diff --git a/vendor/go.etcd.io/etcd/raft/tracker/inflights.go b/vendor/go.etcd.io/etcd/raft/tracker/inflights.go
new file mode 100644
index 0000000..1a05634
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/raft/tracker/inflights.go
@@ -0,0 +1,132 @@
+// 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
+
+// Inflights limits the number of MsgApp (represented by the largest index
+// contained within) sent to followers but not yet acknowledged by them. Callers
+// use Full() to check whether more messages can be sent, call Add() whenever
+// they are sending a new append, and release "quota" via FreeLE() whenever an
+// ack is received.
+type Inflights struct {
+	// the starting index in the buffer
+	start int
+	// number of inflights in the buffer
+	count int
+
+	// the size of the buffer
+	size int
+
+	// buffer contains the index of the last entry
+	// inside one message.
+	buffer []uint64
+}
+
+// NewInflights sets up an Inflights that allows up to 'size' inflight messages.
+func NewInflights(size int) *Inflights {
+	return &Inflights{
+		size: size,
+	}
+}
+
+// Clone returns an *Inflights that is identical to but shares no memory with
+// the receiver.
+func (in *Inflights) Clone() *Inflights {
+	ins := *in
+	ins.buffer = append([]uint64(nil), in.buffer...)
+	return &ins
+}
+
+// Add notifies the Inflights that a new message with the given index is being
+// dispatched. Full() must be called prior to Add() to verify that there is room
+// for one more message, and consecutive calls to add Add() must provide a
+// monotonic sequence of indexes.
+func (in *Inflights) Add(inflight uint64) {
+	if in.Full() {
+		panic("cannot add into a Full inflights")
+	}
+	next := in.start + in.count
+	size := in.size
+	if next >= size {
+		next -= size
+	}
+	if next >= len(in.buffer) {
+		in.grow()
+	}
+	in.buffer[next] = inflight
+	in.count++
+}
+
+// grow the inflight buffer by doubling up to inflights.size. We grow on demand
+// instead of preallocating to inflights.size to handle systems which have
+// thousands of Raft groups per process.
+func (in *Inflights) grow() {
+	newSize := len(in.buffer) * 2
+	if newSize == 0 {
+		newSize = 1
+	} else if newSize > in.size {
+		newSize = in.size
+	}
+	newBuffer := make([]uint64, newSize)
+	copy(newBuffer, in.buffer)
+	in.buffer = newBuffer
+}
+
+// FreeLE frees the inflights smaller or equal to the given `to` flight.
+func (in *Inflights) FreeLE(to uint64) {
+	if in.count == 0 || to < in.buffer[in.start] {
+		// out of the left side of the window
+		return
+	}
+
+	idx := in.start
+	var i int
+	for i = 0; i < in.count; i++ {
+		if to < in.buffer[idx] { // found the first large inflight
+			break
+		}
+
+		// increase index and maybe rotate
+		size := in.size
+		if idx++; idx >= size {
+			idx -= size
+		}
+	}
+	// free i inflights and set new start index
+	in.count -= i
+	in.start = idx
+	if in.count == 0 {
+		// inflights is empty, reset the start index so that we don't grow the
+		// buffer unnecessarily.
+		in.start = 0
+	}
+}
+
+// FreeFirstOne releases the first inflight. This is a no-op if nothing is
+// inflight.
+func (in *Inflights) FreeFirstOne() { in.FreeLE(in.buffer[in.start]) }
+
+// Full returns true if no more messages can be sent at the moment.
+func (in *Inflights) Full() bool {
+	return in.count == in.size
+}
+
+// Count returns the number of inflight messages.
+func (in *Inflights) Count() int { return in.count }
+
+// reset frees all inflights.
+func (in *Inflights) reset() {
+	in.count = 0
+	in.start = 0
+}
diff --git a/vendor/go.etcd.io/etcd/raft/tracker/progress.go b/vendor/go.etcd.io/etcd/raft/tracker/progress.go
new file mode 100644
index 0000000..62c81f4
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/raft/tracker/progress.go
@@ -0,0 +1,259 @@
+// 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"
+)
+
+// Progress represents a follower’s progress in the view of the leader. Leader
+// maintains progresses of all followers, and sends entries to the follower
+// based on its progress.
+//
+// NB(tbg): Progress is basically a state machine whose transitions are mostly
+// strewn around `*raft.raft`. Additionally, some fields are only used when in a
+// certain State. All of this isn't ideal.
+type Progress struct {
+	Match, Next uint64
+	// State defines how the leader should interact with the follower.
+	//
+	// When in StateProbe, leader sends at most one replication message
+	// per heartbeat interval. It also probes actual progress of the follower.
+	//
+	// When in StateReplicate, leader optimistically increases next
+	// to the latest entry sent after sending replication message. This is
+	// an optimized state for fast replicating log entries to the follower.
