avoid allocations when adding packets to the sent packet history

internal/ackhandler/sent_packet_handler_test.go

@@ -38,7 +38,7 @@ var _ = Describe("SentPacketHandler", func() {
 
 	getPacket := func(pn protocol.PacketNumber, encLevel protocol.EncryptionLevel) *Packet {
 		if el, ok := handler.getPacketNumberSpace(encLevel).history.packetMap[pn]; ok {
-			return &el.Value
+			return el.Value
 		}
 		return nil
 	}

internal/ackhandler/sent_packet_history.go

@@ -11,18 +11,18 @@ import (
 
 type sentPacketHistory struct {
 	rttStats              *utils.RTTStats
-	outstandingPacketList *list.List[Packet]
-	etcPacketList         *list.List[Packet]
-	packetMap             map[protocol.PacketNumber]*list.Element[Packet]
+	outstandingPacketList *list.List[*Packet]
+	etcPacketList         *list.List[*Packet]
+	packetMap             map[protocol.PacketNumber]*list.Element[*Packet]
 	highestSent           protocol.PacketNumber
 }
 
 func newSentPacketHistory(rttStats *utils.RTTStats) *sentPacketHistory {
 	return &sentPacketHistory{
 		rttStats:              rttStats,
-		outstandingPacketList: list.New[Packet](),
-		etcPacketList:         list.New[Packet](),
-		packetMap:             make(map[protocol.PacketNumber]*list.Element[Packet]),
+		outstandingPacketList: list.New[*Packet](),
+		etcPacketList:         list.New[*Packet](),
+		packetMap:             make(map[protocol.PacketNumber]*list.Element[*Packet]),
 		highestSent:           protocol.InvalidPacketNumber,
 	}
 }
@@ -33,7 +33,7 @@ func (h *sentPacketHistory) SentPacket(p *Packet, isAckEliciting bool) {
 	}
 	// Skipped packet numbers.
 	for pn := h.highestSent + 1; pn < p.PacketNumber; pn++ {
-		el := h.etcPacketList.PushBack(Packet{
+		el := h.etcPacketList.PushBack(&Packet{
 			PacketNumber:    pn,
 			EncryptionLevel: p.EncryptionLevel,
 			SendTime:        p.SendTime,
@@ -44,11 +44,11 @@ func (h *sentPacketHistory) SentPacket(p *Packet, isAckEliciting bool) {
 	h.highestSent = p.PacketNumber
 
 	if isAckEliciting {
-		var el *list.Element[Packet]
+		var el *list.Element[*Packet]
 		if p.outstanding() {
-			el = h.outstandingPacketList.PushBack(*p)
+			el = h.outstandingPacketList.PushBack(p)
 		} else {
-			el = h.etcPacketList.PushBack(*p)
+			el = h.etcPacketList.PushBack(p)
 		}
 		h.packetMap[p.PacketNumber] = el
 	}
@@ -59,7 +59,7 @@ func (h *sentPacketHistory) Iterate(cb func(*Packet) (cont bool, err error)) err
 	cont := true
 	outstandingEl := h.outstandingPacketList.Front()
 	etcEl := h.etcPacketList.Front()
-	var el *list.Element[Packet]
+	var el *list.Element[*Packet]
 	// whichever has the next packet number is returned first
 	for cont {
 		if outstandingEl == nil || (etcEl != nil && etcEl.Value.PacketNumber < outstandingEl.Value.PacketNumber) {
@@ -76,7 +76,7 @@ func (h *sentPacketHistory) Iterate(cb func(*Packet) (cont bool, err error)) err
 			etcEl = etcEl.Next()
 		}
 		var err error
-		cont, err = cb(&el.Value)
+		cont, err = cb(el.Value)
 		if err != nil {
 			return err
 		}
@@ -90,7 +90,7 @@ func (h *sentPacketHistory) FirstOutstanding() *Packet {
 	if el == nil {
 		return nil
 	}
-	return &el.Value
+	return el.Value
 }
 
 func (h *sentPacketHistory) Len() int {
@@ -114,7 +114,7 @@ func (h *sentPacketHistory) HasOutstandingPackets() bool {
 
 func (h *sentPacketHistory) DeleteOldPackets(now time.Time) {
 	maxAge := 3 * h.rttStats.PTO(false)
-	var nextEl *list.Element[Packet]
+	var nextEl *list.Element[*Packet]
 	// we don't iterate outstandingPacketList, as we should not delete outstanding packets.
 	// being outstanding for more than 3*PTO should only happen in the case of drastic RTT changes.
 	for el := h.etcPacketList.Front(); el != nil; el = nextEl {
@@ -145,10 +145,10 @@ func (h *sentPacketHistory) DeclareLost(p *Packet) *Packet {
 		}
 	}
 	if el == nil {
-		el = h.etcPacketList.PushFront(*p)
+		el = h.etcPacketList.PushFront(p)
 	} else {
-		el = h.etcPacketList.InsertAfter(*p, el)
+		el = h.etcPacketList.InsertAfter(p, el)
 	}
 	h.packetMap[p.PacketNumber] = el
-	return &el.Value
+	return el.Value
 }