commit cfec38f702419e4f2343dbc03cda8c44229fb321
author fayang <fayang@google.com> Wed Jun 10 11:16:51 2020 -0700
committer Copybara-Service <copybara-worker@google.com> Wed Jun 10 11:17:22 2020 -0700
tree 8896b46b8c646dfebb5468af5d35a6f66a2159f8
parent afd8daad85b215c3f1c5e838d95b382da8ed0e7f

In quic, stop blackhole detection if timer based loss detection removes all packets from in flight but no retransmission can be sent (e.g., write blocked, message frame, etc). protected by existing gfe2_reloadable_flag_quic_default_enable_5rto_blackhole_detection2.

Also add QUIC_BUGs to make sure there are bytes in flight when arming blackhole detection and when the blackhole is detected.

PiperOrigin-RevId: 315728450
Change-Id: I017bc77a95b88da460676de21cc40199d4b129c8

quic/core/quic_connection.cc

diff --git a/quic/core/quic_connection.cc b/quic/core/quic_connection.cc
index 7b1b9af..18389f0 100644
--- a/quic/core/quic_connection.cc
+++ b/quic/core/quic_connection.cc
@@ -2695,6 +2695,11 @@
   const bool in_flight = sent_packet_manager_.OnPacketSent(
       packet, packet_send_time, packet->transmission_type,
       IsRetransmittable(*packet));
+  QUIC_BUG_IF(default_enable_5rto_blackhole_detection_ &&
+              blackhole_detector_.IsDetectionInProgress() &&
+              !sent_packet_manager_.HasInFlightPackets())
+      << ENDPOINT
+      << "Trying to start blackhole detection without no bytes in flight";
 
   if (in_flight || !retransmission_alarm_->IsSet()) {
     SetRetransmissionAlarm();
@@ -2985,6 +2990,13 @@
       debug_visitor_->OnNPacketNumbersSkipped(num_packet_numbers_to_skip);
     }
   }
+  if (default_enable_5rto_blackhole_detection_ &&
+      !sent_packet_manager_.HasInFlightPackets() &&
+      blackhole_detector_.IsDetectionInProgress()) {
+    // Stop detection in quiescence.
+    DCHECK_EQ(QuicSentPacketManager::LOSS_MODE, retransmission_mode);
+    blackhole_detector_.StopDetection();
+  }
   WriteIfNotBlocked();
 
   // A write failure can result in the connection being closed, don't attempt to
@@ -4361,6 +4373,11 @@
     // Stop detections in quiecense.
     blackhole_detector_.StopDetection();
   }
+  QUIC_BUG_IF(default_enable_5rto_blackhole_detection_ &&
+              blackhole_detector_.IsDetectionInProgress() &&
+              !sent_packet_manager_.HasInFlightPackets())
+      << ENDPOINT
+      << "Trying to start blackhole detection without no bytes in flight";
 }
 
 QuicPacketNumber QuicConnection::GetLargestReceivedPacketWithAck() const {
@@ -4474,6 +4491,11 @@
 }
 
 void QuicConnection::OnBlackholeDetected() {
+  QUIC_BUG_IF(default_enable_5rto_blackhole_detection_ &&
+              !sent_packet_manager_.HasInFlightPackets())
+      << ENDPOINT
+      << "Closing connection because of blackhole, but there is no bytes in "
+         "flight";
   CloseConnection(QUIC_TOO_MANY_RTOS, "Network blackhole detected.",
                   ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET);
 }