83 lines
2.5 KiB
Go
83 lines
2.5 KiB
Go
// Copyright (C) MongoDB, Inc. 2017-present.
|
||
//
|
||
// 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
|
||
|
||
package readconcern // import "go.mongodb.org/mongo-driver/mongo/readconcern"
|
||
|
||
import (
|
||
"go.mongodb.org/mongo-driver/bson/bsontype"
|
||
"go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
|
||
)
|
||
|
||
// ReadConcern for replica sets and replica set shards determines which data to return from a query.
|
||
type ReadConcern struct {
|
||
level string
|
||
}
|
||
|
||
// Option is an option to provide when creating a ReadConcern.
|
||
type Option func(concern *ReadConcern)
|
||
|
||
// Level creates an option that sets the level of a ReadConcern.
|
||
func Level(level string) Option {
|
||
return func(concern *ReadConcern) {
|
||
concern.level = level
|
||
}
|
||
}
|
||
|
||
// Local specifies that the query should return the instance’s most recent data.
|
||
func Local() *ReadConcern {
|
||
return New(Level("local"))
|
||
}
|
||
|
||
// Majority specifies that the query should return the instance’s most recent data acknowledged as
|
||
// having been written to a majority of members in the replica set.
|
||
func Majority() *ReadConcern {
|
||
return New(Level("majority"))
|
||
}
|
||
|
||
// Linearizable specifies that the query should return data that reflects all successful writes
|
||
// issued with a write concern of "majority" and acknowledged prior to the start of the read operation.
|
||
func Linearizable() *ReadConcern {
|
||
return New(Level("linearizable"))
|
||
}
|
||
|
||
// Available specifies that the query should return data from the instance with no guarantee
|
||
// that the data has been written to a majority of the replica set members (i.e. may be rolled back).
|
||
func Available() *ReadConcern {
|
||
return New(Level("available"))
|
||
}
|
||
|
||
// Snapshot is only available for operations within multi-document transactions.
|
||
func Snapshot() *ReadConcern {
|
||
return New(Level("snapshot"))
|
||
}
|
||
|
||
// New constructs a new read concern from the given string.
|
||
func New(options ...Option) *ReadConcern {
|
||
concern := &ReadConcern{}
|
||
|
||
for _, option := range options {
|
||
option(concern)
|
||
}
|
||
|
||
return concern
|
||
}
|
||
|
||
// MarshalBSONValue implements the bson.ValueMarshaler interface.
|
||
func (rc *ReadConcern) MarshalBSONValue() (bsontype.Type, []byte, error) {
|
||
var elems []byte
|
||
|
||
if len(rc.level) > 0 {
|
||
elems = bsoncore.AppendStringElement(elems, "level", rc.level)
|
||
}
|
||
|
||
return bsontype.EmbeddedDocument, bsoncore.BuildDocument(nil, elems), nil
|
||
}
|
||
|
||
// GetLevel returns the read concern level.
|
||
func (rc *ReadConcern) GetLevel() string {
|
||
return rc.level
|
||
}
|