Change QUIC's RTO implementation. Protected by FLAGS_quic_use_new_rto.

net/quic/quic_sent_packet_manager_test.cc

 // Copyright 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 "net/quic/quic_sent_packet_manager.h"
 
 #include "base/stl_util.h"
 #include "net/quic/quic_flags.h"
 #include "net/quic/test_tools/quic_config_peer.h"
 #include "net/quic/test_tools/quic_sent_packet_manager_peer.h"
@@ skipping 366 matching lines @@
   // No packets remain unacked.
   VerifyUnackedPackets(nullptr, 0);
   EXPECT_FALSE(QuicSentPacketManagerPeer::HasPendingPackets(&manager_));
   VerifyRetransmittablePackets(nullptr, 0);
 
   // Verify that the retransmission alarm would not fire,
   // since there is no retransmittable data outstanding.
   EXPECT_EQ(QuicTime::Zero(), manager_.GetRetransmissionTime());
 }
 
-TEST_F(QuicSentPacketManagerTest, RetransmitTwiceThenAckPreviousBeforeSend) {
+TEST_F(QuicSentPacketManagerTest,
+       DISABLED_RetransmitTwiceThenAckPreviousBeforeSend) {
   SendDataPacket(1);
   RetransmitAndSendPacket(1, 2);
 
   // Fire the RTO, which will mark 2 for retransmission (but will not send it).
   EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
   EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
   manager_.OnRetransmissionTimeout();
   EXPECT_TRUE(manager_.HasPendingRetransmissions());
 
   // Ack 1 but not 2, before 2 is able to be sent.
@@ skipping 438 matching lines @@
     rto_packet_time = clock_.Now();
   }
   EXPECT_CALL(*send_algorithm_, RetransmissionDelay())
       .WillOnce(Return(QuicTime::Delta::FromSeconds(1)));
   EXPECT_EQ(rto_packet_time.Add(QuicTime::Delta::FromSeconds(1)),
             manager_.GetRetransmissionTime());
 
   // Advance the time enough to ensure all packets are RTO'd.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(1000));
 
-  // The final RTO abandons all of them.
-  EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
-  EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
+  if (!FLAGS_quic_use_new_rto) {
+    // The final RTO abandons all of them.
+    EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
+    EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
+  }
   manager_.OnRetransmissionTimeout();
   EXPECT_TRUE(manager_.HasPendingRetransmissions());
   EXPECT_EQ(2u, stats_.tlp_count);
   EXPECT_EQ(1u, stats_.rto_count);
+
+  // Send and Ack the RTO and ensure OnRetransmissionTimeout is called.
+  if (FLAGS_quic_use_new_rto) {
+    EXPECT_EQ(102 * kDefaultLength,
+              QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+
+    RetransmitNextPacket(103);
+    QuicAckFrame ack_frame;
+    ack_frame.largest_observed = 103;
+    for (int i = 0; i < 103; ++i) {
+      ack_frame.missing_packets.insert(i);
+    }
+    EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
+    EXPECT_CALL(*send_algorithm_,
+                OnCongestionEvent(true, _, ElementsAre(Pair(103, _)), _));
+    EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
+    EXPECT_CALL(*network_change_visitor_, OnRttChange());
+    manager_.OnIncomingAck(ack_frame, clock_.ApproximateNow());
+    // All packets before 103 should be lost.
+    EXPECT_EQ(0u, QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  }
 }
 
 TEST_F(QuicSentPacketManagerTest, CryptoHandshakeTimeout) {
   // Send 2 crypto packets and 3 data packets.
   const size_t kNumSentCryptoPackets = 2;
   for (size_t i = 1; i <= kNumSentCryptoPackets; ++i) {
     SendCryptoPacket(i);
   }
   const size_t kNumSentDataPackets = 3;
   for (size_t i = 1; i <= kNumSentDataPackets; ++i) {
@@ skipping 204 matching lines @@
   manager_.OnIncomingAck(ack_frame, clock_.Now());
 
