Merge pull request #10683 from tbg/prs

raft: extract progress tracking into own component

raft/node.go

@@ -353,15 +353,15 @@ func (n *node) run(r *raft) {
 			}
 		case m := <-n.recvc:
 			// filter out response message from unknown From.
-			if pr := r.getProgress(m.From); pr != nil || !IsResponseMsg(m.Type) {
+			if pr := r.prs.getProgress(m.From); pr != nil || !IsResponseMsg(m.Type) {
 				r.Step(m)
 			}
 		case cc := <-n.confc:
 			if cc.NodeID == None {
 				select {
 				case n.confstatec <- pb.ConfState{
-					Nodes:    r.nodes(),
-					Learners: r.learnerNodes()}:
+					Nodes:    r.prs.voterNodes(),
+					Learners: r.prs.learnerNodes()}:
 				case <-n.done:
 				}
 				break
@@ -384,8 +384,8 @@ func (n *node) run(r *raft) {
 			}
 			select {
 			case n.confstatec <- pb.ConfState{
-				Nodes:    r.nodes(),
-				Learners: r.learnerNodes()}:
+				Nodes:    r.prs.voterNodes(),
+				Learners: r.prs.learnerNodes()}:
 			case <-n.done:
 			}
 		case <-n.tickc:

raft/progress.go

@@ -14,7 +14,10 @@
 
 package raft
 
-import "fmt"
+import (
+	"fmt"
+	"sort"
+)
 
 const (
 	ProgressStateProbe ProgressStateType = iota
@@ -283,3 +286,175 @@ func (in *inflights) reset() {
 	in.count = 0
 	in.start = 0
 }
+
+// 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 {
+	nodes    map[uint64]*Progress
+	learners map[uint64]*Progress
+
+	votes map[uint64]bool
+
+	maxInflight int
+	matchBuf    uint64Slice
+}
+
+func makePRS(maxInflight int) progressTracker {
+	p := progressTracker{
+		maxInflight: maxInflight,
+		nodes:       map[uint64]*Progress{},
+		learners:    map[uint64]*Progress{},
+		votes:       map[uint64]bool{},
+	}
+	return p
+}
+
+// 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.nodes) == 1
+}
+
+func (p *progressTracker) quorum() int {
+	return len(p.nodes)/2 + 1
+}
+
+func (p *progressTracker) hasQuorum(m map[uint64]struct{}) bool {
+	return len(m) >= p.quorum()
+}
+
+// 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 {
+	// Preserving matchBuf across calls is an optimization
+	// used to avoid allocating a new slice on each call.
+	if cap(p.matchBuf) < len(p.nodes) {
+		p.matchBuf = make(uint64Slice, len(p.nodes))
+	}
+	p.matchBuf = p.matchBuf[:len(p.nodes)]
+	idx := 0
+	for _, pr := range p.nodes {
+		p.matchBuf[idx] = pr.Match
+		idx++
+	}
+	sort.Sort(&p.matchBuf)
+	return p.matchBuf[len(p.matchBuf)-p.quorum()]
+}
+
+func (p *progressTracker) removeAny(id uint64) {
+	pN := p.nodes[id]
+	pL := p.learners[id]
+
+	if pN == nil && pL == nil {
+		panic("attempting to remove unknown peer %x")
+	} else if pN != nil && pL != nil {
+		panic(fmt.Sprintf("peer %x is both voter and learner", id))
+	}
+
+	delete(p.nodes, id)
+	delete(p.learners, id)
+}
+
+// initProgress initializes a new progress for the given node or learner. The
+// node may not exist yet in either form or a panic will ensue.
+func (p *progressTracker) initProgress(id, match, next uint64, isLearner bool) {
+	if pr := p.nodes[id]; pr != nil {
+		panic(fmt.Sprintf("peer %x already tracked as node %v", id, pr))
+	}
+	if pr := p.learners[id]; pr != nil {
+		panic(fmt.Sprintf("peer %x already tracked as learner %v", id, pr))
+	}
+	if !isLearner {
+		p.nodes[id] = &Progress{Next: next, Match: match, ins: newInflights(p.maxInflight)}
+		return
+	}
+	p.learners[id] = &Progress{Next: next, Match: match, ins: newInflights(p.maxInflight), IsLearner: true}
+}
+
+func (p *progressTracker) getProgress(id uint64) *Progress {
+	if pr, ok := p.nodes[id]; ok {
+		return pr
+	}
+
+	return p.learners[id]
+}
+
+// visit invokes the supplied closure for all tracked progresses.
+func (p *progressTracker) visit(f func(id uint64, pr *Progress)) {
+	for id, pr := range p.nodes {
+		f(id, pr)
+	}
+
+	for id, pr := range p.learners {
+		f(id, pr)
+	}
+}
+
+// checkQuorumActive 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 {
+	var act int
+	p.visit(func(id uint64, pr *Progress) {
+		if pr.RecentActive && !pr.IsLearner {
+			act++
+		}
+	})
+
+	return act >= p.quorum()
+}
+
+func (p *progressTracker) voterNodes() []uint64 {
+	nodes := make([]uint64, 0, len(p.nodes))
+	for id := range p.nodes {
+		nodes = append(nodes, id)
+	}
+	sort.Sort(uint64Slice(nodes))
+	return nodes
+}
+
+func (p *progressTracker) learnerNodes() []uint64 {
+	nodes := make([]uint64, 0, len(p.learners))
+	for id := range p.learners {
+		nodes = append(nodes, id)
+	}
+	sort.Sort(uint64Slice(nodes))
+	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, result electionResult) {
+	for _, v := range p.votes {
+		if v {
+			granted++
+		} else {
+			rejected++
+		}
+	}
+
+	q := p.quorum()
+
+	result = electionIndeterminate
+	if granted >= q {
+		result = electionWon
+	} else if rejected >= q {
+		result = electionLost
+	}
+	return granted, rejected, result
+}

raft/raft.go

@@ -20,7 +20,6 @@ import (
 	"fmt"
 	"math"
 	"math/rand"
-	"sort"
 	"strings"
 	"sync"
 	"time"
@@ -261,18 +260,13 @@ type raft struct {
 
 	maxMsgSize         uint64
 	maxUncommittedSize uint64
-	maxInflight        int
-	prs                map[uint64]*Progress
-	learnerPrs         map[uint64]*Progress
-	matchBuf           uint64Slice
+	prs                progressTracker
 
 	state StateType
 
 	// isLearner is true if the local raft node is a learner.
 	isLearner bool
 
-	votes map[uint64]bool
-
 	msgs []pb.Message
 
 	// the leader id
@@ -348,10 +342,8 @@ func newRaft(c *Config) *raft {
 		isLearner:                 false,
 		raftLog:                   raftlog,
 		maxMsgSize:                c.MaxSizePerMsg,
-		maxInflight:               c.MaxInflightMsgs,
 		maxUncommittedSize:        c.MaxUncommittedEntriesSize,
-		prs:                       make(map[uint64]*Progress),
-		learnerPrs:                make(map[uint64]*Progress),
+		prs:                       makePRS(c.MaxInflightMsgs),
 		electionTimeout:           c.ElectionTick,
 		heartbeatTimeout:          c.HeartbeatTick,
 		logger:                    c.Logger,
@@ -361,13 +353,13 @@ func newRaft(c *Config) *raft {
 		disableProposalForwarding: c.DisableProposalForwarding,
 	}
 	for _, p := range peers {
-		r.prs[p] = &Progress{Next: 1, ins: newInflights(r.maxInflight)}
+		// Add node to active config.
+		r.prs.initProgress(p, 0 /* match */, 1 /* next */, false /* isLearner */)
 	}
 	for _, p := range learners {
-		if _, ok := r.prs[p]; ok {
-			panic(fmt.Sprintf("node %x is in both learner and peer list", p))
-		}
-		r.learnerPrs[p] = &Progress{Next: 1, ins: newInflights(r.maxInflight), IsLearner: true}
+		// Add learner to active config.
+		r.prs.initProgress(p, 0 /* match */, 1 /* next */, true /* isLearner */)
+
 		if r.id == p {
 			r.isLearner = true
 		}
@@ -382,7 +374,7 @@ func newRaft(c *Config) *raft {
 	r.becomeFollower(r.Term, None)
 
 	var nodesStrs []string
-	for _, n := range r.nodes() {
+	for _, n := range r.prs.voterNodes() {
 		nodesStrs = append(nodesStrs, fmt.Sprintf("%x", n))
 	}
 
