Change the pacing sender to always pacing the initial burst, even when

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"
 #include "net/quic/test_tools/quic_test_utils.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using testing::Return;
 using testing::StrictMock;
 using testing::_;
 
 namespace net {
 namespace test {
 
 const QuicByteCount kBytesInFlight = 1024;
+const int kInitialBurstPackets = 10;
 
 class PacingSenderTest : public ::testing::Test {
  protected:
   PacingSenderTest()
       : zero_time_(QuicTime::Delta::Zero()),
         infinite_time_(QuicTime::Delta::Infinite()),
         sequence_number_(1),
         mock_sender_(new StrictMock<MockSendAlgorithm>()),
         pacing_sender_(new PacingSender(mock_sender_,
                                         QuicTime::Delta::FromMilliseconds(1),
@@ skipping 103 matching lines @@
 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();
-  }
-
   // Now update the RTT and verify that packets are actually paced.
   EXPECT_CALL(*mock_sender_, OnCongestionEvent(true, kBytesInFlight, _, _));
   SendAlgorithmInterface::CongestionVector empty_map;
   pacing_sender_->OnCongestionEvent(true, kBytesInFlight, empty_map, empty_map);
 
   CheckPacketIsSentImmediately();
   CheckPacketIsSentImmediately();
   CheckPacketIsSentImmediately();
 
   // The first packet was a "make up", then we sent two packets "into the
@@ skipping 50 matching lines @@
 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::CongestionVector 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.
@@ skipping 54 matching lines @@
   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::CongestionVector empty_map;
   pacing_sender_->OnCongestionEvent(true, kBytesInFlight, empty_map, empty_map);
 
   // Send 10 packets, and verify that they are not paced.
-  for (int i = 0 ; i < 10; ++i) {
+  for (int i = 0 ; i < kInitialBurstPackets; ++i) {
     CheckPacketIsSentImmediately();
   }
 
+  // The first packet was a "make up", then we sent two packets "into the
+  // future", so the delay should be 2ms.
   CheckPacketIsSentImmediately();
   CheckPacketIsSentImmediately();
   CheckPacketIsSentImmediately();
+  CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
 
-  // The first packet was a "make up", then we sent two packets "into the
-  // future", so the delay should be 2.
-  CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
   clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
   CheckPacketIsSentImmediately();
 
+  // Next time TimeUntilSend is called with no bytes in flight, the tokens
+  // should be refilled and there should be no delay.
+  EXPECT_CALL(*mock_sender_,
+              TimeUntilSend(clock_.Now(),
+                            0,
+                            HAS_RETRANSMITTABLE_DATA)).
+      WillOnce(Return(zero_time_));
+  EXPECT_EQ(zero_time_,
+            pacing_sender_->TimeUntilSend(clock_.Now(),
+                                          0,
+                                          HAS_RETRANSMITTABLE_DATA));
+  for (int i = 0 ; i < kInitialBurstPackets; ++i) {
+    CheckPacketIsSentImmediately();
+  }
+
+  // The first packet was a "make up", then we sent two packets "into the
+  // future", so the delay should be 2ms.
+  CheckPacketIsSentImmediately();
+  CheckPacketIsSentImmediately();
+  CheckPacketIsSentImmediately();
+  CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
+}
+
+TEST_F(PacingSenderTest, InitialBurstNoRttMeasurement) {
+  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))));
+
+  // Send 10 packets, and verify that they are not paced.
+  for (int i = 0 ; i < kInitialBurstPackets; ++i) {
+    CheckPacketIsSentImmediately();
+  }
+
+  // The first packet was a "make up", then we sent two packets "into the
+  // future", so the delay should be 2ms.
+  CheckPacketIsSentImmediately();
+  CheckPacketIsSentImmediately();
+  CheckPacketIsSentImmediately();
+  CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
+
+
+  clock_.AdvanceTime(QuicTime::Delta::FromMilliseconds(5));
+  CheckPacketIsSentImmediately();
+
   // Next time TimeUntilSend is called with no bytes in flight, the tokens
   // should be refilled and there should be no delay.
   EXPECT_CALL(*mock_sender_,
               TimeUntilSend(clock_.Now(),
                             0,
                             HAS_RETRANSMITTABLE_DATA)).
       WillOnce(Return(zero_time_));
   EXPECT_EQ(zero_time_,
             pacing_sender_->TimeUntilSend(clock_.Now(),
                                           0,
                                           HAS_RETRANSMITTABLE_DATA));
-  for (int i = 0 ; i < 10; ++i) {
+  // Send 10 packets, and verify that they are not paced.
+  for (int i = 0 ; i < kInitialBurstPackets; ++i) {
     CheckPacketIsSentImmediately();
   }
 
+  // The first packet was a "make up", then we sent two packets "into the
+  // future", so the delay should be 2ms.
   CheckPacketIsSentImmediately();
   CheckPacketIsSentImmediately();
   CheckPacketIsSentImmediately();
-
   CheckPacketIsDelayed(QuicTime::Delta::FromMilliseconds(2));
 }
 
 }  // namespace test
 }  // namespace net