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vdbclient.go
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vdbclient.go
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/*
Copyright 2019 The Vitess Authors.
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,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package vreplication
import (
"io"
"time"
"context"
"vitess.io/vitess/go/mysql"
"vitess.io/vitess/go/sqltypes"
"vitess.io/vitess/go/vt/binlog/binlogplayer"
"vitess.io/vitess/go/vt/log"
)
// vdbClient is a wrapper on binlogplayer.DBClient.
// It allows us to retry a failed transactions on lock errors.
type vdbClient struct {
binlogplayer.DBClient
stats *binlogplayer.Stats
InTransaction bool
startTime time.Time
queries []string
}
func newVDBClient(dbclient binlogplayer.DBClient, stats *binlogplayer.Stats) *vdbClient {
return &vdbClient{
DBClient: dbclient,
stats: stats,
}
}
func (vc *vdbClient) Begin() error {
if vc.InTransaction {
return nil
}
if err := vc.DBClient.Begin(); err != nil {
return err
}
vc.queries = append(vc.queries, "begin")
vc.InTransaction = true
vc.startTime = time.Now()
return nil
}
func (vc *vdbClient) Commit() error {
if err := vc.DBClient.Commit(); err != nil {
return err
}
vc.InTransaction = false
vc.queries = nil
vc.stats.Timings.Record(binlogplayer.BlplTransaction, vc.startTime)
return nil
}
func (vc *vdbClient) Rollback() error {
if !vc.InTransaction {
return nil
}
if err := vc.DBClient.Rollback(); err != nil {
return err
}
vc.InTransaction = false
// Don't reset queries to allow for vplayer to retry.
return nil
}
func (vc *vdbClient) ExecuteFetch(query string, maxrows int) (*sqltypes.Result, error) {
defer vc.stats.Timings.Record(binlogplayer.BlplQuery, time.Now())
if !vc.InTransaction {
vc.queries = []string{query}
} else {
vc.queries = append(vc.queries, query)
}
return vc.DBClient.ExecuteFetch(query, maxrows)
}
// Execute is ExecuteFetch without the maxrows.
func (vc *vdbClient) Execute(query string) (*sqltypes.Result, error) {
// Number of rows should never exceed relayLogMaxItems.
return vc.ExecuteFetch(query, relayLogMaxItems)
}
func (vc *vdbClient) ExecuteWithRetry(ctx context.Context, query string) (*sqltypes.Result, error) {
qr, err := vc.Execute(query)
for err != nil {
if sqlErr, ok := err.(*mysql.SQLError); ok && sqlErr.Number() == mysql.ERLockDeadlock || sqlErr.Number() == mysql.ERLockWaitTimeout {
log.Infof("retryable error: %v, waiting for %v and retrying", sqlErr, dbLockRetryDelay)
if err := vc.Rollback(); err != nil {
return nil, err
}
time.Sleep(dbLockRetryDelay)
// Check context here. Otherwise this can become an infinite loop.
select {
case <-ctx.Done():
return nil, io.EOF
default:
}
qr, err = vc.Retry()
continue
}
return qr, err
}
return qr, nil
}
func (vc *vdbClient) Retry() (*sqltypes.Result, error) {
var qr *sqltypes.Result
for _, q := range vc.queries {
if q == "begin" {
if err := vc.Begin(); err != nil {
return nil, err
}
continue
}
// Number of rows should never exceed relayLogMaxItems.
result, err := vc.DBClient.ExecuteFetch(q, relayLogMaxItems)
if err != nil {
return nil, err
}
qr = result
}
return qr, nil
}