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// Copyright 2018 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package decoder
import (
"sort"
"time"
"github.com/pingcap/parser/mysql"
"github.com/pingcap/tidb/expression"
"github.com/pingcap/tidb/sessionctx"
"github.com/pingcap/tidb/table"
"github.com/pingcap/tidb/table/tables"
"github.com/pingcap/tidb/tablecodec"
"github.com/pingcap/tidb/types"
"github.com/pingcap/tidb/util/chunk"
"github.com/pingcap/tidb/util/rowcodec"
)
// Column contains the info and generated expr of column.
type Column struct {
Col *table.Column
GenExpr expression.Expression
}
// RowDecoder decodes a byte slice into datums and eval the generated column value.
type RowDecoder struct {
tbl table.Table
mutRow chunk.MutRow
columns map[int64]Column
colTypes map[int64]*types.FieldType
defaultVals []types.Datum
}
// NewRowDecoder returns a new RowDecoder.
func NewRowDecoder(tbl table.Table, decodeColMap map[int64]Column) *RowDecoder {
colFieldMap := make(map[int64]*types.FieldType, len(decodeColMap))
for id, col := range decodeColMap {
colFieldMap[id] = &col.Col.ColumnInfo.FieldType
}
cols := tbl.Cols()
tps := make([]*types.FieldType, len(cols))
for _, col := range cols {
tps[col.Offset] = &col.FieldType
}
return &RowDecoder{
tbl: tbl,
mutRow: chunk.MutRowFromTypes(tps),
columns: decodeColMap,
colTypes: colFieldMap,
defaultVals: make([]types.Datum, len(cols)),
}
}
// DecodeAndEvalRowWithMap decodes a byte slice into datums and evaluates the generated column value.
func (rd *RowDecoder) DecodeAndEvalRowWithMap(ctx sessionctx.Context, handle int64, b []byte, decodeLoc, sysLoc *time.Location, row map[int64]types.Datum) (map[int64]types.Datum, error) {
var err error
if rowcodec.IsNewFormat(b) {
row, err = tablecodec.DecodeRowWithMapNew(b, rd.colTypes, decodeLoc, row)
} else {
row, err = tablecodec.DecodeRowWithMap(b, rd.colTypes, decodeLoc, row)
}
if err != nil {
return nil, err
}
for _, dCol := range rd.columns {
colInfo := dCol.Col.ColumnInfo
val, ok := row[colInfo.ID]
if ok || dCol.GenExpr != nil {
rd.mutRow.SetValue(colInfo.Offset, val.GetValue())
continue
}
// Get the default value of the column in the generated column expression.
if dCol.Col.IsPKHandleColumn(rd.tbl.Meta()) {
if mysql.HasUnsignedFlag(colInfo.Flag) {
val.SetUint64(uint64(handle))
} else {
val.SetInt64(handle)
}
} else {
val, err = tables.GetColDefaultValue(ctx, dCol.Col, rd.defaultVals)
if err != nil {
return nil, err
}
}
rd.mutRow.SetValue(colInfo.Offset, val.GetValue())
}
keys := make([]int, 0)
ids := make(map[int]int)
for k, col := range rd.columns {
keys = append(keys, col.Col.Offset)
ids[col.Col.Offset] = int(k)
}
sort.Ints(keys)
for _, id := range keys {
col := rd.columns[int64(ids[id])]
if col.GenExpr == nil {
continue
}
// Eval the column value
val, err := col.GenExpr.Eval(rd.mutRow.ToRow())
if err != nil {
return nil, err
}
val, err = table.CastValue(ctx, val, col.Col.ColumnInfo, false, true)
if err != nil {
return nil, err
}
if val.Kind() == types.KindMysqlTime && sysLoc != time.UTC {
t := val.GetMysqlTime()
if t.Type() == mysql.TypeTimestamp {
err := t.ConvertTimeZone(sysLoc, time.UTC)
if err != nil {
return nil, err
}
val.SetMysqlTime(t)
}
}
rd.mutRow.SetValue(col.Col.Offset, val.GetValue())
row[int64(ids[id])] = val
}
return row, nil
}
// BuildFullDecodeColMap build a map that contains [columnID -> struct{*table.Column, expression.Expression}] from all columns.
func BuildFullDecodeColMap(t table.Table, schema *expression.Schema) map[int64]Column {
decodeColMap := make(map[int64]Column, len(t.Cols()))
for _, col := range t.Cols() {
decodeColMap[col.ID] = Column{
Col: col,
GenExpr: schema.Columns[col.Offset].VirtualExpr,
}
}
return decodeColMap
}