gfe-relnote: In QUIC, add 2 connection options to set the start point of exponential backoff when calculating PTO timeout. Protected by exisiting gfe2_reloadable_flag_quic_enable_pto.
PiperOrigin-RevId: 278370348
Change-Id: I3bbafdc9789b4a38f2fa7175febf86cb8f419a29
diff --git a/quic/core/crypto/crypto_protocol.h b/quic/core/crypto/crypto_protocol.h
index 0e99be9..0aeb1f9 100644
--- a/quic/core/crypto/crypto_protocol.h
+++ b/quic/core/crypto/crypto_protocol.h
@@ -198,6 +198,10 @@
// when computing PTO timeout
// if an immediate ACK is
// expected.
+const QuicTag kPEB1 = TAG('P', 'E', 'B', '1'); // Start exponential backoff
+ // since 1st PTO.
+const QuicTag kPEB2 = TAG('P', 'E', 'B', '2'); // Start exponential backoff
+ // since 2nd PTO.
// Optional support of truncated Connection IDs. If sent by a peer, the value
// is the minimum number of bytes allowed for the connection ID sent to the
diff --git a/quic/core/quic_connection.cc b/quic/core/quic_connection.cc
index d2ec4c8..bf100c5 100644
--- a/quic/core/quic_connection.cc
+++ b/quic/core/quic_connection.cc
@@ -444,11 +444,11 @@
}
if (config.HasClientSentConnectionOption(k7PTO, perspective_)) {
max_consecutive_ptos_ = 6;
- QUIC_RELOADABLE_FLAG_COUNT_N(quic_enable_pto, 3, 5);
+ QUIC_RELOADABLE_FLAG_COUNT_N(quic_enable_pto, 3, 7);
}
if (config.HasClientSentConnectionOption(k8PTO, perspective_)) {
max_consecutive_ptos_ = 7;
- QUIC_RELOADABLE_FLAG_COUNT_N(quic_enable_pto, 4, 5);
+ QUIC_RELOADABLE_FLAG_COUNT_N(quic_enable_pto, 4, 7);
}
}
if (config.HasClientSentConnectionOption(kNSTP, perspective_)) {
diff --git a/quic/core/quic_sent_packet_manager.cc b/quic/core/quic_sent_packet_manager.cc
index 48a11c8..5880ea9 100644
--- a/quic/core/quic_sent_packet_manager.cc
+++ b/quic/core/quic_sent_packet_manager.cc
@@ -104,6 +104,7 @@
forward_secure_packet_acked_(false),
skip_packet_number_for_pto_(false),
always_include_max_ack_delay_for_pto_timeout_(true),
+ pto_exponential_backoff_start_point_(0),
neuter_handshake_packets_once_(
GetQuicReloadableFlag(quic_neuter_handshake_packets_once)) {
SetSendAlgorithm(congestion_control_type);
@@ -150,12 +151,12 @@
if (GetQuicReloadableFlag(quic_enable_pto)) {
if (config.HasClientSentConnectionOption(k2PTO, perspective)) {
pto_enabled_ = true;
- QUIC_RELOADABLE_FLAG_COUNT_N(quic_enable_pto, 2, 5);
+ QUIC_RELOADABLE_FLAG_COUNT_N(quic_enable_pto, 2, 7);
}
if (config.HasClientSentConnectionOption(k1PTO, perspective)) {
pto_enabled_ = true;
max_probe_packets_per_pto_ = 1;
- QUIC_RELOADABLE_FLAG_COUNT_N(quic_enable_pto, 1, 5);
+ QUIC_RELOADABLE_FLAG_COUNT_N(quic_enable_pto, 1, 7);
}
}
@@ -171,10 +172,19 @@
skip_packet_number_for_pto_ = true;
}
- if (pto_enabled_ &&
- config.HasClientSentConnectionOption(kPTOA, perspective)) {
- QUIC_RELOADABLE_FLAG_COUNT_N(quic_enable_pto, 5, 5);
- always_include_max_ack_delay_for_pto_timeout_ = false;
+ if (pto_enabled_) {
+ if (config.HasClientSentConnectionOption(kPTOA, perspective)) {
+ QUIC_RELOADABLE_FLAG_COUNT_N(quic_enable_pto, 5, 7);
+ always_include_max_ack_delay_for_pto_timeout_ = false;
+ }
+ if (config.HasClientSentConnectionOption(kPEB1, perspective)) {
+ QUIC_RELOADABLE_FLAG_COUNT_N(quic_enable_pto, 6, 7);
+ StartExponentialBackoffAfterNthPto(1);
+ }
+ if (config.HasClientSentConnectionOption(kPEB2, perspective)) {
+ QUIC_RELOADABLE_FLAG_COUNT_N(quic_enable_pto, 7, 7);
+ StartExponentialBackoffAfterNthPto(2);
+ }
}
// Configure congestion control.
