net/quic/congestion_control/rtt_stats_test.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/quic/congestion_control/rtt_stats.h"
   6
   7 #include "base/logging.h"
   8 #include "testing/gtest/include/gtest/gtest.h"
   9
  10 namespace net {
  11 namespace test {
  12
  13 class RttStatsPeer {
  14  public:
  15   static QuicTime::Delta GetHalfWindowRtt(const RttStats* rtt_stats) {
  16     return rtt_stats->half_window_rtt_.rtt;
  17   }
  18
  19   static QuicTime::Delta GetQuarterWindowRtt(const RttStats* rtt_stats) {
  20     return rtt_stats->quarter_window_rtt_.rtt;
  21   }
  22 };
  23
  24 class RttStatsTest : public ::testing::Test {
  25  protected:
  26   RttStats rtt_stats_;
  27 };
  28
  29 TEST_F(RttStatsTest, MinRtt) {
  30   rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(100),
  31                        QuicTime::Delta::Zero(),
  32                        QuicTime::Zero());
  33   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(100), rtt_stats_.min_rtt());
  34   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(100),
  35             rtt_stats_.recent_min_rtt());
  36   rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(10),
  37                        QuicTime::Delta::Zero(),
  38                        QuicTime::Zero().Add(
  39                            QuicTime::Delta::FromMilliseconds(10)));
  40   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.min_rtt());
  41   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.recent_min_rtt());
  42   rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(50),
  43                        QuicTime::Delta::Zero(),
  44                        QuicTime::Zero().Add(
  45                            QuicTime::Delta::FromMilliseconds(20)));
  46   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.min_rtt());
  47   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.recent_min_rtt());
  48   rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(50),
  49                        QuicTime::Delta::Zero(),
  50                        QuicTime::Zero().Add(
  51                            QuicTime::Delta::FromMilliseconds(30)));
  52   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.min_rtt());
  53   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.recent_min_rtt());
  54   rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(50),
  55                        QuicTime::Delta::Zero(),
  56                        QuicTime::Zero().Add(
  57                            QuicTime::Delta::FromMilliseconds(40)));
  58   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.min_rtt());
  59   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.recent_min_rtt());
  60 }
  61
  62 TEST_F(RttStatsTest, RecentMinRtt) {
  63   rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(10),
  64                        QuicTime::Delta::Zero(),
  65                        QuicTime::Zero());
  66   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.min_rtt());
  67   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.recent_min_rtt());
  68
  69   rtt_stats_.SampleNewRecentMinRtt(4);
  70   for (int i = 0; i < 3; ++i) {
  71     rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(50),
  72                        QuicTime::Delta::Zero(),
  73                        QuicTime::Zero());
  74     EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.min_rtt());
  75     EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10),
  76               rtt_stats_.recent_min_rtt());
  77   }
  78   rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(50),
  79                         QuicTime::Delta::Zero(),
  80                         QuicTime::Zero());
  81   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.min_rtt());
  82   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(50), rtt_stats_.recent_min_rtt());
  83 }
  84
  85 TEST_F(RttStatsTest, WindowedRecentMinRtt) {
  86   // Set the window to 99ms, so 25ms is more than a quarter rtt.
  87   rtt_stats_.set_recent_min_rtt_window(QuicTime::Delta::FromMilliseconds(99));
  88
  89   QuicTime now = QuicTime::Zero();
  90   QuicTime::Delta rtt_sample = QuicTime::Delta::FromMilliseconds(10);
  91   rtt_stats_.UpdateRtt(rtt_sample, QuicTime::Delta::Zero(), now);
  92   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.min_rtt());
  93   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.recent_min_rtt());
  94
  95   // Gradually increase the rtt samples and ensure the recent_min_rtt starts
  96   // rising.
  97   for (int i = 0; i < 8; ++i) {
  98     now = now.Add(QuicTime::Delta::FromMilliseconds(25));
  99     rtt_sample = rtt_sample.Add(QuicTime::Delta::FromMilliseconds(10));
 100     rtt_stats_.UpdateRtt(rtt_sample, QuicTime::Delta::Zero(), now);
 101     EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.min_rtt());
 102     EXPECT_EQ(rtt_sample, RttStatsPeer::GetQuarterWindowRtt(&rtt_stats_));
 103     EXPECT_EQ(rtt_sample.Subtract(QuicTime::Delta::FromMilliseconds(10)),
 104               RttStatsPeer::GetHalfWindowRtt(&rtt_stats_));
 105     if (i < 3) {
 106       EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10),
 107                 rtt_stats_.recent_min_rtt());
 108     } else if (i < 5) {
 109       EXPECT_EQ(QuicTime::Delta::FromMilliseconds(30),
 110                 rtt_stats_.recent_min_rtt());
 111     } else if (i < 7) {
 112       EXPECT_EQ(QuicTime::Delta::FromMilliseconds(50),
 113                 rtt_stats_.recent_min_rtt());
 114     } else {
 115       EXPECT_EQ(QuicTime::Delta::FromMilliseconds(70),
 116                 rtt_stats_.recent_min_rtt());
 117     }
 118   }
 119
 120   // A new quarter rtt low sets that, but nothing else.
