proxy: optimize packet sorting logic (#4923)

integrationtests/tools/proxy/proxy.go

@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"net"
 	"os"
-	"sort"
+	"slices"
 	"sync"
 	"time"
 
@@ -64,17 +64,11 @@ type packetEntry struct {
 	Raw  []byte
 }
 
-type packetEntries []packetEntry
-
-func (e packetEntries) Len() int           { return len(e) }
-func (e packetEntries) Less(i, j int) bool { return e[i].Time.Before(e[j].Time) }
-func (e packetEntries) Swap(i, j int)      { e[i], e[j] = e[j], e[i] }
-
 type queue struct {
 	sync.Mutex
 
 	timer   *utils.Timer
-	Packets packetEntries
+	Packets []packetEntry // sorted by the packetEntry.Time
 }
 
 func newQueue() *queue {
@@ -83,15 +77,27 @@ func newQueue() *queue {
 
 func (q *queue) Add(e packetEntry) {
 	q.Lock()
+	defer q.Unlock()
+
+	if len(q.Packets) == 0 {
 		q.Packets = append(q.Packets, e)
-	if len(q.Packets) > 1 {
+		q.timer.Reset(e.Time)
-		lastIndex := len(q.Packets) - 1
+		return
-		if q.Packets[lastIndex].Time.Before(q.Packets[lastIndex-1].Time) {
-			sort.Stable(q.Packets)
 	}
+
+	// The packets slice is sorted by the packetEntry.Time.
+	// We only need to insert the packet at the correct position.
+	idx := slices.IndexFunc(q.Packets, func(p packetEntry) bool {
+		return p.Time.After(e.Time)
+	})
+	if idx == -1 {
+		q.Packets = append(q.Packets, e)
+	} else {
+		q.Packets = slices.Insert(q.Packets, idx, e)
 	}
+	if idx == 0 {
 		q.timer.Reset(q.Packets[0].Time)
-	q.Unlock()
+	}
 }
 
 func (q *queue) Get() []byte {

integrationtests/tools/proxy/proxy_test.go

@@ -13,6 +13,32 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func TestPacketQueue(t *testing.T) {
+	q := newQueue()
+
+	getPackets := func() []string {
+		packets := make([]string, 0, len(q.Packets))
+		for _, p := range q.Packets {
+			packets = append(packets, string(p.Raw))
+		}
+		return packets
+	}
+
+	require.Empty(t, getPackets())
+	now := time.Now()
+
+	q.Add(packetEntry{Time: now, Raw: []byte("p3")})
+	require.Equal(t, []string{"p3"}, getPackets())
+	q.Add(packetEntry{Time: now.Add(time.Second), Raw: []byte("p4")})
+	require.Equal(t, []string{"p3", "p4"}, getPackets())
+	q.Add(packetEntry{Time: now.Add(-time.Second), Raw: []byte("p1")})
+	require.Equal(t, []string{"p1", "p3", "p4"}, getPackets())
+	q.Add(packetEntry{Time: now.Add(time.Second), Raw: []byte("p5")})
+	require.Equal(t, []string{"p1", "p3", "p4", "p5"}, getPackets())
+	q.Add(packetEntry{Time: now.Add(-time.Second), Raw: []byte("p2")})
+	require.Equal(t, []string{"p1", "p2", "p3", "p4", "p5"}, getPackets())
+}
+
 func newUPDConnLocalhost(t testing.TB) *net.UDPConn {
 	t.Helper()
 	conn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 0})