Reduce the BWE with 50% when feedback is received too late.

webrtc/modules/congestion_controller/transport_feedback_adapter_unittest.cc

 /*
  *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 20 matching lines @@
 class TransportFeedbackAdapterTest : public ::testing::Test {
  public:
   TransportFeedbackAdapterTest()
       : clock_(0), bitrate_controller_(this), target_bitrate_bps_(0) {}
 
   virtual ~TransportFeedbackAdapterTest() {}
 
   virtual void SetUp() {
     adapter_.reset(new TransportFeedbackAdapter(&clock_, &bitrate_controller_));
     adapter_->InitBwe();
+    adapter_->SetStartBitrate(300000);
   }
 
   virtual void TearDown() { adapter_.reset(); }
 
  protected:
   // Proxy class used since TransportFeedbackAdapter will own the instance
   // passed at construction.
   class MockBitrateControllerAdapter : public MockBitrateController {
    public:
     explicit MockBitrateControllerAdapter(TransportFeedbackAdapterTest* owner)
@@ skipping 71 matching lines @@
     EXPECT_TRUE(feedback.AddReceivedPacket(packet.sequence_number,
                                            packet.arrival_time_ms * 1000));
   }
 
   feedback.Build();
 
   adapter_->OnTransportFeedback(feedback);
   ComparePacketVectors(packets, adapter_->GetTransportFeedbackVector());
 }
 
-TEST_F(TransportFeedbackAdapterTest, Timeout) {
+TEST_F(TransportFeedbackAdapterTest, LongFeedbackDelays) {
   const int64_t kFeedbackTimeoutMs = 60001;
-  {
+  const int kMaxConsecutiveFailedLookups = 5;
+  for (int i = 0; i < kMaxConsecutiveFailedLookups; ++i) {
     std::vector<PacketInfo> packets;
-    packets.push_back(PacketInfo(100, 200, 0, 1500, 0));
-    packets.push_back(PacketInfo(110, 210, 1, 1500, 0));
-    packets.push_back(PacketInfo(120, 220, 2, 1500, 0));
-    packets.push_back(PacketInfo(130, 230, 3, 1500, 1));
-    packets.push_back(PacketInfo(140, 240, 4, 1500, 1));
+    packets.push_back(PacketInfo(i * 100, 2 * i * 100, 0, 1500, 0));
+    packets.push_back(PacketInfo(i * 100 + 10, 2 * i * 100 + 10, 1, 1500, 0));
+    packets.push_back(PacketInfo(i * 100 + 20, 2 * i * 100 + 20, 2, 1500, 0));
+    packets.push_back(PacketInfo(i * 100 + 30, 2 * i * 100 + 30, 3, 1500, 1));
+    packets.push_back(PacketInfo(i * 100 + 40, 2 * i * 100 + 40, 4, 1500, 1));
 
     for (const PacketInfo& packet : packets)
       OnSentPacket(packet);
 
     rtcp::TransportFeedback feedback;
     feedback.SetBase(packets[0].sequence_number,
                      packets[0].arrival_time_ms * 1000);
 
     for (const PacketInfo& packet : packets) {
       EXPECT_TRUE(feedback.AddReceivedPacket(packet.sequence_number,
                                              packet.arrival_time_ms * 1000));
     }
 
     feedback.Build();
 
     clock_.AdvanceTimeMilliseconds(kFeedbackTimeoutMs);
-    PacketInfo later_packet(kFeedbackTimeoutMs + 140, kFeedbackTimeoutMs + 240,
-                            5, 1500, 1);
+    PacketInfo later_packet(kFeedbackTimeoutMs + i * 100 + 40,
+                            kFeedbackTimeoutMs + i * 200 + 40, 5, 1500, 1);
     OnSentPacket(later_packet);
 
     adapter_->OnTransportFeedback(feedback);
-    EXPECT_EQ(0, rtc::checked_cast<int>(
-                     adapter_->GetTransportFeedbackVector().size()));
+
+    // Check that packets have timed out.
+    for (PacketInfo& packet : packets) {
+      packet.send_time_ms = -1;
+      packet.payload_size = 0;
+      packet.probe_cluster_id = -1;
+    }
+    ComparePacketVectors(packets, adapter_->GetTransportFeedbackVector());
   }
 
+  // Target bitrate should have halved due to feedback delays.
+  EXPECT_EQ(150000u, target_bitrate_bps_);
+
+  // Test with feedback that isn't late enough to time out.
   {
     std::vector<PacketInfo> packets;
     packets.push_back(PacketInfo(100, 200, 0, 1500, 0));
     packets.push_back(PacketInfo(110, 210, 1, 1500, 0));
     packets.push_back(PacketInfo(120, 220, 2, 1500, 0));
     packets.push_back(PacketInfo(130, 230, 3, 1500, 1));
     packets.push_back(PacketInfo(140, 240, 4, 1500, 1));
 
     for (const PacketInfo& packet : packets)
       OnSentPacket(packet);
@@ skipping 42 matching lines @@
   for (const PacketInfo& packet : packets) {
     if (packet.sequence_number <= kReceiveSideDropAfter) {
       EXPECT_TRUE(feedback.AddReceivedPacket(packet.sequence_number,
                                              packet.arrival_time_ms * 1000));
     }
   }
 
   feedback.Build();
 
   std::vector<PacketInfo> expected_packets(
-      packets.begin() + kSendSideDropBefore,
-      packets.begin() + kReceiveSideDropAfter + 1);
+      packets.begin(), packets.begin() + kReceiveSideDropAfter + 1);
+  // Packets that have timed out on the send-side have lost the
+  // information stored on the send-side.
+  for (size_t i = 0; i < kSendSideDropBefore; ++i) {
+    expected_packets[i].send_time_ms = -1;
+    expected_packets[i].probe_cluster_id = -1;
+    expected_packets[i].payload_size = 0;
+  }
 
   adapter_->OnTransportFeedback(feedback);
   ComparePacketVectors(expected_packets,
                        adapter_->GetTransportFeedbackVector());
 }
 
 TEST_F(TransportFeedbackAdapterTest, SendTimeWrapsBothWays) {
   int64_t kHighArrivalTimeMs = rtcp::TransportFeedback::kDeltaScaleFactor *
                                static_cast<int64_t>(1 << 8) *
                                static_cast<int64_t>((1 << 23) - 1) / 1000;
@@ skipping 173 matching lines @@
     EXPECT_TRUE(feedback.get() != nullptr);
     adapter_->OnTransportFeedback(*feedback.get());
     clock_.AdvanceTimeMilliseconds(50);
     ++seq_num;
   }
   EXPECT_GT(target_bitrate_bps_, 0u);
 }
 
 }  // namespace test
 }  // namespace webrtc