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Scott Baker2c1c4822019-10-16 11:02:41 -07001// Copyright 2019 The etcd Authors
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15package raftpb
16
17import (
18 "fmt"
19 "strconv"
20 "strings"
21
22 "github.com/gogo/protobuf/proto"
23)
24
25// ConfChangeI abstracts over ConfChangeV2 and (legacy) ConfChange to allow
26// treating them in a unified manner.
27type ConfChangeI interface {
28 AsV2() ConfChangeV2
29 AsV1() (ConfChange, bool)
30}
31
32// MarshalConfChange calls Marshal on the underlying ConfChange or ConfChangeV2
33// and returns the result along with the corresponding EntryType.
34func MarshalConfChange(c ConfChangeI) (EntryType, []byte, error) {
35 var typ EntryType
36 var ccdata []byte
37 var err error
38 if ccv1, ok := c.AsV1(); ok {
39 typ = EntryConfChange
40 ccdata, err = ccv1.Marshal()
41 } else {
42 ccv2 := c.AsV2()
43 typ = EntryConfChangeV2
44 ccdata, err = ccv2.Marshal()
45 }
46 return typ, ccdata, err
47}
48
49// AsV2 returns a V2 configuration change carrying out the same operation.
50func (c ConfChange) AsV2() ConfChangeV2 {
51 return ConfChangeV2{
52 Changes: []ConfChangeSingle{{
53 Type: c.Type,
54 NodeID: c.NodeID,
55 }},
56 Context: c.Context,
57 }
58}
59
60// AsV1 returns the ConfChange and true.
61func (c ConfChange) AsV1() (ConfChange, bool) {
62 return c, true
63}
64
65// AsV2 is the identity.
66func (c ConfChangeV2) AsV2() ConfChangeV2 { return c }
67
68// AsV1 returns ConfChange{} and false.
69func (c ConfChangeV2) AsV1() (ConfChange, bool) { return ConfChange{}, false }
70
71// EnterJoint returns two bools. The second bool is true if and only if this
72// config change will use Joint Consensus, which is the case if it contains more
73// than one change or if the use of Joint Consensus was requested explicitly.
74// The first bool can only be true if second one is, and indicates whether the
75// Joint State will be left automatically.
76func (c *ConfChangeV2) EnterJoint() (autoLeave bool, ok bool) {
77 // NB: in theory, more config changes could qualify for the "simple"
78 // protocol but it depends on the config on top of which the changes apply.
79 // For example, adding two learners is not OK if both nodes are part of the
80 // base config (i.e. two voters are turned into learners in the process of
81 // applying the conf change). In practice, these distinctions should not
82 // matter, so we keep it simple and use Joint Consensus liberally.
83 if c.Transition != ConfChangeTransitionAuto || len(c.Changes) > 1 {
84 // Use Joint Consensus.
85 var autoLeave bool
86 switch c.Transition {
87 case ConfChangeTransitionAuto:
88 autoLeave = true
89 case ConfChangeTransitionJointImplicit:
90 autoLeave = true
91 case ConfChangeTransitionJointExplicit:
92 default:
93 panic(fmt.Sprintf("unknown transition: %+v", c))
94 }
95 return autoLeave, true
96 }
97 return false, false
98}
99
100// LeaveJoint is true if the configuration change leaves a joint configuration.
101// This is the case if the ConfChangeV2 is zero, with the possible exception of
102// the Context field.
103func (c *ConfChangeV2) LeaveJoint() bool {
104 cpy := *c
105 cpy.Context = nil
106 return proto.Equal(&cpy, &ConfChangeV2{})
107}
108
109// ConfChangesFromString parses a Space-delimited sequence of operations into a
110// slice of ConfChangeSingle. The supported operations are:
111// - vn: make n a voter,
112// - ln: make n a learner,
113// - rn: remove n, and
114// - un: update n.
115func ConfChangesFromString(s string) ([]ConfChangeSingle, error) {
116 var ccs []ConfChangeSingle
117 toks := strings.Split(strings.TrimSpace(s), " ")
118 if toks[0] == "" {
119 toks = nil
120 }
121 for _, tok := range toks {
122 if len(tok) < 2 {
123 return nil, fmt.Errorf("unknown token %s", tok)
124 }
125 var cc ConfChangeSingle
126 switch tok[0] {
127 case 'v':
128 cc.Type = ConfChangeAddNode
129 case 'l':
130 cc.Type = ConfChangeAddLearnerNode
131 case 'r':
132 cc.Type = ConfChangeRemoveNode
133 case 'u':
134 cc.Type = ConfChangeUpdateNode
135 default:
136 return nil, fmt.Errorf("unknown input: %s", tok)
137 }
138 id, err := strconv.ParseUint(tok[1:], 10, 64)
139 if err != nil {
140 return nil, err
141 }
142 cc.NodeID = id
143 ccs = append(ccs, cc)
144 }
145 return ccs, nil
146}
147
148// ConfChangesToString is the inverse to ConfChangesFromString.
149func ConfChangesToString(ccs []ConfChangeSingle) string {
150 var buf strings.Builder
151 for i, cc := range ccs {
152 if i > 0 {
153 buf.WriteByte(' ')
154 }
155 switch cc.Type {
156 case ConfChangeAddNode:
157 buf.WriteByte('v')
158 case ConfChangeAddLearnerNode:
159 buf.WriteByte('l')
160 case ConfChangeRemoveNode:
161 buf.WriteByte('r')
162 case ConfChangeUpdateNode:
163 buf.WriteByte('u')
164 default:
165 buf.WriteString("unknown")
166 }
167 fmt.Fprintf(&buf, "%d", cc.NodeID)
168 }
169 return buf.String()
170}