@@ -800,6 +810,11 @@
uber_loss_algorithm_.SetLossDetectionType(kIetfLossDetection);
}
+void QuicSentPacketManager::StartExponentialBackoffAfterNthPto(
+ size_t exponential_backoff_start_point) {
+ pto_exponential_backoff_start_point_ = exponential_backoff_start_point;
+}
+
QuicSentPacketManager::RetransmissionTimeoutMode
QuicSentPacketManager::GetRetransmissionMode() const {
DCHECK(unacked_packets_.HasInFlightPackets() ||
@@ -1026,7 +1041,9 @@
std::max(4 * rtt_stats_.mean_deviation(),
QuicTime::Delta::FromMilliseconds(1)) +
(ShouldAddMaxAckDelay() ? peer_max_ack_delay_ : QuicTime::Delta::Zero());
- return pto_delay * (1 << consecutive_pto_count_);
+ return pto_delay * (1 << (consecutive_pto_count_ -
+ std::min(consecutive_pto_count_,
+ pto_exponential_backoff_start_point_)));
}
QuicTime::Delta QuicSentPacketManager::GetSlowStartDuration() const {
diff --git a/quic/core/quic_sent_packet_manager.h b/quic/core/quic_sent_packet_manager.h
index f15b3d5..5d362f4 100644
--- a/quic/core/quic_sent_packet_manager.h
+++ b/quic/core/quic_sent_packet_manager.h
@@ -383,6 +383,11 @@
// Also enable IETF loss detection.
void EnableIetfPtoAndLossDetection();
+ // Called to set the start point of doing exponential backoff when calculating
+ // PTO timeout.
+ void StartExponentialBackoffAfterNthPto(
+ size_t exponential_backoff_start_point);
+
bool supports_multiple_packet_number_spaces() const {
return unacked_packets_.supports_multiple_packet_number_spaces();
}
@@ -631,6 +636,11 @@
// If true, always include peer_max_ack_delay_ when calculating PTO timeout.
bool always_include_max_ack_delay_for_pto_timeout_;
+ // When calculating PTO timeout, the start point of doing exponential backoff.
+ // For example, 0 : always do exponential backoff. n : do exponential backoff
+ // since nth PTO.
+ size_t pto_exponential_backoff_start_point_;
+
// Latched value of quic_neuter_handshake_packets_once.
const bool neuter_handshake_packets_once_;
};
diff --git a/quic/core/quic_sent_packet_manager_test.cc b/quic/core/quic_sent_packet_manager_test.cc
index f2a72e0..c9d70b9 100644
--- a/quic/core/quic_sent_packet_manager_test.cc
+++ b/quic/core/quic_sent_packet_manager_test.cc
@@ -2882,6 +2882,121 @@
manager_.GetRetransmissionTime());
}
+TEST_F(QuicSentPacketManagerTest, StartExponentialBackoffSince2ndPto) {
+ EnablePto(k2PTO);
+ QuicConfig config;
+ QuicTagVector options;
+ options.push_back(kPEB2);
+ QuicConfigPeer::SetReceivedConnectionOptions(&config, options);
+ EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
+ EXPECT_CALL(*network_change_visitor_, OnCongestionChange());
+ manager_.SetFromConfig(config);
+
+ EXPECT_CALL(*send_algorithm_, PacingRate(_))
+ .WillRepeatedly(Return(QuicBandwidth::Zero()));
+ EXPECT_CALL(*send_algorithm_, GetCongestionWindow())
+ .WillRepeatedly(Return(10 * kDefaultTCPMSS));
+ RttStats* rtt_stats = const_cast<RttStats*>(manager_.GetRttStats());
+ rtt_stats->UpdateRtt(QuicTime::Delta::FromMilliseconds(100),
+ QuicTime::Delta::Zero(), QuicTime::Zero());
+ QuicTime::Delta srtt = rtt_stats->smoothed_rtt();
+
+ SendDataPacket(1, ENCRYPTION_FORWARD_SECURE);
+ // Verify PTO is correctly set.
+ QuicTime::Delta expected_pto_delay =
+ srtt + 4 * rtt_stats->mean_deviation() +
+ QuicTime::Delta::FromMilliseconds(kDefaultDelayedAckTimeMs);
+ EXPECT_EQ(clock_.Now() + expected_pto_delay,
+ manager_.GetRetransmissionTime());
+
+ clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(10));
+ SendDataPacket(2, ENCRYPTION_FORWARD_SECURE);
+ // Verify PTO is correctly set based on sent time of packet 2.
