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, DefaultsBeforeUpdate) {
  30   EXPECT_LT(0u, rtt_stats_.initial_rtt_us());
  31   EXPECT_EQ(QuicTime::Delta::FromMicroseconds(rtt_stats_.initial_rtt_us()),
  32             rtt_stats_.MinRtt());
  33   EXPECT_EQ(QuicTime::Delta::FromMicroseconds(rtt_stats_.initial_rtt_us()),
  34             rtt_stats_.SmoothedRtt());
  35 }
  36
  37 TEST_F(RttStatsTest, MinRtt) {
  38   rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(200),
  39                        QuicTime::Delta::Zero(),
  40                        QuicTime::Zero());
  41   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(200), rtt_stats_.MinRtt());
  42   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(200),
  43             rtt_stats_.recent_min_rtt());
  44   rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(10),
  45                        QuicTime::Delta::Zero(),
  46                        QuicTime::Zero().Add(
  47                            QuicTime::Delta::FromMilliseconds(10)));
  48   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.MinRtt());
  49   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.recent_min_rtt());
  50   rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(50),
  51                        QuicTime::Delta::Zero(),
  52                        QuicTime::Zero().Add(
  53                            QuicTime::Delta::FromMilliseconds(20)));
  54   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.MinRtt());
  55   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.recent_min_rtt());
  56   rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(50),
  57                        QuicTime::Delta::Zero(),
  58                        QuicTime::Zero().Add(
  59                            QuicTime::Delta::FromMilliseconds(30)));
  60   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.MinRtt());
  61   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.recent_min_rtt());
  62   rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(50),
  63                        QuicTime::Delta::Zero(),
  64                        QuicTime::Zero().Add(
  65                            QuicTime::Delta::FromMilliseconds(40)));
  66   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.MinRtt());
  67   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.recent_min_rtt());
  68 }
  69
  70 TEST_F(RttStatsTest, RecentMinRtt) {
  71   rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(10),
  72                        QuicTime::Delta::Zero(),
  73                        QuicTime::Zero());
  74   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.MinRtt());
  75   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.recent_min_rtt());
  76
  77   rtt_stats_.SampleNewRecentMinRtt(4);
  78   for (int i = 0; i < 3; ++i) {
  79     rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(50),
  80                        QuicTime::Delta::Zero(),
  81                        QuicTime::Zero());
  82     EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.MinRtt());
  83     EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10),
  84               rtt_stats_.recent_min_rtt());
  85   }
  86   rtt_stats_.UpdateRtt(QuicTime::Delta::FromMilliseconds(50),
  87                         QuicTime::Delta::Zero(),
  88                         QuicTime::Zero());
  89   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.MinRtt());
  90   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(50), rtt_stats_.recent_min_rtt());
  91 }
  92
  93 TEST_F(RttStatsTest, WindowedRecentMinRtt) {
  94   // Set the window to 99ms, so 25ms is more than a quarter rtt.
  95   rtt_stats_.set_recent_min_rtt_window(QuicTime::Delta::FromMilliseconds(99));
  96
  97   QuicTime now = QuicTime::Zero();
  98   QuicTime::Delta rtt_sample = QuicTime::Delta::FromMilliseconds(10);
  99   rtt_stats_.UpdateRtt(rtt_sample, QuicTime::Delta::Zero(), now);
 100   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.MinRtt());
 101   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.recent_min_rtt());
 102
 103   // Gradually increase the rtt samples and ensure the recent_min_rtt starts
 104   // rising.
 105   for (int i = 0; i < 8; ++i) {
 106     now = now.Add(QuicTime::Delta::FromMilliseconds(25));
 107     rtt_sample = rtt_sample.Add(QuicTime::Delta::FromMilliseconds(10));
 108     rtt_stats_.UpdateRtt(rtt_sample, QuicTime::Delta::Zero(), now);
 109     EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.MinRtt());
 110     EXPECT_EQ(rtt_sample, RttStatsPeer::GetQuarterWindowRtt(&rtt_stats_));
 111     EXPECT_EQ(rtt_sample.Subtract(QuicTime::Delta::FromMilliseconds(10)),
 112               RttStatsPeer::GetHalfWindowRtt(&rtt_stats_));
 113     if (i < 3) {
 114       EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10),
 115                 rtt_stats_.recent_min_rtt());
 116     } else if (i < 5) {
 117       EXPECT_EQ(QuicTime::Delta::FromMilliseconds(30),
 118                 rtt_stats_.recent_min_rtt());
 119     } else if (i < 7) {
 120       EXPECT_EQ(QuicTime::Delta::FromMilliseconds(50),
 121                 rtt_stats_.recent_min_rtt());
 122     } else {
 123       EXPECT_EQ(QuicTime::Delta::FromMilliseconds(70),
 124                 rtt_stats_.recent_min_rtt());
 125     }
 126   }
 127
 128   // A new quarter rtt low sets that, but nothing else.
