gfe-relnote: (n/a) Record total loss detection time in QuicConnectionStats. Stats only, not protected.

PiperOrigin-RevId: 297595275
Change-Id: Ie049bd1dbaa28aebb5d43e2d4ab6c79a655f6136

quic/core/quic_connection_stats.h

diff --git a/quic/core/quic_connection_stats.h b/quic/core/quic_connection_stats.h
index a99c055..9f4deca 100644
--- a/quic/core/quic_connection_stats.h
+++ b/quic/core/quic_connection_stats.h
@@ -45,6 +45,9 @@
   QuicPacketCount packets_spuriously_retransmitted = 0;
   // Number of packets abandoned as lost by the loss detection algorithm.
   QuicPacketCount packets_lost = 0;
+  // The sum of the detection time of all lost packets. The detection time of a
+  // lost packet is defined as: T(detection) - T(send).
+  QuicTime::Delta total_loss_detection_time = QuicTime::Delta::Zero();
 
   // Number of times this connection went through the slow start phase.
   uint32_t slowstart_count = 0;

quic/core/quic_sent_packet_manager.cc

diff --git a/quic/core/quic_sent_packet_manager.cc b/quic/core/quic_sent_packet_manager.cc
index a055299..d92883b 100644
--- a/quic/core/quic_sent_packet_manager.cc
+++ b/quic/core/quic_sent_packet_manager.cc
@@ -891,12 +891,19 @@
                                 largest_newly_acked_, packets_acked_,
                                 &packets_lost_);
   for (const LostPacket& packet : packets_lost_) {
+    QuicTransmissionInfo* info =
+        unacked_packets_.GetMutableTransmissionInfo(packet.packet_number);
     ++stats_->packets_lost;
+    if (time > info->sent_time) {
+      stats_->total_loss_detection_time =
+          stats_->total_loss_detection_time + (time - info->sent_time);
+    }
     if (debug_delegate_ != nullptr) {
       debug_delegate_->OnPacketLoss(packet.packet_number, LOSS_RETRANSMISSION,
                                     time);
     }
-    unacked_packets_.RemoveFromInFlight(packet.packet_number);
+    unacked_packets_.RemoveFromInFlight(info);
+
     MarkForRetransmission(packet.packet_number, LOSS_RETRANSMISSION);
   }
 }

quic/core/quic_sent_packet_manager_test.cc

diff --git a/quic/core/quic_sent_packet_manager_test.cc b/quic/core/quic_sent_packet_manager_test.cc
index 60c84a7..99ddfcd 100644
--- a/quic/core/quic_sent_packet_manager_test.cc
+++ b/quic/core/quic_sent_packet_manager_test.cc
@@ -619,6 +619,8 @@
   // Spurious retransmission is detected when packet 3 gets acked. We cannot
   // know packet 2 is a spurious until it gets acked.
   EXPECT_EQ(1u, stats_.packets_spuriously_retransmitted);
+  EXPECT_EQ(1u, stats_.packets_lost);
+  EXPECT_LT(QuicTime::Delta::Zero(), stats_.total_loss_detection_time);
 }
 
 TEST_F(QuicSentPacketManagerTest, AckOriginalTransmission) {