github.com/pingcap/tiflow@v0.0.0-20240520035814-5bf52d54e205/cdc/redo/writer/blackhole/blackhole_log_writer.go (about)

     1  // Copyright 2023 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 blackhole
    15  
    16  import (
    17  	"context"
    18  	"errors"
    19  
    20  	"github.com/pingcap/log"
    21  	"github.com/pingcap/tiflow/cdc/redo/writer"
    22  	"go.uber.org/zap"
    23  )
    24  
    25  var _ writer.RedoLogWriter = (*blackHoleWriter)(nil)
    26  
    27  // blackHoleSink defines a blackHole storage, it receives events and persists
    28  // without any latency
    29  type blackHoleWriter struct {
    30  	invalid bool
    31  }
    32  
    33  // NewLogWriter creates a blackHole writer
    34  func NewLogWriter(invalid bool) *blackHoleWriter {
    35  	return &blackHoleWriter{
    36  		invalid: invalid,
    37  	}
    38  }
    39  
    40  func (bs *blackHoleWriter) WriteEvents(_ context.Context, events ...writer.RedoEvent) (err error) {
    41  	if bs.invalid {
    42  		return errors.New("[WriteLog] invalid black hole writer")
    43  	}
    44  	if len(events) == 0 {
    45  		return nil
    46  	}
    47  	rl := events[len(events)-1].ToRedoLog()
    48  	current := rl.GetCommitTs()
    49  	log.Debug("write redo events", zap.Int("count", len(events)),
    50  		zap.Uint64("current", current))
    51  	return
    52  }
    53  
    54  func (bs *blackHoleWriter) FlushLog(_ context.Context) error {
    55  	if bs.invalid {
    56  		return errors.New("[FlushLog] invalid black hole writer")
    57  	}
    58  	return nil
    59  }
    60  
    61  func (bs *blackHoleWriter) Close() error {
    62  	return nil
    63  }