reuse existing buffer

Author: Reinier Schoof

server/resp.go

@@ -125,7 +125,7 @@ func (c *Conn) writeResultset(r *Resultset) error {
 		return err
 	}
 
-	if err := c.writeFieldList(r.Fields); err != nil {
+	if err := c.writeFieldList(r.Fields, data); err != nil {
 		return err
 	}
 
@@ -144,8 +144,10 @@ func (c *Conn) writeResultset(r *Resultset) error {
 	return nil
 }
 
-func (c *Conn) writeFieldList(fs []*Field) error {
-	data := make([]byte, 4, 1024)
+func (c *Conn) writeFieldList(fs []*Field, data []byte) error {
+	if data == nil {
+		data = make([]byte, 4, 1024)
+	}
 
 	for _, v := range fs {
 		data = data[0:4]
@@ -181,7 +183,7 @@ func (c *Conn) writeValue(value interface{}) error {
 			return c.writeOK(v)
 		}
 	case []*Field:
-		return c.writeFieldList(v)
+		return c.writeFieldList(v, nil)
 	case *Stmt:
 		return c.writePrepare(v)
 	default:

server/resp_test.go

@@ -182,7 +182,7 @@ func (t *respConnTestSuite) TestConnWriteFieldList(c *check.C) {
 
 	r, err := mysql.BuildSimpleTextResultset([]string{"c"}, [][]interface{}{{"d"}})
 	c.Assert(err, check.IsNil)
-	err = conn.writeFieldList(r.Fields)
+	err = conn.writeFieldList(r.Fields, nil)
 	c.Assert(err, check.IsNil)
 
 	// column length 1