reduce allocation for interpolateParams

Author: shogo82148

buffer.go

@@ -31,6 +31,13 @@ func (wb *writeBuffer) takeBuffer(length int) []byte {
 	return make([]byte, length)
 }
 
+func (wb *writeBuffer) store(buf []byte) {
+	if cap(buf) < cap(wb.buf) || cap(buf) > maxPacketSize {
+		return
+	}
+	wb.buf = buf
+}
+
 type readBuffer struct {
 	buf []byte
 	idx int

connection.go

@@ -278,7 +278,9 @@ func (mc *mysqlConn) interpolateParams(query string, args []driver.Value) (strin
 	if argPos != len(args) {
 		return "", driver.ErrSkip
 	}
-	return string(buf), nil
+	s := string(buf)
+	mc.wbuf.store(buf[:0])
+	return s, nil
 }
 
 func (mc *mysqlConn) Exec(query string, args []driver.Value) (driver.Result, error) {