Implement a QUIC No PRR connection option, NPRR. Protected by FLAGS_quic_allow_no_prr

net/quic/congestion_control/tcp_cubic_sender_bytes_test.cc

 // Copyright (c) 2015 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 "net/quic/congestion_control/tcp_cubic_sender_bytes.h"
 
 #include <algorithm>
 #include <cstdint>
 #include <memory>
 
@@ skipping 762 matching lines @@
   EXPECT_TRUE(
       sender_->TimeUntilSend(QuicTime::Zero(), kDefaultTCPMSS).IsZero());
   EXPECT_TRUE(
       sender_->TimeUntilSend(QuicTime::Zero(), 2 * kDefaultTCPMSS).IsZero());
   EXPECT_TRUE(
       sender_->TimeUntilSend(QuicTime::Zero(), 3 * kDefaultTCPMSS).IsZero());
   EXPECT_FALSE(
       sender_->TimeUntilSend(QuicTime::Zero(), 4 * kDefaultTCPMSS).IsZero());
 }
 
+TEST_F(TcpCubicSenderBytesTest, NoPRR) {
+  ValueRestore<bool> old_flag(&FLAGS_quic_allow_noprr, true);
+  QuicTime::Delta rtt = QuicTime::Delta::FromMilliseconds(100);
+  sender_->rtt_stats_.UpdateRtt(rtt, QuicTime::Delta::Zero(), QuicTime::Zero());
+
+  sender_->SetNumEmulatedConnections(1);
+  // Verify that kCOPT: kNPRR allows all packets to be sent, even if only one
+  // ack has been received.
+  QuicTagVector options;
+  options.push_back(kNPRR);
+  QuicConfig config;
+  QuicConfigPeer::SetReceivedConnectionOptions(&config, options);
+  sender_->SetFromConfig(config, Perspective::IS_SERVER);
+  SendAvailableSendWindow();
+  LoseNPackets(9);
+  AckNPackets(1);
+
+  // We should now have fallen out of slow start with a reduced window.
+  EXPECT_EQ(kRenoBeta * kDefaultWindowTCP, sender_->GetCongestionWindow());
+  const QuicPacketCount window_in_packets =
+      kRenoBeta * kDefaultWindowTCP / kDefaultTCPMSS;
+  const QuicBandwidth expected_pacing_rate =
+      QuicBandwidth::FromBytesAndTimeDelta(kRenoBeta * kDefaultWindowTCP,
+                                           sender_->rtt_stats_.smoothed_rtt());
+  EXPECT_EQ(expected_pacing_rate, sender_->PacingRate());
+  EXPECT_EQ(window_in_packets,
+            static_cast<uint64_t>(SendAvailableSendWindow()));
+  EXPECT_EQ(expected_pacing_rate, sender_->PacingRate());
+}
+
 TEST_F(TcpCubicSenderBytesTest, ResetAfterConnectionMigration) {
   // Starts from slow start.
   sender_->SetNumEmulatedConnections(1);
   const int kNumberOfAcks = 10;
   for (int i = 0; i < kNumberOfAcks; ++i) {
     // Send our full send window.
     SendAvailableSendWindow();
     AckNPackets(2);
   }
   SendAvailableSendWindow();
@@ skipping 32 matching lines @@
     acked_packets.push_back(std::make_pair(i, 1350));
     sender->OnCongestionEvent(true, sender->GetCongestionWindow(),
                               acked_packets, missing_packets);
   }
   EXPECT_EQ(kDefaultMaxCongestionWindowPackets,
             sender->GetCongestionWindow() / kDefaultTCPMSS);
 }
 
 }  // namespace test
 }  // namespace net