tidb txn_scope_var 源码
tidb txn_scope_var 代码
文件路径：/kv/txn_scope_var.go
// Copyright 2021 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 kv
import (
"github.com/pingcap/tidb/config"
"github.com/tikv/client-go/v2/oracle"
)
// TxnScopeVar indicates the used txnScope for oracle
type TxnScopeVar struct {
// varValue indicates the value of @@txn_scope, which can only be `global` or `local`
varValue string
// txnScope indicates the value which the tidb-server holds to request tso to pd
txnScope string
}
// NewDefaultTxnScopeVar creates a default TxnScopeVar according to the config.
// If zone label is set, we will check whether it's not the GlobalTxnScope and create a new Local TxnScopeVar.
// If zone label is not set, we will create a new Global TxnScopeVar.
func NewDefaultTxnScopeVar() TxnScopeVar {
if txnScope := config.GetTxnScopeFromConfig(); txnScope != GlobalTxnScope {
return NewLocalTxnScopeVar(txnScope)
}
return NewGlobalTxnScopeVar()
}
// NewGlobalTxnScopeVar creates a Global TxnScopeVar
func NewGlobalTxnScopeVar() TxnScopeVar {
return newTxnScopeVar(GlobalTxnScope, GlobalTxnScope)
}
// NewLocalTxnScopeVar creates a Local TxnScopeVar with given real txnScope value.
func NewLocalTxnScopeVar(txnScope string) TxnScopeVar {
return newTxnScopeVar(LocalTxnScope, txnScope)
}
// GetVarValue returns the value of @@txn_scope which can only be `global` or `local`
func (t TxnScopeVar) GetVarValue() string {
return t.varValue
}
// GetTxnScope returns the value of the tidb-server holds to request tso to pd.
// When varValue is 'global`, directly return global here
func (t TxnScopeVar) GetTxnScope() string {
return t.txnScope
}
func newTxnScopeVar(varValue string, txnScope string) TxnScopeVar {
return TxnScopeVar{
varValue: varValue,
txnScope: txnScope,
}
}
// Transaction scopes constants.
const (
// GlobalTxnScope is synced with PD's define of global scope.
// If we want to remove the dependency on store/tikv here, we need to map
// the two GlobalTxnScopes in the driver layer.
GlobalTxnScope = oracle.GlobalTxnScope
// LocalTxnScope indicates the transaction should use local ts.
LocalTxnScope = "local"
)
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