diff --git a/vendor/go.etcd.io/etcd/mvcc/kvstore.go b/vendor/go.etcd.io/etcd/mvcc/kvstore.go
new file mode 100644
index 0000000..e367ebb
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/mvcc/kvstore.go
@@ -0,0 +1,620 @@
+// Copyright 2015 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 mvcc
+
+import (
+	"context"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"hash/crc32"
+	"math"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"go.etcd.io/etcd/lease"
+	"go.etcd.io/etcd/mvcc/backend"
+	"go.etcd.io/etcd/mvcc/mvccpb"
+	"go.etcd.io/etcd/pkg/schedule"
+
+	"github.com/coreos/pkg/capnslog"
+	"go.uber.org/zap"
+)
+
+var (
+	keyBucketName  = []byte("key")
+	metaBucketName = []byte("meta")
+
+	consistentIndexKeyName  = []byte("consistent_index")
+	scheduledCompactKeyName = []byte("scheduledCompactRev")
+	finishedCompactKeyName  = []byte("finishedCompactRev")
+
+	ErrCompacted = errors.New("mvcc: required revision has been compacted")
+	ErrFutureRev = errors.New("mvcc: required revision is a future revision")
+	ErrCanceled  = errors.New("mvcc: watcher is canceled")
+	ErrClosed    = errors.New("mvcc: closed")
+
+	plog = capnslog.NewPackageLogger("go.etcd.io/etcd", "mvcc")
+)
+
+const (
+	// markedRevBytesLen is the byte length of marked revision.
+	// The first `revBytesLen` bytes represents a normal revision. The last
+	// one byte is the mark.
+	markedRevBytesLen      = revBytesLen + 1
+	markBytePosition       = markedRevBytesLen - 1
+	markTombstone     byte = 't'
+)
+
+var restoreChunkKeys = 10000 // non-const for testing
+var defaultCompactBatchLimit = 1000
+
+// ConsistentIndexGetter is an interface that wraps the Get method.
+// Consistent index is the offset of an entry in a consistent replicated log.
+type ConsistentIndexGetter interface {
+	// ConsistentIndex returns the consistent index of current executing entry.
+	ConsistentIndex() uint64
+}
+
+type StoreConfig struct {
+	CompactionBatchLimit int
+}
+
+type store struct {
+	ReadView
+	WriteView
+
+	// consistentIndex caches the "consistent_index" key's value. Accessed
+	// through atomics so must be 64-bit aligned.
+	consistentIndex uint64
+
+	cfg StoreConfig
+
+	// mu read locks for txns and write locks for non-txn store changes.
+	mu sync.RWMutex
+
+	ig ConsistentIndexGetter
+
+	b       backend.Backend
+	kvindex index
+
+	le lease.Lessor
+
+	// revMuLock protects currentRev and compactMainRev.
+	// Locked at end of write txn and released after write txn unlock lock.
+	// Locked before locking read txn and released after locking.
+	revMu sync.RWMutex
+	// currentRev is the revision of the last completed transaction.
+	currentRev int64
+	// compactMainRev is the main revision of the last compaction.
+	compactMainRev int64
+
+	// bytesBuf8 is a byte slice of length 8
+	// to avoid a repetitive allocation in saveIndex.
+	bytesBuf8 []byte
+
+	fifoSched schedule.Scheduler
+
+	stopc chan struct{}
+
+	lg *zap.Logger
+}
+
+// NewStore returns a new store. It is useful to create a store inside
+// mvcc pkg. It should only be used for testing externally.
+func NewStore(lg *zap.Logger, b backend.Backend, le lease.Lessor, ig ConsistentIndexGetter, cfg StoreConfig) *store {
+	if cfg.CompactionBatchLimit == 0 {
+		cfg.CompactionBatchLimit = defaultCompactBatchLimit
+	}
+	s := &store{
+		cfg:     cfg,
+		b:       b,
+		ig:      ig,
+		kvindex: newTreeIndex(lg),
+
+		le: le,
+
+		currentRev:     1,
+		compactMainRev: -1,
+
+		bytesBuf8: make([]byte, 8),
+		fifoSched: schedule.NewFIFOScheduler(),
+
+		stopc: make(chan struct{}),
+
+		lg: lg,
+	}
+	s.ReadView = &readView{s}
+	s.WriteView = &writeView{s}
+	if s.le != nil {
+		s.le.SetRangeDeleter(func() lease.TxnDelete { return s.Write() })
+	}
+
+	tx := s.b.BatchTx()
+	tx.Lock()
+	tx.UnsafeCreateBucket(keyBucketName)
+	tx.UnsafeCreateBucket(metaBucketName)
+	tx.Unlock()
+	s.b.ForceCommit()
+
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if err := s.restore(); err != nil {
+		// TODO: return the error instead of panic here?