 129   rtt_sample = rtt_sample.Subtract(QuicTime::Delta::FromMilliseconds(5));
 130   rtt_stats_.UpdateRtt(rtt_sample, QuicTime::Delta::Zero(), now);
 131   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.MinRtt());
 132   EXPECT_EQ(rtt_sample, RttStatsPeer::GetQuarterWindowRtt(&rtt_stats_));
 133   EXPECT_EQ(rtt_sample.Subtract(QuicTime::Delta::FromMilliseconds(5)),
 134             RttStatsPeer::GetHalfWindowRtt(&rtt_stats_));
 135   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(70),
 136             rtt_stats_.recent_min_rtt());
 137
 138   // A new half rtt low sets that and the quarter rtt low.
 139   rtt_sample = rtt_sample.Subtract(QuicTime::Delta::FromMilliseconds(15));
 140   rtt_stats_.UpdateRtt(rtt_sample, QuicTime::Delta::Zero(), now);
 141   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.MinRtt());
 142   EXPECT_EQ(rtt_sample, RttStatsPeer::GetQuarterWindowRtt(&rtt_stats_));
 143   EXPECT_EQ(rtt_sample, RttStatsPeer::GetHalfWindowRtt(&rtt_stats_));
 144   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(70),
 145             rtt_stats_.recent_min_rtt());
 146
 147   // A new full window loss sets the recent_min_rtt, but not min_rtt.
 148   rtt_sample = QuicTime::Delta::FromMilliseconds(65);
 149   rtt_stats_.UpdateRtt(rtt_sample, QuicTime::Delta::Zero(), now);
 150   EXPECT_EQ(QuicTime::Delta::FromMilliseconds(10), rtt_stats_.MinRtt());
 151   EXPECT_EQ(rtt_sample, RttStatsPeer::GetQuarterWindowRtt(&rtt_stats_));
 152   EXPECT_EQ(rtt_sample, RttStatsPeer::GetHalfWindowRtt(&rtt_stats_));
 153   EXPECT_EQ(rtt_sample, rtt_stats_.recent_min_rtt());
 154
 155   // A new all time low sets both the min_rtt and the recent_min_rtt.
 156   rtt_sample = QuicTime::Delta::FromMilliseconds(5);
 157   rtt_stats_.UpdateRtt(rtt_sample, QuicTime::Delta::Zero(), now);
 158
 159   EXPECT_EQ(rtt_sample, rtt_stats_.MinRtt());
 160   EXPECT_EQ(rtt_sample, RttStatsPeer::GetQuarterWindowRtt(&rtt_stats_));
 161   EXPECT_EQ(rtt_sample, RttStatsPeer::GetHalfWindowRtt(&rtt_stats_));
 162   EXPECT_EQ(rtt_sample, rtt_stats_.recent_min_rtt());
 163 }
 164
 165 TEST_F(RttStatsTest, ExpireSmoothedMetrics) {
 166   QuicTime::Delta initial_rtt = QuicTime::Delta::FromMilliseconds(10);
 167   rtt_stats_.UpdateRtt(initial_rtt, QuicTime::Delta::Zero(), QuicTime::Zero());
 168   EXPECT_EQ(initial_rtt, rtt_stats_.MinRtt());
 169   EXPECT_EQ(initial_rtt, rtt_stats_.recent_min_rtt());
 170   EXPECT_EQ(initial_rtt, rtt_stats_.SmoothedRtt());
 171
 172   EXPECT_EQ(initial_rtt.Multiply(0.5), rtt_stats_.mean_deviation());
 173
 174   // Update once with a 20ms RTT.
 175   QuicTime::Delta doubled_rtt = initial_rtt.Multiply(2);
 176   rtt_stats_.UpdateRtt(doubled_rtt, QuicTime::Delta::Zero(), QuicTime::Zero());
 177   EXPECT_EQ(initial_rtt.Multiply(1.125), rtt_stats_.SmoothedRtt());
 178
 179   // Expire the smoothed metrics, increasing smoothed rtt and mean deviation.
 180   rtt_stats_.ExpireSmoothedMetrics();
 181   EXPECT_EQ(doubled_rtt, rtt_stats_.SmoothedRtt());
 182   EXPECT_EQ(initial_rtt.Multiply(0.875), rtt_stats_.mean_deviation());
 183
 184   // Now go back down to 5ms and expire the smoothed metrics, and ensure the
 185   // mean deviation increases to 15ms.
 186   QuicTime::Delta half_rtt = initial_rtt.Multiply(0.5);
 187   rtt_stats_.UpdateRtt(half_rtt, QuicTime::Delta::Zero(), QuicTime::Zero());
 188   EXPECT_GT(doubled_rtt, rtt_stats_.SmoothedRtt());
 189   EXPECT_LT(initial_rtt, rtt_stats_.mean_deviation());
 190 }
 191
 192 }  // namespace test
 193 }  // namespace net