@@ -403,26 +395,6 @@ func (r *raft) hardState() pb.HardState {
 	}
 }
 
-func (r *raft) quorum() int { return len(r.prs)/2 + 1 }
-
-func (r *raft) nodes() []uint64 {
-	nodes := make([]uint64, 0, len(r.prs))
-	for id := range r.prs {
-		nodes = append(nodes, id)
-	}
-	sort.Sort(uint64Slice(nodes))
-	return nodes
-}
-
-func (r *raft) learnerNodes() []uint64 {
-	nodes := make([]uint64, 0, len(r.learnerPrs))
-	for id := range r.learnerPrs {
-		nodes = append(nodes, id)
-	}
-	sort.Sort(uint64Slice(nodes))
-	return nodes
-}
-
 // send persists state to stable storage and then sends to its mailbox.
 func (r *raft) send(m pb.Message) {
 	m.From = r.id
@@ -457,14 +429,6 @@ func (r *raft) send(m pb.Message) {
 	r.msgs = append(r.msgs, m)
 }
 
-func (r *raft) getProgress(id uint64) *Progress {
-	if pr, ok := r.prs[id]; ok {
-		return pr
-	}
-
-	return r.learnerPrs[id]
-}
-
 // sendAppend sends an append RPC with new entries (if any) and the
 // current commit index to the given peer.
 func (r *raft) sendAppend(to uint64) {
@@ -477,7 +441,7 @@ func (r *raft) sendAppend(to uint64) {
 // ("empty" messages are useful to convey updated Commit indexes, but
 // are undesirable when we're sending multiple messages in a batch).
 func (r *raft) maybeSendAppend(to uint64, sendIfEmpty bool) bool {
-	pr := r.getProgress(to)
+	pr := r.prs.getProgress(to)
 	if pr.IsPaused() {
 		return false
 	}
@@ -546,7 +510,7 @@ func (r *raft) sendHeartbeat(to uint64, ctx []byte) {
 	// or it might not have all the committed entries.
 	// The leader MUST NOT forward the follower's commit to
 	// an unmatched index.
-	commit := min(r.getProgress(to).Match, r.raftLog.committed)
+	commit := min(r.prs.getProgress(to).Match, r.raftLog.committed)
 	m := pb.Message{
 		To:      to,
 		Type:    pb.MsgHeartbeat,
@@ -557,20 +521,10 @@ func (r *raft) sendHeartbeat(to uint64, ctx []byte) {
 	r.send(m)
 }
 
-func (r *raft) forEachProgress(f func(id uint64, pr *Progress)) {
-	for id, pr := range r.prs {
-		f(id, pr)
-	}
-
-	for id, pr := range r.learnerPrs {
-		f(id, pr)
-	}
-}
-
 // bcastAppend sends RPC, with entries to all peers that are not up-to-date
 // according to the progress recorded in r.prs.
 func (r *raft) bcastAppend() {
-	r.forEachProgress(func(id uint64, _ *Progress) {
+	r.prs.visit(func(id uint64, _ *Progress) {
 		if id == r.id {
 			return
 		}
@@ -590,7 +544,7 @@ func (r *raft) bcastHeartbeat() {
 }
 
 func (r *raft) bcastHeartbeatWithCtx(ctx []byte) {
-	r.forEachProgress(func(id uint64, _ *Progress) {
+	r.prs.visit(func(id uint64, _ *Progress) {
 		if id == r.id {
 			return
 		}
@@ -602,19 +556,7 @@ func (r *raft) bcastHeartbeatWithCtx(ctx []byte) {
 // the commit index changed (in which case the caller should call
 // r.bcastAppend).
 func (r *raft) maybeCommit() bool {
-	// Preserving matchBuf across calls is an optimization
-	// used to avoid allocating a new slice on each call.
-	if cap(r.matchBuf) < len(r.prs) {
-		r.matchBuf = make(uint64Slice, len(r.prs))
-	}
-	r.matchBuf = r.matchBuf[:len(r.prs)]
-	idx := 0
-	for _, p := range r.prs {
-		r.matchBuf[idx] = p.Match
-		idx++
-	}
-	sort.Sort(&r.matchBuf)
-	mci := r.matchBuf[len(r.matchBuf)-r.quorum()]
+	mci := r.prs.committed()
 	return r.raftLog.maybeCommit(mci, r.Term)
 }
 
@@ -631,9 +573,14 @@ func (r *raft) reset(term uint64) {
 
 	r.abortLeaderTransfer()
 
-	r.votes = make(map[uint64]bool)
-	r.forEachProgress(func(id uint64, pr *Progress) {
-		*pr = Progress{Next: r.raftLog.lastIndex() + 1, ins: newInflights(r.maxInflight), IsLearner: pr.IsLearner}
+	r.prs.resetVotes()
+	r.prs.visit(func(id uint64, pr *Progress) {
+		*pr = Progress{
+			Match:     0,
+			Next:      r.raftLog.lastIndex() + 1,
+			ins:       newInflights(r.prs.maxInflight),
+			IsLearner: pr.IsLearner,
+		}
 		if id == r.id {
 			pr.Match = r.raftLog.lastIndex()
 		}
@@ -661,7 +608,7 @@ func (r *raft) appendEntry(es ...pb.Entry) (accepted bool) {
 	}
 	// use latest "last" index after truncate/append
 	li = r.raftLog.append(es...)
-	r.getProgress(r.id).maybeUpdate(li)
+	r.prs.getProgress(r.id).maybeUpdate(li)
 	// Regardless of maybeCommit's return, our caller will call bcastAppend.
 	r.maybeCommit()
 	return true
@@ -734,7 +681,7 @@ func (r *raft) becomePreCandidate() {
 	// but doesn't change anything else. In particular it does not increase
 	// r.Term or change r.Vote.
 	r.step = stepCandidate
-	r.votes = make(map[uint64]bool)
+	r.prs.resetVotes()
 	r.tick = r.tickElection
 	r.lead = None
 	r.state = StatePreCandidate
@@ -755,7 +702,7 @@ func (r *raft) becomeLeader() {
 	// (perhaps after having received a snapshot as a result). The leader is
 	// trivially in this state. Note that r.reset() has initialized this
 	// progress with the last index already.
-	r.prs[r.id].becomeReplicate()
+	r.prs.getProgress(r.id).becomeReplicate()
 
 	// Conservatively set the pendingConfIndex to the last index in the
 	// log. There may or may not be a pending config change, but it's
@@ -790,7 +737,7 @@ func (r *raft) campaign(t CampaignType) {
 		voteMsg = pb.MsgVote
 		term = r.Term
 	}
-	if r.quorum() == r.poll(r.id, voteRespMsgType(voteMsg), true) {
+	if _, _, res := r.poll(r.id, voteRespMsgType(voteMsg), true); res == electionWon {
 		// We won the election after voting for ourselves (which must mean that
 		// this is a single-node cluster). Advance to the next state.
 		if t == campaignPreElection {
@@ -800,7 +747,7 @@ func (r *raft) campaign(t CampaignType) {
 		}
 		return
 	}
-	for id := range r.prs {
+	for id := range r.prs.nodes {
 		if id == r.id {
 			continue
 		}
@@ -815,21 +762,22 @@ func (r *raft) campaign(t CampaignType) {
 	}
 }
 
