Don Newton | 379ae25 | 2019-04-01 12:17:06 -0400 | [diff] [blame^] | 1 | // Copyright (C) MongoDB, Inc. 2017-present. |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); you may |
| 4 | // not use this file except in compliance with the License. You may obtain |
| 5 | // a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 |
| 6 | |
| 7 | package writeconcern |
| 8 | |
| 9 | import ( |
| 10 | "errors" |
| 11 | "time" |
| 12 | |
| 13 | "github.com/mongodb/mongo-go-driver/bson" |
| 14 | "github.com/mongodb/mongo-go-driver/bson/bsontype" |
| 15 | "github.com/mongodb/mongo-go-driver/x/bsonx/bsoncore" |
| 16 | ) |
| 17 | |
| 18 | // ErrInconsistent indicates that an inconsistent write concern was specified. |
| 19 | var ErrInconsistent = errors.New("a write concern cannot have both w=0 and j=true") |
| 20 | |
| 21 | // ErrEmptyWriteConcern indicates that a write concern has no fields set. |
| 22 | var ErrEmptyWriteConcern = errors.New("a write concern must have at least one field set") |
| 23 | |
| 24 | // ErrNegativeW indicates that a negative integer `w` field was specified. |
| 25 | var ErrNegativeW = errors.New("write concern `w` field cannot be a negative number") |
| 26 | |
| 27 | // ErrNegativeWTimeout indicates that a negative WTimeout was specified. |
| 28 | var ErrNegativeWTimeout = errors.New("write concern `wtimeout` field cannot be negative") |
| 29 | |
| 30 | // WriteConcern describes the level of acknowledgement requested from MongoDB for write operations |
| 31 | // to a standalone mongod or to replica sets or to sharded clusters. |
| 32 | type WriteConcern struct { |
| 33 | w interface{} |
| 34 | j bool |
| 35 | wTimeout time.Duration |
| 36 | } |
| 37 | |
| 38 | // Option is an option to provide when creating a ReadConcern. |
| 39 | type Option func(concern *WriteConcern) |
| 40 | |
| 41 | // New constructs a new WriteConcern. |
| 42 | func New(options ...Option) *WriteConcern { |
| 43 | concern := &WriteConcern{} |
| 44 | |
| 45 | for _, option := range options { |
| 46 | option(concern) |
| 47 | } |
| 48 | |
| 49 | return concern |
| 50 | } |
| 51 | |
| 52 | // W requests acknowledgement that write operations propagate to the specified number of mongod |
| 53 | // instances. |
| 54 | func W(w int) Option { |
| 55 | return func(concern *WriteConcern) { |
| 56 | concern.w = w |
| 57 | } |
| 58 | } |
| 59 | |
| 60 | // WMajority requests acknowledgement that write operations propagate to the majority of mongod |
| 61 | // instances. |
| 62 | func WMajority() Option { |
| 63 | return func(concern *WriteConcern) { |
| 64 | concern.w = "majority" |
| 65 | } |
| 66 | } |
| 67 | |
| 68 | // WTagSet requests acknowledgement that write operations propagate to the specified mongod |
| 69 | // instance. |
| 70 | func WTagSet(tag string) Option { |
| 71 | return func(concern *WriteConcern) { |
| 72 | concern.w = tag |
| 73 | } |
| 74 | } |
| 75 | |
| 76 | // J requests acknowledgement from MongoDB that write operations are written to |
| 77 | // the journal. |
| 78 | func J(j bool) Option { |
| 79 | return func(concern *WriteConcern) { |
| 80 | concern.j = j |
| 81 | } |
| 82 | } |
| 83 | |
