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bocadillo/binlog/event_table_map.go

90 lines
2.3 KiB
Go

package binlog
import (
"github.com/localhots/bocadillo/mysql"
"github.com/localhots/bocadillo/tools"
)
// TableDescription contains table details required to process rows events.
type TableDescription struct {
Flags uint16
SchemaName string
TableName string
ColumnCount uint64
ColumnTypes []byte
ColumnMeta []uint16
NullBitmask []byte
}
// TableMapEvent contains table description alongside an ID that would be used
// to reference the table in the following rows events.
type TableMapEvent struct {
TableID uint64
TableDescription
}
// Decode decodes given buffer into a table map event.
// Spec: https://dev.mysql.com/doc/internals/en/table-map-event.html
func (e *TableMapEvent) Decode(connBuff []byte, fd FormatDescription) error {
buf := tools.NewBuffer(connBuff)
idSize := fd.TableIDSize(EventTypeTableMap)
if idSize == 6 {
e.TableID = buf.ReadUint48()
} else {
e.TableID = uint64(buf.ReadUint32())
}
e.Flags = buf.ReadUint16()
schemaName, _ := buf.ReadStringLenEnc()
e.SchemaName = string(schemaName)
buf.Skip(1) // Always 0x00
tableName, _ := buf.ReadStringLenEnc()
e.TableName = string(tableName)
buf.Skip(1) // Always 0x00
e.ColumnCount, _, _ = buf.ReadUintLenEnc()
e.ColumnTypes = buf.ReadStringVarLen(int(e.ColumnCount))
colMeta, _ := buf.ReadStringLenEnc()
e.ColumnMeta = decodeColumnMeta(colMeta, e.ColumnTypes)
e.NullBitmask = buf.ReadStringVarLen(int(e.ColumnCount+8) / 7)
return nil
}
func decodeColumnMeta(data []byte, cols []byte) []uint16 {
pos := 0
meta := make([]uint16, len(cols))
for i, typ := range cols {
switch mysql.ColumnType(typ) {
case mysql.ColumnTypeString:
// 1st: Type
// 2nd: Length
meta[i] = uint16(data[pos])<<8 | uint16(data[pos+1])
pos += 2
case mysql.ColumnTypeNewDecimal:
// 1st: Precision
// 2nd: Decimal places
meta[i] = uint16(data[pos])<<8 | uint16(data[pos+1])
pos += 2
case mysql.ColumnTypeVarchar,
mysql.ColumnTypeVarstring,
mysql.ColumnTypeBit:
// Likely it's length
meta[i] = mysql.DecodeUint16(data[pos:])
pos += 2
case mysql.ColumnTypeFloat,
mysql.ColumnTypeDouble,
mysql.ColumnTypeBlob,
mysql.ColumnTypeGeometry,
mysql.ColumnTypeJSON,
mysql.ColumnTypeTime2,
mysql.ColumnTypeDatetime2,
mysql.ColumnTypeTimestamp2:
meta[i] = uint16(data[pos])
pos++
}
}
return meta
}