-func (r *raft) poll(id uint64, t pb.MessageType, v bool) (granted int) {
+type electionResult byte
+
+const (
+	electionIndeterminate electionResult = iota
+	electionLost
+	electionWon
+)
+
+func (r *raft) poll(id uint64, t pb.MessageType, v bool) (granted int, rejected int, result electionResult) {
 	if v {
 		r.logger.Infof("%x received %s from %x at term %d", r.id, t, id, r.Term)
 	} else {
 		r.logger.Infof("%x received %s rejection from %x at term %d", r.id, t, id, r.Term)
 	}
-	if _, ok := r.votes[id]; !ok {
-		r.votes[id] = v
-	}
-	for _, vv := range r.votes {
-		if vv {
-			granted++
-		}
-	}
-	return granted
+	r.prs.recordVote(id, v)
+	return r.prs.tallyVotes()
 }
 
 func (r *raft) Step(m pb.Message) error {
@@ -985,16 +933,32 @@ func stepLeader(r *raft, m pb.Message) error {
 		r.bcastHeartbeat()
 		return nil
 	case pb.MsgCheckQuorum:
-		if !r.checkQuorumActive() {
+		// The leader should always see itself as active. As a precaution, handle
+		// the case in which the leader isn't in the configuration any more (for
+		// example if it just removed itself).
+		//
+		// TODO(tbg): I added a TODO in removeNode, it doesn't seem that the
+		// leader steps down when removing itself. I might be missing something.
+		if pr := r.prs.getProgress(r.id); pr != nil {
+			pr.RecentActive = true
+		}
+		if !r.prs.quorumActive() {
 			r.logger.Warningf("%x stepped down to follower since quorum is not active", r.id)
 			r.becomeFollower(r.Term, None)
 		}
+		// Mark everyone (but ourselves) as inactive in preparation for the next
+		// CheckQuorum.
+		r.prs.visit(func(id uint64, pr *Progress) {
+			if id != r.id {
+				pr.RecentActive = false
+			}
+		})
 		return nil
 	case pb.MsgProp:
 		if len(m.Entries) == 0 {
 			r.logger.Panicf("%x stepped empty MsgProp", r.id)
 		}
-		if _, ok := r.prs[r.id]; !ok {
+		if r.prs.getProgress(r.id) == nil {
 			// If we are not currently a member of the range (i.e. this node
 			// was removed from the configuration while serving as leader),
 			// drop any new proposals.
@@ -1024,7 +988,7 @@ func stepLeader(r *raft, m pb.Message) error {
 		r.bcastAppend()
 		return nil
 	case pb.MsgReadIndex:
-		if r.quorum() > 1 {
+		if !r.prs.isSingleton() { // more than one voting member in cluster
 			if r.raftLog.zeroTermOnErrCompacted(r.raftLog.term(r.raftLog.committed)) != r.Term {
 				// Reject read only request when this leader has not committed any log entry at its term.
 				return nil
@@ -1036,6 +1000,8 @@ func stepLeader(r *raft, m pb.Message) error {
 			switch r.readOnly.option {
 			case ReadOnlySafe:
 				r.readOnly.addRequest(r.raftLog.committed, m)
+				// The local node automatically acks the request.
+				r.readOnly.recvAck(r.id, m.Entries[0].Data)
 				r.bcastHeartbeatWithCtx(m.Entries[0].Data)
 			case ReadOnlyLeaseBased:
 				ri := r.raftLog.committed
@@ -1045,7 +1011,7 @@ func stepLeader(r *raft, m pb.Message) error {
 					r.send(pb.Message{To: m.From, Type: pb.MsgReadIndexResp, Index: ri, Entries: m.Entries})
 				}
 			}
-		} else { // there is only one voting member (the leader) in the cluster
+		} else { // only one voting member (the leader) in the cluster
 			if m.From == None || m.From == r.id { // from leader itself
 				r.readStates = append(r.readStates, ReadState{Index: r.raftLog.committed, RequestCtx: m.Entries[0].Data})
 			} else { // from learner member
@@ -1057,7 +1023,7 @@ func stepLeader(r *raft, m pb.Message) error {
 	}
 
 	// All other message types require a progress for m.From (pr).
-	pr := r.getProgress(m.From)
+	pr := r.prs.getProgress(m.From)
 	if pr == nil {
 		r.logger.Debugf("%x no progress available for %x", r.id, m.From)
 		return nil
@@ -1133,8 +1099,7 @@ func stepLeader(r *raft, m pb.Message) error {
 			return nil
 		}
 
-		ackCount := r.readOnly.recvAck(m)
-		if ackCount < r.quorum() {
+		if !r.prs.hasQuorum(r.readOnly.recvAck(m.From, m.Context)) {
 			return nil
 		}
 
@@ -1231,17 +1196,17 @@ func stepCandidate(r *raft, m pb.Message) error {
 		r.becomeFollower(m.Term, m.From) // always m.Term == r.Term
 		r.handleSnapshot(m)
 	case myVoteRespType:
-		gr := r.poll(m.From, m.Type, !m.Reject)
-		r.logger.Infof("%x [quorum:%d] has received %d %s votes and %d vote rejections", r.id, r.quorum(), gr, m.Type, len(r.votes)-gr)
-		switch r.quorum() {
-		case gr:
+		gr, rj, res := r.poll(m.From, m.Type, !m.Reject)
+		r.logger.Infof("%x has received %d %s votes and %d vote rejections", r.id, gr, m.Type, rj)
+		switch res {
+		case electionWon:
 			if r.state == StatePreCandidate {
 				r.campaign(campaignElection)
 			} else {
 				r.becomeLeader()
 				r.bcastAppend()
 			}
-		case len(r.votes) - gr:
+		case electionLost:
 			// pb.MsgPreVoteResp contains future term of pre-candidate
 			// m.Term > r.Term; reuse r.Term
 			r.becomeFollower(r.Term, None)
@@ -1370,8 +1335,7 @@ func (r *raft) restore(s pb.Snapshot) bool {
 		r.id, r.raftLog.committed, r.raftLog.lastIndex(), r.raftLog.lastTerm(), s.Metadata.Index, s.Metadata.Term)
 
 	r.raftLog.restore(s)
-	r.prs = make(map[uint64]*Progress)
-	r.learnerPrs = make(map[uint64]*Progress)
+	r.prs = makePRS(r.prs.maxInflight)
 	r.restoreNode(s.Metadata.ConfState.Nodes, false)
 	r.restoreNode(s.Metadata.ConfState.Learners, true)
 	return true
@@ -1384,16 +1348,16 @@ func (r *raft) restoreNode(nodes []uint64, isLearner bool) {
 			match = next - 1
 			r.isLearner = isLearner
 		}
-		r.setProgress(n, match, next, isLearner)
-		r.logger.Infof("%x restored progress of %x [%s]", r.id, n, r.getProgress(n))
+		r.prs.initProgress(n, match, next, isLearner)
+		r.logger.Infof("%x restored progress of %x [%s]", r.id, n, r.prs.getProgress(n))
 	}
 }
 
 // promotable indicates whether state machine can be promoted to leader,
 // which is true when its own id is in progress list.
 func (r *raft) promotable() bool {
-	_, ok := r.prs[r.id]
-	return ok
+	pr := r.prs.getProgress(r.id)
+	return pr != nil && !pr.IsLearner
 }
 
 func (r *raft) addNode(id uint64) {
@@ -1405,12 +1369,12 @@ func (r *raft) addLearner(id uint64) {
 }
 
 func (r *raft) addNodeOrLearnerNode(id uint64, isLearner bool) {
-	pr := r.getProgress(id)
+	pr := r.prs.getProgress(id)
 	if pr == nil {
-		r.setProgress(id, 0, r.raftLog.lastIndex()+1, isLearner)
+		r.prs.initProgress(id, 0, r.raftLog.lastIndex()+1, isLearner)
 	} else {
 		if isLearner && !pr.IsLearner {
-			// can only change Learner to Voter
+			// Can only change Learner to Voter.
 			r.logger.Infof("%x ignored addLearner: do not support changing %x from raft peer to learner.", r.id, id)
 			return
 		}
@@ -1421,10 +1385,11 @@ func (r *raft) addNodeOrLearnerNode(id uint64, isLearner bool) {
 			return
 		}
 
-		// change Learner to Voter, use origin Learner progress
-		delete(r.learnerPrs, id)
+		// Change Learner to Voter, use origin Learner progress.
+		r.prs.removeAny(id)
+		r.prs.initProgress(id, 0 /* match */, 1 /* next */, false /* isLearner */)
 		pr.IsLearner = false
-		r.prs[id] = pr
+		*r.prs.getProgress(id) = *pr
 	}
 
 	if r.id == id {
@@ -1434,18 +1399,20 @@ func (r *raft) addNodeOrLearnerNode(id uint64, isLearner bool) {
 	// When a node is first added, we should mark it as recently active.
 	// Otherwise, CheckQuorum may cause us to step down if it is invoked
 	// before the added node has a chance to communicate with us.
-	pr = r.getProgress(id)
-	pr.RecentActive = true
+	r.prs.getProgress(id).RecentActive = true
 }
 
 func (r *raft) removeNode(id uint64) {
-	r.delProgress(id)
+	r.prs.removeAny(id)
 
