From 781875a1df573b3044493530be861fec09647e7e Mon Sep 17 00:00:00 2001
From: Jana Iyengar <jri.ietf@gmail.com>
Date: Thu, 11 Apr 2019 22:23:19 -0700
Subject: [PATCH] Simplify UpdateRtt pseudocode

---
 draft-ietf-quic-recovery.md | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/draft-ietf-quic-recovery.md b/draft-ietf-quic-recovery.md
index 857dbebdb9..07582273a8 100644
--- a/draft-ietf-quic-recovery.md
+++ b/draft-ietf-quic-recovery.md
@@ -1101,22 +1101,24 @@ OnAckReceived(ack, pn_space):
 
 
 UpdateRtt(latest_rtt, ack_delay):
+  if (smoothed_rtt == 0):
+    // First RTT sample.
+    min_rtt = latest_rtt
+    smoothed_rtt = latest_rtt
+    rttvar = latest_rtt / 2
+    return
+
   // min_rtt ignores ack delay.
   min_rtt = min(min_rtt, latest_rtt)
   // Limit ack_delay by max_ack_delay
   ack_delay = min(ack_delay, max_ack_delay)
-  // Adjust for ack delay if it's plausible.
+  // Adjust for ack delay if plausible.
   adjusted_rtt = latest_rtt
-  if (latest_rtt - min_rtt > ack_delay):
+  if (latest_rtt > min_rtt + ack_delay):
     adjusted_rtt = latest_rtt - ack_delay
-  // First RTT sample.
-  if (smoothed_rtt == 0):
-    smoothed_rtt = latest_rtt
-    rttvar = latest_rtt / 2
-  else:
-    rttvar_sample = abs(smoothed_rtt - adjusted_rtt)
-    rttvar = 3/4 * rttvar + 1/4 * rttvar_sample
-    smoothed_rtt = 7/8 * smoothed_rtt + 1/8 * adjusted_rtt
+
+  rttvar = 3/4 * rttvar + 1/4 * abs(smoothed_rtt - adjusted_rtt)
+  smoothed_rtt = 7/8 * smoothed_rtt + 1/8 * adjusted_rtt
 ~~~