commit 1b2f7836bbb2f99adf94953ea368759f910ea71d
author zhongyi <zhongyi@google.com> Fri Jun 14 13:31:34 2019 -0700
committer Copybara-Service <copybara-worker@google.com> Fri Jun 14 13:32:10 2019 -0700
tree 39e5d1b95c004797f60acc4721751f311a4c5515
parent 96c1767f35ee4d796c63ebb38d7d1a126e1bb778

gfe-relnote: only respect TLPR when there is pending non-crypto stream data. Flag protected by quic_ignore_tlpr_if_no_pending_stream_data and session_decides_what_to_write.

When calculating the tail loss probe delay and TLPR option is enabled, only use half tail loss probe when session has pending stream data. Otherwise, ignore TLPR.

PiperOrigin-RevId: 253286073
Change-Id: I9321c9d0608f68bb4ec0f7f4fbba1e470e4a0a3c

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 c8ae53b..d92ee66 100644
--- a/quic/core/quic_sent_packet_manager.cc
+++ b/quic/core/quic_sent_packet_manager.cc
@@ -118,7 +118,9 @@
       acked_packets_iter_(last_ack_frame_.packets.rbegin()),
       tolerate_reneging_(GetQuicReloadableFlag(quic_tolerate_reneging)),
       loss_removes_from_inflight_(
-          GetQuicReloadableFlag(quic_loss_removes_from_inflight)) {
+          GetQuicReloadableFlag(quic_loss_removes_from_inflight)),
+      ignore_tlpr_if_no_pending_stream_data_(
+          GetQuicReloadableFlag(quic_ignore_tlpr_if_no_pending_stream_data)) {
   if (tolerate_reneging_) {
     QUIC_RELOADABLE_FLAG_COUNT(quic_tolerate_reneging);
   }
@@ -1017,7 +1019,16 @@
     size_t consecutive_tlp_count) const {
   QuicTime::Delta srtt = rtt_stats_.SmoothedOrInitialRtt();
   if (enable_half_rtt_tail_loss_probe_ && consecutive_tlp_count == 0u) {
-    return std::max(min_tlp_timeout_, srtt * 0.5);
+    if (!ignore_tlpr_if_no_pending_stream_data_ ||
+        !session_decides_what_to_write()) {
+      return std::max(min_tlp_timeout_, srtt * 0.5);
+    }
+    QUIC_RELOADABLE_FLAG_COUNT_N(quic_ignore_tlpr_if_no_pending_stream_data, 1,
+                                 5);
+    if (unacked_packets().HasUnackedStreamData()) {
+      // Enable TLPR if there are pending data packets.
+      return std::max(min_tlp_timeout_, srtt * 0.5);
+    }
   }
   if (ietf_style_tlp_) {
     return std::max(min_tlp_timeout_, 1.5 * srtt + rtt_stats_.max_ack_delay());