feat(jce): optimize ReadSlice performance.

name                   old time/op    new time/op    delta
JceReader_ReadSlice-8    1.09ms ± 7%    0.52ms ± 1%   -52.48%  (p=0.000 n=10+10)

name                   old speed      new speed      delta
JceReader_ReadSlice-8  19.4MB/s ± 7%  40.8MB/s ± 1%  +110.25%  (p=0.000 n=10+10)

name                   old alloc/op   new alloc/op   delta
JceReader_ReadSlice-8     594kB ± 1%     266kB ± 0%   -55.22%  (p=0.000 n=9+9)

name                   old allocs/op  new allocs/op  delta
JceReader_ReadSlice-8     22.6k ± 0%     18.0k ± 0%   -19.98%  (p=0.000 n=10+10)

binary/jce/reader.go

@@ -380,26 +380,26 @@ func (r *JceReader) ReadSlice(i interface{}, tag int) {
 	if t.Kind() != reflect.Ptr || t.Elem().Kind() != reflect.Slice {
 		return
 	}
-	if v.IsNil() {
-		return
-	}
+	t = t.Elem()
 	if !r.skipToTag(tag) {
 		return
 	}
 	hd, _ := r.readHead()
 	if hd.Type == 9 {
 		s := r.ReadInt32(0)
+		sv := reflect.MakeSlice(t, int(s), int(s))
+		t = t.Elem()
+		val := reflect.New(t)
 		for i := 0; i < int(s); i++ {
-			val := r.readObject(t.Elem(), 0)
-			v.Set(reflect.Append(v, val))
+			r.ReadObject(val.Interface(), 0)
+			sv.Index(i).Set(val.Elem())
 		}
+		v.Set(sv)
 	}
-	if hd.Type == 13 {
+	if hd.Type == 13 && t.Elem().Kind() == reflect.Uint8 {
 		r.readHead()
 		arr := r.readBytes(int(r.ReadInt32(0)))
-		for _, b := range arr {
-			v.Set(reflect.Append(v, reflect.ValueOf(b)))
-		}
+		v.SetBytes(arr)
 	}
 }
 
@@ -427,8 +427,12 @@ func (r *JceReader) ReadObject(i interface{}, tag int) {
 		*o = r.ReadFloat64(tag)
 	case *string:
 		*o = r.ReadString(tag)
+	case *[]byte:
+		r.ReadSlice(o, tag)
 	case IJceStruct:
+		r.readHead()
 		o.ReadFrom(r)
+		r.skipToStructEnd()
 	}
 }
 

binary/jce/reader_test.go

@@ -0,0 +1,43 @@
+package jce
+
+import (
+	"math/rand"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestJceReader_ReadSlice(t *testing.T) {
+	s := make([]int64, 50)
+	for i := range s {
+		s[i] = rand.Int63()
+	}
+	w := NewJceWriter()
+	w.WriteObject(s, 1)
+	r := NewJceReader(w.Bytes())
+	var result []int64
+	r.ReadSlice(&result, 1)
+	assert.Equal(t, s, result)
+}
+
+var test []*BigDataIPInfo
+
+func BenchmarkJceReader_ReadSlice(b *testing.B) {
+	for i := 0; i <= 500; i++ {
+		test = append(test, &BigDataIPInfo{
+			Type:   1,
+			Server: "test1",
+			Port:   8080,
+		})
+	}
+	w := NewJceWriter()
+	w.WriteObject(test, 1)
+	src := w.Bytes()
+	b.SetBytes(int64(len(src)))
+	b.StartTimer()
+	var result = []BigDataIPInfo{}
+	for i := 0; i < b.N; i++ {
+		r := NewJceReader(src)
+		r.ReadSlice(&result, 1)
+	}
+}

go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/json-iterator/go v1.1.10
 	github.com/modern-go/reflect2 v1.0.1
 	github.com/pkg/errors v0.9.1
+	github.com/stretchr/testify v1.3.0
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
 	google.golang.org/protobuf v1.25.0
 )