mirror of
https://github.com/ceph/ceph-csi.git
synced 2024-12-19 11:30:24 +00:00
289 lines
8.5 KiB
Go
289 lines
8.5 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 tracker
|
|
|
|
import (
|
|
"fmt"
|
|
"sort"
|
|
"strings"
|
|
|
|
"go.etcd.io/etcd/raft/quorum"
|
|
pb "go.etcd.io/etcd/raft/raftpb"
|
|
)
|
|
|
|
// Config reflects the configuration tracked in a ProgressTracker.
|
|
type Config struct {
|
|
Voters quorum.JointConfig
|
|
// AutoLeave is true if the configuration is joint and a transition to the
|
|
// incoming configuration should be carried out automatically by Raft when
|
|
// this is possible. If false, the configuration will be joint until the
|
|
// application initiates the transition manually.
|
|
AutoLeave bool
|
|
// Learners is a set of IDs corresponding to the learners active in the
|
|
// current configuration.
|
|
//
|
|
// Invariant: Learners and Voters does not intersect, i.e. if a peer is in
|
|
// either half of the joint config, it can't be a learner; if it is a
|
|
// learner it can't be in either half of the joint config. This invariant
|
|
// simplifies the implementation since it allows peers to have clarity about
|
|
// its current role without taking into account joint consensus.
|
|
Learners map[uint64]struct{}
|
|
// When we turn a voter into a learner during a joint consensus transition,
|
|
// we cannot add the learner directly when entering the joint state. This is
|
|
// because this would violate the invariant that the intersection of
|
|
// voters and learners is empty. For example, assume a Voter is removed and
|
|
// immediately re-added as a learner (or in other words, it is demoted):
|
|
//
|
|
// Initially, the configuration will be
|
|
//
|
|
// voters: {1 2 3}
|
|
// learners: {}
|
|
//
|
|
// and we want to demote 3. Entering the joint configuration, we naively get
|
|
//
|
|
// voters: {1 2} & {1 2 3}
|
|
// learners: {3}
|
|
//
|
|
// but this violates the invariant (3 is both voter and learner). Instead,
|
|
// we get
|
|
//
|
|
// voters: {1 2} & {1 2 3}
|
|
// learners: {}
|
|
// next_learners: {3}
|
|
//
|
|
// Where 3 is now still purely a voter, but we are remembering the intention
|
|
// to make it a learner upon transitioning into the final configuration:
|
|
//
|
|
// voters: {1 2}
|
|
// learners: {3}
|
|
// next_learners: {}
|
|
//
|
|
// Note that next_learners is not used while adding a learner that is not
|
|
// also a voter in the joint config. In this case, the learner is added
|
|
// right away when entering the joint configuration, so that it is caught up
|
|
// as soon as possible.
|
|
LearnersNext map[uint64]struct{}
|
|
}
|
|
|
|
func (c Config) String() string {
|
|
var buf strings.Builder
|
|
fmt.Fprintf(&buf, "voters=%s", c.Voters)
|
|
if c.Learners != nil {
|
|
fmt.Fprintf(&buf, " learners=%s", quorum.MajorityConfig(c.Learners).String())
|
|
}
|
|
if c.LearnersNext != nil {
|
|
fmt.Fprintf(&buf, " learners_next=%s", quorum.MajorityConfig(c.LearnersNext).String())
|
|
}
|
|
if c.AutoLeave {
|
|
fmt.Fprintf(&buf, " autoleave")
|
|
}
|
|
return buf.String()
|
|
}
|
|
|
|
// Clone returns a copy of the Config that shares no memory with the original.
|
|
func (c *Config) Clone() Config {
|
|
clone := func(m map[uint64]struct{}) map[uint64]struct{} {
|
|
if m == nil {
|
|
return nil
|
|
}
|
|
mm := make(map[uint64]struct{}, len(m))
|
|
for k := range m {
|
|
mm[k] = struct{}{}
|
|
}
|
|
return mm
|
|
}
|
|
return Config{
|
|
Voters: quorum.JointConfig{clone(c.Voters[0]), clone(c.Voters[1])},
|
|
Learners: clone(c.Learners),
|
|
LearnersNext: clone(c.LearnersNext),
|
|
}
|
|
}
|
|
|
|
// ProgressTracker tracks the currently active configuration and the information
|
|
// known about the nodes and learners in it. In particular, it tracks the match
|
|
// index for each peer which in turn allows reasoning about the committed index.
|
|
type ProgressTracker struct {
|
|
Config
|
|
|
|
Progress ProgressMap
|
|
|
|
Votes map[uint64]bool
|
|
|
|
MaxInflight int
|
|
}
|
|
|
|
// MakeProgressTracker initializes a ProgressTracker.
|
|
func MakeProgressTracker(maxInflight int) ProgressTracker {
|
|
p := ProgressTracker{
|
|
MaxInflight: maxInflight,
|
|
Config: Config{
|
|
Voters: quorum.JointConfig{
|
|
quorum.MajorityConfig{},
|
|
nil, // only populated when used
|
|
},
|
|
Learners: nil, // only populated when used
|
|
LearnersNext: nil, // only populated when used
|
|
},
|
|
Votes: map[uint64]bool{},
|
|
Progress: map[uint64]*Progress{},
|
|
}
|
|
return p
|
|
}
|
|
|
|
// ConfState returns a ConfState representing the active configuration.