+	//
+	// When in StateSnapshot, leader should have sent out snapshot
+	// before and stops sending any replication message.
+	State StateType
+
+	// PendingSnapshot is used in StateSnapshot.
+	// If there is a pending snapshot, the pendingSnapshot will be set to the
+	// index of the snapshot. If pendingSnapshot is set, the replication process of
+	// this Progress will be paused. raft will not resend snapshot until the pending one
+	// is reported to be failed.
+	PendingSnapshot uint64
+
+	// RecentActive is true if the progress is recently active. Receiving any messages
+	// from the corresponding follower indicates the progress is active.
+	// RecentActive can be reset to false after an election timeout.
+	//
+	// TODO(tbg): the leader should always have this set to true.
+	RecentActive bool
+
+	// ProbeSent is used while this follower is in StateProbe. When ProbeSent is
+	// true, raft should pause sending replication message to this peer until
+	// ProbeSent is reset. See ProbeAcked() and IsPaused().
+	ProbeSent bool
+
+	// Inflights is a sliding window for the inflight messages.
+	// Each inflight message contains one or more log entries.
+	// The max number of entries per message is defined in raft config as MaxSizePerMsg.
+	// Thus inflight effectively limits both the number of inflight messages
+	// and the bandwidth each Progress can use.
+	// When inflights is Full, no more message should be sent.
+	// When a leader sends out a message, the index of the last
+	// entry should be added to inflights. The index MUST be added
+	// into inflights in order.
+	// When a leader receives a reply, the previous inflights should
+	// be freed by calling inflights.FreeLE with the index of the last
+	// received entry.
+	Inflights *Inflights
+
+	// IsLearner is true if this progress is tracked for a learner.
+	IsLearner bool
+}
+
+// ResetState moves the Progress into the specified State, resetting ProbeSent,
+// PendingSnapshot, and Inflights.
+func (pr *Progress) ResetState(state StateType) {
+	pr.ProbeSent = false
+	pr.PendingSnapshot = 0
+	pr.State = state
+	pr.Inflights.reset()
+}
+
+func max(a, b uint64) uint64 {
+	if a > b {
+		return a
+	}
+	return b
+}
+
+func min(a, b uint64) uint64 {
+	if a > b {
+		return b
+	}
+	return a
+}
+
+// ProbeAcked is called when this peer has accepted an append. It resets
+// ProbeSent to signal that additional append messages should be sent without
+// further delay.
+func (pr *Progress) ProbeAcked() {
+	pr.ProbeSent = false
+}
+
+// BecomeProbe transitions into StateProbe. Next is reset to Match+1 or,
+// optionally and if larger, the index of the pending snapshot.
+func (pr *Progress) BecomeProbe() {
+	// If the original state is StateSnapshot, progress knows that
+	// the pending snapshot has been sent to this peer successfully, then
+	// probes from pendingSnapshot + 1.
+	if pr.State == StateSnapshot {
+		pendingSnapshot := pr.PendingSnapshot
+		pr.ResetState(StateProbe)
+		pr.Next = max(pr.Match+1, pendingSnapshot+1)
+	} else {
+		pr.ResetState(StateProbe)
+		pr.Next = pr.Match + 1
+	}
+}
+
+// BecomeReplicate transitions into StateReplicate, resetting Next to Match+1.
+func (pr *Progress) BecomeReplicate() {
+	pr.ResetState(StateReplicate)
+	pr.Next = pr.Match + 1
+}
+
+// BecomeSnapshot moves the Progress to StateSnapshot with the specified pending
+// snapshot index.
+func (pr *Progress) BecomeSnapshot(snapshoti uint64) {
+	pr.ResetState(StateSnapshot)
+	pr.PendingSnapshot = snapshoti
+}
+
+// MaybeUpdate is called when an MsgAppResp arrives from the follower, with the
+// index acked by it. The method returns false if the given n index comes from
+// an outdated message. Otherwise it updates the progress and returns true.
+func (pr *Progress) MaybeUpdate(n uint64) bool {
+	var updated bool
+	if pr.Match < n {
+		pr.Match = n
+		updated = true
+		pr.ProbeAcked()
+	}
+	if pr.Next < n+1 {
+		pr.Next = n + 1
+	}
+	return updated
+}
+
+// OptimisticUpdate signals that appends all the way up to and including index n
+// are in-flight. As a result, Next is increased to n+1.
+func (pr *Progress) OptimisticUpdate(n uint64) { pr.Next = n + 1 }
+
+// MaybeDecrTo adjusts the Progress to the receipt of a MsgApp rejection. The
+// arguments are the index the follower rejected to append to its log, and its
+// last index.
