src/net/quic/congestion_control/hybrid_slow_start_test.cc

   1 // Copyright (c) 2012 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 "base/logging.h"
   6 #include "base/memory/scoped_ptr.h"
   7 #include "net/quic/congestion_control/hybrid_slow_start.h"
   8 #include "net/quic/test_tools/mock_clock.h"
   9 #include "testing/gtest/include/gtest/gtest.h"
  10
  11 namespace net {
  12 namespace test {
  13
  14 class HybridSlowStartTest : public ::testing::Test {
  15  protected:
  16   HybridSlowStartTest()
  17      : one_ms_(QuicTime::Delta::FromMilliseconds(1)),
  18        rtt_(QuicTime::Delta::FromMilliseconds(60)) {
  19   }
  20   virtual void SetUp() {
  21     slowStart_.reset(new HybridSlowStart(&clock_));
  22   }
  23   const QuicTime::Delta one_ms_;
  24   const QuicTime::Delta rtt_;
  25   MockClock clock_;
  26   scoped_ptr<HybridSlowStart> slowStart_;
  27 };
  28
  29 TEST_F(HybridSlowStartTest, Simple) {
  30   QuicPacketSequenceNumber sequence_number = 1;
  31   QuicPacketSequenceNumber end_sequence_number = 3;
  32   slowStart_->Reset(end_sequence_number);
  33
  34   EXPECT_FALSE(slowStart_->EndOfRound(sequence_number++));
  35
  36   // Test duplicates.
  37   EXPECT_FALSE(slowStart_->EndOfRound(sequence_number));
  38
  39   EXPECT_FALSE(slowStart_->EndOfRound(sequence_number++));
  40   EXPECT_TRUE(slowStart_->EndOfRound(sequence_number++));
  41
  42   // Test without a new registered end_sequence_number;
  43   EXPECT_TRUE(slowStart_->EndOfRound(sequence_number++));
  44
  45   end_sequence_number = 20;
  46   slowStart_->Reset(end_sequence_number);
  47   while (sequence_number < end_sequence_number) {
  48     EXPECT_FALSE(slowStart_->EndOfRound(sequence_number++));
  49   }
  50   EXPECT_TRUE(slowStart_->EndOfRound(sequence_number++));
  51 }
  52
  53 TEST_F(HybridSlowStartTest, AckTrain) {
  54   // At a typical RTT 60 ms, assuming that the inter arrival is 1 ms,
  55   // we expect to be able to send a burst of 30 packet before we trigger the
  56   // ack train detection.
  57   const int kMaxLoopCount = 5;
  58   QuicPacketSequenceNumber sequence_number = 2;
  59   QuicPacketSequenceNumber end_sequence_number = 2;
  60   for (int burst = 0; burst < kMaxLoopCount; ++burst) {
  61     slowStart_->Reset(end_sequence_number);
  62     do {
  63       clock_.AdvanceTime(one_ms_);
  64       slowStart_->Update(rtt_, rtt_);
  65       EXPECT_FALSE(slowStart_->Exit());
  66     }  while (!slowStart_->EndOfRound(sequence_number++));
  67     end_sequence_number *= 2;  // Exponential growth.
  68   }
  69   slowStart_->Reset(end_sequence_number);
  70
  71   for (int n = 0; n < 29 && !slowStart_->EndOfRound(sequence_number++); ++n) {
  72     clock_.AdvanceTime(one_ms_);
  73     slowStart_->Update(rtt_, rtt_);
  74     EXPECT_FALSE(slowStart_->Exit());
  75   }
  76   clock_.AdvanceTime(one_ms_);
  77   slowStart_->Update(rtt_, rtt_);
  78   EXPECT_TRUE(slowStart_->Exit());
  79 }
  80
  81 TEST_F(HybridSlowStartTest, Delay) {
  82   // We expect to detect the increase at +1/16 of the RTT; hence at a typical
  83   // RTT of 60ms the detection will happen at 63.75 ms.
  84   const int kHybridStartMinSamples = 8;  // Number of acks required to trigger.
  85
  86   QuicPacketSequenceNumber end_sequence_number = 1;
  87   slowStart_->Reset(end_sequence_number++);
  88
  89   // Will not trigger since our lowest RTT in our burst is the same as the long
  90   // term RTT provided.
  91   for (int n = 0; n < kHybridStartMinSamples; ++n) {
  92     slowStart_->Update(rtt_.Add(QuicTime::Delta::FromMilliseconds(n)), rtt_);
  93     EXPECT_FALSE(slowStart_->Exit());
  94   }
  95   slowStart_->Reset(end_sequence_number++);
  96   for (int n = 1; n < kHybridStartMinSamples; ++n) {
  97     slowStart_->Update(rtt_.Add(QuicTime::Delta::FromMilliseconds(n + 4)),
  98                        rtt_);
  99     EXPECT_FALSE(slowStart_->Exit());
 100   }
 101   // Expect to trigger since all packets in this burst was above the long term
 102   // RTT provided.
 103   slowStart_->Update(rtt_.Add(QuicTime::Delta::FromMilliseconds(4)), rtt_);
 104   EXPECT_TRUE(slowStart_->Exit());
 105 }
 106
 107 }  // namespace test
 108 }  // namespace net