   EXPECT_EQ(min_rtt,
             QuicSentPacketManagerPeer::GetRttStats(&manager_)->min_rtt());
   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(100),
             QuicSentPacketManagerPeer::GetRttStats(
                 &manager_)->recent_min_rtt());
 }
 
 TEST_F(QuicSentPacketManagerTest, RetransmissionTimeout) {
-  // Send 100 packets and then ensure all are abandoned when the RTO fires.
+  // Send 100 packets.
   const size_t kNumSentPackets = 100;
   for (size_t i = 1; i <= kNumSentPackets; ++i) {
     SendDataPacket(i);
   }
 
-  EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
-  EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
+  if (!FLAGS_quic_use_new_rto) {
+    EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
+    EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
+  }
   EXPECT_FALSE(manager_.MaybeRetransmitTailLossProbe());
   manager_.OnRetransmissionTimeout();
+  EXPECT_TRUE(manager_.HasPendingRetransmissions());
+  if (FLAGS_quic_use_new_rto) {
+    EXPECT_EQ(100 * kDefaultLength,
+              QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  } else {
+    // Ensure all are abandoned when the RTO fires.
+    EXPECT_EQ(0u, QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  }
+  RetransmitNextPacket(101);
+  RetransmitNextPacket(102);
+  if (FLAGS_quic_use_new_rto) {
+    EXPECT_FALSE(manager_.HasPendingRetransmissions());
+  } else {
+    EXPECT_TRUE(manager_.HasPendingRetransmissions());
+  }
+
+  // Ack a retransmission.
+  if (FLAGS_quic_use_new_rto) {
+    EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
+  }
+  QuicAckFrame ack_frame;
+  ack_frame.delta_time_largest_observed = QuicTime::Delta::Zero();
+  ack_frame.largest_observed = 102;
+  for (int i = 0; i < 102; ++i) {
+    ack_frame.missing_packets.insert(i);
+  }
+  EXPECT_CALL(*send_algorithm_,
+              OnCongestionEvent(true, _, ElementsAre(Pair(102, _)), _));
+  EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
+  EXPECT_CALL(*network_change_visitor_, OnRttChange());
+  manager_.OnIncomingAck(ack_frame, clock_.Now());
+}
+
+TEST_F(QuicSentPacketManagerTest, TwoRetransmissionTimeoutsAckSecond) {
+  // Send 1 packet.
+  SendDataPacket(1);
+
+  if (!FLAGS_quic_use_new_rto) {
+    EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
+    EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
+  }
+  manager_.OnRetransmissionTimeout();
+  EXPECT_TRUE(manager_.HasPendingRetransmissions());
+  if (FLAGS_quic_use_new_rto) {
+    EXPECT_EQ(kDefaultLength,
+              QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  } else {
+    // Ensure all are abandoned when the RTO fires.
+    EXPECT_EQ(0u, QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  }
+  RetransmitNextPacket(2);
+  EXPECT_FALSE(manager_.HasPendingRetransmissions());
+
+  // Rto a second time.
+  if (!FLAGS_quic_use_new_rto) {
+    EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
+    EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
+  }
+  manager_.OnRetransmissionTimeout();
+  EXPECT_TRUE(manager_.HasPendingRetransmissions());
+  if (FLAGS_quic_use_new_rto) {
+    EXPECT_EQ(2 * kDefaultLength,
