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| 1 // Copyright (c) 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/prr_sender.h" | |
| 6 | |
| 7 #include <algorithm> | |
| 8 | |
| 9 #include "base/logging.h" | |
| 10 #include "net/quic/crypto/crypto_protocol.h" | |
| 11 #include "net/quic/quic_bandwidth.h" | |
| 12 #include "net/quic/quic_protocol.h" | |
| 13 #include "testing/gtest/include/gtest/gtest.h" | |
| 14 | |
| 15 namespace net { | |
| 16 namespace test { | |
| 17 | |
| 18 namespace { | |
| 19 // Constant based on TCP defaults. | |
| 20 const QuicByteCount kMaxSegmentSize = kDefaultTCPMSS; | |
| 21 } // namespace | |
| 22 | |
| 23 class PrrSenderTest : public ::testing::Test {}; | |
| 24 | |
| 25 TEST_F(PrrSenderTest, SingleLossResultsInSendOnEveryOtherAck) { | |
| 26 PrrSender prr; | |
| 27 QuicPacketCount num_packets_in_flight = 50; | |
| 28 QuicByteCount bytes_in_flight = num_packets_in_flight * kMaxSegmentSize; | |
| 29 const QuicPacketCount ssthresh_after_loss = num_packets_in_flight / 2; | |
| 30 const QuicByteCount congestion_window = ssthresh_after_loss * kMaxSegmentSize; | |
| 31 | |
| 32 prr.OnPacketLost(bytes_in_flight); | |
| 33 // Ack a packet. PRR allows one packet to leave immediately. | |
| 34 prr.OnPacketAcked(kMaxSegmentSize); | |
| 35 bytes_in_flight -= kMaxSegmentSize; | |
| 36 EXPECT_EQ(QuicTime::Delta::Zero(), | |
| 37 prr.TimeUntilSend(congestion_window, bytes_in_flight, | |
| 38 ssthresh_after_loss)); | |
| 39 // Send retransmission. | |
| 40 prr.OnPacketSent(kMaxSegmentSize); | |
| 41 // PRR shouldn't allow sending any more packets. | |
| 42 EXPECT_EQ(QuicTime::Delta::Infinite(), | |
| 43 prr.TimeUntilSend(congestion_window, bytes_in_flight, | |
| 44 ssthresh_after_loss)); | |
| 45 | |
| 46 // One packet is lost, and one ack was consumed above. PRR now paces | |
| 47 // transmissions through the remaining 48 acks. PRR will alternatively | |
| 48 // disallow and allow a packet to be sent in response to an ack. | |
| 49 for (uint64 i = 0; i < ssthresh_after_loss - 1; ++i) { | |
| 50 // Ack a packet. PRR shouldn't allow sending a packet in response. | |
| 51 prr.OnPacketAcked(kMaxSegmentSize); | |
| 52 bytes_in_flight -= kMaxSegmentSize; | |
| 53 EXPECT_EQ(QuicTime::Delta::Infinite(), | |
| 54 prr.TimeUntilSend(congestion_window, bytes_in_flight, | |
| 55 ssthresh_after_loss)); | |
| 56 // Ack another packet. PRR should now allow sending a packet in response. | |
| 57 prr.OnPacketAcked(kMaxSegmentSize); | |
| 58 bytes_in_flight -= kMaxSegmentSize; | |
| 59 EXPECT_EQ(QuicTime::Delta::Zero(), | |
| 60 prr.TimeUntilSend(congestion_window, bytes_in_flight, | |
| 61 ssthresh_after_loss)); | |
| 62 // Send a packet in response. | |
| 63 prr.OnPacketSent(kMaxSegmentSize); | |
| 64 bytes_in_flight += kMaxSegmentSize; | |
| 65 } | |
| 66 | |
| 67 // Since bytes_in_flight is now equal to congestion_window, PRR now maintains | |
