dial.go: Re-use tickers during OpenConnectionRequest/Reply sequence.

Author: Sandertv

conn.go

@@ -105,7 +105,7 @@ func newConn(conn net.PacketConn, raddr net.Addr, mtu uint16, h connectionHandle
 		win:            newDatagramWindow(),
 		packetQueue:    newPacketQueue(),
 		retransmission: newRecoveryQueue(),
-		buf:            bytes.NewBuffer(make([]byte, 0, mtu)),
+		buf:            bytes.NewBuffer(make([]byte, 0, mtu-28)), // - headers.
 		ackBuf:         bytes.NewBuffer(make([]byte, 0, 128)),
 		nackBuf:        bytes.NewBuffer(make([]byte, 0, 64)),
 	}
@@ -160,7 +160,7 @@ func (conn *Conn) startTicking() {
 				_ = conn.send(&message.ConnectedPing{ClientTimestamp: timestamp()})
 
 				conn.mu.Lock()
-				if t.Sub(*conn.lastActivity.Load()) > time.Second*5+conn.retransmission.rtt()*2 {
+				if t.Sub(*conn.lastActivity.Load()) > time.Second*5+conn.retransmission.rtt(t)*2 {
 					// No activity for too long: Start timeout.
 					_ = conn.Close()
 				}
@@ -196,7 +196,7 @@ func (conn *Conn) checkResend(now time.Time) {
 
 	var (
 		resend []uint24
-		rtt    = conn.retransmission.rtt()
+		rtt    = conn.retransmission.rtt(now)
 		delay  = rtt + rtt/2
 	)
 	conn.rtt.Store(int64(rtt))

dial.go

@@ -219,7 +219,8 @@ func (dialer Dialer) DialContext(ctx context.Context, address string) (*Conn, er
 		return nil, dialer.error("dial", err)
 	}
 
-	cs := &connState{conn: conn, raddr: conn.RemoteAddr(), id: atomic.AddInt64(&dialerID, 1)}
+	cs := &connState{conn: conn, raddr: conn.RemoteAddr(), id: atomic.AddInt64(&dialerID, 1), ticker: time.NewTicker(time.Second / 2)}
+	defer cs.ticker.Stop()
 	if err = cs.discoverMTU(ctx); err != nil {
 		return nil, dialer.error("dial", err)
 	} else if err = cs.openConnection(ctx); err != nil {
@@ -285,6 +286,8 @@ type connState struct {
 
 	serverSecurity bool
 	cookie         uint32
+
+	ticker *time.Ticker
 }
 
 var mtuSizes = []uint16{1492, 1200, 576}
@@ -337,14 +340,12 @@ func (state *connState) discoverMTU(ctx context.Context) error {
 // request1 sends a message.OpenConnectionRequest1 three times for each mtu
 // size passed, spaced by 500ms.
 func (state *connState) request1(ctx context.Context, sizes []uint16) {
-	ticker := time.NewTicker(time.Second / 2)
-	defer ticker.Stop()
-
+	state.ticker.Reset(time.Second / 2)
 	for _, size := range sizes {
 		for range 3 {
 			state.openConnectionRequest1(size)
 			select {
-			case <-ticker.C:
+			case <-state.ticker.C:
 				continue
 			case <-ctx.Done():
 				return
@@ -384,13 +385,11 @@ func (state *connState) openConnection(ctx context.Context) error {
 
 // request2 continuously sends a message.OpenConnectionRequest2 every 500ms.
 func (state *connState) request2(ctx context.Context, mtu uint16) {
-	ticker := time.NewTicker(time.Second / 2)
-	defer ticker.Stop()
-
+	state.ticker.Reset(time.Second / 2)
 	for {
 		state.openConnectionRequest2(mtu)
 		select {
-		case <-ticker.C:
+		case <-state.ticker.C:
 			continue
 		case <-ctx.Done():
 			return

resend_map.go

@@ -1,6 +1,7 @@
 package raknet
 
 import (
+	"maps"
 	"time"
 )
 
@@ -60,23 +61,20 @@ func (m *resendMap) remove(index uint24, mul int) (*packet, bool) {
 // rtt returns the average round trip time between the putting of the value
 // into the recovery queue and the taking out of it again. It is measured over
 // the last delayRecordCount values add in.
-func (m *resendMap) rtt() time.Duration {
-	const maxRTT = time.Second * 5
-	var (
-		total, records time.Duration
-		now            = time.Now()
-	)
-	for t, rtt := range m.delays {
-		if now.Sub(t) > maxRTT {
-			delete(m.delays, t)
-			continue
-		}
-		total += rtt
-		records++
-	}
-	if records == 0 {
-		// No records yet, generally should not happen. Just return a reasonable amount of time.
+func (m *resendMap) rtt(now time.Time) time.Duration {
+	const rttCalculationWindow = time.Second * 5
+	maps.DeleteFunc(m.delays, func(t time.Time, duration time.Duration) bool {
+		// Remove records that are older than the max window.
+		return now.Sub(t) > rttCalculationWindow
+	})
+	if len(m.delays) == 0 {
+		// No records yet, generally should not happen. Just return a reasonable
+		// amount of time.
 		return time.Millisecond * 50
 	}
-	return total / records
+	var total time.Duration
+	for _, rtt := range m.delays {
+		total += rtt
+	}
+	return total / time.Duration(len(m.delays))
 }