-	// do not try to commit or abort transferring if there is no nodes in the cluster.
-	if len(r.prs) == 0 && len(r.learnerPrs) == 0 {
+	// Do not try to commit or abort transferring if the cluster is now empty.
+	if len(r.prs.nodes) == 0 && len(r.prs.learners) == 0 {
 		return
 	}
 
+	// TODO(tbg): won't bad (or at least unfortunate) things happen if the
+	// leader just removed itself?
+
 	// The quorum size is now smaller, so see if any pending entries can
 	// be committed.
 	if r.maybeCommit() {
@@ -1457,24 +1424,6 @@ func (r *raft) removeNode(id uint64) {
 	}
 }
 
-func (r *raft) setProgress(id, match, next uint64, isLearner bool) {
-	if !isLearner {
-		delete(r.learnerPrs, id)
-		r.prs[id] = &Progress{Next: next, Match: match, ins: newInflights(r.maxInflight)}
-		return
-	}
-
-	if _, ok := r.prs[id]; ok {
-		panic(fmt.Sprintf("%x unexpected changing from voter to learner for %x", r.id, id))
-	}
-	r.learnerPrs[id] = &Progress{Next: next, Match: match, ins: newInflights(r.maxInflight), IsLearner: true}
-}
-
-func (r *raft) delProgress(id uint64) {
-	delete(r.prs, id)
-	delete(r.learnerPrs, id)
-}
-
 func (r *raft) loadState(state pb.HardState) {
 	if state.Commit < r.raftLog.committed || state.Commit > r.raftLog.lastIndex() {
 		r.logger.Panicf("%x state.commit %d is out of range [%d, %d]", r.id, state.Commit, r.raftLog.committed, r.raftLog.lastIndex())
@@ -1495,29 +1444,6 @@ func (r *raft) resetRandomizedElectionTimeout() {
 	r.randomizedElectionTimeout = r.electionTimeout + globalRand.Intn(r.electionTimeout)
 }
 
-// checkQuorumActive returns true if the quorum is active from
-// the view of the local raft state machine. Otherwise, it returns
-// false.
-// checkQuorumActive also resets all RecentActive to false.
-func (r *raft) checkQuorumActive() bool {
-	var act int
-
-	r.forEachProgress(func(id uint64, pr *Progress) {
-		if id == r.id { // self is always active
-			act++
-			return
-		}
-
-		if pr.RecentActive && !pr.IsLearner {
-			act++
-		}
-
-		pr.RecentActive = false
-	})
-
-	return act >= r.quorum()
-}
-
 func (r *raft) sendTimeoutNow(to uint64) {
 	r.send(pb.Message{To: to, Type: pb.MsgTimeoutNow})
 }

raft/raft_flow_control_test.go

@@ -29,11 +29,11 @@ func TestMsgAppFlowControlFull(t *testing.T) {
 	r.becomeCandidate()
 	r.becomeLeader()
 
-	pr2 := r.prs[2]
+	pr2 := r.prs.nodes[2]
 	// force the progress to be in replicate state
 	pr2.becomeReplicate()
 	// fill in the inflights window
-	for i := 0; i < r.maxInflight; i++ {
+	for i := 0; i < r.prs.maxInflight; i++ {
 		r.Step(pb.Message{From: 1, To: 1, Type: pb.MsgProp, Entries: []pb.Entry{{Data: []byte("somedata")}}})
 		ms := r.readMessages()
 		if len(ms) != 1 {
@@ -65,18 +65,18 @@ func TestMsgAppFlowControlMoveForward(t *testing.T) {
 	r.becomeCandidate()
 	r.becomeLeader()
 
-	pr2 := r.prs[2]
+	pr2 := r.prs.nodes[2]
 	// force the progress to be in replicate state
 	pr2.becomeReplicate()
 	// fill in the inflights window
-	for i := 0; i < r.maxInflight; i++ {
+	for i := 0; i < r.prs.maxInflight; i++ {
 		r.Step(pb.Message{From: 1, To: 1, Type: pb.MsgProp, Entries: []pb.Entry{{Data: []byte("somedata")}}})
 		r.readMessages()
 	}
 
 	// 1 is noop, 2 is the first proposal we just sent.
 	// so we start with 2.
-	for tt := 2; tt < r.maxInflight; tt++ {
+	for tt := 2; tt < r.prs.maxInflight; tt++ {
 		// move forward the window
 		r.Step(pb.Message{From: 2, To: 1, Type: pb.MsgAppResp, Index: uint64(tt)})
 		r.readMessages()
@@ -110,11 +110,11 @@ func TestMsgAppFlowControlRecvHeartbeat(t *testing.T) {
 	r.becomeCandidate()
 	r.becomeLeader()
 
-	pr2 := r.prs[2]
+	pr2 := r.prs.nodes[2]
 	// force the progress to be in replicate state
 	pr2.becomeReplicate()
 	// fill in the inflights window
-	for i := 0; i < r.maxInflight; i++ {
+	for i := 0; i < r.prs.maxInflight; i++ {
 		r.Step(pb.Message{From: 1, To: 1, Type: pb.MsgProp, Entries: []pb.Entry{{Data: []byte("somedata")}}})
 		r.readMessages()
 	}

raft/raft_paper_test.go

@@ -169,7 +169,7 @@ func testNonleaderStartElection(t *testing.T, state StateType) {
 	if r.state != StateCandidate {
 		t.Errorf("state = %s, want %s", r.state, StateCandidate)
 	}
-	if !r.votes[r.id] {
+	if !r.prs.votes[r.id] {
 		t.Errorf("vote for self = false, want true")
 	}
 	msgs := r.readMessages()

raft/raft_snap_test.go

@@ -40,11 +40,11 @@ func TestSendingSnapshotSetPendingSnapshot(t *testing.T) {
 
 	// force set the next of node 2, so that
 	// node 2 needs a snapshot
-	sm.prs[2].Next = sm.raftLog.firstIndex()
+	sm.prs.nodes[2].Next = sm.raftLog.firstIndex()
 
-	sm.Step(pb.Message{From: 2, To: 1, Type: pb.MsgAppResp, Index: sm.prs[2].Next - 1, Reject: true})
-	if sm.prs[2].PendingSnapshot != 11 {
-		t.Fatalf("PendingSnapshot = %d, want 11", sm.prs[2].PendingSnapshot)
+	sm.Step(pb.Message{From: 2, To: 1, Type: pb.MsgAppResp, Index: sm.prs.nodes[2].Next - 1, Reject: true})
+	if sm.prs.nodes[2].PendingSnapshot != 11 {
+		t.Fatalf("PendingSnapshot = %d, want 11", sm.prs.nodes[2].PendingSnapshot)
 	}
 }
 
@@ -56,7 +56,7 @@ func TestPendingSnapshotPauseReplication(t *testing.T) {
 	sm.becomeCandidate()
 	sm.becomeLeader()
 
-	sm.prs[2].becomeSnapshot(11)
+	sm.prs.nodes[2].becomeSnapshot(11)
 
 	sm.Step(pb.Message{From: 1, To: 1, Type: pb.MsgProp, Entries: []pb.Entry{{Data: []byte("somedata")}}})
 	msgs := sm.readMessages()
@@ -73,18 +73,18 @@ func TestSnapshotFailure(t *testing.T) {
 	sm.becomeCandidate()
 	sm.becomeLeader()
 
-	sm.prs[2].Next = 1
-	sm.prs[2].becomeSnapshot(11)
+	sm.prs.nodes[2].Next = 1
+	sm.prs.nodes[2].becomeSnapshot(11)
 
 	sm.Step(pb.Message{From: 2, To: 1, Type: pb.MsgSnapStatus, Reject: true})
-	if sm.prs[2].PendingSnapshot != 0 {
-		t.Fatalf("PendingSnapshot = %d, want 0", sm.prs[2].PendingSnapshot)
+	if sm.prs.nodes[2].PendingSnapshot != 0 {
+		t.Fatalf("PendingSnapshot = %d, want 0", sm.prs.nodes[2].PendingSnapshot)
 	}
-	if sm.prs[2].Next != 1 {
-		t.Fatalf("Next = %d, want 1", sm.prs[2].Next)
+	if sm.prs.nodes[2].Next != 1 {
+		t.Fatalf("Next = %d, want 1", sm.prs.nodes[2].Next)
 	}
-	if !sm.prs[2].Paused {
-		t.Errorf("Paused = %v, want true", sm.prs[2].Paused)
+	if !sm.prs.nodes[2].Paused {
+		t.Errorf("Paused = %v, want true", sm.prs.nodes[2].Paused)
 	}
 }
 
