From b06ea77b59e53614da541b21060d01da23b94503 Mon Sep 17 00:00:00 2001
From: Nonoo <nonoo@nonoo.hu>
Date: Sun, 22 Nov 2020 14:01:59 +0100
Subject: [PATCH] Lock seqbuf for at least the duration of the RTT

---
 pkt7.go   | 4 ++++
 seqbuf.go | 8 ++++++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/pkt7.go b/pkt7.go
index e4788f3..4ae0eb9 100644
--- a/pkt7.go
+++ b/pkt7.go
@@ -27,6 +27,8 @@ type pkt7Type struct {
 	periodicStopFinishedChan chan bool
 }
 
+var controlStreamLatency time.Duration
+
 func (p *pkt7Type) isPkt7(r []byte) bool {
 	return len(r) == 21 && bytes.Equal(r[1:6], []byte{0x00, 0x00, 0x00, 0x07, 0x00}) // Note that the first byte can be 0x15 or 0x00, so we ignore that.
 }
@@ -54,6 +56,8 @@ func (p *pkt7Type) handle(s *streamCommon, r []byte) error {
 				p.latency += time.Since(p.lastSendAt)
 				p.latency /= 2
 				statusLog.reportRTTLatency(p.latency)
+
+				controlStreamLatency = p.latency
 			}
 		}
 
diff --git a/seqbuf.go b/seqbuf.go
index cf1c4e9..dce356f 100644
--- a/seqbuf.go
+++ b/seqbuf.go
@@ -228,8 +228,12 @@ func (s *seqBuf) add(seq seqNum, data []byte) error {
 
 func (s *seqBuf) checkLockTimeout() (timeout bool, shouldRetryIn time.Duration) {
 	timeSinceLastInvalidSeq := time.Since(s.lockedAt)
-	if s.length > timeSinceLastInvalidSeq {
-		shouldRetryIn = s.length - timeSinceLastInvalidSeq
+	lockDuration := s.length
+	if lockDuration < controlStreamLatency*2 {
+		lockDuration = controlStreamLatency * 2
+	}
+	if lockDuration > timeSinceLastInvalidSeq {
+		shouldRetryIn = lockDuration - timeSinceLastInvalidSeq
 		return
 	}