 121   rtt_sample = rtt_sample.Subtract(QuicTime::Delta::FromMilliseconds(5));
 122   rtt_stats_.UpdateRtt(rtt_sample, QuicTime::Delta::Zero(), now);
 123   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.min_rtt());
 124   EXPECT_EQ(rtt_sample, RttStatsPeer::GetQuarterWindowRtt(&rtt_stats_));
 125   EXPECT_EQ(rtt_sample.Subtract(QuicTime::Delta::FromMilliseconds(5)),
 126             RttStatsPeer::GetHalfWindowRtt(&rtt_stats_));
 127   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(70),
 128             rtt_stats_.recent_min_rtt());
 129
 130   // A new half rtt low sets that and the quarter rtt low.
 131   rtt_sample = rtt_sample.Subtract(QuicTime::Delta::FromMilliseconds(15));
 132   rtt_stats_.UpdateRtt(rtt_sample, QuicTime::Delta::Zero(), now);
 133   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.min_rtt());
 134   EXPECT_EQ(rtt_sample, RttStatsPeer::GetQuarterWindowRtt(&rtt_stats_));
 135   EXPECT_EQ(rtt_sample, RttStatsPeer::GetHalfWindowRtt(&rtt_stats_));
 136   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(70),
 137             rtt_stats_.recent_min_rtt());
 138
 139   // A new full window loss sets the recent_min_rtt, but not min_rtt.
 140   rtt_sample = QuicTime::Delta::FromMilliseconds(65);
 141   rtt_stats_.UpdateRtt(rtt_sample, QuicTime::Delta::Zero(), now);
 142   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.min_rtt());
 143   EXPECT_EQ(rtt_sample, RttStatsPeer::GetQuarterWindowRtt(&rtt_stats_));
 144   EXPECT_EQ(rtt_sample, RttStatsPeer::GetHalfWindowRtt(&rtt_stats_));
 145   EXPECT_EQ(rtt_sample, rtt_stats_.recent_min_rtt());
 146
 147   // A new all time low sets both the min_rtt and the recent_min_rtt.
 148   rtt_sample = QuicTime::Delta::FromMilliseconds(5);
 149   rtt_stats_.UpdateRtt(rtt_sample, QuicTime::Delta::Zero(), now);
 150
 151   EXPECT_EQ(rtt_sample, rtt_stats_.min_rtt());
 152   EXPECT_EQ(rtt_sample, RttStatsPeer::GetQuarterWindowRtt(&rtt_stats_));
 153   EXPECT_EQ(rtt_sample, RttStatsPeer::GetHalfWindowRtt(&rtt_stats_));
 154   EXPECT_EQ(rtt_sample, rtt_stats_.recent_min_rtt());
 155 }
 156
 157 TEST_F(RttStatsTest, ExpireSmoothedMetrics) {
 158   QuicTime::Delta initial_rtt = QuicTime::Delta::FromMilliseconds(10);
 159   rtt_stats_.UpdateRtt(initial_rtt, QuicTime::Delta::Zero(), QuicTime::Zero());
 160   EXPECT_EQ(initial_rtt, rtt_stats_.min_rtt());
 161   EXPECT_EQ(initial_rtt, rtt_stats_.recent_min_rtt());
 162   EXPECT_EQ(initial_rtt, rtt_stats_.SmoothedRtt());
 163
 164   EXPECT_EQ(initial_rtt.Multiply(0.5), rtt_stats_.mean_deviation());
 165
 166   // Update once with a 20ms RTT.
 167   QuicTime::Delta doubled_rtt = initial_rtt.Multiply(2);
 168   rtt_stats_.UpdateRtt(doubled_rtt, QuicTime::Delta::Zero(), QuicTime::Zero());
 169   EXPECT_EQ(initial_rtt.Multiply(1.125), rtt_stats_.SmoothedRtt());
 170
 171   // Expire the smoothed metrics, increasing smoothed rtt and mean deviation.
 172   rtt_stats_.ExpireSmoothedMetrics();
 173   EXPECT_EQ(doubled_rtt, rtt_stats_.SmoothedRtt());
 174   EXPECT_EQ(initial_rtt.Multiply(0.875), rtt_stats_.mean_deviation());
 175 }
 176
 177 }  // namespace test
 178 }  // namespace net