@@ -96,18 +96,18 @@ func TestSnapshotSucceed(t *testing.T) {
 	sm.becomeCandidate()
 	sm.becomeLeader()
 
-	sm.prs[2].Next = 1
-	sm.prs[2].becomeSnapshot(11)
+	sm.prs.nodes[2].Next = 1
+	sm.prs.nodes[2].becomeSnapshot(11)
 
 	sm.Step(pb.Message{From: 2, To: 1, Type: pb.MsgSnapStatus, Reject: false})
-	if sm.prs[2].PendingSnapshot != 0 {
-		t.Fatalf("PendingSnapshot = %d, want 0", sm.prs[2].PendingSnapshot)
+	if sm.prs.nodes[2].PendingSnapshot != 0 {
+		t.Fatalf("PendingSnapshot = %d, want 0", sm.prs.nodes[2].PendingSnapshot)
 	}
-	if sm.prs[2].Next != 12 {
-		t.Fatalf("Next = %d, want 12", sm.prs[2].Next)
+	if sm.prs.nodes[2].Next != 12 {
+		t.Fatalf("Next = %d, want 12", sm.prs.nodes[2].Next)
 	}
-	if !sm.prs[2].Paused {
-		t.Errorf("Paused = %v, want true", sm.prs[2].Paused)
+	if !sm.prs.nodes[2].Paused {
+		t.Errorf("Paused = %v, want true", sm.prs.nodes[2].Paused)
 	}
 }
 
@@ -206,7 +206,7 @@ func TestSnapshotSucceedViaAppResp(t *testing.T) {
 	mustSend(n2, n1, pb.MsgAppResp)
 
 	// Leader has correct state for follower.
-	pr := n1.prs[2]
+	pr := n1.prs.nodes[2]
 	if pr.State != ProgressStateReplicate {
 		t.Fatalf("unexpected state %v", pr)
 	}
@@ -227,23 +227,23 @@ func TestSnapshotAbort(t *testing.T) {
 	sm.becomeCandidate()
 	sm.becomeLeader()
 
-	sm.prs[2].Next = 1
-	sm.prs[2].becomeSnapshot(11)
+	sm.prs.nodes[2].Next = 1
+	sm.prs.nodes[2].becomeSnapshot(11)
 
 	// A successful msgAppResp that has a higher/equal index than the
 	// pending snapshot should abort the pending snapshot.
 	sm.Step(pb.Message{From: 2, To: 1, Type: pb.MsgAppResp, Index: 11})
-	if sm.prs[2].PendingSnapshot != 0 {
-		t.Fatalf("PendingSnapshot = %d, want 0", sm.prs[2].PendingSnapshot)
+	if sm.prs.nodes[2].PendingSnapshot != 0 {
+		t.Fatalf("PendingSnapshot = %d, want 0", sm.prs.nodes[2].PendingSnapshot)
 	}
 	// The follower entered ProgressStateReplicate and the leader send an append
 	// and optimistically updated the progress (so we see 13 instead of 12).
 	// There is something to append because the leader appended an empty entry
 	// to the log at index 12 when it assumed leadership.
-	if sm.prs[2].Next != 13 {
-		t.Fatalf("Next = %d, want 13", sm.prs[2].Next)
+	if sm.prs.nodes[2].Next != 13 {
+		t.Fatalf("Next = %d, want 13", sm.prs.nodes[2].Next)
 	}
-	if n := sm.prs[2].ins.count; n != 1 {
+	if n := sm.prs.nodes[2].ins.count; n != 1 {
 		t.Fatalf("expected an inflight message, got %d", n)
 	}
 }

raft/raft_test.go

@@ -271,12 +271,12 @@ func TestProgressLeader(t *testing.T) {
 	r := newTestRaft(1, []uint64{1, 2}, 5, 1, NewMemoryStorage())
 	r.becomeCandidate()
 	r.becomeLeader()
-	r.prs[2].becomeReplicate()
+	r.prs.nodes[2].becomeReplicate()
 
 	// Send proposals to r1. The first 5 entries should be appended to the log.
 	propMsg := pb.Message{From: 1, To: 1, Type: pb.MsgProp, Entries: []pb.Entry{{Data: []byte("foo")}}}
 	for i := 0; i < 5; i++ {
-		if pr := r.prs[r.id]; pr.State != ProgressStateReplicate || pr.Match != uint64(i+1) || pr.Next != pr.Match+1 {
+		if pr := r.prs.nodes[r.id]; pr.State != ProgressStateReplicate || pr.Match != uint64(i+1) || pr.Next != pr.Match+1 {
 			t.Errorf("unexpected progress %v", pr)
 		}
 		if err := r.Step(propMsg); err != nil {
@@ -291,17 +291,17 @@ func TestProgressResumeByHeartbeatResp(t *testing.T) {
 	r.becomeCandidate()
 	r.becomeLeader()
 
-	r.prs[2].Paused = true
+	r.prs.nodes[2].Paused = true
 
 	r.Step(pb.Message{From: 1, To: 1, Type: pb.MsgBeat})
-	if !r.prs[2].Paused {
-		t.Errorf("paused = %v, want true", r.prs[2].Paused)
+	if !r.prs.nodes[2].Paused {
+		t.Errorf("paused = %v, want true", r.prs.nodes[2].Paused)
 	}
 
-	r.prs[2].becomeReplicate()
+	r.prs.nodes[2].becomeReplicate()
 	r.Step(pb.Message{From: 2, To: 1, Type: pb.MsgHeartbeatResp})
-	if r.prs[2].Paused {
-		t.Errorf("paused = %v, want false", r.prs[2].Paused)
+	if r.prs.nodes[2].Paused {
+		t.Errorf("paused = %v, want false", r.prs.nodes[2].Paused)
 	}
 }
 
@@ -331,7 +331,7 @@ func TestProgressFlowControl(t *testing.T) {
 	r.readMessages()
 
 	// While node 2 is in probe state, propose a bunch of entries.
-	r.prs[2].becomeProbe()
+	r.prs.nodes[2].becomeProbe()
 	blob := []byte(strings.Repeat("a", 1000))
 	for i := 0; i < 10; i++ {
 		r.Step(pb.Message{From: 1, To: 1, Type: pb.MsgProp, Entries: []pb.Entry{{Data: blob}}})
@@ -409,8 +409,8 @@ func TestUncommittedEntryLimit(t *testing.T) {
 
 	// Set the two followers to the replicate state. Commit to tail of log.
 	const numFollowers = 2
-	r.prs[2].becomeReplicate()
-	r.prs[3].becomeReplicate()
+	r.prs.nodes[2].becomeReplicate()
+	r.prs.nodes[3].becomeReplicate()
 	r.uncommittedSize = 0
 
 	// Send proposals to r1. The first 5 entries should be appended to the log.
@@ -889,7 +889,7 @@ func TestLearnerLogReplication(t *testing.T) {
 		t.Errorf("peer 2 wants committed to %d, but still %d", n1.raftLog.committed, n2.raftLog.committed)
 	}
 
