all: implement AppendText alongside MarshalText (#9207)

This eventually allows encoding packages that may respect
the proposed encoding.TextAppender interface.
The performance gains from this is between 10-30%.

Updates tailscale/corp#14379

Signed-off-by: Joe Tsai <joetsai@digital-static.net>

control/controlclient/status.go

@@ -37,6 +37,10 @@
 	StateSynchronized // connected and received map update
 )
 
+func (s State) AppendText(b []byte) ([]byte, error) {
+	return append(b, s.String()...), nil
+}
+
 func (s State) MarshalText() ([]byte, error) {
 	return []byte(s.String()), nil
 }

tailcfg/tailcfg.go

@@ -7,7 +7,6 @@
 
 import (
 	"bytes"
-	"encoding/hex"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -445,6 +444,10 @@ func (n *Node) InitDisplayNames(networkMagicDNSSuffix string) {
 	MachineInvalid      // server has explicitly rejected this machine key
 )
 
+func (m MachineStatus) AppendText(b []byte) ([]byte, error) {
+	return append(b, m.String()...), nil
+}
+
 func (m MachineStatus) MarshalText() ([]byte, error) {
 	return []byte(m.String()), nil
 }
@@ -921,6 +924,10 @@ func appendStructPtrDiff(base []string, pfx string, p1, p2 reflect.Value) (ret [
 	SignatureV2
 )
 
+func (st SignatureType) AppendText(b []byte) ([]byte, error) {
+	return append(b, st.String()...), nil
+}
+
 func (st SignatureType) MarshalText() ([]byte, error) {
 	return []byte(st.String()), nil
 }
@@ -1765,18 +1772,6 @@ type Debug struct {
 	Exit *int `json:",omitempty"`
 }
 
-func appendKey(base []byte, prefix string, k [32]byte) []byte {
-	ret := append(base, make([]byte, len(prefix)+64)...)
-	buf := ret[len(base):]
-	copy(buf, prefix)
-	hex.Encode(buf[len(prefix):], k[:])
-	return ret
-}
-
-func keyMarshalText(prefix string, k [32]byte) []byte {
-	return appendKey(nil, prefix, k)
-}
-
 func (id ID) String() string      { return fmt.Sprintf("id:%x", int64(id)) }
 func (id UserID) String() string  { return fmt.Sprintf("userid:%x", int64(id)) }
 func (id LoginID) String() string { return fmt.Sprintf("loginid:%x", int64(id)) }

tailcfg/tailcfg_export_test.go

@@ -1,6 +0,0 @@
-// Copyright (c) Tailscale Inc & AUTHORS
-// SPDX-License-Identifier: BSD-3-Clause
-
-package tailcfg
-
-var ExportKeyMarshalText = keyMarshalText

tailcfg/tailcfg_test.go

@@ -16,11 +16,9 @@
 	"time"
 
 	. "tailscale.com/tailcfg"
-	"tailscale.com/tstest"
 	"tailscale.com/types/key"
 	"tailscale.com/types/ptr"
 	"tailscale.com/util/must"
-	"tailscale.com/version"
 )
 
 func fieldsOf(t reflect.Type) (fields []string) {
@@ -683,29 +681,6 @@ func TestEndpointTypeMarshal(t *testing.T) {
 	}
 }
 
-var sinkBytes []byte
-
-func BenchmarkKeyMarshalText(b *testing.B) {
-	b.ReportAllocs()
-	var k [32]byte
-	for i := 0; i < b.N; i++ {
-		sinkBytes = ExportKeyMarshalText("prefix", k)
-	}
-}
-
-func TestAppendKeyAllocs(t *testing.T) {
-	if version.IsRace() {
-		t.Skip("skipping in race detector") // append(b, make([]byte, N)...) not optimized in compiler with race
-	}
-	var k [32]byte
-	err := tstest.MinAllocsPerRun(t, 1, func() {
-		sinkBytes = ExportKeyMarshalText("prefix", k)
-	})
-	if err != nil {
-		t.Fatal(err)
-	}
-}
-
 func TestRegisterRequestNilClone(t *testing.T) {
 	var nilReq *RegisterRequest
 	got := nilReq.Clone()

tka/aum.go

@@ -9,6 +9,7 @@
 	"encoding/base32"
 	"errors"
 	"fmt"
+	"slices"
 
 	"github.com/fxamacker/cbor/v2"
 	"golang.org/x/crypto/blake2s"
@@ -37,11 +38,22 @@ func (h *AUMHash) UnmarshalText(text []byte) error {
 	return nil
 }
 
+// TODO(https://go.dev/issue/53693): Use base32.Encoding.AppendEncode instead.
+func base32AppendEncode(enc *base32.Encoding, dst, src []byte) []byte {
+	n := enc.EncodedLen(len(src))
+	dst = slices.Grow(dst, n)
+	enc.Encode(dst[len(dst):][:n], src)
+	return dst[:len(dst)+n]
+}
+
+// AppendText implements encoding.TextAppender.
+func (h AUMHash) AppendText(b []byte) ([]byte, error) {
+	return base32AppendEncode(base32StdNoPad, b, h[:]), nil
+}
+
 // MarshalText implements encoding.TextMarshaler.
 func (h AUMHash) MarshalText() ([]byte, error) {
-	b := make([]byte, base32StdNoPad.EncodedLen(len(h)))
+	return h.AppendText(nil)
-	base32StdNoPad.Encode(b, h[:])
-	return b, nil
 }
 
