mirror of
https://github.com/etcd-io/etcd.git
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94 lines
2.6 KiB
Go
94 lines
2.6 KiB
Go
// Copyright 2021 The etcd Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package schema
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import (
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"go.etcd.io/etcd/server/v3/storage/backend"
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"go.uber.org/zap"
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)
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type action interface {
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// unsafeDo executes the action and returns revert action, when executed
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// should restore the state from before.
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unsafeDo(tx backend.BatchTx) (revert action, err error)
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}
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type setKeyAction struct {
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Bucket backend.Bucket
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FieldName []byte
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FieldValue []byte
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}
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func (a setKeyAction) unsafeDo(tx backend.BatchTx) (action, error) {
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revert := restoreFieldValueAction(tx, a.Bucket, a.FieldName)
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tx.UnsafePut(a.Bucket, a.FieldName, a.FieldValue)
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return revert, nil
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}
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type deleteKeyAction struct {
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Bucket backend.Bucket
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FieldName []byte
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}
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func (a deleteKeyAction) unsafeDo(tx backend.BatchTx) (action, error) {
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revert := restoreFieldValueAction(tx, a.Bucket, a.FieldName)
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tx.UnsafeDelete(a.Bucket, a.FieldName)
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return revert, nil
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}
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func restoreFieldValueAction(tx backend.BatchTx, bucket backend.Bucket, fieldName []byte) action {
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_, vs := tx.UnsafeRange(bucket, fieldName, nil, 1)
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if len(vs) == 1 {
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return &setKeyAction{
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Bucket: bucket,
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FieldName: fieldName,
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FieldValue: vs[0],
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}
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}
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return &deleteKeyAction{
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Bucket: bucket,
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FieldName: fieldName,
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}
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}
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type ActionList []action
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// unsafeExecute executes actions one by one. If one of actions returns error,
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// it will revert them.
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func (as ActionList) unsafeExecute(lg *zap.Logger, tx backend.BatchTx) error {
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var revertActions = make(ActionList, 0, len(as))
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for _, a := range as {
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revert, err := a.unsafeDo(tx)
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if err != nil {
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revertActions.unsafeExecuteInReversedOrder(lg, tx)
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return err
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}
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revertActions = append(revertActions, revert)
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}
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return nil
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}
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// unsafeExecuteInReversedOrder executes actions in revered order. Will panic on
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// action error. Should be used when reverting.
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func (as ActionList) unsafeExecuteInReversedOrder(lg *zap.Logger, tx backend.BatchTx) {
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for j := len(as) - 1; j >= 0; j-- {
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_, err := as[j].unsafeDo(tx)
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if err != nil {
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lg.Panic("Cannot recover from revert error", zap.Error(err))
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}
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}
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}
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