use map to speedup lookup of fields

Author: dveeden

serialization/serialization.go

@@ -16,8 +16,9 @@ import (
 
 // Message is a mysql::serialization message
 type Message struct {
-	Version uint8 // >= 0
-	Format  Format
+	Version    uint8 // >= 0
+	Format     Format
+	fieldIndex map[string]int
 }
 
 func (m *Message) String() (text string) {
@@ -30,10 +31,8 @@ func (m *Message) String() (text string) {
 
 // GetFieldByName returns a field if the name matches and an error if there is no match
 func (m *Message) GetFieldByName(name string) (Field, error) {
-	for _, f := range m.Format.Fields {
-		if f.Name == name {
-			return f, nil
-		}
+	if idx, ok := m.fieldIndex[name]; ok {
+		return m.Format.Fields[idx], nil
 	}
 	return Field{}, fmt.Errorf("field not found: %s", name)
 }
@@ -125,6 +124,12 @@ func Unmarshal(data []byte, v interface{}) error {
 		if err != nil {
 			return err
 		}
+		if m.fieldIndex == nil {
+			m.fieldIndex = make(map[string]int, len(m.Format.Fields))
+		}
+		for _, field := range m.Format.Fields {
+			m.fieldIndex[field.Name] = field.ID
+		}
 	case *Format:
 		pos := uint64(0)
 		m.Size = uint64(data[pos] >> 1)

serialization/serialization_test.go

@@ -382,6 +382,20 @@ func TestUmarshal_event1(t *testing.T) {
 				},
 			},
 		},
+		fieldIndex: map[string]int{
+			"gtid_flags":                 0,
+			"uuid":                       1,
+			"gno":                        2,
+			"tag":                        3,
+			"last_committed":             4,
+			"sequence_number":            5,
+			"immediate_commit_timestamp": 6,
+			"original_commit_timestamp":  7,
+			"transaction_length":         8,
+			"immediate_server_version":   9,
+			"original_server_version":    10,
+			"commit_group_ticket":        11,
+		},
 	}
 
 	err := Unmarshal(data, &msg)
@@ -392,4 +406,8 @@ func TestUmarshal_event1(t *testing.T) {
 	}
 
 	require.Equal(t, expected, msg)
+
+	sv, err := msg.GetFieldByName("immediate_server_version")
+	require.NoError(t, err)
+	require.Equal(t, 9, sv.ID)
 }