github.com/pingcap/tiflow@v0.0.0-20240520035814-5bf52d54e205/cdc/sink/dmlsink/mq/dispatcher/partition/index_value.go (about)

     1  // Copyright 2022 PingCAP, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package partition
    15  
    16  import (
    17  	"strconv"
    18  	"sync"
    19  
    20  	"github.com/pingcap/log"
    21  	"github.com/pingcap/tiflow/cdc/model"
    22  	"github.com/pingcap/tiflow/pkg/errors"
    23  	"github.com/pingcap/tiflow/pkg/hash"
    24  	"go.uber.org/zap"
    25  )
    26  
    27  // IndexValueDispatcher is a partition dispatcher which dispatches events based on the index value.
    28  type IndexValueDispatcher struct {
    29  	hasher *hash.PositionInertia
    30  	lock   sync.Mutex
    31  
    32  	IndexName string
    33  }
    34  
    35  // NewIndexValueDispatcher creates a IndexValueDispatcher.
    36  func NewIndexValueDispatcher(indexName string) *IndexValueDispatcher {
    37  	return &IndexValueDispatcher{
    38  		hasher:    hash.NewPositionInertia(),
    39  		IndexName: indexName,
    40  	}
    41  }
    42  
    43  // DispatchRowChangedEvent returns the target partition to which
    44  // a row changed event should be dispatched.
    45  func (r *IndexValueDispatcher) DispatchRowChangedEvent(row *model.RowChangedEvent, partitionNum int32) (int32, string, error) {
    46  	r.lock.Lock()
    47  	defer r.lock.Unlock()
    48  	r.hasher.Reset()
    49  	r.hasher.Write([]byte(row.TableInfo.GetSchemaName()), []byte(row.TableInfo.GetTableName()))
    50  
    51  	dispatchCols := row.Columns
    52  	if len(row.Columns) == 0 {
    53  		dispatchCols = row.PreColumns
    54  	}
    55  
    56  	// the most normal case, index-name is not set, use the handle key columns.
    57  	if r.IndexName == "" {
    58  		tableInfo := row.TableInfo
    59  		for _, col := range dispatchCols {
    60  			if col == nil {
    61  				continue
    62  			}
    63  			if tableInfo.ForceGetColumnFlagType(col.ColumnID).IsHandleKey() {
    64  				r.hasher.Write([]byte(tableInfo.ForceGetColumnName(col.ColumnID)), []byte(model.ColumnValueString(col.Value)))
    65  			}
    66  		}
    67  	} else {
    68  		names, offsets, ok := row.TableInfo.IndexByName(r.IndexName)
    69  		if !ok {
    70  			log.Error("index not found when dispatch event",
    71  				zap.Any("tableName", row.TableInfo.GetTableName()),
    72  				zap.String("indexName", r.IndexName))
    73  			return 0, "", errors.ErrDispatcherFailed.GenWithStack(
    74  				"index not found when dispatch event, table: %v, index: %s", row.TableInfo.GetTableName(), r.IndexName)
    75  		}
    76  		for idx := 0; idx < len(names); idx++ {
    77  			col := dispatchCols[offsets[idx]]
    78  			if col == nil {
    79  				continue
    80  			}
    81  			r.hasher.Write([]byte(names[idx]), []byte(model.ColumnValueString(col.Value)))
    82  		}
    83  	}
    84  
    85  	sum32 := r.hasher.Sum32()
    86  	return int32(sum32 % uint32(partitionNum)), strconv.FormatInt(int64(sum32), 10), nil
    87  }