github.com/pingcap/tiflow@v0.0.0-20240520035814-5bf52d54e205/cdc/capture/election.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 capture
    15  
    16  import (
    17  	"context"
    18  
    19  	"github.com/pingcap/errors"
    20  	"github.com/pingcap/failpoint"
    21  	"go.etcd.io/etcd/client/v3/concurrency"
    22  	"go.etcd.io/etcd/server/v3/mvcc"
    23  )
    24  
    25  // election wraps the owner election methods.
    26  // It is useful in testing.
    27  type election interface {
    28  	campaign(ctx context.Context, key string) error
    29  	resign(ctx context.Context) error
    30  }
    31  
    32  type electionImpl struct {
    33  	election *concurrency.Election
    34  }
    35  
    36  func newElection(sess *concurrency.Session, key string) election {
    37  	return &electionImpl{
    38  		election: concurrency.NewElection(sess, key),
    39  	}
    40  }
    41  
    42  func (e *electionImpl) campaign(ctx context.Context, val string) error {
    43  	failpoint.Inject("capture-campaign-compacted-error", func() {
    44  		failpoint.Return(errors.Trace(mvcc.ErrCompacted))
    45  	})
    46  	return e.election.Campaign(ctx, val)
    47  }
    48  
    49  func (e *electionImpl) resign(ctx context.Context) error {
    50  	return e.election.Resign(ctx)
    51  }