 // IsZero returns true if the hash is the empty value.

types/key/chal.go

@@ -72,9 +72,14 @@ func (k ChallengePublic) String() string {
 	return string(bs)
 }
 
+// AppendText implements encoding.TextAppender.
+func (k ChallengePublic) AppendText(b []byte) ([]byte, error) {
+	return appendHexKey(b, chalPublicHexPrefix, k.k[:]), nil
+}
+
 // MarshalText implements encoding.TextMarshaler.
 func (k ChallengePublic) MarshalText() ([]byte, error) {
-	return toHex(k.k[:], chalPublicHexPrefix), nil
+	return k.AppendText(nil)
 }
 
 // UnmarshalText implements encoding.TextUnmarshaler.

types/key/disco.go

@@ -127,9 +127,14 @@ func (k DiscoPublic) String() string {
 	return string(bs)
 }
 
+// AppendText implements encoding.TextAppender.
+func (k DiscoPublic) AppendText(b []byte) ([]byte, error) {
+	return appendHexKey(b, discoPublicHexPrefix, k.k[:]), nil
+}
+
 // MarshalText implements encoding.TextMarshaler.
 func (k DiscoPublic) MarshalText() ([]byte, error) {
-	return toHex(k.k[:], discoPublicHexPrefix), nil
+	return k.AppendText(nil)
 }
 
 // MarshalText implements encoding.TextUnmarshaler.

types/key/machine.go

@@ -67,9 +67,14 @@ func (k MachinePrivate) Public() MachinePublic {
 	return ret
 }
 
+// AppendText implements encoding.TextAppender.
+func (k MachinePrivate) AppendText(b []byte) ([]byte, error) {
+	return appendHexKey(b, machinePrivateHexPrefix, k.k[:]), nil
+}
+
 // MarshalText implements encoding.TextMarshaler.
 func (k MachinePrivate) MarshalText() ([]byte, error) {
-	return toHex(k.k[:], machinePrivateHexPrefix), nil
+	return k.AppendText(nil)
 }
 
 // MarshalText implements encoding.TextUnmarshaler.
@@ -243,9 +248,14 @@ func (k MachinePublic) String() string {
 	return string(bs)
 }
 
+// AppendText implements encoding.TextAppender.
+func (k MachinePublic) AppendText(b []byte) ([]byte, error) {
+	return appendHexKey(b, machinePublicHexPrefix, k.k[:]), nil
+}
+
 // MarshalText implements encoding.TextMarshaler.
 func (k MachinePublic) MarshalText() ([]byte, error) {
-	return toHex(k.k[:], machinePublicHexPrefix), nil
+	return k.AppendText(nil)
 }
 
 // MarshalText implements encoding.TextUnmarshaler.

types/key/nl.go

@@ -61,9 +61,14 @@ func (k *NLPrivate) UnmarshalText(b []byte) error {
 	return parseHex(k.k[:], mem.B(b), mem.S(nlPrivateHexPrefix))
 }
 
+// AppendText implements encoding.TextAppender.
+func (k NLPrivate) AppendText(b []byte) ([]byte, error) {
+	return appendHexKey(b, nlPrivateHexPrefix, k.k[:]), nil
+}
+
 // MarshalText implements encoding.TextMarshaler.
 func (k NLPrivate) MarshalText() ([]byte, error) {
-	return toHex(k.k[:], nlPrivateHexPrefix), nil
+	return k.AppendText(nil)
 }
 
 // Equal reports whether k and other are the same key.
@@ -132,10 +137,15 @@ func (k *NLPublic) UnmarshalText(b []byte) error {
 	return parseHex(k.k[:], mem.B(b), mem.S(nlPublicHexPrefix))
 }
 
+// AppendText implements encoding.TextAppender.
+func (k NLPublic) AppendText(b []byte) ([]byte, error) {
+	return appendHexKey(b, nlPublicHexPrefix, k.k[:]), nil
+}
+
 // MarshalText implements encoding.TextMarshaler, emitting a
 // representation of the form nlpub:<hex>.
 func (k NLPublic) MarshalText() ([]byte, error) {
-	return toHex(k.k[:], nlPublicHexPrefix), nil
+	return k.AppendText(nil)
 }
 
 // CLIString returns a marshalled representation suitable for use
@@ -143,7 +153,7 @@ func (k NLPublic) MarshalText() ([]byte, error) {
 // the nlpub:<hex> form emitted by MarshalText. Both forms can
 // be decoded by UnmarshalText.
 func (k NLPublic) CLIString() string {
-	return string(toHex(k.k[:], nlPublicHexPrefixCLI))
+	return string(appendHexKey(nil, nlPublicHexPrefixCLI, k.k[:]))
 }
 
