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/*
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Copyright 2020 The Qmgo Authors.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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*/
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package qmgo
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import (
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"context"
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opts "github.com/qiniu/qmgo/options"
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"go.mongodb.org/mongo-driver/mongo"
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"go.mongodb.org/mongo-driver/mongo/options"
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"go.mongodb.org/mongo-driver/x/mongo/driver"
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)
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// Session is an struct that represents a MongoDB logical session
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type Session struct {
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session mongo.Session
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}
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// StartTransaction starts transaction
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//precondition：
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//- version of mongoDB server >= v4.0
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//- Topology of mongoDB server is not Single
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//At the same time, please pay attention to the following
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//- make sure all operations in callback use the sessCtx as context parameter
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//- Dont forget to call EndSession if session is not used anymore
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//- if operations in callback takes more than(include equal) 120s, the operations will not take effect,
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//- if operation in callback return qmgo.ErrTransactionRetry,
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// the whole transaction will retry, so this transaction must be idempotent
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//- if operations in callback return qmgo.ErrTransactionNotSupported,
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//- If the ctx parameter already has a Session attached to it, it will be replaced by this session.
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func (s *Session) StartTransaction(ctx context.Context, cb func(sessCtx context.Context) (interface{}, error), opts ...*opts.TransactionOptions) (interface{}, error) {
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transactionOpts := options.Transaction()
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if len(opts) > 0 && opts[0].TransactionOptions != nil {
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transactionOpts = opts[0].TransactionOptions
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}
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result, err := s.session.WithTransaction(ctx, wrapperCustomCb(cb), transactionOpts)
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if err != nil {
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return nil, err
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}
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return result, nil
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}
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// EndSession will abort any existing transactions and close the session.
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func (s *Session) EndSession(ctx context.Context) {
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s.session.EndSession(ctx)
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}
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// AbortTransaction aborts the active transaction for this session. This method will return an error if there is no
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// active transaction for this session or the transaction has been committed or aborted.
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func (s *Session) AbortTransaction(ctx context.Context) error {
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return s.session.AbortTransaction(ctx)
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}
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// wrapperCustomF wrapper caller's callback function to mongo dirver's
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func wrapperCustomCb(cb func(ctx context.Context) (interface{}, error)) func(sessCtx mongo.SessionContext) (interface{}, error) {
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return func(sessCtx mongo.SessionContext) (interface{}, error) {
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result, err := cb(sessCtx)
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if err == ErrTransactionRetry {
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return nil, mongo.CommandError{Labels: []string{driver.TransientTransactionError}}
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}
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return result, err
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}
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}
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