+              QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  } else {
+    // Ensure all are abandoned when the RTO fires.
+    EXPECT_EQ(0u, QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  }
+  RetransmitNextPacket(3);
+  EXPECT_FALSE(manager_.HasPendingRetransmissions());
+
+  // Ack a retransmission and ensure OnRetransmissionTimeout is called.
+  if (FLAGS_quic_use_new_rto) {
+    EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
+  }
+  QuicAckFrame ack_frame;
+  ack_frame.delta_time_largest_observed = QuicTime::Delta::Zero();
+  ack_frame.largest_observed = 2;
+  ack_frame.missing_packets.insert(1);
+  if (FLAGS_quic_use_new_rto) {
+    ExpectAck(2);
+  } else {
+    ExpectUpdatedRtt(2);
+  }
+  manager_.OnIncomingAck(ack_frame, clock_.Now());
+
+  if (FLAGS_quic_use_new_rto) {
+    // The original packet and newest should be outstanding.
+    EXPECT_EQ(2 * kDefaultLength,
+              QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  } else {
+    EXPECT_EQ(kDefaultLength,
+              QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  }
+}
+
+TEST_F(QuicSentPacketManagerTest, TwoRetransmissionTimeoutsAckFirst) {
+  // Send 1 packet.
+  SendDataPacket(1);
+
+  if (!FLAGS_quic_use_new_rto) {
+    EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
+    EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
+  }
+  manager_.OnRetransmissionTimeout();
+  EXPECT_TRUE(manager_.HasPendingRetransmissions());
+  if (FLAGS_quic_use_new_rto) {
+    EXPECT_EQ(kDefaultLength,
+              QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  } else {
+    // Ensure all are abandoned when the RTO fires.
+    EXPECT_EQ(0u, QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  }
+  RetransmitNextPacket(2);
+  EXPECT_FALSE(manager_.HasPendingRetransmissions());
+
+  // Rto a second time.
+  if (!FLAGS_quic_use_new_rto) {
+    EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
+    EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
+  }
+  manager_.OnRetransmissionTimeout();
+  EXPECT_TRUE(manager_.HasPendingRetransmissions());
+  if (FLAGS_quic_use_new_rto) {
+    EXPECT_EQ(2 * kDefaultLength,
+              QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  } else {
+    // Ensure all are abandoned when the RTO fires.
+    EXPECT_EQ(0u, QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  }
+  RetransmitNextPacket(3);
+  EXPECT_FALSE(manager_.HasPendingRetransmissions());
+
+  // Ack a retransmission and ensure OnRetransmissionTimeout is called.
+  if (FLAGS_quic_use_new_rto) {
+    EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
+  }
+  QuicAckFrame ack_frame;
+  ack_frame.delta_time_largest_observed = QuicTime::Delta::Zero();
+  ack_frame.largest_observed = 3;
+  ack_frame.missing_packets.insert(1);
+  ack_frame.missing_packets.insert(2);
+  ExpectAck(3);
+  manager_.OnIncomingAck(ack_frame, clock_.Now());
+
+  if (FLAGS_quic_use_new_rto) {
+    // The first two packets should still be outstanding.
+    EXPECT_EQ(2 * kDefaultLength,
+              QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  } else {
+    EXPECT_EQ(0u, QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  }
 }
 
