clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(100));
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
// Wake up early, but after enough time has passed to permit a send.
clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(1));
CheckPacketIsSentImmediately();
}
TEST_F(PacingSenderTest, InitialBurst) {
// Configure pacing rate of 1 packet per 1 ms.
InitPacingRate(
10, QuicBandwidth::FromBytesAndTimeDelta(
kMaxOutgoingPacketSize, QuicTime::Delta::FromMilliseconds(1)));
// Update the RTT and verify that the first 10 packets aren't paced.
UpdateRtt();
// Send 10 packets, and verify that they are not paced.
for (int i = 0; i < kInitialBurstPackets; ++i) {
CheckPacketIsSentImmediately();
}
// The first packet was a "make up", then we sent two packets "into the
// future", so the delay should be 2ms.
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
CheckPacketIsSentImmediately();
// Next time TimeUntilSend is called with no bytes in flight, pacing should
// allow a packet to be sent, and when it's sent, the tokens are refilled.
CheckPacketIsSentImmediately(HAS_RETRANSMITTABLE_DATA, 0, false, 10);
for (int i = 0; i < kInitialBurstPackets - 1; ++i) {
CheckPacketIsSentImmediately();
}
// The first packet was a "make up", then we sent two packets "into the
// future", so the delay should be 2ms.
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
}
TEST_F(PacingSenderTest, InitialBurstNoRttMeasurement) {
// Configure pacing rate of 1 packet per 1 ms.
InitPacingRate(
10, QuicBandwidth::FromBytesAndTimeDelta(
kMaxOutgoingPacketSize, QuicTime::Delta::FromMilliseconds(1)));
// Send 10 packets, and verify that they are not paced.
for (int i = 0; i < kInitialBurstPackets; ++i) {
CheckPacketIsSentImmediately();
}
// The first packet was a "make up", then we sent two packets "into the
// future", so the delay should be 2ms.
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
CheckPacketIsSentImmediately();
// Next time TimeUntilSend is called with no bytes in flight, the tokens
// should be refilled and there should be no delay.
CheckPacketIsSentImmediately(HAS_RETRANSMITTABLE_DATA, 0, false, 10);
// Send 10 packets, and verify that they are not paced.
for (int i = 0; i < kInitialBurstPackets - 1; ++i) {
CheckPacketIsSentImmediately();
}
// The first packet was a "make up", then we sent two packets "into the
// future", so the delay should be 2ms.
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
}
TEST_F(PacingSenderTest, FastSending) {
// Ensure the pacing sender paces, even when the inter-packet spacing(0.5ms)
// is less than the pacing granularity(1ms).
InitPacingRate(10, QuicBandwidth::FromBytesAndTimeDelta(
2 * kMaxOutgoingPacketSize,
QuicTime::Delta::FromMilliseconds(1)));
// Update the RTT and verify that the first 10 packets aren't paced.
UpdateRtt();
// Send 10 packets, and verify that they are not paced.
for (int i = 0; i < kInitialBurstPackets; ++i) {
CheckPacketIsSentImmediately();
}
CheckPacketIsSentImmediately(); // Make up
CheckPacketIsSentImmediately(); // Lumpy token
CheckPacketIsSentImmediately(); // "In the future" but within granularity.
CheckPacketIsSentImmediately(); // Lumpy token
CheckPacketIsDelayed(QuicTime::Delta::FromMicroseconds(2000));
clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
CheckPacketIsSentImmediately();
// Next time TimeUntilSend is called with no bytes in flight, the tokens
// should be refilled and there should be no delay.
CheckPacketIsSentImmediately(HAS_RETRANSMITTABLE_DATA, 0, false, 10);
for (int i = 0; i < kInitialBurstPackets - 1; ++i) {
CheckPacketIsSentImmediately();
}
// The first packet was a "make up", then we sent two packets "into the
// future", so the delay should be 1.5ms.
CheckPacketIsSentImmediately(); // Make up
CheckPacketIsSentImmediately(); // Lumpy token
CheckPacketIsSentImmediately(); // "In the future" but within granularity.
CheckPacketIsSentImmediately(); // Lumpy token
CheckPacketIsDelayed(QuicTime::Delta::FromMicroseconds(2000));
}
TEST_F(PacingSenderTest, NoBurstEnteringRecovery) {
// Configure pacing rate of 1 packet per 1 ms with no burst tokens.
InitPacingRate(
0, QuicBandwidth::FromBytesAndTimeDelta(
kMaxOutgoingPacketSize, QuicTime::Delta::FromMilliseconds(1)));
// Sending a packet will set burst tokens.
CheckPacketIsSentImmediately();
// Losing a packet will set clear burst tokens.
LostPacketVector lost_packets;
lost_packets.push_back(
LostPacket(QuicPacketNumber(1), kMaxOutgoingPacketSize));
AckedPacketVector empty_acked;
EXPECT_CALL(*mock_sender_, OnCongestionEvent(true, kMaxOutgoingPacketSize, _,
testing::IsEmpty(), _));
pacing_sender_->OnCongestionEvent(true, kMaxOutgoingPacketSize, clock_.Now(),
empty_acked, lost_packets);
// One packet is sent immediately, because of 1ms pacing granularity.