| 68 // packet conservation, allowing one packet to be sent in response to an ack. | |
| 69 EXPECT_EQ(congestion_window, bytes_in_flight); | |
| 70 for (int i = 0; i < 10; ++i) { | |
| 71 // Ack a packet. | |
| 72 prr.OnPacketAcked(kMaxSegmentSize); | |
| 73 bytes_in_flight -= kMaxSegmentSize; | |
| 74 EXPECT_EQ(QuicTime::Delta::Zero(), | |
| 75 prr.TimeUntilSend(congestion_window, bytes_in_flight, | |
| 76 ssthresh_after_loss)); | |
| 77 // Send a packet in response, since PRR allows it. | |
| 78 prr.OnPacketSent(kMaxSegmentSize); | |
| 79 bytes_in_flight += kMaxSegmentSize; | |
| 80 | |
| 81 // Since bytes_in_flight is equal to the congestion_window, | |
| 82 // PRR disallows sending. | |
| 83 EXPECT_EQ(congestion_window, bytes_in_flight); | |
| 84 EXPECT_EQ(QuicTime::Delta::Infinite(), | |
| 85 prr.TimeUntilSend(congestion_window, bytes_in_flight, | |
| 86 ssthresh_after_loss)); | |
| 87 } | |
| 88 } | |
| 89 | |
| 90 TEST_F(PrrSenderTest, BurstLossResultsInSlowStart) { | |
| 91 PrrSender prr; | |
| 92 QuicByteCount bytes_in_flight = 20 * kMaxSegmentSize; | |
| 93 const QuicPacketCount num_packets_lost = 13; | |
| 94 const QuicPacketCount ssthresh_after_loss = 10; | |
| 95 const QuicByteCount congestion_window = ssthresh_after_loss * kMaxSegmentSize; | |
| 96 | |
| 97 // Lose 13 packets. | |
| 98 bytes_in_flight -= num_packets_lost * kMaxSegmentSize; | |
| 99 prr.OnPacketLost(bytes_in_flight); | |
| 100 | |
| 101 // PRR-SSRB will allow the following 3 acks to send up to 2 packets. | |
| 102 for (int i = 0; i < 3; ++i) { | |
| 103 prr.OnPacketAcked(kMaxSegmentSize); | |
| 104 bytes_in_flight -= kMaxSegmentSize; | |
| 105 // PRR-SSRB should allow two packets to be sent. | |
| 106 for (int j = 0; j < 2; ++j) { | |
| 107 EXPECT_EQ(QuicTime::Delta::Zero(), | |
| 108 prr.TimeUntilSend(congestion_window, bytes_in_flight, | |
| 109 ssthresh_after_loss)); | |
| 110 // Send a packet in response. | |
| 111 prr.OnPacketSent(kMaxSegmentSize); | |
| 112 bytes_in_flight += kMaxSegmentSize; | |
| 113 } | |
| 114 // PRR should allow no more than 2 packets in response to an ack. | |
| 115 EXPECT_EQ(QuicTime::Delta::Infinite(), | |
| 116 prr.TimeUntilSend(congestion_window, bytes_in_flight, | |
| 117 ssthresh_after_loss)); | |
| 118 } | |
| 119 | |
| 120 // Out of SSRB mode, PRR allows one send in response to each ack. | |
| 121 for (int i = 0; i < 10; ++i) { | |
| 122 prr.OnPacketAcked(kMaxSegmentSize); | |
| 123 bytes_in_flight -= kMaxSegmentSize; | |
| 124 EXPECT_EQ(QuicTime::Delta::Zero(), | |
| 125 prr.TimeUntilSend(congestion_window, bytes_in_flight, | |
| 126 ssthresh_after_loss)); | |
| 127 // Send a packet in response. | |
| 128 prr.OnPacketSent(kMaxSegmentSize); | |
| 129 bytes_in_flight += kMaxSegmentSize; | |
| 130 } | |
| 131 } | |
| 132 | |
| 133 } // namespace test | |
| 134 } // namespace net | |
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