allow concurrent calls to Close and SetTTL in the ObservedAddrManager

p2p/protocol/identify/obsaddr.go

@@ -530,9 +530,14 @@ func (oas *ObservedAddrManager) emitSpecificNATType(addrs []*observedAddr, proto
 func (oas *ObservedAddrManager) Close() error {
 	oas.closeOnce.Do(func() {
 		oas.ctxCancel()
+
+		oas.mu.Lock()
+		oas.refreshTimer.Stop()
+		oas.refreshTimer = nil
+		oas.mu.Unlock()
+
 		oas.refCount.Wait()
 		oas.reachabilitySub.Close()
-		oas.refreshTimer.Stop()
 		oas.host.Network().StopNotify((*obsAddrNotifiee)(oas))
 	})
 	return nil
@@ -558,6 +563,9 @@ func observerGroup(m ma.Multiaddr) string {
 func (oas *ObservedAddrManager) SetTTL(ttl time.Duration) {
 	oas.mu.Lock()
 	defer oas.mu.Unlock()
+	if oas.refreshTimer == nil { // set to nil when we're closing
+		return
+	}
 	oas.ttl = ttl
 	// refresh every ttl/2 so we don't forget observations from connected peers
 	oas.refreshTimer.Reset(ttl / 2)