From 94e812df12ad87199f12545540873ef09285f9bb Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Thu, 1 Feb 2018 13:33:25 +0800
Subject: [PATCH] optimize deleting packets from the packet history

DeleteBelow is often called with the same value, so we can improve the
performance by introducing a short path for this case.
---
 ackhandler/received_packet_history.go | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/ackhandler/received_packet_history.go b/ackhandler/received_packet_history.go
index b8321f60..ba119544 100644
--- a/ackhandler/received_packet_history.go
+++ b/ackhandler/received_packet_history.go
@@ -76,7 +76,10 @@ func (h *receivedPacketHistory) ReceivedPacket(p protocol.PacketNumber) error {
 
 // DeleteBelow deletes all entries below (but not including) p
 func (h *receivedPacketHistory) DeleteBelow(p protocol.PacketNumber) {
-	h.lowestInReceivedPacketNumbers = utils.MaxPacketNumber(h.lowestInReceivedPacketNumbers, p)
+	if p <= h.lowestInReceivedPacketNumbers {
+		return
+	}
+	h.lowestInReceivedPacketNumbers = p
 
 	nextEl := h.ranges.Front()
 	for el := h.ranges.Front(); nextEl != nil; el = nextEl {