Delay the first Initial ACK sent by the server so it can be bundled with the server's first Initial packet.
Protected by FLAGS_quic_reloadable_flag_quic_delay_initial_ack.
PiperOrigin-RevId: 338518843
Change-Id: Ib8cb7375f212ac5f028bd2c7f6a191278ac01540
diff --git a/quic/core/quic_connection.cc b/quic/core/quic_connection.cc
index 7f7089b..5b9ab32 100644
--- a/quic/core/quic_connection.cc
+++ b/quic/core/quic_connection.cc
@@ -5113,7 +5113,8 @@
<< " supports multiple packet number spaces";
framer_.EnableMultiplePacketNumberSpacesSupport();
sent_packet_manager_.EnableMultiplePacketNumberSpacesSupport();
- uber_received_packet_manager_.EnableMultiplePacketNumberSpacesSupport();
+ uber_received_packet_manager_.EnableMultiplePacketNumberSpacesSupport(
+ perspective_);
}
bool QuicConnection::SupportsMultiplePacketNumberSpaces() const {
diff --git a/quic/core/quic_received_packet_manager.cc b/quic/core/quic_received_packet_manager.cc
index 0a91709..98f450c 100644
--- a/quic/core/quic_received_packet_manager.cc
+++ b/quic/core/quic_received_packet_manager.cc
@@ -264,8 +264,11 @@
return;
}
- MaybeUpdateAckTimeoutTo(
- now + GetMaxAckDelay(last_received_packet_number, *rtt_stats));
+ QuicTime updated_ack_time =
+ now + GetMaxAckDelay(last_received_packet_number, *rtt_stats);
+ if (!ack_timeout_.IsInitialized() || ack_timeout_ > updated_ack_time) {
+ ack_timeout_ = updated_ack_time;
+ }
}
void QuicReceivedPacketManager::ResetAckStates() {
@@ -275,12 +278,6 @@
last_sent_largest_acked_ = LargestAcked(ack_frame_);
}
-void QuicReceivedPacketManager::MaybeUpdateAckTimeoutTo(QuicTime time) {
- if (!ack_timeout_.IsInitialized() || ack_timeout_ > time) {
- ack_timeout_ = time;
- }
-}
-
bool QuicReceivedPacketManager::HasMissingPackets() const {
if (ack_frame_.packets.Empty()) {
return false;
diff --git a/quic/core/uber_received_packet_manager.cc b/quic/core/uber_received_packet_manager.cc
index 7b2b32f..025da64 100644
--- a/quic/core/uber_received_packet_manager.cc
+++ b/quic/core/uber_received_packet_manager.cc
@@ -98,9 +98,15 @@
}
received_packet_managers_[QuicUtils::GetPacketNumberSpace(encryption_level)]
.ResetAckStates();
+ if (encryption_level == ENCRYPTION_INITIAL) {
+ // After one Initial ACK is sent, the others should be sent 'immediately'.
+ received_packet_managers_[INITIAL_DATA].set_local_max_ack_delay(
+ kAlarmGranularity);
+ }
}
-void UberReceivedPacketManager::EnableMultiplePacketNumberSpacesSupport() {
+void UberReceivedPacketManager::EnableMultiplePacketNumberSpacesSupport(
+ Perspective perspective) {
if (supports_multiple_packet_number_spaces_) {
QUIC_BUG << "Multiple packet number spaces has already been enabled";
return;
@@ -112,8 +118,15 @@
}
// In IETF QUIC, the peer is expected to acknowledge packets in Initial and
// Handshake packets with minimal delay.
- received_packet_managers_[INITIAL_DATA].set_local_max_ack_delay(
- kAlarmGranularity);
+ if (!GetQuicReloadableFlag(quic_delay_initial_ack) ||
+ perspective == Perspective::IS_CLIENT) {
+ // Delay the first server ACK, because server ACKs are padded to
+ // full size and count towards the amplification limit.
