| // Copyright (c) 2014 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "quiche/quic/core/congestion_control/prr_sender.h" |
| |
| #include <algorithm> |
| |
| #include "quiche/quic/core/crypto/crypto_protocol.h" |
| #include "quiche/quic/core/quic_constants.h" |
| #include "quiche/quic/platform/api/quic_test.h" |
| |
| namespace quic { |
| namespace test { |
| |
| namespace { |
| // Constant based on TCP defaults. |
| const QuicByteCount kMaxSegmentSize = kDefaultTCPMSS; |
| } // namespace |
| |
| class PrrSenderTest : public QuicTest {}; |
| |
| TEST_F(PrrSenderTest, SingleLossResultsInSendOnEveryOtherAck) { |
| PrrSender prr; |
| QuicPacketCount num_packets_in_flight = 50; |
| QuicByteCount bytes_in_flight = num_packets_in_flight * kMaxSegmentSize; |
| const QuicPacketCount ssthresh_after_loss = num_packets_in_flight / 2; |
| const QuicByteCount congestion_window = ssthresh_after_loss * kMaxSegmentSize; |
| |
| prr.OnPacketLost(bytes_in_flight); |
| // Ack a packet. PRR allows one packet to leave immediately. |
| prr.OnPacketAcked(kMaxSegmentSize); |
| bytes_in_flight -= kMaxSegmentSize; |
| EXPECT_TRUE(prr.CanSend(congestion_window, bytes_in_flight, |
| ssthresh_after_loss * kMaxSegmentSize)); |
| // Send retransmission. |
| prr.OnPacketSent(kMaxSegmentSize); |
| // PRR shouldn't allow sending any more packets. |
| EXPECT_FALSE(prr.CanSend(congestion_window, bytes_in_flight, |
| ssthresh_after_loss * kMaxSegmentSize)); |
| |
| // One packet is lost, and one ack was consumed above. PRR now paces |
| // transmissions through the remaining 48 acks. PRR will alternatively |
| // disallow and allow a packet to be sent in response to an ack. |
| for (uint64_t i = 0; i < ssthresh_after_loss - 1; ++i) { |
| // Ack a packet. PRR shouldn't allow sending a packet in response. |
| prr.OnPacketAcked(kMaxSegmentSize); |
| bytes_in_flight -= kMaxSegmentSize; |
| EXPECT_FALSE(prr.CanSend(congestion_window, bytes_in_flight, |
| ssthresh_after_loss * kMaxSegmentSize)); |
| // Ack another packet. PRR should now allow sending a packet in response. |
| prr.OnPacketAcked(kMaxSegmentSize); |
| bytes_in_flight -= kMaxSegmentSize; |
| EXPECT_TRUE(prr.CanSend(congestion_window, bytes_in_flight, |
| ssthresh_after_loss * kMaxSegmentSize)); |
| // Send a packet in response. |
| prr.OnPacketSent(kMaxSegmentSize); |
| bytes_in_flight += kMaxSegmentSize; |
| } |
| |
| // Since bytes_in_flight is now equal to congestion_window, PRR now maintains |
| // packet conservation, allowing one packet to be sent in response to an ack. |
| EXPECT_EQ(congestion_window, bytes_in_flight); |
| for (int i = 0; i < 10; ++i) { |
| // Ack a packet. |
| prr.OnPacketAcked(kMaxSegmentSize); |
| bytes_in_flight -= kMaxSegmentSize; |
| EXPECT_TRUE(prr.CanSend(congestion_window, bytes_in_flight, |
| ssthresh_after_loss * kMaxSegmentSize)); |
| // Send a packet in response, since PRR allows it. |
| prr.OnPacketSent(kMaxSegmentSize); |
| bytes_in_flight += kMaxSegmentSize; |
| |
| // Since bytes_in_flight is equal to the congestion_window, |
| // PRR disallows sending. |
| EXPECT_EQ(congestion_window, bytes_in_flight); |
| EXPECT_FALSE(prr.CanSend(congestion_window, bytes_in_flight, |
| ssthresh_after_loss * kMaxSegmentSize)); |
| } |
| } |
| |
| TEST_F(PrrSenderTest, BurstLossResultsInSlowStart) { |
| PrrSender prr; |
| QuicByteCount bytes_in_flight = 20 * kMaxSegmentSize; |
| const QuicPacketCount num_packets_lost = 13; |
| const QuicPacketCount ssthresh_after_loss = 10; |
| const QuicByteCount congestion_window = ssthresh_after_loss * kMaxSegmentSize; |
| |
| // Lose 13 packets. |
| bytes_in_flight -= num_packets_lost * kMaxSegmentSize; |
| prr.OnPacketLost(bytes_in_flight); |
| |
| // PRR-SSRB will allow the following 3 acks to send up to 2 packets. |
| for (int i = 0; i < 3; ++i) { |
| prr.OnPacketAcked(kMaxSegmentSize); |
| bytes_in_flight -= kMaxSegmentSize; |
| // PRR-SSRB should allow two packets to be sent. |
| for (int j = 0; j < 2; ++j) { |
| EXPECT_TRUE(prr.CanSend(congestion_window, bytes_in_flight, |
| ssthresh_after_loss * kMaxSegmentSize)); |
| // Send a packet in response. |
| prr.OnPacketSent(kMaxSegmentSize); |
| bytes_in_flight += kMaxSegmentSize; |
| } |
| // PRR should allow no more than 2 packets in response to an ack. |
| EXPECT_FALSE(prr.CanSend(congestion_window, bytes_in_flight, |
| ssthresh_after_loss * kMaxSegmentSize)); |
| } |
| |
| // Out of SSRB mode, PRR allows one send in response to each ack. |
| for (int i = 0; i < 10; ++i) { |
| prr.OnPacketAcked(kMaxSegmentSize); |
| bytes_in_flight -= kMaxSegmentSize; |
| EXPECT_TRUE(prr.CanSend(congestion_window, bytes_in_flight, |
| ssthresh_after_loss * kMaxSegmentSize)); |
| // Send a packet in response. |
| prr.OnPacketSent(kMaxSegmentSize); |
| bytes_in_flight += kMaxSegmentSize; |
| } |
| } |
| |
| } // namespace test |
| } // namespace quic |