-	match := n1.getProgress(2).Match
+	match := n1.prs.getProgress(2).Match
 	if match != n2.raftLog.committed {
 		t.Errorf("progress 2 of leader 1 wants match %d, but got %d", n2.raftLog.committed, match)
 	}
@@ -1351,8 +1351,9 @@ func TestCommit(t *testing.T) {
 		storage.hardState = pb.HardState{Term: tt.smTerm}
 
 		sm := newTestRaft(1, []uint64{1}, 10, 2, storage)
+		sm.prs.removeAny(1)
 		for j := 0; j < len(tt.matches); j++ {
-			sm.setProgress(uint64(j)+1, tt.matches[j], tt.matches[j]+1, false)
+			sm.prs.initProgress(uint64(j)+1, tt.matches[j], tt.matches[j]+1, false)
 		}
 		sm.maybeCommit()
 		if g := sm.raftLog.committed; g != tt.w {
@@ -2137,7 +2138,7 @@ func TestNonPromotableVoterWithCheckQuorum(t *testing.T) {
 	nt := newNetwork(a, b)
 	setRandomizedElectionTimeout(b, b.electionTimeout+1)
 	// Need to remove 2 again to make it a non-promotable node since newNetwork overwritten some internal states
-	b.delProgress(2)
+	b.prs.removeAny(2)
 
 	if b.promotable() {
 		t.Fatalf("promotable = %v, want false", b.promotable())
@@ -2631,7 +2632,7 @@ func TestLeaderAppResp(t *testing.T) {
 		sm.readMessages()
 		sm.Step(pb.Message{From: 2, Type: pb.MsgAppResp, Index: tt.index, Term: sm.Term, Reject: tt.reject, RejectHint: tt.index})
 
-		p := sm.prs[2]
+		p := sm.prs.nodes[2]
 		if p.Match != tt.wmatch {
 			t.Errorf("#%d match = %d, want %d", i, p.Match, tt.wmatch)
 		}
@@ -2678,9 +2679,9 @@ func TestBcastBeat(t *testing.T) {
 		mustAppendEntry(sm, pb.Entry{Index: uint64(i) + 1})
 	}
 	// slow follower
-	sm.prs[2].Match, sm.prs[2].Next = 5, 6
+	sm.prs.nodes[2].Match, sm.prs.nodes[2].Next = 5, 6
 	// normal follower
-	sm.prs[3].Match, sm.prs[3].Next = sm.raftLog.lastIndex(), sm.raftLog.lastIndex()+1
+	sm.prs.nodes[3].Match, sm.prs.nodes[3].Next = sm.raftLog.lastIndex(), sm.raftLog.lastIndex()+1
 
 	sm.Step(pb.Message{Type: pb.MsgBeat})
 	msgs := sm.readMessages()
@@ -2688,8 +2689,8 @@ func TestBcastBeat(t *testing.T) {
 		t.Fatalf("len(msgs) = %v, want 2", len(msgs))
 	}
 	wantCommitMap := map[uint64]uint64{
-		2: min(sm.raftLog.committed, sm.prs[2].Match),
-		3: min(sm.raftLog.committed, sm.prs[3].Match),
+		2: min(sm.raftLog.committed, sm.prs.nodes[2].Match),
+		3: min(sm.raftLog.committed, sm.prs.nodes[3].Match),
 	}
 	for i, m := range msgs {
 		if m.Type != pb.MsgHeartbeat {
@@ -2775,11 +2776,11 @@ func TestLeaderIncreaseNext(t *testing.T) {
 		sm.raftLog.append(previousEnts...)
 		sm.becomeCandidate()
 		sm.becomeLeader()
-		sm.prs[2].State = tt.state
-		sm.prs[2].Next = tt.next
+		sm.prs.nodes[2].State = tt.state
+		sm.prs.nodes[2].Next = tt.next
 		sm.Step(pb.Message{From: 1, To: 1, Type: pb.MsgProp, Entries: []pb.Entry{{Data: []byte("somedata")}}})
 
-		p := sm.prs[2]
+		p := sm.prs.nodes[2]
 		if p.Next != tt.wnext {
 			t.Errorf("#%d next = %d, want %d", i, p.Next, tt.wnext)
 		}
@@ -2791,7 +2792,7 @@ func TestSendAppendForProgressProbe(t *testing.T) {
 	r.becomeCandidate()
 	r.becomeLeader()
 	r.readMessages()
-	r.prs[2].becomeProbe()
+	r.prs.nodes[2].becomeProbe()
 
 	// each round is a heartbeat
 	for i := 0; i < 3; i++ {
@@ -2810,8 +2811,8 @@ func TestSendAppendForProgressProbe(t *testing.T) {
 			}
 		}
 
-		if !r.prs[2].Paused {
-			t.Errorf("paused = %v, want true", r.prs[2].Paused)
+		if !r.prs.nodes[2].Paused {
+			t.Errorf("paused = %v, want true", r.prs.nodes[2].Paused)
 		}
 		for j := 0; j < 10; j++ {
 			mustAppendEntry(r, pb.Entry{Data: []byte("somedata")})
@@ -2825,8 +2826,8 @@ func TestSendAppendForProgressProbe(t *testing.T) {
 		for j := 0; j < r.heartbeatTimeout; j++ {
 			r.Step(pb.Message{From: 1, To: 1, Type: pb.MsgBeat})
 		}
-		if !r.prs[2].Paused {
-			t.Errorf("paused = %v, want true", r.prs[2].Paused)
+		if !r.prs.nodes[2].Paused {
+			t.Errorf("paused = %v, want true", r.prs.nodes[2].Paused)
 		}
 
 		// consume the heartbeat
@@ -2848,8 +2849,8 @@ func TestSendAppendForProgressProbe(t *testing.T) {
 	if msg[0].Index != 0 {
 		t.Errorf("index = %d, want %d", msg[0].Index, 0)
 	}
-	if !r.prs[2].Paused {
-		t.Errorf("paused = %v, want true", r.prs[2].Paused)
+	if !r.prs.nodes[2].Paused {
+		t.Errorf("paused = %v, want true", r.prs.nodes[2].Paused)
 	}
 }
 
@@ -2858,7 +2859,7 @@ func TestSendAppendForProgressReplicate(t *testing.T) {
 	r.becomeCandidate()
 	r.becomeLeader()
 	r.readMessages()
-	r.prs[2].becomeReplicate()
+	r.prs.nodes[2].becomeReplicate()
 
 	for i := 0; i < 10; i++ {
 		mustAppendEntry(r, pb.Entry{Data: []byte("somedata")})
@@ -2875,7 +2876,7 @@ func TestSendAppendForProgressSnapshot(t *testing.T) {
 	r.becomeCandidate()
 	r.becomeLeader()
 	r.readMessages()
-	r.prs[2].becomeSnapshot(10)
+	r.prs.nodes[2].becomeSnapshot(10)
 
 	for i := 0; i < 10; i++ {
 		mustAppendEntry(r, pb.Entry{Data: []byte("somedata")})
@@ -2896,17 +2897,17 @@ func TestRecvMsgUnreachable(t *testing.T) {
 	r.becomeLeader()
 	r.readMessages()
 	// set node 2 to state replicate
-	r.prs[2].Match = 3
-	r.prs[2].becomeReplicate()
-	r.prs[2].optimisticUpdate(5)
+	r.prs.nodes[2].Match = 3
+	r.prs.nodes[2].becomeReplicate()
+	r.prs.nodes[2].optimisticUpdate(5)
 
 	r.Step(pb.Message{From: 2, To: 1, Type: pb.MsgUnreachable})
 
-	if r.prs[2].State != ProgressStateProbe {
-		t.Errorf("state = %s, want %s", r.prs[2].State, ProgressStateProbe)
+	if r.prs.nodes[2].State != ProgressStateProbe {
+		t.Errorf("state = %s, want %s", r.prs.nodes[2].State, ProgressStateProbe)
 	}
-	if wnext := r.prs[2].Match + 1; r.prs[2].Next != wnext {
-		t.Errorf("next = %d, want %d", r.prs[2].Next, wnext)
+	if wnext := r.prs.nodes[2].Match + 1; r.prs.nodes[2].Next != wnext {
+		t.Errorf("next = %d, want %d", r.prs.nodes[2].Next, wnext)
 	}
 }
 