 TEST_F(QuicSentPacketManagerTest, GetTransmissionTime) {
   EXPECT_EQ(QuicTime::Zero(), manager_.GetRetransmissionTime());
 }
 
 TEST_F(QuicSentPacketManagerTest, GetTransmissionTimeCryptoHandshake) {
   SendCryptoPacket(1);
 
   // Check the min.
@@ skipping 51 matching lines @@
   EXPECT_CALL(*send_algorithm_, TimeUntilSend(_, _, _)).WillOnce(Return(
       QuicTime::Delta::Infinite()));
   EXPECT_EQ(QuicTime::Delta::Infinite(),
             manager_.TimeUntilSend(clock_.Now(), HAS_RETRANSMITTABLE_DATA));
   EXPECT_FALSE(manager_.HasPendingRetransmissions());
 
   expected_time = clock_.Now().Add(expected_tlp_delay);
   EXPECT_EQ(expected_time, manager_.GetRetransmissionTime());
 }
 
-TEST_F(QuicSentPacketManagerTest, GetTransmissionTimeRTO) {
+TEST_F(QuicSentPacketManagerTest, GetTransmissionTimeSpuriousRTO) {
   QuicSentPacketManagerPeer::GetRttStats(&manager_)->UpdateRtt(
       QuicTime::Delta::FromMilliseconds(100),
       QuicTime::Delta::Zero(),
       QuicTime::Zero());
 
   SendDataPacket(1);
   SendDataPacket(2);
   SendDataPacket(3);
   SendDataPacket(4);
 
   QuicTime::Delta expected_rto_delay = QuicTime::Delta::FromMilliseconds(500);
   EXPECT_CALL(*send_algorithm_, RetransmissionDelay())
       .WillRepeatedly(Return(expected_rto_delay));
   QuicTime expected_time = clock_.Now().Add(expected_rto_delay);
   EXPECT_EQ(expected_time, manager_.GetRetransmissionTime());
 
   // Retransmit the packet by invoking the retransmission timeout.
-  EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
-  EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
+  if (!FLAGS_quic_use_new_rto) {
+    EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
+    EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
+  }
   clock_.AdvanceTime(expected_rto_delay);
   manager_.OnRetransmissionTimeout();
-  EXPECT_EQ(0u, QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  if (FLAGS_quic_use_new_rto) {
+    // All packets are still considered inflight.
+    EXPECT_EQ(4 * kDefaultLength,
+              QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  } else {
+    EXPECT_EQ(0u, QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  }
   RetransmitNextPacket(5);
   RetransmitNextPacket(6);
-  EXPECT_EQ(2 * kDefaultLength,
-            QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
-  EXPECT_TRUE(manager_.HasPendingRetransmissions());
+  if (FLAGS_quic_use_new_rto) {
+    // All previous packets are inflight, plus two rto retransmissions.
+    EXPECT_EQ(6 * kDefaultLength,
+              QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+    EXPECT_FALSE(manager_.HasPendingRetransmissions());
+  } else {
+    EXPECT_EQ(2 * kDefaultLength,
+              QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+    EXPECT_TRUE(manager_.HasPendingRetransmissions());
+  }
 
   // The delay should double the second time.
   expected_time = clock_.Now().Add(expected_rto_delay).Add(expected_rto_delay);
-  EXPECT_EQ(expected_time, manager_.GetRetransmissionTime());
+  // Once we always base the timer on the right edge, leaving the older packets
+  // in flight doesn't change the timeout.
+  if (!FLAGS_quic_use_new_rto || FLAGS_quic_rto_uses_last_sent) {
+    EXPECT_EQ(expected_time, manager_.GetRetransmissionTime());
+  }
 
-  // Ack a packet and ensure the RTO goes back to the original value.
+  // Ack a packet before the first RTO and ensure the RTO timeout returns to the
+  // original value and OnRetransmissionTimeout is not called or reverted.
   QuicAckFrame ack_frame;
   ack_frame.largest_observed = 2;
   ack_frame.missing_packets.insert(1);
-  ExpectUpdatedRtt(2);
-  EXPECT_CALL(*send_algorithm_, RevertRetransmissionTimeout());
+  if (FLAGS_quic_use_new_rto) {
+    ExpectAck(2);
+  } else {
+    ExpectUpdatedRtt(2);
+    EXPECT_CALL(*send_algorithm_, RevertRetransmissionTimeout());
+  }
   manager_.OnIncomingAck(ack_frame, clock_.ApproximateNow());
   EXPECT_FALSE(manager_.HasPendingRetransmissions());
-  EXPECT_EQ(4 * kDefaultLength,
-            QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  if (FLAGS_quic_use_new_rto) {
+    EXPECT_EQ(5 * kDefaultLength,
+              QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  } else {
+    EXPECT_EQ(4 * kDefaultLength,
+              QuicSentPacketManagerPeer::GetBytesInFlight(&manager_));
+  }
 