+//
+// Rejections can happen spuriously as messages are sent out of order or
+// duplicated. In such cases, the rejection pertains to an index that the
+// Progress already knows were previously acknowledged, and false is returned
+// without changing the Progress.
+//
+// If the rejection is genuine, Next is lowered sensibly, and the Progress is
+// cleared for sending log entries.
+func (pr *Progress) MaybeDecrTo(rejected, last uint64) bool {
+	if pr.State == StateReplicate {
+		// The rejection must be stale if the progress has matched and "rejected"
+		// is smaller than "match".
+		if rejected <= pr.Match {
+			return false
+		}
+		// Directly decrease next to match + 1.
+		//
+		// TODO(tbg): why not use last if it's larger?
+		pr.Next = pr.Match + 1
+		return true
+	}
+
+	// The rejection must be stale if "rejected" does not match next - 1. This
+	// is because non-replicating followers are probed one entry at a time.
+	if pr.Next-1 != rejected {
+		return false
+	}
+
+	if pr.Next = min(rejected, last+1); pr.Next < 1 {
+		pr.Next = 1
+	}
+	pr.ProbeSent = false
+	return true
+}
+
+// IsPaused returns whether sending log entries to this node has been throttled.
+// This is done when a node has rejected recent MsgApps, is currently waiting
+// for a snapshot, or has reached the MaxInflightMsgs limit. In normal
+// operation, this is false. A throttled node will be contacted less frequently
+// until it has reached a state in which it's able to accept a steady stream of
+// log entries again.
+func (pr *Progress) IsPaused() bool {
+	switch pr.State {
+	case StateProbe:
+		return pr.ProbeSent
+	case StateReplicate:
+		return pr.Inflights.Full()
+	case StateSnapshot:
+		return true
+	default:
+		panic("unexpected state")
+	}
+}
+
+func (pr *Progress) String() string {
+	var buf strings.Builder
+	fmt.Fprintf(&buf, "%s match=%d next=%d", pr.State, pr.Match, pr.Next)
+	if pr.IsLearner {
+		fmt.Fprint(&buf, " learner")
+	}
+	if pr.IsPaused() {
+		fmt.Fprint(&buf, " paused")
+	}
+	if pr.PendingSnapshot > 0 {
+		fmt.Fprintf(&buf, " pendingSnap=%d", pr.PendingSnapshot)
+	}
+	if !pr.RecentActive {
+		fmt.Fprintf(&buf, " inactive")
+	}
+	if n := pr.Inflights.Count(); n > 0 {
+		fmt.Fprintf(&buf, " inflight=%d", n)
+		if pr.Inflights.Full() {
+			fmt.Fprint(&buf, "[full]")
+		}
+	}
+	return buf.String()
+}
+
+// ProgressMap is a map of *Progress.
+type ProgressMap map[uint64]*Progress
+
+// String prints the ProgressMap in sorted key order, one Progress per line.
+func (m ProgressMap) String() string {
+	ids := make([]uint64, 0, len(m))
+	for k := range m {
+		ids = append(ids, k)
+	}
+	sort.Slice(ids, func(i, j int) bool {
+		return ids[i] < ids[j]
+	})
+	var buf strings.Builder
+	for _, id := range ids {
+		fmt.Fprintf(&buf, "%d: %s\n", id, m[id])
+	}
+	return buf.String()
+}
diff --git a/vendor/go.etcd.io/etcd/raft/tracker/state.go b/vendor/go.etcd.io/etcd/raft/tracker/state.go
new file mode 100644
index 0000000..285b4b8
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/raft/tracker/state.go
@@ -0,0 +1,42 @@
+// 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
+
+// StateType is the state of a tracked follower.
+type StateType uint64
+
+const (
+	// StateProbe indicates a follower whose last index isn't known. Such a
+	// follower is "probed" (i.e. an append sent periodically) to narrow down
+	// its last index. In the ideal (and common) case, only one round of probing
+	// is necessary as the follower will react with a hint. Followers that are
+	// probed over extended periods of time are often offline.
+	StateProbe StateType = iota
+	// StateReplicate is the state steady in which a follower eagerly receives
+	// log entries to append to its log.
+	StateReplicate
+	// StateSnapshot indicates a follower that needs log entries not available
+	// from the leader's Raft log. Such a follower needs a full snapshot to
+	// return to StateReplicate.
+	StateSnapshot
+)
+
+var prstmap = [...]string{
+	"StateProbe",
+	"StateReplicate",
+	"StateSnapshot",
+}
+
+func (st StateType) String() string { return prstmap[uint64(st)] }
diff --git a/vendor/go.etcd.io/etcd/raft/tracker/tracker.go b/vendor/go.etcd.io/etcd/raft/tracker/tracker.go
new file mode 100644
index 0000000..a458114
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/raft/tracker/tracker.go
@@ -0,0 +1,288 @@
+// 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
+}