@@ -2931,7 +2932,7 @@ func TestRestore(t *testing.T) {
 	if mustTerm(sm.raftLog.term(s.Metadata.Index)) != s.Metadata.Term {
 		t.Errorf("log.lastTerm = %d, want %d", mustTerm(sm.raftLog.term(s.Metadata.Index)), s.Metadata.Term)
 	}
-	sg := sm.nodes()
+	sg := sm.prs.voterNodes()
 	if !reflect.DeepEqual(sg, s.Metadata.ConfState.Nodes) {
 		t.Errorf("sm.Nodes = %+v, want %+v", sg, s.Metadata.ConfState.Nodes)
 	}
@@ -2963,22 +2964,22 @@ func TestRestoreWithLearner(t *testing.T) {
 	if mustTerm(sm.raftLog.term(s.Metadata.Index)) != s.Metadata.Term {
 		t.Errorf("log.lastTerm = %d, want %d", mustTerm(sm.raftLog.term(s.Metadata.Index)), s.Metadata.Term)
 	}
-	sg := sm.nodes()
+	sg := sm.prs.voterNodes()
 	if len(sg) != len(s.Metadata.ConfState.Nodes) {
 		t.Errorf("sm.Nodes = %+v, length not equal with %+v", sg, s.Metadata.ConfState.Nodes)
 	}
-	lns := sm.learnerNodes()
+	lns := sm.prs.learnerNodes()
 	if len(lns) != len(s.Metadata.ConfState.Learners) {
 		t.Errorf("sm.LearnerNodes = %+v, length not equal with %+v", sg, s.Metadata.ConfState.Learners)
 	}
 	for _, n := range s.Metadata.ConfState.Nodes {
-		if sm.prs[n].IsLearner {
-			t.Errorf("sm.Node %x isLearner = %s, want %t", n, sm.prs[n], false)
+		if sm.prs.nodes[n].IsLearner {
+			t.Errorf("sm.Node %x isLearner = %s, want %t", n, sm.prs.nodes[n], false)
 		}
 	}
 	for _, n := range s.Metadata.ConfState.Learners {
-		if !sm.learnerPrs[n].IsLearner {
-			t.Errorf("sm.Node %x isLearner = %s, want %t", n, sm.prs[n], true)
+		if !sm.prs.learners[n].IsLearner {
+			t.Errorf("sm.Node %x isLearner = %s, want %t", n, sm.prs.nodes[n], true)
 		}
 	}
 
@@ -3120,8 +3121,8 @@ func TestProvideSnap(t *testing.T) {
 	sm.becomeLeader()
 
 	// force set the next of node 2, so that node 2 needs a snapshot
-	sm.prs[2].Next = sm.raftLog.firstIndex()
-	sm.Step(pb.Message{From: 2, To: 1, Type: pb.MsgAppResp, Index: sm.prs[2].Next - 1, Reject: true})
+	sm.prs.nodes[2].Next = sm.raftLog.firstIndex()
+	sm.Step(pb.Message{From: 2, To: 1, Type: pb.MsgAppResp, Index: sm.prs.nodes[2].Next - 1, Reject: true})
 
 	msgs := sm.readMessages()
 	if len(msgs) != 1 {
@@ -3151,8 +3152,8 @@ func TestIgnoreProvidingSnap(t *testing.T) {
 
 	// force set the next of node 2, so that node 2 needs a snapshot
 	// change node 2 to be inactive, expect node 1 ignore sending snapshot to 2
-	sm.prs[2].Next = sm.raftLog.firstIndex() - 1
-	sm.prs[2].RecentActive = false
+	sm.prs.nodes[2].Next = sm.raftLog.firstIndex() - 1
+	sm.prs.nodes[2].RecentActive = false
 
 	sm.Step(pb.Message{From: 1, To: 1, Type: pb.MsgProp, Entries: []pb.Entry{{Data: []byte("somedata")}}})
 
@@ -3192,7 +3193,7 @@ func TestSlowNodeRestore(t *testing.T) {
 	}
 	lead := nt.peers[1].(*raft)
 	nextEnts(lead, nt.storage[1])
-	nt.storage[1].CreateSnapshot(lead.raftLog.applied, &pb.ConfState{Nodes: lead.nodes()}, nil)
+	nt.storage[1].CreateSnapshot(lead.raftLog.applied, &pb.ConfState{Nodes: lead.prs.voterNodes()}, nil)
 	nt.storage[1].Compact(lead.raftLog.applied)
 
 	nt.recover()
@@ -3200,7 +3201,7 @@ func TestSlowNodeRestore(t *testing.T) {
 	// node 3 will only be considered as active when node 1 receives a reply from it.
 	for {
 		nt.send(pb.Message{From: 1, To: 1, Type: pb.MsgBeat})
-		if lead.prs[3].RecentActive {
+		if lead.prs.nodes[3].RecentActive {
 			break
 		}
 	}
@@ -3287,7 +3288,7 @@ func TestNewLeaderPendingConfig(t *testing.T) {
 func TestAddNode(t *testing.T) {
 	r := newTestRaft(1, []uint64{1}, 10, 1, NewMemoryStorage())
 	r.addNode(2)
-	nodes := r.nodes()
+	nodes := r.prs.voterNodes()
 	wnodes := []uint64{1, 2}
 	if !reflect.DeepEqual(nodes, wnodes) {
 		t.Errorf("nodes = %v, want %v", nodes, wnodes)
@@ -3298,13 +3299,13 @@ func TestAddNode(t *testing.T) {
 func TestAddLearner(t *testing.T) {
 	r := newTestRaft(1, []uint64{1}, 10, 1, NewMemoryStorage())
 	r.addLearner(2)
-	nodes := r.learnerNodes()
+	nodes := r.prs.learnerNodes()
 	wnodes := []uint64{2}
 	if !reflect.DeepEqual(nodes, wnodes) {
 		t.Errorf("nodes = %v, want %v", nodes, wnodes)
 	}
-	if !r.learnerPrs[2].IsLearner {
-		t.Errorf("node 2 is learner %t, want %t", r.prs[2].IsLearner, true)
+	if !r.prs.learners[2].IsLearner {
+		t.Errorf("node 2 is learner %t, want %t", r.prs.nodes[2].IsLearner, true)
 	}
 }
 
@@ -3348,14 +3349,14 @@ func TestRemoveNode(t *testing.T) {
 	r := newTestRaft(1, []uint64{1, 2}, 10, 1, NewMemoryStorage())
 	r.removeNode(2)
 	w := []uint64{1}
-	if g := r.nodes(); !reflect.DeepEqual(g, w) {
+	if g := r.prs.voterNodes(); !reflect.DeepEqual(g, w) {
 		t.Errorf("nodes = %v, want %v", g, w)
 	}
 
 	// remove all nodes from cluster
 	r.removeNode(1)
 	w = []uint64{}
-	if g := r.nodes(); !reflect.DeepEqual(g, w) {
+	if g := r.prs.voterNodes(); !reflect.DeepEqual(g, w) {
 		t.Errorf("nodes = %v, want %v", g, w)
 	}
 }
@@ -3366,18 +3367,18 @@ func TestRemoveLearner(t *testing.T) {
 	r := newTestLearnerRaft(1, []uint64{1}, []uint64{2}, 10, 1, NewMemoryStorage())
 	r.removeNode(2)
 	w := []uint64{1}
-	if g := r.nodes(); !reflect.DeepEqual(g, w) {
+	if g := r.prs.voterNodes(); !reflect.DeepEqual(g, w) {
 		t.Errorf("nodes = %v, want %v", g, w)
 	}
 
 	w = []uint64{}
-	if g := r.learnerNodes(); !reflect.DeepEqual(g, w) {
+	if g := r.prs.learnerNodes(); !reflect.DeepEqual(g, w) {
 		t.Errorf("nodes = %v, want %v", g, w)
 	}
 
 	// remove all nodes from cluster
 	r.removeNode(1)
-	if g := r.nodes(); !reflect.DeepEqual(g, w) {
+	if g := r.prs.voterNodes(); !reflect.DeepEqual(g, w) {
 		t.Errorf("nodes = %v, want %v", g, w)
 	}
 }
@@ -3416,8 +3417,8 @@ func TestRaftNodes(t *testing.T) {
 	}
 	for i, tt := range tests {
 		r := newTestRaft(1, tt.ids, 10, 1, NewMemoryStorage())
-		if !reflect.DeepEqual(r.nodes(), tt.wids) {
-			t.Errorf("#%d: nodes = %+v, want %+v", i, r.nodes(), tt.wids)
+		if !reflect.DeepEqual(r.prs.voterNodes(), tt.wids) {
+			t.Errorf("#%d: nodes = %+v, want %+v", i, r.prs.voterNodes(), tt.wids)
 		}
 	}
 }
@@ -3618,8 +3619,8 @@ func TestLeaderTransferToSlowFollower(t *testing.T) {
 
 	nt.recover()
 	lead := nt.peers[1].(*raft)
-	if lead.prs[3].Match != 1 {
-		t.Fatalf("node 1 has match %x for node 3, want %x", lead.prs[3].Match, 1)
+	if lead.prs.nodes[3].Match != 1 {
+		t.Fatalf("node 1 has match %x for node 3, want %x", lead.prs.nodes[3].Match, 1)
 	}
 
