network: don't allocate in DedupAddrs

core/network/network.go

@@ -9,9 +9,10 @@ import (
 	"bytes"
 	"context"
 	"io"
-	"sort"
 	"time"
 
+	"golang.org/x/exp/slices"
+
 	"github.com/libp2p/go-libp2p/core/peer"
 	"github.com/libp2p/go-libp2p/core/peerstore"
 
@@ -203,7 +204,8 @@ func DedupAddrs(addrs []ma.Multiaddr) []ma.Multiaddr {
 	if len(addrs) == 0 {
 		return addrs
 	}
-	sort.Slice(addrs, func(i, j int) bool { return bytes.Compare(addrs[i].Bytes(), addrs[j].Bytes()) < 0 })
+	// Use the new slices package here, as the sort function doesn't allocate (sort.Slice does).
+	slices.SortFunc(addrs, func(a, b ma.Multiaddr) bool { return bytes.Compare(a.Bytes(), b.Bytes()) < 0 })
 	idx := 1
 	for i := 1; i < len(addrs); i++ {
 		if !addrs[i-1].Equal(addrs[i]) {

core/network/network_test.go

@@ -2,6 +2,8 @@ package network
 
 import (
 	"fmt"
+	"math"
+	"math/rand"
 	"testing"
 
 	ma "github.com/multiformats/go-multiaddr"
@@ -34,3 +36,24 @@ func TestDedupAddrs(t *testing.T) {
 		})
 	}
 }
+
+func BenchmarkDedupAddrs(b *testing.B) {
+	b.ReportAllocs()
+	var addrs []ma.Multiaddr
+	r := rand.New(rand.NewSource(1234))
+	for i := 0; i < 100; i++ {
+		tcpAddr := ma.StringCast(fmt.Sprintf("/ip4/127.0.0.1/tcp/%d", r.Intn(math.MaxUint16)))
+		quicAddr := ma.StringCast(fmt.Sprintf("/ip4/127.0.0.1/udp/%d/quic-v1", r.Intn(math.MaxUint16)))
+		wsAddr := ma.StringCast(fmt.Sprintf("/ip4/127.0.0.1/tcp/%d/ws", r.Intn(math.MaxUint16)))
+		addrs = append(addrs, tcpAddr, tcpAddr, quicAddr, quicAddr, wsAddr)
+	}
+	for _, sz := range []int{10, 20, 30, 50, 100} {
+		b.Run(fmt.Sprintf("%d", sz), func(b *testing.B) {
+			items := make([]ma.Multiaddr, sz)
+			for i := 0; i < b.N; i++ {
+				copy(items, addrs[:sz])
+				DedupAddrs(items)
+			}
+		})
+	}
+}