Change QUIC's pacing sender to send at 1.25x the estimated bandwidth

net/quic/congestion_control/pacing_sender_test.cc

 // Copyright (c) 2013 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/pacing_sender.h"
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "net/quic/quic_protocol.h"
 #include "net/quic/test_tools/mock_clock.h"
@@ skipping 115 matching lines @@
                                              HAS_RETRANSMITTABLE_DATA))
         .WillOnce(Return(zero_time_));
     EXPECT_EQ(zero_time_,
               pacing_sender_->TimeUntilSend(clock_.Now(),
                                             kBytesInFlight,
                                             HAS_RETRANSMITTABLE_DATA));
   }
 }
 
 TEST_F(PacingSenderTest, VariousSending) {
+  // Start the test in slow start.
+  EXPECT_CALL(*mock_sender_, InSlowStart()).WillRepeatedly(Return(true));
+
   // Configure bandwith of 1 packet per 2 ms, for which the pacing rate
   // will be 1 packet per 1 ms.
   EXPECT_CALL(*mock_sender_, BandwidthEstimate())
       .WillRepeatedly(Return(QuicBandwidth::FromBytesAndTimeDelta(
           kMaxPacketSize, QuicTime::Delta::FromMilliseconds(2))));
 
   // Send a whole pile of packets, and verify that they are not paced.
   for (int i = 0 ; i < 1000; ++i) {
     CheckPacketIsSentImmediately();
   }
@@ skipping 51 matching lines @@
 
   // Wake up too early.
   CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
 
   // Wake up early, but after enough time has passed to permit a send.
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(1));
   CheckPacketIsSentImmediately();
   CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
 }
 
+TEST_F(PacingSenderTest, CongestionAvoidanceSending) {
+  // Start the test in congestion avoidance.
+  EXPECT_CALL(*mock_sender_, InSlowStart()).WillRepeatedly(Return(false));
+
+  // Configure bandwith of 1 packet per 2 ms, for which the pacing rate
+  // will be 1 packet per 1 ms.
+  EXPECT_CALL(*mock_sender_, BandwidthEstimate())
+      .WillRepeatedly(Return(QuicBandwidth::FromBytesAndTimeDelta(
+          kMaxPacketSize, QuicTime::Delta::FromMilliseconds(2))));
+
+  // Send a whole pile of packets, and verify that they are not paced.
+  for (int i = 0 ; i < 1000; ++i) {
+    CheckPacketIsSentImmediately();
+  }
+
+  // Now update the RTT and verify that packets are actually paced.
+  EXPECT_CALL(*mock_sender_, OnCongestionEvent(true, kBytesInFlight, _, _));
+  SendAlgorithmInterface::CongestionMap empty_map;
+  pacing_sender_->OnCongestionEvent(true, kBytesInFlight, empty_map, empty_map);
+
+  CheckPacketIsSentImmediately();
+  CheckPacketIsSentImmediately();
+
+  // The first packet was a "make up", then we sent two packets "into the
+  // future", so the delay should be 2200us.
+  CheckPacketIsDelayed(QuicTime::Delta::FromMicroseconds(2200));
+
+  // Wake up on time.
+  clock_.AdvanceTime(QuicTime::Delta::FromMicroseconds(2200));
+  CheckPacketIsSentImmediately();
+  CheckPacketIsDelayed(QuicTime::Delta::FromMicroseconds(1600));
+  CheckAckIsSentImmediately();
+
+  // Wake up late.
+  clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(4));
+  CheckPacketIsSentImmediately();
+  CheckPacketIsSentImmediately();
+  CheckPacketIsSentImmediately();
+  CheckPacketIsDelayed(QuicTime::Delta::FromMicroseconds(2400));
+
+  // Wake up really late.
+  clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(8));
+  CheckPacketIsSentImmediately();
+  CheckPacketIsSentImmediately();
+  CheckPacketIsSentImmediately();
+  CheckPacketIsSentImmediately();
+  CheckPacketIsSentImmediately();
+  CheckPacketIsDelayed(QuicTime::Delta::FromMicroseconds(2400));
+
+  // Wake up really late again, but application pause partway through.
+  clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(8));
+  CheckPacketIsSentImmediately();
+  CheckPacketIsSentImmediately();
+  clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(100));
+  CheckPacketIsSentImmediately();
+  CheckPacketIsSentImmediately();
+  CheckPacketIsSentImmediately();
+  CheckPacketIsDelayed(QuicTime::Delta::FromMicroseconds(2200));
+
+  // Wake up too early.
+  CheckPacketIsDelayed(QuicTime::Delta::FromMicroseconds(2200));
+
+  // Wake up early, but after enough time has passed to permit a send.
+  clock_.AdvanceTime(QuicTime::Delta::FromMicroseconds(1200));
+  CheckPacketIsSentImmediately();
+  CheckPacketIsDelayed(QuicTime::Delta::FromMicroseconds(2600));
+}
+
 TEST_F(PacingSenderTest, InitialBurst) {
   pacing_sender_.reset();
   mock_sender_ = new StrictMock<MockSendAlgorithm>();
   pacing_sender_.reset(new PacingSender(mock_sender_,
                                         QuicTime::Delta::FromMilliseconds(1),
                                         10));
+  // Start the test in slow start.
+  EXPECT_CALL(*mock_sender_, InSlowStart()).WillRepeatedly(Return(true));
 
   // Configure bandwith of 1 packet per 2 ms, for which the pacing rate
   // will be 1 packet per 1 ms.
   EXPECT_CALL(*mock_sender_, BandwidthEstimate())
       .WillRepeatedly(Return(QuicBandwidth::FromBytesAndTimeDelta(
           kMaxPacketSize, QuicTime::Delta::FromMilliseconds(2))));
 
   // Update the RTT and verify that the first 10 packets aren't paced.
   EXPECT_CALL(*mock_sender_, OnCongestionEvent(true, kBytesInFlight, _, _));
   SendAlgorithmInterface::CongestionMap empty_map;
@@ skipping 31 matching lines @@
 
   CheckPacketIsSentImmediately();
   CheckPacketIsSentImmediately();
   CheckPacketIsSentImmediately();
 
   CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
 }
 
 }  // namespace test
 }  // namespace net