CheckPacketIsSentImmediately();
// Ensure packets are immediately paced.
EXPECT_CALL(*mock_sender_, CanSend(kMaxOutgoingPacketSize))
.WillOnce(Return(true));
// Verify the next packet is paced and delayed 2ms due to granularity.
EXPECT_EQ(
QuicTime::Delta::FromMilliseconds(2),
pacing_sender_->TimeUntilSend(clock_.Now(), kMaxOutgoingPacketSize));
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
}
TEST_F(PacingSenderTest, NoBurstInRecovery) {
// Configure pacing rate of 1 packet per 1 ms with no burst tokens.
InitPacingRate(
0, QuicBandwidth::FromBytesAndTimeDelta(
kMaxOutgoingPacketSize, QuicTime::Delta::FromMilliseconds(1)));
UpdateRtt();
// Ensure only one packet is sent immediately and the rest are paced.
CheckPacketIsSentImmediately(HAS_RETRANSMITTABLE_DATA, 0, true, 10);
CheckPacketIsSentImmediately();
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
}
TEST_F(PacingSenderTest, CwndLimited) {
// Configure pacing rate of 1 packet per 1 ms, no initial burst.
InitPacingRate(
0, QuicBandwidth::FromBytesAndTimeDelta(
kMaxOutgoingPacketSize, QuicTime::Delta::FromMilliseconds(1)));
UpdateRtt();
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
// Packet 3 will be delayed 2ms.
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
// Wake up on time.
clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(2));
// After sending packet 3, cwnd is limited.
// This test is slightly odd because bytes_in_flight is calculated using
// kMaxOutgoingPacketSize and CWND is calculated using kDefaultTCPMSS,
// which is 8 bytes larger, so 3 packets can be sent for a CWND of 2.
CheckPacketIsSentImmediately(HAS_RETRANSMITTABLE_DATA,
2 * kMaxOutgoingPacketSize, false, 2);
clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(100));
// Verify pacing sender stops making up for lost time after sending packet 3.
// Packet 6 will be delayed 2ms.
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
}
TEST_F(PacingSenderTest, LumpyPacingWithInitialBurstToken) {
// Set lumpy size to be 3, and cwnd faction to 0.5
SetQuicFlag(quic_lumpy_pacing_size, 3);
SetQuicFlag(quic_lumpy_pacing_cwnd_fraction, 0.5f);
// Configure pacing rate of 1 packet per 1 ms.
InitPacingRate(
10, QuicBandwidth::FromBytesAndTimeDelta(
kMaxOutgoingPacketSize, QuicTime::Delta::FromMilliseconds(1)));
UpdateRtt();
// Send 10 packets, and verify that they are not paced.
for (int i = 0; i < kInitialBurstPackets; ++i) {
CheckPacketIsSentImmediately();
}
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
// Packet 14 will be delayed 3ms.
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(3));
// Wake up on time.
clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(3));
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
// Packet 17 will be delayed 3ms.
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(3));
// Application throttles sending.
OnApplicationLimited();
clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(100));
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
CheckPacketIsSentImmediately();
// Packet 20 will be delayed 3ms.
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(3));
// Wake up on time.
clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(3));
CheckPacketIsSentImmediately();
// After sending packet 21, cwnd is limited.
// This test is slightly odd because bytes_in_flight is calculated using
// kMaxOutgoingPacketSize and CWND is calculated using kDefaultTCPMSS,
// which is 8 bytes larger, so 21 packets can be sent for a CWND of 20.
CheckPacketIsSentImmediately(HAS_RETRANSMITTABLE_DATA,
20 * kMaxOutgoingPacketSize, false, 20);
clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(100));
// Suppose cwnd size is 5, so that lumpy size becomes 2.
CheckPacketIsSentImmediately(HAS_RETRANSMITTABLE_DATA, kBytesInFlight, false,
5);
CheckPacketIsSentImmediately();
// Packet 24 will be delayed 2ms.
CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
}
TEST_F(PacingSenderTest, NoLumpyPacingForLowBandwidthFlows) {
// Set lumpy size to be 3, and cwnd fraction to 0.5
SetQuicFlag(quic_lumpy_pacing_size, 3);
SetQuicFlag(quic_lumpy_pacing_cwnd_fraction, 0.5f);
// Configure pacing rate of 1 packet per 100 ms.
QuicTime::Delta inter_packet_delay = QuicTime::Delta::FromMilliseconds(100);
InitPacingRate(kInitialBurstPackets,
QuicBandwidth::FromBytesAndTimeDelta(kMaxOutgoingPacketSize,
inter_packet_delay));
UpdateRtt();
// Send kInitialBurstPackets packets, and verify that they are not paced.
for (int i = 0; i < kInitialBurstPackets; ++i) {
CheckPacketIsSentImmediately();
}
// The first packet after burst token exhausted is also sent immediately,
// because ideal_next_packet_send_time has not been set yet.
