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| 1 // Copyright (c) 2014 The Chromium Authors. All rights reserved. | 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 | 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/core/congestion_control/prr_sender.h" | 5 #include "net/quic/core/congestion_control/prr_sender.h" |
| 6 | 6 |
| 7 #include "net/quic/core/quic_packets.h" | 7 #include "net/quic/core/quic_packets.h" |
| 8 | 8 |
| 9 namespace net { | 9 namespace net { |
| 10 | 10 |
| 11 namespace { | 11 namespace { |
| 12 // Constant based on TCP defaults. | 12 // Constant based on TCP defaults. |
| 13 const QuicByteCount kMaxSegmentSize = kDefaultTCPMSS; | 13 const QuicByteCount kMaxQuicSegmentSize = kDefaultTCPMSS; |
| 14 } // namespace | 14 } // namespace |
| 15 | 15 |
| 16 PrrSender::PrrSender() | 16 PrrSender::PrrSender() |
| 17 : bytes_sent_since_loss_(0), | 17 : bytes_sent_since_loss_(0), |
| 18 bytes_delivered_since_loss_(0), | 18 bytes_delivered_since_loss_(0), |
| 19 ack_count_since_loss_(0), | 19 ack_count_since_loss_(0), |
| 20 bytes_in_flight_before_loss_(0) {} | 20 bytes_in_flight_before_loss_(0) {} |
| 21 | 21 |
| 22 void PrrSender::OnPacketSent(QuicByteCount sent_bytes) { | 22 void PrrSender::OnPacketSent(QuicByteCount sent_bytes) { |
| 23 bytes_sent_since_loss_ += sent_bytes; | 23 bytes_sent_since_loss_ += sent_bytes; |
| (...skipping 12 matching lines...) Expand all Loading... |
| 36 } | 36 } |
| 37 | 37 |
| 38 QuicTime::Delta PrrSender::TimeUntilSend( | 38 QuicTime::Delta PrrSender::TimeUntilSend( |
| 39 QuicByteCount congestion_window, | 39 QuicByteCount congestion_window, |
| 40 QuicByteCount bytes_in_flight, | 40 QuicByteCount bytes_in_flight, |
| 41 QuicByteCount slowstart_threshold) const { | 41 QuicByteCount slowstart_threshold) const { |
| 42 // if (FLAGS_?? && bytes_in_flight < congestion_window) { | 42 // if (FLAGS_?? && bytes_in_flight < congestion_window) { |
| 43 // return QuicTime::Delta::Zero(); | 43 // return QuicTime::Delta::Zero(); |
| 44 // } | 44 // } |
| 45 // Return QuicTime::Zero In order to ensure limited transmit always works. | 45 // Return QuicTime::Zero In order to ensure limited transmit always works. |
| 46 if (bytes_sent_since_loss_ == 0 || bytes_in_flight < kMaxSegmentSize) { | 46 if (bytes_sent_since_loss_ == 0 || bytes_in_flight < kMaxQuicSegmentSize) { |
| 47 return QuicTime::Delta::Zero(); | 47 return QuicTime::Delta::Zero(); |
| 48 } | 48 } |
| 49 if (congestion_window > bytes_in_flight) { | 49 if (congestion_window > bytes_in_flight) { |
| 50 // During PRR-SSRB, limit outgoing packets to 1 extra MSS per ack, instead | 50 // During PRR-SSRB, limit outgoing packets to 1 extra MSS per ack, instead |
| 51 // of sending the entire available window. This prevents burst retransmits | 51 // of sending the entire available window. This prevents burst retransmits |
| 52 // when more packets are lost than the CWND reduction. | 52 // when more packets are lost than the CWND reduction. |
| 53 // limit = MAX(prr_delivered - prr_out, DeliveredData) + MSS | 53 // limit = MAX(prr_delivered - prr_out, DeliveredData) + MSS |
| 54 if (bytes_delivered_since_loss_ + ack_count_since_loss_ * kMaxSegmentSize <= | 54 if (bytes_delivered_since_loss_ + ack_count_since_loss_ * kMaxQuicSegmentSiz
e <= |
| 55 bytes_sent_since_loss_) { | 55 bytes_sent_since_loss_) { |
| 56 return QuicTime::Delta::Infinite(); | 56 return QuicTime::Delta::Infinite(); |
| 57 } | 57 } |
| 58 return QuicTime::Delta::Zero(); | 58 return QuicTime::Delta::Zero(); |
| 59 } | 59 } |
| 60 // Implement Proportional Rate Reduction (RFC6937). | 60 // Implement Proportional Rate Reduction (RFC6937). |
| 61 // Checks a simplified version of the PRR formula that doesn't use division: | 61 // Checks a simplified version of the PRR formula that doesn't use division: |
| 62 // AvailableSendWindow = | 62 // AvailableSendWindow = |
| 63 // CEIL(prr_delivered * ssthresh / BytesInFlightAtLoss) - prr_sent | 63 // CEIL(prr_delivered * ssthresh / BytesInFlightAtLoss) - prr_sent |
| 64 if (bytes_delivered_since_loss_ * slowstart_threshold > | 64 if (bytes_delivered_since_loss_ * slowstart_threshold > |
| 65 bytes_sent_since_loss_ * bytes_in_flight_before_loss_) { | 65 bytes_sent_since_loss_ * bytes_in_flight_before_loss_) { |
| 66 return QuicTime::Delta::Zero(); | 66 return QuicTime::Delta::Zero(); |
| 67 } | 67 } |
| 68 return QuicTime::Delta::Infinite(); | 68 return QuicTime::Delta::Infinite(); |
| 69 } | 69 } |
| 70 | 70 |
| 71 } // namespace net | 71 } // namespace net |
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