wal: move record method to record.go

wal/record.go

@@ -17,6 +17,7 @@ limitations under the License.
 package wal
 
 import (
+	"encoding/binary"
 	"io"
 )
 
@@ -45,3 +46,13 @@ func readRecord(r io.Reader, rec *Record) error {
 	}
 	return rec.Unmarshal(d)
 }
+
+func writeInt64(w io.Writer, n int64) error {
+	return binary.Write(w, binary.LittleEndian, n)
+}
+
+func readInt64(r io.Reader) (int64, error) {
+	var n int64
+	err := binary.Read(r, binary.LittleEndian, &n)
+	return n, err
+}

wal/wal.go

@@ -19,7 +19,6 @@ package wal
 import (
 	"bufio"
 	"bytes"
-	"encoding/binary"
 	"fmt"
 	"io"
 	"log"
@@ -372,16 +371,6 @@ func parseWalName(str string) (seq, index int64, err error) {
 	return
 }
 
-func writeInt64(w io.Writer, n int64) error {
-	return binary.Write(w, binary.LittleEndian, n)
-}
-
-func readInt64(r io.Reader) (int64, error) {
-	var n int64
-	err := binary.Read(r, binary.LittleEndian, &n)
-	return n, err
-}
-
 func max(a, b int64) int64 {
 	if a > b {
 		return a