| 84 | // WTimeout specifies specifies a time limit for the write concern. |
| 85 | func WTimeout(d time.Duration) Option { |
| 86 | return func(concern *WriteConcern) { |
| 87 | concern.wTimeout = d |
| 88 | } |
| 89 | } |
| 90 | |
| 91 | // MarshalBSONValue implements the bson.ValueMarshaler interface. |
| 92 | func (wc *WriteConcern) MarshalBSONValue() (bsontype.Type, []byte, error) { |
| 93 | if !wc.IsValid() { |
| 94 | return bsontype.Type(0), nil, ErrInconsistent |
| 95 | } |
| 96 | |
| 97 | var elems []byte |
| 98 | |
| 99 | if wc.w != nil { |
| 100 | switch t := wc.w.(type) { |
| 101 | case int: |
| 102 | if t < 0 { |
| 103 | return bsontype.Type(0), nil, ErrNegativeW |
| 104 | } |
| 105 | |
| 106 | elems = bsoncore.AppendInt32Element(elems, "w", int32(t)) |
| 107 | case string: |
| 108 | elems = bsoncore.AppendStringElement(elems, "w", string(t)) |
| 109 | } |
| 110 | } |
| 111 | |
| 112 | if wc.j { |
| 113 | elems = bsoncore.AppendBooleanElement(elems, "j", wc.j) |
| 114 | } |
| 115 | |
| 116 | if wc.wTimeout < 0 { |
| 117 | return bsontype.Type(0), nil, ErrNegativeWTimeout |
| 118 | } |
| 119 | |
| 120 | if wc.wTimeout != 0 { |
| 121 | elems = bsoncore.AppendInt64Element(elems, "wtimeout", int64(wc.wTimeout/time.Millisecond)) |
| 122 | } |
| 123 | |
| 124 | if len(elems) == 0 { |
| 125 | return bsontype.Type(0), nil, ErrEmptyWriteConcern |
| 126 | } |
| 127 | return bsontype.EmbeddedDocument, bsoncore.BuildDocument(nil, elems), nil |
| 128 | } |
| 129 | |
| 130 | // AcknowledgedValue returns true if a BSON RawValue for a write concern represents an acknowledged write concern. |
| 131 | // The element's value must be a document representing a write concern. |
| 132 | func AcknowledgedValue(rawv bson.RawValue) bool { |
| 133 | doc, ok := bsoncore.Value{Type: rawv.Type, Data: rawv.Value}.DocumentOK() |
| 134 | if !ok { |
| 135 | return false |
| 136 | } |
| 137 | |
| 138 | val, err := doc.LookupErr("w") |
| 139 | if err != nil { |
| 140 | // key w not found --> acknowledged |
| 141 | return true |
| 142 | } |
| 143 | |
| 144 | i32, ok := val.Int32OK() |
| 145 | if !ok { |
| 146 | return false |
| 147 | } |
| 148 | return i32 != 0 |
| 149 | } |
| 150 | |
| 151 | // Acknowledged indicates whether or not a write with the given write concern will be acknowledged. |
| 152 | func (wc *WriteConcern) Acknowledged() bool { |
| 153 | if wc == nil || wc.j { |
| 154 | return true |
| 155 | } |
| 156 | |
| 157 | switch v := wc.w.(type) { |
| 158 | case int: |
| 159 | if v == 0 { |
| 160 | return false |
| 161 | } |
| 162 | } |
| 163 | |
| 164 | return true |
| 165 | } |
| 166 | |
| 167 | // IsValid checks whether the write concern is invalid. |
| 168 | func (wc *WriteConcern) IsValid() bool { |
| 169 | if !wc.j { |
| 170 | return true |
| 171 | } |
| 172 | |
| 173 | switch v := wc.w.(type) { |
| 174 | case int: |
| 175 | if v == 0 { |
| 176 | return false |
| 177 | } |
| 178 | } |
| 179 | |
| 180 | return true |
| 181 | } |
| 182 | |
| 183 | // AckWrite returns true if a write concern represents an acknowledged write |
| 184 | func AckWrite(wc *WriteConcern) bool { |
| 185 | return wc == nil || wc.Acknowledged() |
| 186 | } |