tidb schema_checker 源码
tidb schema_checker 代码
文件路径：/domain/schema_checker.go
// 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,
// 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 domain
import (
"time"
"github.com/pingcap/tidb/metrics"
"github.com/tikv/client-go/v2/tikv"
"github.com/tikv/client-go/v2/txnkv/transaction"
atomicutil "go.uber.org/atomic"
)
// SchemaChecker is used for checking schema-validity.
type SchemaChecker struct {
SchemaValidator
schemaVer int64
relatedTableIDs []int64
needCheckSchema bool
}
type intSchemaVer int64
func (i intSchemaVer) SchemaMetaVersion() int64 {
return int64(i)
}
var (
// SchemaOutOfDateRetryInterval is the backoff time before retrying.
SchemaOutOfDateRetryInterval = atomicutil.NewDuration(500 * time.Millisecond)
// SchemaOutOfDateRetryTimes is the max retry count when the schema is out of date.
SchemaOutOfDateRetryTimes = atomicutil.NewInt32(10)
)
// NewSchemaChecker creates a new schema checker.
func NewSchemaChecker(do *Domain, schemaVer int64, relatedTableIDs []int64, needCheckSchema bool) *SchemaChecker {
return &SchemaChecker{
SchemaValidator: do.SchemaValidator,
schemaVer: schemaVer,
relatedTableIDs: relatedTableIDs,
needCheckSchema: needCheckSchema,
}
}
// Check checks the validity of the schema version.
func (s *SchemaChecker) Check(txnTS uint64) (*transaction.RelatedSchemaChange, error) {
return s.CheckBySchemaVer(txnTS, intSchemaVer(s.schemaVer))
}
// CheckBySchemaVer checks if the schema version valid or not at txnTS.
func (s *SchemaChecker) CheckBySchemaVer(txnTS uint64, startSchemaVer tikv.SchemaVer) (*transaction.RelatedSchemaChange, error) {
schemaOutOfDateRetryInterval := SchemaOutOfDateRetryInterval.Load()
schemaOutOfDateRetryTimes := int(SchemaOutOfDateRetryTimes.Load())
for i := 0; i < schemaOutOfDateRetryTimes; i++ {
relatedChange, CheckResult := s.SchemaValidator.Check(txnTS, startSchemaVer.SchemaMetaVersion(), s.relatedTableIDs, s.needCheckSchema)
switch CheckResult {
case ResultSucc:
return nil, nil
case ResultFail:
metrics.SchemaLeaseErrorCounter.WithLabelValues("changed").Inc()
return relatedChange, ErrInfoSchemaChanged
case ResultUnknown:
time.Sleep(schemaOutOfDateRetryInterval)
}
}
metrics.SchemaLeaseErrorCounter.WithLabelValues("outdated").Inc()
return nil, ErrInfoSchemaExpired
}
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