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

webrtc/modules/congestion_controller/transport_feedback_adapter_unittest.cc

Index: webrtc/modules/congestion_controller/transport_feedback_adapter_unittest.cc
diff --git a/webrtc/modules/congestion_controller/transport_feedback_adapter_unittest.cc b/webrtc/modules/congestion_controller/transport_feedback_adapter_unittest.cc
index 2c94c71c75e5f55af57d397cc4a410034117db75..a87f2af02d205b21cca7a3d9f91bd75d623f666d 100644
--- a/webrtc/modules/congestion_controller/transport_feedback_adapter_unittest.cc
+++ b/webrtc/modules/congestion_controller/transport_feedback_adapter_unittest.cc
@@ -37,6 +37,7 @@ class TransportFeedbackAdapterTest : public ::testing::Test {
   virtual void SetUp() {
     adapter_.reset(new TransportFeedbackAdapter(&clock_, &bitrate_controller_));
     adapter_->InitBwe();
+    adapter_->SetStartBitrate(300000);
   }
 
   virtual void TearDown() { adapter_.reset(); }
@@ -128,6 +129,83 @@ TEST_F(TransportFeedbackAdapterTest, AdaptsFeedbackAndPopulatesSendTimes) {
   ComparePacketVectors(packets, adapter_->GetTransportFeedbackVector());
 }
 
+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(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 + i * 100 + 40,
+                            kFeedbackTimeoutMs + i * 200 + 40, 5, 1500, 1);
+    OnSentPacket(later_packet);
+
+    adapter_->OnTransportFeedback(feedback);
+
+    // 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 bitate 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);
+
+    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 - 1);
+    PacketInfo later_packet(kFeedbackTimeoutMs + 140, kFeedbackTimeoutMs + 240,
+                            5, 1500, 1);
+    OnSentPacket(later_packet);
+
+    adapter_->OnTransportFeedback(feedback);
+    ComparePacketVectors(packets, adapter_->GetTransportFeedbackVector());
+  }
+}
+
 TEST_F(TransportFeedbackAdapterTest, HandlesDroppedPackets) {
   std::vector<PacketInfo> packets;
   packets.push_back(PacketInfo(100, 200, 0, 1500, 1));
@@ -158,8 +236,14 @@ TEST_F(TransportFeedbackAdapterTest, HandlesDroppedPackets) {
   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,