From 53ac47950c19c7547ed6cc9b7b215a1b5ef5c5e5 Mon Sep 17 00:00:00 2001
From: wdvxdr <wdvxdr1123@gmail.com>
Date: Tue, 17 Aug 2021 16:27:58 +0800
Subject: [PATCH] jce: optimize readByte.
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name                            old time/op    new time/op    delta
JceReader_ReadSlice-8              271µs ± 2%     228µs ± 7%  -15.97%  (p=0.000 n=9+10)
RequestDataVersion2_ReadFrom-8    4.57µs ± 6%    4.08µs ± 2%  -10.74%  (p=0.000 n=10+10)

name                            old speed      new speed      delta
JceReader_ReadSlice-8           77.6MB/s ± 2%  92.5MB/s ± 7%  +19.14%  (p=0.000 n=9+10)
RequestDataVersion2_ReadFrom-8  20.4MB/s ± 6%  22.8MB/s ± 2%  +11.92%  (p=0.000 n=10+10)

name                            old alloc/op   new alloc/op   delta
JceReader_ReadSlice-8             73.4kB ± 0%    65.3kB ± 0%  -10.96%  (p=0.000 n=9+6)
RequestDataVersion2_ReadFrom-8    2.64kB ± 0%    2.59kB ± 0%   -1.93%  (p=0.000 n=10+10)

name                            old allocs/op  new allocs/op  delta
JceReader_ReadSlice-8              6.02k ± 0%     3.01k ± 0%  -49.96%  (p=0.000 n=10+10)
RequestDataVersion2_ReadFrom-8      67.0 ± 0%      46.0 ± 0%  -31.34%  (p=0.000 n=10+10)
---
 binary/jce/reader.go      | 20 ++++++++++++--------
 binary/jce/reader_test.go |  2 +-
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/binary/jce/reader.go b/binary/jce/reader.go
index 7771a3bd..558cef0a 100644
--- a/binary/jce/reader.go
+++ b/binary/jce/reader.go
@@ -3,13 +3,13 @@ package jce
 import (
 	"bytes"
 	goBinary "encoding/binary"
+	"io"
 	"math"
 	"reflect"
 )
 
 type JceReader struct {
-	buf  *bytes.Reader
-	data []byte
+	buf *bytes.Reader
 }
 
 type HeadData struct {
@@ -19,7 +19,7 @@ type HeadData struct {
 
 func NewJceReader(data []byte) *JceReader {
 	buf := bytes.NewReader(data)
-	return &JceReader{buf: buf, data: data}
+	return &JceReader{buf: buf}
 }
 
 func (r *JceReader) readHead() (hd HeadData, l int32) {
@@ -34,10 +34,10 @@ func (r *JceReader) readHead() (hd HeadData, l int32) {
 	return hd, 1
 }
 
-func (r *JceReader) peakHead() (HeadData, int32) {
-	offset := r.buf.Size() - int64(r.buf.Len())
-	n := NewJceReader(r.data[offset:])
-	return n.readHead()
+func (r *JceReader) peakHead() (h HeadData, l int32) {
+	h, l = r.readHead()
+	_, _ = r.buf.Seek(int64(-l), io.SeekCurrent)
+	return
 }
 
 func (r *JceReader) skip(l int) {
@@ -99,7 +99,11 @@ func (r *JceReader) readBytes(len int) []byte {
 }
 
 func (r *JceReader) readByte() byte {
-	return r.readBytes(1)[0]
+	b, err := r.buf.ReadByte()
+	if err != nil {
+		panic(err)
+	}
+	return b
 }
 
 func (r *JceReader) readUInt16() uint16 {
diff --git a/binary/jce/reader_test.go b/binary/jce/reader_test.go
index 0a687501..cebad57b 100644
--- a/binary/jce/reader_test.go
+++ b/binary/jce/reader_test.go
@@ -35,7 +35,7 @@ func BenchmarkJceReader_ReadSlice(b *testing.B) {
 	src := w.Bytes()
 	b.SetBytes(int64(len(src)))
 	b.StartTimer()
-	var result = []BigDataIPInfo{}
+	result := make([]BigDataIPInfo, 0)
 	for i := 0; i < b.N; i++ {
 		r := NewJceReader(src)
 		r.ReadSlice(&result, 1)