CheckPacketIsSentImmediately();
for (int i = 0; i < 200; ++i) {
CheckPacketIsDelayed(inter_packet_delay);
}
}
// Regression test for b/184471302 to ensure that ACKs received back-to-back
// don't cause bursts in sending.
TEST_F(PacingSenderTest, NoBurstsForLumpyPacingWithAckAggregation) {
// Configure pacing rate of 1 packet per millisecond.
QuicTime::Delta inter_packet_delay = QuicTime::Delta::FromMilliseconds(1);
InitPacingRate(kInitialBurstPackets,
QuicBandwidth::FromBytesAndTimeDelta(kMaxOutgoingPacketSize,
inter_packet_delay));
UpdateRtt();
// Send kInitialBurstPackets packets, and verify that they are not paced.
for (int i = 0; i < kInitialBurstPackets; ++i) {
CheckPacketIsSentImmediately();
}
// The last packet of the burst causes the sender to be CWND limited.
CheckPacketIsSentImmediately(HAS_RETRANSMITTABLE_DATA,
10 * kMaxOutgoingPacketSize, false, 10);
// The last sent packet made the connection CWND limited, so no lumpy tokens
// should be available.
EXPECT_EQ(0u, pacing_sender_->lumpy_tokens());
CheckPacketIsSentImmediately(HAS_RETRANSMITTABLE_DATA,
10 * kMaxOutgoingPacketSize, false, 10);
EXPECT_EQ(0u, pacing_sender_->lumpy_tokens());
CheckPacketIsDelayed(2 * inter_packet_delay);
}
TEST_F(PacingSenderTest, IdealNextPacketSendTimeWithLumpyPacing) {
// Set lumpy size to be 3, and cwnd faction to 0.5
SetQuicFlag(quic_lumpy_pacing_size, 3);
SetQuicFlag(quic_lumpy_pacing_cwnd_fraction, 0.5f);
// Configure pacing rate of 1 packet per millisecond.
QuicTime::Delta inter_packet_delay = QuicTime::Delta::FromMilliseconds(1);
InitPacingRate(kInitialBurstPackets,
QuicBandwidth::FromBytesAndTimeDelta(kMaxOutgoingPacketSize,
inter_packet_delay));
// Send kInitialBurstPackets packets, and verify that they are not paced.
for (int i = 0; i < kInitialBurstPackets; ++i) {
CheckPacketIsSentImmediately();
}
CheckPacketIsSentImmediately();
EXPECT_EQ(pacing_sender_->ideal_next_packet_send_time(),
clock_.Now() + inter_packet_delay);
EXPECT_EQ(pacing_sender_->lumpy_tokens(), 2u);
CheckPacketIsSentImmediately();
EXPECT_EQ(pacing_sender_->ideal_next_packet_send_time(),
clock_.Now() + 2 * inter_packet_delay);
EXPECT_EQ(pacing_sender_->lumpy_tokens(), 1u);
CheckPacketIsSentImmediately();
EXPECT_EQ(pacing_sender_->ideal_next_packet_send_time(),
clock_.Now() + 3 * inter_packet_delay);
EXPECT_EQ(pacing_sender_->lumpy_tokens(), 0u);
CheckPacketIsDelayed(3 * inter_packet_delay);
// Wake up on time.
clock_.AdvanceTime(3 * inter_packet_delay);
CheckPacketIsSentImmediately();
EXPECT_EQ(pacing_sender_->ideal_next_packet_send_time(),
clock_.Now() + inter_packet_delay);
EXPECT_EQ(pacing_sender_->lumpy_tokens(), 2u);
CheckPacketIsSentImmediately();
EXPECT_EQ(pacing_sender_->ideal_next_packet_send_time(),
clock_.Now() + 2 * inter_packet_delay);
EXPECT_EQ(pacing_sender_->lumpy_tokens(), 1u);
CheckPacketIsSentImmediately();
EXPECT_EQ(pacing_sender_->ideal_next_packet_send_time(),
clock_.Now() + 3 * inter_packet_delay);
EXPECT_EQ(pacing_sender_->lumpy_tokens(), 0u);
CheckPacketIsDelayed(3 * inter_packet_delay);
// Wake up late.
clock_.AdvanceTime(4.5 * inter_packet_delay);
CheckPacketIsSentImmediately();
EXPECT_EQ(pacing_sender_->ideal_next_packet_send_time(),
clock_.Now() - 0.5 * inter_packet_delay);
EXPECT_EQ(pacing_sender_->lumpy_tokens(), 2u);
CheckPacketIsSentImmediately();
EXPECT_EQ(pacing_sender_->ideal_next_packet_send_time(),
clock_.Now() + 0.5 * inter_packet_delay);
EXPECT_EQ(pacing_sender_->lumpy_tokens(), 1u);
CheckPacketIsSentImmediately();
EXPECT_EQ(pacing_sender_->ideal_next_packet_send_time(),
clock_.Now() + 1.5 * inter_packet_delay);
EXPECT_EQ(pacing_sender_->lumpy_tokens(), 0u);
CheckPacketIsDelayed(1.5 * inter_packet_delay);
}
} // namespace test
} // namespace quic