Refactor decodeOptionalMeta

Author: huangjunwen

replication/row_event.go

@@ -40,7 +40,7 @@ type TableMapEvent struct {
 
 SignednessBitmap []byte
 
-// DefaultCharset[0] is the default collation;
+// DefaultCharset[0] is the default collation of character columns.
 // For character columns that have different charset,
 // (character column index, column collation) pairs follows
 DefaultCharset []uint64
@@ -206,7 +206,7 @@ func (e *TableMapEvent) decodeMeta(data []byte) error {
 return nil
 }
 
-func (e *TableMapEvent) decodeOptionalMeta(data []byte) error {
+func (e *TableMapEvent) decodeOptionalMeta(data []byte) (err error) {
 
 pos := 0
 for pos < len(data) {
@@ -227,53 +227,30 @@ func (e *TableMapEvent) decodeOptionalMeta(data []byte) error {
 e.SignednessBitmap = v
 
 case TABLE_MAP_OPT_META_DEFAULT_CHARSET:
-p := 0
-for p < len(v) {
-c, _, n := LengthEncodedInt(v[p:])
-p += n
-e.DefaultCharset = append(e.DefaultCharset, c)
+e.DefaultCharset, err = e.decodeDefaultCharset(v)
+if err != nil {
+return err
 }
 
 case TABLE_MAP_OPT_META_COLUMN_CHARSET:
-p := 0
-for p < len(v) {
-c, _, n := LengthEncodedInt(v[p:])
-p += n
-e.ColumnCharset = append(e.ColumnCharset, c)
+e.ColumnCharset, err = e.decodeColumnCharset(v)
+if err != nil {
+return err
 }
 
 case TABLE_MAP_OPT_META_COLUMN_NAME:
-p := 0
-e.ColumnName = make([][]byte, 0, e.ColumnCount)
-for p < len(v) {
-n := int(v[p])
-p++
-e.ColumnName = append(e.ColumnName, v[p:p+n])
-p += n
-}
-
-if len(e.ColumnName) != int(e.ColumnCount) {
-return errors.Errorf("Expect %d column names but got %d", e.ColumnCount, len(e.ColumnName))
+if err = e.decodeColumnNames(v); err != nil {
+return err
 }
 
 case TABLE_MAP_OPT_META_SIMPLE_PRIMARY_KEY:
-p := 0
-for p < len(v) {
-i, _, n := LengthEncodedInt(v[p:])
-e.PrimaryKey = append(e.PrimaryKey, i)
-e.PrimaryKeyPrefix = append(e.PrimaryKeyPrefix, 0)
-p += n
+if err = e.decodeSimplePrimaryKey(v); err != nil {
+return err
 }
 
 case TABLE_MAP_OPT_META_PRIMARY_KEY_WITH_PREFIX:
-p := 0
-for p < len(v) {
-i, _, n := LengthEncodedInt(v[p:])
-e.PrimaryKey = append(e.PrimaryKey, i)
-p += n
-i, _, n = LengthEncodedInt(v[p:])
-e.PrimaryKeyPrefix = append(e.PrimaryKeyPrefix, i)
-p += n
+if err = e.decodePrimaryKeyWithPrefix(v); err != nil {
+return err
 }
 
 default:
@@ -285,6 +262,70 @@ func (e *TableMapEvent) decodeOptionalMeta(data []byte) error {
 return nil
 }
 
+func (e *TableMapEvent) decodeDefaultCharset(v []byte) (ret []uint64, err error) {
+p := 0
+for p < len(v) {
+c, _, n := LengthEncodedInt(v[p:])
+p += n
+ret = append(ret, c)
+}
+
+if len(ret)%2 != 1 {
+return nil, errors.Errorf("Expect odd item in DefaultCharset but got %d", len(ret))
+}
+return
+}
+
+func (e *TableMapEvent) decodeColumnCharset(v []byte) (ret []uint64, err error) {
+p := 0
+for p < len(v) {
+c, _, n := LengthEncodedInt(v[p:])
+p += n
+ret = append(ret, c)
+}
+return
+}
+
+func (e *TableMapEvent) decodeColumnNames(v []byte) error {
+p := 0
+e.ColumnName = make([][]byte, 0, e.ColumnCount)
+for p < len(v) {
+n := int(v[p])
+p++
+e.ColumnName = append(e.ColumnName, v[p:p+n])
+p += n
+}
+
+if len(e.ColumnName) != int(e.ColumnCount) {
+return errors.Errorf("Expect %d column names but got %d", e.ColumnCount, len(e.ColumnName))
+}
+return nil
+}
+
+func (e *TableMapEvent) decodeSimplePrimaryKey(v []byte) error {
+p := 0
+for p < len(v) {
+i, _, n := LengthEncodedInt(v[p:])
+e.PrimaryKey = append(e.PrimaryKey, i)
+e.PrimaryKeyPrefix = append(e.PrimaryKeyPrefix, 0)
+p += n
+}
+return nil
+}
+
+func (e *TableMapEvent) decodePrimaryKeyWithPrefix(v []byte) error {
+p := 0
+for p < len(v) {
+i, _, n := LengthEncodedInt(v[p:])
+e.PrimaryKey = append(e.PrimaryKey, i)
+p += n
+i, _, n = LengthEncodedInt(v[p:])
+e.PrimaryKeyPrefix = append(e.PrimaryKeyPrefix, i)
+p += n
+}
+return nil
+}
+
 func (e *TableMapEvent) Dump(w io.Writer) {
 fmt.Fprintf(w, "TableID: %d\n", e.TableID)
 fmt.Fprintf(w, "TableID size: %d\n", e.tableIDSize)
@@ -464,7 +505,6 @@ func (e *TableMapEvent) realType(i int) byte {
 
 case MYSQL_TYPE_DATE:
 return MYSQL_TYPE_NEWDATE
-
 }
 
 return typ