chore: preallocate slices (#1842)

* Preallocate slices

* Move slice allocs to right before they're used

* Revert slice assignments to append

* Don't preallocate for tests or deprecated code

* Don't preallocate too much

core/peer/addrinfo.go

@@ -86,14 +86,14 @@ func AddrInfoFromP2pAddr(m ma.Multiaddr) (*AddrInfo, error) {
 
 // AddrInfoToP2pAddrs converts an AddrInfo to a list of Multiaddrs.
 func AddrInfoToP2pAddrs(pi *AddrInfo) ([]ma.Multiaddr, error) {
-	var addrs []ma.Multiaddr
 	p2ppart, err := ma.NewComponent("p2p", Encode(pi.ID))
 	if err != nil {
 		return nil, err
 	}
 	if len(pi.Addrs) == 0 {
 		return []ma.Multiaddr{p2ppart}, nil
 	}
+	addrs := make([]ma.Multiaddr, 0, len(pi.Addrs))
 	for _, addr := range pi.Addrs {
 		addrs = append(addrs, addr.Encapsulate(p2ppart))
 	}

core/peer/record.go

@@ -231,7 +231,7 @@ func (r *PeerRecord) ToProtobuf() (*pb.PeerRecord, error) {
 }
 
 func addrsFromProtobuf(addrs []*pb.PeerRecord_AddressInfo) []ma.Multiaddr {
-	var out []ma.Multiaddr
+	out := make([]ma.Multiaddr, 0, len(addrs))
 	for _, addr := range addrs {
 		a, err := ma.NewMultiaddrBytes(addr.Multiaddr)
 		if err != nil {
@@ -243,7 +243,7 @@ func addrsFromProtobuf(addrs []*pb.PeerRecord_AddressInfo) []ma.Multiaddr {
 }
 
 func addrsToProtobuf(addrs []ma.Multiaddr) []*pb.PeerRecord_AddressInfo {
-	var out []*pb.PeerRecord_AddressInfo
+	out := make([]*pb.PeerRecord_AddressInfo, 0, len(addrs))
 	for _, addr := range addrs {
 		out = append(out, &pb.PeerRecord_AddressInfo{Multiaddr: addr.Bytes()})
 	}

p2p/discovery/routing/routing_test.go

@@ -135,7 +135,7 @@ func TestDiscoveryRouting(t *testing.T) {
 
 	pch := r2.FindProvidersAsync(ctx, c, 20)
 
-	var allAIs []peer.AddrInfo
+	allAIs := make([]peer.AddrInfo, 0, len(pch))
 	for ai := range pch {
 		allAIs = append(allAIs, ai)
 	}

p2p/discovery/util/util.go

@@ -14,13 +14,13 @@ var log = logging.Logger("discovery-util")
 
 // FindPeers is a utility function that synchronously collects peers from a Discoverer.
 func FindPeers(ctx context.Context, d discovery.Discoverer, ns string, opts ...discovery.Option) ([]peer.AddrInfo, error) {
-	var res []peer.AddrInfo
 
 	ch, err := d.FindPeers(ctx, ns, opts...)
 	if err != nil {
 		return nil, err
 	}
 
+	res := make([]peer.AddrInfo, 0, len(ch))
 	for pi := range ch {
 		res = append(res, pi)
 	}

p2p/net/mock/mock_peernet.go

@@ -255,7 +255,7 @@ func (pn *peernet) ConnsToPeer(p peer.ID) []network.Conn {
 		return nil
 	}
 
-	var cs2 []network.Conn
+	cs2 := make([]network.Conn, 0, len(cs))
 	for c := range cs {
 		cs2 = append(cs2, c)
 	}

p2p/protocol/circuitv2/util/pbconv.go

@@ -36,10 +36,7 @@ func PeerToPeerInfoV1(p *pbv1.CircuitRelay_Peer) (peer.AddrInfo, error) {
 }
 
 func PeerInfoToPeerV1(pi peer.AddrInfo) *pbv1.CircuitRelay_Peer {
-	var addrs [][]byte
-	if len(pi.Addrs) > 0 {
-		addrs = make([][]byte, 0, len(pi.Addrs))
-	}
+	addrs := make([][]byte, 0, len(pi.Addrs))
 
 	for _, addr := range pi.Addrs {
 		addrs = append(addrs, addr.Bytes())
@@ -62,10 +59,7 @@ func PeerToPeerInfoV2(p *pbv2.Peer) (peer.AddrInfo, error) {
 		return peer.AddrInfo{}, err
 	}
 
-	var addrs []ma.Multiaddr
-	if len(p.Addrs) > 0 {
-		addrs = make([]ma.Multiaddr, 0, len(p.Addrs))
-	}
+	addrs := make([]ma.Multiaddr, 0, len(p.Addrs))
 
 	for _, addrBytes := range p.Addrs {
 		a, err := ma.NewMultiaddrBytes(addrBytes)
@@ -78,11 +72,7 @@ func PeerToPeerInfoV2(p *pbv2.Peer) (peer.AddrInfo, error) {
 }
 
 func PeerInfoToPeerV2(pi peer.AddrInfo) *pbv2.Peer {
-	var addrs [][]byte
-
-	if len(pi.Addrs) > 0 {
-		addrs = make([][]byte, 0, len(pi.Addrs))
-	}
+	addrs := make([][]byte, 0, len(pi.Addrs))
 
 	for _, addr := range pi.Addrs {
 		addrs = append(addrs, addr.Bytes())