|
|
func (p *ProgressTracker) ConfState() pb.ConfState {
|
|
return pb.ConfState{
|
|
Voters: p.Voters[0].Slice(),
|
|
VotersOutgoing: p.Voters[1].Slice(),
|
|
Learners: quorum.MajorityConfig(p.Learners).Slice(),
|
|
LearnersNext: quorum.MajorityConfig(p.LearnersNext).Slice(),
|
|
AutoLeave: p.AutoLeave,
|
|
}
|
|
}
|
|
|
|
// IsSingleton returns true if (and only if) there is only one voting member
|
|
// (i.e. the leader) in the current configuration.
|
|
func (p *ProgressTracker) IsSingleton() bool {
|
|
return len(p.Voters[0]) == 1 && len(p.Voters[1]) == 0
|
|
}
|
|
|
|
type matchAckIndexer map[uint64]*Progress
|
|
|
|
var _ quorum.AckedIndexer = matchAckIndexer(nil)
|
|
|
|
// AckedIndex implements IndexLookuper.
|
|
func (l matchAckIndexer) AckedIndex(id uint64) (quorum.Index, bool) {
|
|
pr, ok := l[id]
|
|
if !ok {
|
|
return 0, false
|
|
}
|
|
return quorum.Index(pr.Match), true
|
|
}
|
|
|
|
// Committed returns the largest log index known to be committed based on what
|
|
// the voting members of the group have acknowledged.
|
|
func (p *ProgressTracker) Committed() uint64 {
|
|
return uint64(p.Voters.CommittedIndex(matchAckIndexer(p.Progress)))
|
|
}
|
|
|
|
func insertionSort(sl []uint64) {
|
|
a, b := 0, len(sl)
|
|
for i := a + 1; i < b; i++ {
|
|
for j := i; j > a && sl[j] < sl[j-1]; j-- {
|
|
sl[j], sl[j-1] = sl[j-1], sl[j]
|
|
}
|
|
}
|
|
}
|
|
|
|
// Visit invokes the supplied closure for all tracked progresses in stable order.
|
|
func (p *ProgressTracker) Visit(f func(id uint64, pr *Progress)) {
|
|
n := len(p.Progress)
|
|
// We need to sort the IDs and don't want to allocate since this is hot code.
|
|
// The optimization here mirrors that in `(MajorityConfig).CommittedIndex`,
|
|
// see there for details.
|
|
var sl [7]uint64
|
|
ids := sl[:]
|
|
if len(sl) >= n {
|
|
ids = sl[:n]
|
|
} else {
|
|
ids = make([]uint64, n)
|
|
}
|
|
for id := range p.Progress {
|
|
n--
|
|
ids[n] = id
|
|
}
|
|
insertionSort(ids)
|
|
for _, id := range ids {
|
|
f(id, p.Progress[id])
|
|
}
|
|
}
|
|
|
|
// QuorumActive returns true if the quorum is active from the view of the local
|
|
// raft state machine. Otherwise, it returns false.
|
|
func (p *ProgressTracker) QuorumActive() bool {
|
|
votes := map[uint64]bool{}
|
|
p.Visit(func(id uint64, pr *Progress) {
|
|
if pr.IsLearner {
|
|
return
|
|
}
|
|
votes[id] = pr.RecentActive
|
|
})
|
|
|
|
return p.Voters.VoteResult(votes) == quorum.VoteWon
|
|
}
|
|
|
|
// VoterNodes returns a sorted slice of voters.
|
|
func (p *ProgressTracker) VoterNodes() []uint64 {
|
|
m := p.Voters.IDs()
|
|
nodes := make([]uint64, 0, len(m))
|
|
for id := range m {
|
|
nodes = append(nodes, id)
|
|
}
|
|
sort.Slice(nodes, func(i, j int) bool { return nodes[i] < nodes[j] })
|
|
return nodes
|
|
}
|
|
|
|
// LearnerNodes returns a sorted slice of learners.
|
|
func (p *ProgressTracker) LearnerNodes() []uint64 {
|
|
if len(p.Learners) == 0 {
|
|
return nil
|
|
}
|
|
nodes := make([]uint64, 0, len(p.Learners))
|
|
for id := range p.Learners {
|
|
nodes = append(nodes, id)
|
|
}
|
|
sort.Slice(nodes, func(i, j int) bool { return nodes[i] < nodes[j] })
|
|
return nodes
|
|
}
|
|
|
|
// ResetVotes prepares for a new round of vote counting via recordVote.
|
|
func (p *ProgressTracker) ResetVotes() {
|
|
p.Votes = map[uint64]bool{}
|
|
}
|
|
|
|
// RecordVote records that the node with the given id voted for this Raft
|
|
// instance if v == true (and declined it otherwise).
|
|
func (p *ProgressTracker) RecordVote(id uint64, v bool) {
|
|
_, ok := p.Votes[id]
|
|
if !ok {
|
|
p.Votes[id] = v
|
|
}
|
|
}
|
|
|
|
// TallyVotes returns the number of granted and rejected Votes, and whether the
|
|
// election outcome is known.
|
|
func (p *ProgressTracker) TallyVotes() (granted int, rejected int, _ quorum.VoteResult) {
|
|
// Make sure to populate granted/rejected correctly even if the Votes slice
|
|
// contains members no longer part of the configuration. This doesn't really
|
|
// matter in the way the numbers are used (they're informational), but might
|
|
// as well get it right.
|
|
for id, pr := range p.Progress {
|
|
if pr.IsLearner {
|
|
continue
|
|
}
|
|
v, voted := p.Votes[id]
|
|
if !voted {
|
|
continue
|
|
}
|
|
if v {
|
|
granted++
|
|
} else {
|
|
rejected++
|
|
}
|
|
}
|
|
result := p.Voters.VoteResult(p.Votes)
|
|
return granted, rejected, result
|
|
}
|