 // Verifier returns a ed25519.PublicKey that can be used to

types/key/node.go

@@ -103,9 +103,14 @@ func (k NodePrivate) Public() NodePublic {
 	return ret
 }
 
+// AppendText implements encoding.TextAppender.
+func (k NodePrivate) AppendText(b []byte) ([]byte, error) {
+	return appendHexKey(b, nodePrivateHexPrefix, k.k[:]), nil
+}
+
 // MarshalText implements encoding.TextMarshaler.
 func (k NodePrivate) MarshalText() ([]byte, error) {
-	return toHex(k.k[:], nodePrivateHexPrefix), nil
+	return k.AppendText(nil)
 }
 
 // MarshalText implements encoding.TextUnmarshaler.
@@ -308,9 +313,14 @@ func (k NodePublic) String() string {
 	return string(bs)
 }
 
+// AppendText implements encoding.TextAppender.
+func (k NodePublic) AppendText(b []byte) ([]byte, error) {
+	return appendHexKey(b, nodePublicHexPrefix, k.k[:]), nil
+}
+
 // MarshalText implements encoding.TextMarshaler.
 func (k NodePublic) MarshalText() ([]byte, error) {
-	return toHex(k.k[:], nodePublicHexPrefix), nil
+	return k.AppendText(nil)
 }
 
 // MarshalText implements encoding.TextUnmarshaler.

types/key/util.go

@@ -10,6 +10,7 @@
 	"errors"
 	"fmt"
 	"io"
+	"slices"
 
 	"go4.org/mem"
 )
@@ -49,11 +50,19 @@ func clamp25519Private(b []byte) {
 	b[31] = (b[31] & 127) | 64
 }
 
-func toHex(k []byte, prefix string) []byte {
+func appendHexKey(dst []byte, prefix string, key []byte) []byte {
-	ret := make([]byte, len(prefix)+len(k)*2)
+	dst = slices.Grow(dst, len(prefix)+hex.EncodedLen(len(key)))
-	copy(ret, prefix)
+	dst = append(dst, prefix...)
-	hex.Encode(ret[len(prefix):], k)
+	dst = hexAppendEncode(dst, key)
-	return ret
+	return dst
+}
+
+// TODO(https://go.dev/issue/53693): Use hex.AppendEncode instead.
+func hexAppendEncode(dst, src []byte) []byte {
+	n := hex.EncodedLen(len(src))
+	dst = slices.Grow(dst, n)
+	hex.Encode(dst[len(dst):][:n], src)
+	return dst[:len(dst)+n]
 }
 
 // parseHex decodes a key string of the form "<prefix><hex string>"

types/logid/id.go

@@ -38,8 +38,12 @@ func ParsePrivateID(in string) (out PrivateID, err error) {
 	return out, err
 }
 
+func (id PrivateID) AppendText(b []byte) ([]byte, error) {
+	return hexAppendEncode(b, id[:]), nil
+}
+
 func (id PrivateID) MarshalText() ([]byte, error) {
-	return formatID(id), nil
+	return id.AppendText(nil)
 }
 
 func (id *PrivateID) UnmarshalText(in []byte) error {
@@ -47,7 +51,7 @@ func (id *PrivateID) UnmarshalText(in []byte) error {
 }
 
 func (id PrivateID) String() string {
-	return string(formatID(id))
+	return string(hexAppendEncode(nil, id[:]))
 }
 
 func (id PrivateID) IsZero() bool {
@@ -70,8 +74,12 @@ func ParsePublicID(in string) (out PublicID, err error) {
 	return out, err
 }
 
+func (id PublicID) AppendText(b []byte) ([]byte, error) {
+	return hexAppendEncode(b, id[:]), nil
+}
+
 func (id PublicID) MarshalText() ([]byte, error) {
-	return formatID(id), nil
+	return id.AppendText(nil)
 }
 
 func (id *PublicID) UnmarshalText(in []byte) error {
@@ -79,7 +87,7 @@ func (id *PublicID) UnmarshalText(in []byte) error {
 }
 
 func (id PublicID) String() string {
-	return string(formatID(id))
+	return string(hexAppendEncode(nil, id[:]))
 }
 
 func (id1 PublicID) Less(id2 PublicID) bool {
@@ -98,10 +106,12 @@ func (id PublicID) Prefix64() uint64 {
 	return binary.BigEndian.Uint64(id[:8])
 }
 
-func formatID(in [32]byte) []byte {
+// TODO(https://go.dev/issue/53693): Use hex.AppendEncode instead.
-	var hexArr [2 * len(in)]byte
+func hexAppendEncode(dst, src []byte) []byte {
-	hex.Encode(hexArr[:], in[:])
+	n := hex.EncodedLen(len(src))
-	return hexArr[:]
+	dst = slices.Grow(dst, n)
+	hex.Encode(dst[len(dst):][:n], src)
+	return dst[:len(dst)+n]
 }
 
 func parseID[Bytes []byte | string](funcName string, out *[32]byte, in Bytes) (err error) {