   // Wait 2RTTs from now for the RTO, since it's the max of the RTO time
   // and the TLP time.  In production, there would always be two TLP's first.
   // Since retransmission was spurious, smoothed_rtt_ is expired, and replaced
   // by the latest RTT sample of 500ms.
   expected_time = clock_.Now().Add(QuicTime::Delta::FromMilliseconds(1000));
-  EXPECT_EQ(expected_time, manager_.GetRetransmissionTime());
+  // Once we always base the timer on the right edge, leaving the older packets
+  // in flight doesn't change the timeout.
+  if (!FLAGS_quic_use_new_rto || FLAGS_quic_rto_uses_last_sent) {
+    EXPECT_EQ(expected_time, manager_.GetRetransmissionTime());
+  }
 }
 
 TEST_F(QuicSentPacketManagerTest, GetTransmissionDelayMin) {
   SendDataPacket(1);
   EXPECT_CALL(*send_algorithm_, RetransmissionDelay())
       .WillRepeatedly(Return(QuicTime::Delta::FromMilliseconds(1)));
   QuicTime::Delta delay = QuicTime::Delta::FromMilliseconds(200);
 
   // If the delay is smaller than the min, ensure it exponentially backs off
   // from the min.
   for (int i = 0; i < 5; ++i) {
     EXPECT_EQ(delay,
               QuicSentPacketManagerPeer::GetRetransmissionDelay(&manager_));
     delay = delay.Add(delay);
-    EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
-    EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
+    if (!FLAGS_quic_use_new_rto) {
+      EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
+      EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
+    }
     manager_.OnRetransmissionTimeout();
     RetransmitNextPacket(i + 2);
   }
 }
 
 TEST_F(QuicSentPacketManagerTest, GetTransmissionDelayMax) {
   EXPECT_CALL(*send_algorithm_, RetransmissionDelay())
       .WillOnce(Return(QuicTime::Delta::FromSeconds(500)));
 
   EXPECT_EQ(QuicTime::Delta::FromSeconds(60),
             QuicSentPacketManagerPeer::GetRetransmissionDelay(&manager_));
 }
 
 TEST_F(QuicSentPacketManagerTest, GetTransmissionDelay) {
   SendDataPacket(1);
   QuicTime::Delta delay = QuicTime::Delta::FromMilliseconds(500);
   EXPECT_CALL(*send_algorithm_, RetransmissionDelay())
       .WillRepeatedly(Return(delay));
 
   // Delay should back off exponentially.
   for (int i = 0; i < 5; ++i) {
     EXPECT_EQ(delay,
               QuicSentPacketManagerPeer::GetRetransmissionDelay(&manager_));
     delay = delay.Add(delay);
-    EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
-    EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
+    if (!FLAGS_quic_use_new_rto) {
+      EXPECT_CALL(*network_change_visitor_, OnCongestionWindowChange());
+      EXPECT_CALL(*send_algorithm_, OnRetransmissionTimeout(true));
+    }
     manager_.OnRetransmissionTimeout();
     RetransmitNextPacket(i + 2);
   }
 }
 
 TEST_F(QuicSentPacketManagerTest, GetLossDelay) {
   MockLossAlgorithm* loss_algorithm = new MockLossAlgorithm();
   QuicSentPacketManagerPeer::SetLossAlgorithm(&manager_, loss_algorithm);
 
   EXPECT_CALL(*loss_algorithm, GetLossTimeout())
@@ skipping 243 matching lines @@
 
   EXPECT_CALL(*send_algorithm_, ResumeConnectionState(_));
   manager_.ResumeConnectionState(cached_network_params);
   EXPECT_EQ(kRttMs * kNumMicrosPerMilli,
             static_cast<uint64>(manager_.GetRttStats()->initial_rtt_us()));
 }
 
 }  // namespace
 }  // namespace test
 }  // namespace net