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1 // Copyright 2014 The Chromium Authors. All rights reserved. | 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 | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #include "net/quic/congestion_control/time_loss_algorithm.h" | 5 #include "net/quic/congestion_control/time_loss_algorithm.h" |
6 | 6 |
7 #include "net/quic/congestion_control/rtt_stats.h" | 7 #include "net/quic/congestion_control/rtt_stats.h" |
8 #include "net/quic/quic_protocol.h" | 8 #include "net/quic/quic_protocol.h" |
9 | 9 |
10 namespace net { | 10 namespace net { |
11 namespace { | 11 namespace { |
12 | 12 |
13 // The minimum delay before a packet will be considered lost, | 13 // The minimum delay before a packet will be considered lost, |
14 // regardless of SRTT. Half of the minimum TLP, since the loss algorithm only | 14 // regardless of SRTT. Half of the minimum TLP, since the loss algorithm only |
15 // triggers when a nack has been receieved for the packet. | 15 // triggers when a nack has been receieved for the packet. |
16 static const size_t kMinLossDelayMs = 5; | 16 static const size_t kMinLossDelayMs = 5; |
17 | 17 |
18 // How many RTTs the algorithm waits before determining a packet is lost. | 18 // How many RTTs the algorithm waits before determining a packet is lost. |
19 static const double kLossDelayMultiplier = 1.25; | 19 static const double kLossDelayMultiplier = 1.25; |
20 | 20 |
21 } // namespace | 21 } // namespace |
22 | 22 |
23 TimeLossAlgorithm::TimeLossAlgorithm() | 23 TimeLossAlgorithm::TimeLossAlgorithm() |
24 : loss_detection_timeout_(QuicTime::Zero()) { } | 24 : loss_detection_timeout_(QuicTime::Zero()) { |
| 25 } |
25 | 26 |
26 LossDetectionType TimeLossAlgorithm::GetLossDetectionType() const { | 27 LossDetectionType TimeLossAlgorithm::GetLossDetectionType() const { |
27 return kTime; | 28 return kTime; |
28 } | 29 } |
29 | 30 |
30 SequenceNumberSet TimeLossAlgorithm::DetectLostPackets( | 31 SequenceNumberSet TimeLossAlgorithm::DetectLostPackets( |
31 const QuicUnackedPacketMap& unacked_packets, | 32 const QuicUnackedPacketMap& unacked_packets, |
32 const QuicTime& time, | 33 const QuicTime& time, |
33 QuicPacketSequenceNumber largest_observed, | 34 QuicPacketSequenceNumber largest_observed, |
34 const RttStats& rtt_stats) { | 35 const RttStats& rtt_stats) { |
35 SequenceNumberSet lost_packets; | 36 SequenceNumberSet lost_packets; |
36 loss_detection_timeout_ = QuicTime::Zero(); | 37 loss_detection_timeout_ = QuicTime::Zero(); |
37 QuicTime::Delta loss_delay = QuicTime::Delta::Max( | 38 QuicTime::Delta loss_delay = QuicTime::Delta::Max( |
38 QuicTime::Delta::FromMilliseconds(kMinLossDelayMs), | 39 QuicTime::Delta::FromMilliseconds(kMinLossDelayMs), |
39 QuicTime::Delta::Max(rtt_stats.SmoothedRtt(), rtt_stats.latest_rtt()) | 40 QuicTime::Delta::Max(rtt_stats.SmoothedRtt(), rtt_stats.latest_rtt()) |
40 .Multiply(kLossDelayMultiplier)); | 41 .Multiply(kLossDelayMultiplier)); |
41 | 42 |
42 for (QuicUnackedPacketMap::const_iterator it = unacked_packets.begin(); | 43 for (QuicUnackedPacketMap::const_iterator it = unacked_packets.begin(); |
43 it != unacked_packets.end() && it->first <= largest_observed; ++it) { | 44 it != unacked_packets.end() && it->first <= largest_observed; |
| 45 ++it) { |
44 if (!it->second.pending) { | 46 if (!it->second.pending) { |
45 continue; | 47 continue; |
46 } | 48 } |
47 LOG_IF(DFATAL, it->second.nack_count == 0) | 49 LOG_IF(DFATAL, it->second.nack_count == 0) |
48 << "All packets less than largest observed should have been nacked."; | 50 << "All packets less than largest observed should have been nacked."; |
49 | 51 |
50 // Packets are sent in order, so break when we haven't waited long enough | 52 // Packets are sent in order, so break when we haven't waited long enough |
51 // to lose any more packets and leave the loss_time_ set for the timeout. | 53 // to lose any more packets and leave the loss_time_ set for the timeout. |
52 QuicTime when_lost = it->second.sent_time.Add(loss_delay); | 54 QuicTime when_lost = it->second.sent_time.Add(loss_delay); |
53 if (time < when_lost) { | 55 if (time < when_lost) { |
54 loss_detection_timeout_ = when_lost; | 56 loss_detection_timeout_ = when_lost; |
55 break; | 57 break; |
56 } | 58 } |
57 lost_packets.insert(it->first); | 59 lost_packets.insert(it->first); |
58 } | 60 } |
59 | 61 |
60 return lost_packets; | 62 return lost_packets; |
61 } | 63 } |
62 | 64 |
63 // loss_time_ is updated in DetectLostPackets, which must be called every time | 65 // loss_time_ is updated in DetectLostPackets, which must be called every time |
64 // an ack is received or the timeout expires. | 66 // an ack is received or the timeout expires. |
65 QuicTime TimeLossAlgorithm::GetLossTimeout() const { | 67 QuicTime TimeLossAlgorithm::GetLossTimeout() const { |
66 return loss_detection_timeout_; | 68 return loss_detection_timeout_; |
67 } | 69 } |
68 | 70 |
69 } // namespace net | 71 } // namespace net |
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