 	// Transfer leadership to 3 when node 3 is lack of log.
@@ -3637,12 +3638,12 @@ func TestLeaderTransferAfterSnapshot(t *testing.T) {
 	nt.send(pb.Message{From: 1, To: 1, Type: pb.MsgProp, Entries: []pb.Entry{{}}})
 	lead := nt.peers[1].(*raft)
 	nextEnts(lead, nt.storage[1])
-	nt.storage[1].CreateSnapshot(lead.raftLog.applied, &pb.ConfState{Nodes: lead.nodes()}, nil)
+	nt.storage[1].CreateSnapshot(lead.raftLog.applied, &pb.ConfState{Nodes: lead.prs.voterNodes()}, nil)
 	nt.storage[1].Compact(lead.raftLog.applied)
 
 	nt.recover()
-	if lead.prs[3].Match != 1 {
-		t.Fatalf("node 1 has match %x for node 3, want %x", lead.prs[3].Match, 1)
+	if lead.prs.nodes[3].Match != 1 {
+		t.Fatalf("node 1 has match %x for node 3, want %x", lead.prs.nodes[3].Match, 1)
 	}
 
 	// Transfer leadership to 3 when node 3 is lack of snapshot.
@@ -3721,8 +3722,8 @@ func TestLeaderTransferIgnoreProposal(t *testing.T) {
 		t.Fatalf("should return drop proposal error while transferring")
 	}
 
-	if lead.prs[1].Match != 1 {
-		t.Fatalf("node 1 has match %x, want %x", lead.prs[1].Match, 1)
+	if lead.prs.nodes[1].Match != 1 {
+		t.Fatalf("node 1 has match %x, want %x", lead.prs.nodes[1].Match, 1)
 	}
 }
 
@@ -4294,18 +4295,18 @@ func newNetworkWithConfig(configFunc func(*Config), peers ...stateMachine) *netw
 			sm := newRaft(cfg)
 			npeers[id] = sm
 		case *raft:
-			learners := make(map[uint64]bool, len(v.learnerPrs))
-			for i := range v.learnerPrs {
+			learners := make(map[uint64]bool, len(v.prs.learners))
+			for i := range v.prs.learners {
 				learners[i] = true
 			}
 			v.id = id
-			v.prs = make(map[uint64]*Progress)
-			v.learnerPrs = make(map[uint64]*Progress)
+			v.prs.nodes = make(map[uint64]*Progress)
+			v.prs.learners = make(map[uint64]*Progress)
 			for i := 0; i < size; i++ {
 				if _, ok := learners[peerAddrs[i]]; ok {
-					v.learnerPrs[peerAddrs[i]] = &Progress{IsLearner: true}
+					v.prs.learners[peerAddrs[i]] = &Progress{IsLearner: true}
 				} else {
-					v.prs[peerAddrs[i]] = &Progress{}
+					v.prs.nodes[peerAddrs[i]] = &Progress{}
 				}
 			}
 			v.reset(v.Term)

raft/rawnode.go

@@ -166,7 +166,7 @@ func (rn *RawNode) ProposeConfChange(cc pb.ConfChange) error {
 // ApplyConfChange applies a config change to the local node.
 func (rn *RawNode) ApplyConfChange(cc pb.ConfChange) *pb.ConfState {
 	if cc.NodeID == None {
-		return &pb.ConfState{Nodes: rn.raft.nodes(), Learners: rn.raft.learnerNodes()}
+		return &pb.ConfState{Nodes: rn.raft.prs.voterNodes(), Learners: rn.raft.prs.learnerNodes()}
 	}
 	switch cc.Type {
 	case pb.ConfChangeAddNode:
@@ -179,7 +179,7 @@ func (rn *RawNode) ApplyConfChange(cc pb.ConfChange) *pb.ConfState {
 	default:
 		panic("unexpected conf type")
 	}
-	return &pb.ConfState{Nodes: rn.raft.nodes(), Learners: rn.raft.learnerNodes()}
+	return &pb.ConfState{Nodes: rn.raft.prs.voterNodes(), Learners: rn.raft.prs.learnerNodes()}
 }
 
 // Step advances the state machine using the given message.
@@ -188,7 +188,7 @@ func (rn *RawNode) Step(m pb.Message) error {
 	if IsLocalMsg(m.Type) {
 		return ErrStepLocalMsg
 	}
-	if pr := rn.raft.getProgress(m.From); pr != nil || !IsResponseMsg(m.Type) {
+	if pr := rn.raft.prs.getProgress(m.From); pr != nil || !IsResponseMsg(m.Type) {
 		return rn.raft.Step(m)
 	}
 	return ErrStepPeerNotFound
@@ -257,16 +257,15 @@ const (
 // WithProgress is a helper to introspect the Progress for this node and its
 // peers.
 func (rn *RawNode) WithProgress(visitor func(id uint64, typ ProgressType, pr Progress)) {
-	for id, pr := range rn.raft.prs {
-		pr := *pr
-		pr.ins = nil
-		visitor(id, ProgressTypePeer, pr)
-	}
-	for id, pr := range rn.raft.learnerPrs {
-		pr := *pr
-		pr.ins = nil
-		visitor(id, ProgressTypeLearner, pr)
-	}
+	rn.raft.prs.visit(func(id uint64, pr *Progress) {
+		typ := ProgressTypePeer
+		if pr.IsLearner {
+			typ = ProgressTypeLearner
+		}
+		p := *pr
+		p.ins = nil
+		visitor(id, typ, p)
+	})
 }
 
 // ReportUnreachable reports the given node is not reachable for the last send.

raft/read_only.go

@@ -50,26 +50,25 @@ func newReadOnly(option ReadOnlyOption) *readOnly {
 // the read only request.
 // `m` is the original read only request message from the local or remote node.
 func (ro *readOnly) addRequest(index uint64, m pb.Message) {
-	ctx := string(m.Entries[0].Data)
-	if _, ok := ro.pendingReadIndex[ctx]; ok {
+	s := string(m.Entries[0].Data)
+	if _, ok := ro.pendingReadIndex[s]; ok {
 		return
 	}
-	ro.pendingReadIndex[ctx] = &readIndexStatus{index: index, req: m, acks: make(map[uint64]struct{})}
-	ro.readIndexQueue = append(ro.readIndexQueue, ctx)
+	ro.pendingReadIndex[s] = &readIndexStatus{index: index, req: m, acks: make(map[uint64]struct{})}
+	ro.readIndexQueue = append(ro.readIndexQueue, s)
 }
 
 // recvAck notifies the readonly struct that the raft state machine received
 // an acknowledgment of the heartbeat that attached with the read only request
 // context.
-func (ro *readOnly) recvAck(m pb.Message) int {
-	rs, ok := ro.pendingReadIndex[string(m.Context)]
+func (ro *readOnly) recvAck(id uint64, context []byte) map[uint64]struct{} {
+	rs, ok := ro.pendingReadIndex[string(context)]
 	if !ok {
-		return 0
+		return nil
 	}
 
-	rs.acks[m.From] = struct{}{}
-	// add one to include an ack from local node
-	return len(rs.acks) + 1
+	rs.acks[id] = struct{}{}
+	return rs.acks
 }
 
 // advance advances the read only request queue kept by the readonly struct.

raft/status.go

@@ -33,15 +33,18 @@ type Status struct {
 }
 
 func getProgressCopy(r *raft) map[uint64]Progress {
-	prs := make(map[uint64]Progress)
-	for id, p := range r.prs {
-		prs[id] = *p
-	}
+	m := make(map[uint64]Progress)
+	r.prs.visit(func(id uint64, pr *Progress) {
+		var p Progress
+		p, pr = *pr, nil /* avoid accidental reuse below */
 
-	for id, p := range r.learnerPrs {
-		prs[id] = *p
-	}
-	return prs
+		// The inflight buffer is tricky to copy and besides, it isn't exposed
+		// to the client, so pretend it's nil.
+		p.ins = nil
+
+		m[id] = p
+	})
+	return m
 }
 
 func getStatusWithoutProgress(r *raft) Status {