Land Recent QUIC Changes.

net/quic/congestion_control/tcp_loss_algorithm_test.cc

 // Copyright 2014 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/congestion_control/tcp_loss_algorithm.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/stl_util.h"
+#include "net/quic/congestion_control/rtt_stats.h"
 #include "net/quic/quic_unacked_packet_map.h"
 #include "net/quic/test_tools/mock_clock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace net {
 namespace test {
 namespace {
 
 class TcpLossAlgorithmTest : public ::testing::Test {
  protected:
   TcpLossAlgorithmTest()
-      : unacked_packets_(true),
-        srtt_(QuicTime::Delta::FromMilliseconds(100)) { }
+      : unacked_packets_() {
+    rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(100),
+                         QuicTime::Delta::Zero());
+  }
 
   void SendDataPacket(QuicPacketSequenceNumber sequence_number) {
     SerializedPacket packet(sequence_number, PACKET_1BYTE_SEQUENCE_NUMBER,
                             NULL, 0, new RetransmittableFrames());
     unacked_packets_.AddPacket(packet);
     unacked_packets_.SetPending(sequence_number, clock_.Now(), 1000);
   }
 
   void VerifyLosses(QuicPacketSequenceNumber largest_observed,
                     QuicPacketSequenceNumber* losses_expected,
                     size_t num_losses) {
     SequenceNumberSet lost_packets =
         loss_algorithm_.DetectLostPackets(
-            unacked_packets_, clock_.Now(), largest_observed, srtt_, srtt_);
+            unacked_packets_, clock_.Now(), largest_observed, rtt_stats_);
     EXPECT_EQ(num_losses, lost_packets.size());
     for (size_t i = 0; i < num_losses; ++i) {
       EXPECT_TRUE(ContainsKey(lost_packets, losses_expected[i]));
     }
   }
 
   QuicUnackedPacketMap unacked_packets_;
   TCPLossAlgorithm loss_algorithm_;
-  QuicTime::Delta srtt_;
+  RttStats rtt_stats_;
   MockClock clock_;
 };
 
 TEST_F(TcpLossAlgorithmTest, NackRetransmit1Packet) {
   const size_t kNumSentPackets = 5;
   // Transmit 5 packets.
   for (size_t i = 1; i <= kNumSentPackets; ++i) {
     SendDataPacket(i);
   }
   // No loss on one ack.
@@ skipping 52 matching lines @@
 TEST_F(TcpLossAlgorithmTest, EarlyRetransmit1Packet) {
   const size_t kNumSentPackets = 2;
   // Transmit 2 packets.
   for (size_t i = 1; i <= kNumSentPackets; ++i) {
     SendDataPacket(i);
   }
   // Early retransmit when the final packet gets acked and the first is nacked.
   unacked_packets_.SetNotPending(2);
   unacked_packets_.NackPacket(1, 1);
   VerifyLosses(2, NULL, 0);
-  EXPECT_EQ(clock_.Now().Add(srtt_.Multiply(1.25)),
+  EXPECT_EQ(clock_.Now().Add(rtt_stats_.SmoothedRtt().Multiply(1.25)),
             loss_algorithm_.GetLossTimeout());
 
-  clock_.AdvanceTime(srtt_.Multiply(1.25));
+  clock_.AdvanceTime(rtt_stats_.latest_rtt().Multiply(1.25));
   QuicPacketSequenceNumber lost[] = { 1 };
   VerifyLosses(2, lost, arraysize(lost));
   EXPECT_EQ(QuicTime::Zero(), loss_algorithm_.GetLossTimeout());
 }
 
 TEST_F(TcpLossAlgorithmTest, EarlyRetransmitAllPackets) {
   const size_t kNumSentPackets = 5;
   for (size_t i = 1; i <= kNumSentPackets; ++i) {
     SendDataPacket(i);
+    // Advance the time 1/4 RTT between 3 and 4.
+    if (i == 3) {
+      clock_.AdvanceTime(rtt_stats_.SmoothedRtt().Multiply(0.25));
+    }
   }
-  // Early retransmit when the final packet gets acked and the first 4 are
-  // nacked multiple times via FACK.
+
+  // Early retransmit when the final packet gets acked and 1.25 RTTs have
+  // elapsed since the packets were sent.
   unacked_packets_.SetNotPending(kNumSentPackets);
+  // This simulates a single ack following multiple missing packets with FACK.
   for (size_t i = 1; i < kNumSentPackets; ++i) {
     unacked_packets_.NackPacket(i, kNumSentPackets - i);
   }
   QuicPacketSequenceNumber lost[] = { 1, 2 };
   VerifyLosses(kNumSentPackets, lost, arraysize(lost));
-  EXPECT_EQ(clock_.Now().Add(srtt_.Multiply(1.25)),
+  // The time has already advanced 1/4 an RTT, so ensure the timeout is set
+  // 1.25 RTTs after the earliest pending packet(3), not the last(4).
+  EXPECT_EQ(clock_.Now().Add(rtt_stats_.SmoothedRtt()),
             loss_algorithm_.GetLossTimeout());
 
-  clock_.AdvanceTime(srtt_.Multiply(1.25));
-  QuicPacketSequenceNumber lost2[] = { 1, 2, 3, 4 };
+  clock_.AdvanceTime(rtt_stats_.SmoothedRtt());
+  QuicPacketSequenceNumber lost2[] = { 1, 2, 3 };
   VerifyLosses(kNumSentPackets, lost2, arraysize(lost2));
+  EXPECT_EQ(clock_.Now().Add(rtt_stats_.SmoothedRtt().Multiply(0.25)),
+            loss_algorithm_.GetLossTimeout());
+  clock_.AdvanceTime(rtt_stats_.SmoothedRtt().Multiply(0.25));
+  QuicPacketSequenceNumber lost3[] = { 1, 2, 3, 4 };
+  VerifyLosses(kNumSentPackets, lost3, arraysize(lost3));
   EXPECT_EQ(QuicTime::Zero(), loss_algorithm_.GetLossTimeout());
 }
 
 TEST_F(TcpLossAlgorithmTest, DontEarlyRetransmitNeuteredPacket) {
   const size_t kNumSentPackets = 2;
   // Transmit 2 packets.
   for (size_t i = 1; i <= kNumSentPackets; ++i) {
     SendDataPacket(i);
   }
   // Early retransmit when the final packet gets acked and the first is nacked.
   unacked_packets_.SetNotPending(2);
   unacked_packets_.NackPacket(1, 1);
   unacked_packets_.NeuterPacket(1);
   VerifyLosses(2, NULL, 0);
   EXPECT_EQ(QuicTime::Zero(), loss_algorithm_.GetLossTimeout());
 }
 
 }  // namespace
 }  // namespace test
 }  // namespace net