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dex/vendor/go.etcd.io/etcd/raft/raftpb/confchange.go
2020-01-31 10:32:00 +01:00

171 lines
4.9 KiB
Go

// Copyright 2019 The etcd Authors
//
// 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
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package raftpb
import (
"fmt"
"strconv"
"strings"
"github.com/gogo/protobuf/proto"
)
// ConfChangeI abstracts over ConfChangeV2 and (legacy) ConfChange to allow
// treating them in a unified manner.
type ConfChangeI interface {
AsV2() ConfChangeV2
AsV1() (ConfChange, bool)
}
// MarshalConfChange calls Marshal on the underlying ConfChange or ConfChangeV2
// and returns the result along with the corresponding EntryType.
func MarshalConfChange(c ConfChangeI) (EntryType, []byte, error) {
var typ EntryType
var ccdata []byte
var err error
if ccv1, ok := c.AsV1(); ok {
typ = EntryConfChange
ccdata, err = ccv1.Marshal()
} else {
ccv2 := c.AsV2()
typ = EntryConfChangeV2
ccdata, err = ccv2.Marshal()
}
return typ, ccdata, err
}
// AsV2 returns a V2 configuration change carrying out the same operation.
func (c ConfChange) AsV2() ConfChangeV2 {
return ConfChangeV2{
Changes: []ConfChangeSingle{{
Type: c.Type,
NodeID: c.NodeID,
}},
Context: c.Context,
}
}
// AsV1 returns the ConfChange and true.
func (c ConfChange) AsV1() (ConfChange, bool) {
return c, true
}
// AsV2 is the identity.
func (c ConfChangeV2) AsV2() ConfChangeV2 { return c }
// AsV1 returns ConfChange{} and false.
func (c ConfChangeV2) AsV1() (ConfChange, bool) { return ConfChange{}, false }
// EnterJoint returns two bools. The second bool is true if and only if this
// config change will use Joint Consensus, which is the case if it contains more
// than one change or if the use of Joint Consensus was requested explicitly.
// The first bool can only be true if second one is, and indicates whether the
// Joint State will be left automatically.
func (c *ConfChangeV2) EnterJoint() (autoLeave bool, ok bool) {
// NB: in theory, more config changes could qualify for the "simple"
// protocol but it depends on the config on top of which the changes apply.
// For example, adding two learners is not OK if both nodes are part of the
// base config (i.e. two voters are turned into learners in the process of
// applying the conf change). In practice, these distinctions should not
// matter, so we keep it simple and use Joint Consensus liberally.
if c.Transition != ConfChangeTransitionAuto || len(c.Changes) > 1 {
// Use Joint Consensus.
var autoLeave bool
switch c.Transition {
case ConfChangeTransitionAuto:
autoLeave = true
case ConfChangeTransitionJointImplicit:
autoLeave = true
case ConfChangeTransitionJointExplicit:
default:
panic(fmt.Sprintf("unknown transition: %+v", c))
}
return autoLeave, true
}
return false, false
}
// LeaveJoint is true if the configuration change leaves a joint configuration.
// This is the case if the ConfChangeV2 is zero, with the possible exception of
// the Context field.
func (c *ConfChangeV2) LeaveJoint() bool {
cpy := *c
cpy.Context = nil
return proto.Equal(&cpy, &ConfChangeV2{})
}
// ConfChangesFromString parses a Space-delimited sequence of operations into a
// slice of ConfChangeSingle. The supported operations are:
// - vn: make n a voter,
// - ln: make n a learner,
// - rn: remove n, and
// - un: update n.
func ConfChangesFromString(s string) ([]ConfChangeSingle, error) {
var ccs []ConfChangeSingle
toks := strings.Split(strings.TrimSpace(s), " ")
if toks[0] == "" {
toks = nil
}
for _, tok := range toks {
if len(tok) < 2 {
return nil, fmt.Errorf("unknown token %s", tok)
}
var cc ConfChangeSingle
switch tok[0] {
case 'v':
cc.Type = ConfChangeAddNode
case 'l':
cc.Type = ConfChangeAddLearnerNode
case 'r':
cc.Type = ConfChangeRemoveNode
case 'u':
cc.Type = ConfChangeUpdateNode
default:
return nil, fmt.Errorf("unknown input: %s", tok)
}
id, err := strconv.ParseUint(tok[1:], 10, 64)
if err != nil {
return nil, err
}
cc.NodeID = id
ccs = append(ccs, cc)
}
return ccs, nil
}
// ConfChangesToString is the inverse to ConfChangesFromString.
func ConfChangesToString(ccs []ConfChangeSingle) string {
var buf strings.Builder
for i, cc := range ccs {
if i > 0 {
buf.WriteByte(' ')
}
switch cc.Type {
case ConfChangeAddNode:
buf.WriteByte('v')
case ConfChangeAddLearnerNode:
buf.WriteByte('l')
case ConfChangeRemoveNode:
buf.WriteByte('r')
case ConfChangeUpdateNode:
buf.WriteByte('u')
default:
buf.WriteString("unknown")
}
fmt.Fprintf(&buf, "%d", cc.NodeID)
}
return buf.String()
}