+ EXPECT_EQ(clock_.Now() + expected_pto_delay,
+ manager_.GetRetransmissionTime());
+ EXPECT_EQ(0u, stats_.pto_count);
+
+ // Invoke PTO.
+ clock_.AdvanceTime(expected_pto_delay);
+ manager_.OnRetransmissionTimeout();
+ EXPECT_EQ(QuicTime::Delta::Zero(), manager_.TimeUntilSend(clock_.Now()));
+ EXPECT_EQ(1u, stats_.pto_count);
+
+ // Verify two probe packets get sent.
+ EXPECT_CALL(notifier_, RetransmitFrames(_, _))
+ .Times(2)
+ .WillOnce(WithArgs<1>(Invoke([this](TransmissionType type) {
+ RetransmitDataPacket(3, type, ENCRYPTION_FORWARD_SECURE);
+ })))
+ .WillOnce(WithArgs<1>(Invoke([this](TransmissionType type) {
+ RetransmitDataPacket(4, type, ENCRYPTION_FORWARD_SECURE);
+ })));
+ manager_.MaybeSendProbePackets();
+ // Verify no exponential backoff.
+ EXPECT_EQ(clock_.Now() + expected_pto_delay,
+ manager_.GetRetransmissionTime());
+
+ // Invoke 2nd PTO.
+ clock_.AdvanceTime(expected_pto_delay);
+ manager_.OnRetransmissionTimeout();
+ EXPECT_EQ(QuicTime::Delta::Zero(), manager_.TimeUntilSend(clock_.Now()));
+ EXPECT_EQ(2u, stats_.pto_count);
+
+ // Verify two probe packets get sent.
+ EXPECT_CALL(notifier_, RetransmitFrames(_, _))
+ .Times(2)
+ .WillOnce(WithArgs<1>(Invoke([this](TransmissionType type) {
+ RetransmitDataPacket(5, type, ENCRYPTION_FORWARD_SECURE);
+ })))
+ .WillOnce(WithArgs<1>(Invoke([this](TransmissionType type) {
+ RetransmitDataPacket(6, type, ENCRYPTION_FORWARD_SECURE);
+ })));
+ manager_.MaybeSendProbePackets();
+ // Verify still no exponential backoff.
+ EXPECT_EQ(clock_.Now() + expected_pto_delay,
+ manager_.GetRetransmissionTime());
+
+ // Invoke 3rd PTO.
+ clock_.AdvanceTime(expected_pto_delay);
+ manager_.OnRetransmissionTimeout();
+ EXPECT_EQ(QuicTime::Delta::Zero(), manager_.TimeUntilSend(clock_.Now()));
+ EXPECT_EQ(3u, stats_.pto_count);
+
+ // Verify two probe packets get sent.
+ EXPECT_CALL(notifier_, RetransmitFrames(_, _))
+ .Times(2)
+ .WillOnce(WithArgs<1>(Invoke([this](TransmissionType type) {
+ RetransmitDataPacket(7, type, ENCRYPTION_FORWARD_SECURE);
+ })))
+ .WillOnce(WithArgs<1>(Invoke([this](TransmissionType type) {
+ RetransmitDataPacket(8, type, ENCRYPTION_FORWARD_SECURE);
+ })));
+ manager_.MaybeSendProbePackets();
+ // Verify exponential backoff starts.
+ EXPECT_EQ(clock_.Now() + expected_pto_delay * 2,
+ manager_.GetRetransmissionTime());
+
+ // Invoke 4th PTO.
+ clock_.AdvanceTime(expected_pto_delay * 2);
+ manager_.OnRetransmissionTimeout();
+ EXPECT_EQ(QuicTime::Delta::Zero(), manager_.TimeUntilSend(clock_.Now()));
+ EXPECT_EQ(4u, stats_.pto_count);
+
+ // Verify two probe packets get sent.
+ EXPECT_CALL(notifier_, RetransmitFrames(_, _))
+ .Times(2)
+ .WillOnce(WithArgs<1>(Invoke([this](TransmissionType type) {
+ RetransmitDataPacket(9, type, ENCRYPTION_FORWARD_SECURE);
+ })))
+ .WillOnce(WithArgs<1>(Invoke([this](TransmissionType type) {
+ RetransmitDataPacket(10, type, ENCRYPTION_FORWARD_SECURE);
+ })));
+ manager_.MaybeSendProbePackets();
+ // Verify exponential backoff continues.
+ EXPECT_EQ(clock_.Now() + expected_pto_delay * 4,
+ manager_.GetRetransmissionTime());
+}
+
} // namespace
} // namespace test
} // namespace quic