+ received_packet_managers_[INITIAL_DATA].set_local_max_ack_delay(
+ kAlarmGranularity);
+ } else {
+ QUIC_RELOADABLE_FLAG_COUNT(quic_delay_initial_ack);
+ }
received_packet_managers_[HANDSHAKE_DATA].set_local_max_ack_delay(
kAlarmGranularity);
diff --git a/quic/core/uber_received_packet_manager.h b/quic/core/uber_received_packet_manager.h
index 17b5e26..a9f1775 100644
--- a/quic/core/uber_received_packet_manager.h
+++ b/quic/core/uber_received_packet_manager.h
@@ -54,7 +54,7 @@
void ResetAckStates(EncryptionLevel encryption_level);
// Called to enable multiple packet number support.
- void EnableMultiplePacketNumberSpacesSupport();
+ void EnableMultiplePacketNumberSpacesSupport(Perspective perspective);
// Returns true if ACK frame has been updated since GetUpdatedAckFrame was
// last called.
diff --git a/quic/core/uber_received_packet_manager_test.cc b/quic/core/uber_received_packet_manager_test.cc
index b7063d2..3a1531b 100644
--- a/quic/core/uber_received_packet_manager_test.cc
+++ b/quic/core/uber_received_packet_manager_test.cc
@@ -439,7 +439,7 @@
TEST_F(UberReceivedPacketManagerTest,
DontWaitForPacketsBeforeMultiplePacketNumberSpaces) {
- manager_->EnableMultiplePacketNumberSpacesSupport();
+ manager_->EnableMultiplePacketNumberSpacesSupport(Perspective::IS_CLIENT);
EXPECT_FALSE(
manager_->GetLargestObserved(ENCRYPTION_HANDSHAKE).IsInitialized());
EXPECT_FALSE(
@@ -469,10 +469,42 @@
}
TEST_F(UberReceivedPacketManagerTest, AckSendingDifferentPacketNumberSpaces) {
- manager_->EnableMultiplePacketNumberSpacesSupport();
+ manager_->EnableMultiplePacketNumberSpacesSupport(Perspective::IS_SERVER);
EXPECT_FALSE(HasPendingAck());
EXPECT_FALSE(manager_->IsAckFrameUpdated());
+ RecordPacketReceipt(ENCRYPTION_INITIAL, 3);
+ EXPECT_TRUE(manager_->IsAckFrameUpdated());
+ MaybeUpdateAckTimeout(kInstigateAck, ENCRYPTION_INITIAL, 3);
+ EXPECT_TRUE(HasPendingAck());
+ // Delayed ack is scheduled.
+ if (GetQuicReloadableFlag(quic_delay_initial_ack)) {
+ CheckAckTimeout(clock_.ApproximateNow() +
+ QuicTime::Delta::FromMilliseconds(25));
+ // Send delayed handshake data ACK.
+ clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(25));
+ } else {
+ CheckAckTimeout(clock_.ApproximateNow() +
+ QuicTime::Delta::FromMilliseconds(1));
+ // Send delayed handshake data ACK.
+ clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(1));
+ }
+ CheckAckTimeout(clock_.ApproximateNow());
+ EXPECT_FALSE(HasPendingAck());
+
+ // Second delayed ack should have a shorter delay.
+ RecordPacketReceipt(ENCRYPTION_INITIAL, 4);
+ EXPECT_TRUE(manager_->IsAckFrameUpdated());
+ MaybeUpdateAckTimeout(kInstigateAck, ENCRYPTION_INITIAL, 4);
+ EXPECT_TRUE(HasPendingAck());
+ // Delayed ack is scheduled.
+ CheckAckTimeout(clock_.ApproximateNow() +
+ QuicTime::Delta::FromMilliseconds(1));
+ // Send delayed handshake data ACK.
+ clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(1));
+ CheckAckTimeout(clock_.ApproximateNow());
+ EXPECT_FALSE(HasPendingAck());
+
RecordPacketReceipt(ENCRYPTION_HANDSHAKE, 3);
EXPECT_TRUE(manager_->IsAckFrameUpdated());
MaybeUpdateAckTimeout(kInstigateAck, ENCRYPTION_HANDSHAKE, 3);