+		panic("failed to recover store from backend")
+	}
+
+	return s
+}
+
+func (s *store) compactBarrier(ctx context.Context, ch chan struct{}) {
+	if ctx == nil || ctx.Err() != nil {
+		s.mu.Lock()
+		select {
+		case <-s.stopc:
+		default:
+			f := func(ctx context.Context) { s.compactBarrier(ctx, ch) }
+			s.fifoSched.Schedule(f)
+		}
+		s.mu.Unlock()
+		return
+	}
+	close(ch)
+}
+
+func (s *store) Hash() (hash uint32, revision int64, err error) {
+	// TODO: hash and revision could be inconsistent, one possible fix is to add s.revMu.RLock() at the beginning of function, which is costly
+	start := time.Now()
+
+	s.b.ForceCommit()
+	h, err := s.b.Hash(DefaultIgnores)
+
+	hashSec.Observe(time.Since(start).Seconds())
+	return h, s.currentRev, err
+}
+
+func (s *store) HashByRev(rev int64) (hash uint32, currentRev int64, compactRev int64, err error) {
+	start := time.Now()
+
+	s.mu.RLock()
+	s.revMu.RLock()
+	compactRev, currentRev = s.compactMainRev, s.currentRev
+	s.revMu.RUnlock()
+
+	if rev > 0 && rev <= compactRev {
+		s.mu.RUnlock()
+		return 0, 0, compactRev, ErrCompacted
+	} else if rev > 0 && rev > currentRev {
+		s.mu.RUnlock()
+		return 0, currentRev, 0, ErrFutureRev
+	}
+
+	if rev == 0 {
+		rev = currentRev
+	}
+	keep := s.kvindex.Keep(rev)
+
+	tx := s.b.ReadTx()
+	tx.RLock()
+	defer tx.RUnlock()
+	s.mu.RUnlock()
+
+	upper := revision{main: rev + 1}
+	lower := revision{main: compactRev + 1}
+	h := crc32.New(crc32.MakeTable(crc32.Castagnoli))
+
+	h.Write(keyBucketName)
+	err = tx.UnsafeForEach(keyBucketName, func(k, v []byte) error {
+		kr := bytesToRev(k)
+		if !upper.GreaterThan(kr) {
+			return nil
+		}
+		// skip revisions that are scheduled for deletion
+		// due to compacting; don't skip if there isn't one.
+		if lower.GreaterThan(kr) && len(keep) > 0 {
+			if _, ok := keep[kr]; !ok {
+				return nil
+			}
+		}
+		h.Write(k)
+		h.Write(v)
+		return nil
+	})
+	hash = h.Sum32()
+
+	hashRevSec.Observe(time.Since(start).Seconds())
+	return hash, currentRev, compactRev, err
+}
+
+func (s *store) updateCompactRev(rev int64) (<-chan struct{}, error) {
+	s.revMu.Lock()
+	if rev <= s.compactMainRev {
+		ch := make(chan struct{})
+		f := func(ctx context.Context) { s.compactBarrier(ctx, ch) }
+		s.fifoSched.Schedule(f)
+		s.revMu.Unlock()
+		return ch, ErrCompacted
+	}
+	if rev > s.currentRev {
+		s.revMu.Unlock()
+		return nil, ErrFutureRev
+	}
+
+	s.compactMainRev = rev
+
+	rbytes := newRevBytes()
+	revToBytes(revision{main: rev}, rbytes)
+
+	tx := s.b.BatchTx()
+	tx.Lock()
+	tx.UnsafePut(metaBucketName, scheduledCompactKeyName, rbytes)
+	tx.Unlock()
+	// ensure that desired compaction is persisted
+	s.b.ForceCommit()
+
+	s.revMu.Unlock()
+
+	return nil, nil
+}
+
+func (s *store) compact(rev int64) (<-chan struct{}, error) {
+	start := time.Now()
+	keep := s.kvindex.Compact(rev)
+	ch := make(chan struct{})
+	var j = func(ctx context.Context) {
+		if ctx.Err() != nil {
+			s.compactBarrier(ctx, ch)
+			return
+		}
+		if !s.scheduleCompaction(rev, keep) {
+			s.compactBarrier(nil, ch)
+			return
+		}
+		close(ch)
+	}
+
+	s.fifoSched.Schedule(j)
+
+	indexCompactionPauseMs.Observe(float64(time.Since(start) / time.Millisecond))
+	return ch, nil
+}
+
+func (s *store) compactLockfree(rev int64) (<-chan struct{}, error) {
+	ch, err := s.updateCompactRev(rev)
+	if nil != err {
+		return ch, err
+	}
+
+	return s.compact(rev)
+}
+
+func (s *store) Compact(rev int64) (<-chan struct{}, error) {
+	s.mu.Lock()
+
+	ch, err := s.updateCompactRev(rev)
+
+	if err != nil {
+		s.mu.Unlock()
+		return ch, err
+	}
+	s.mu.Unlock()
+
+	return s.compact(rev)
+}
+
+// DefaultIgnores is a map of keys to ignore in hash checking.
+var DefaultIgnores map[backend.IgnoreKey]struct{}
+
+func init() {
+	DefaultIgnores = map[backend.IgnoreKey]struct{}{
+		// consistent index might be changed due to v2 internal sync, which
+		// is not controllable by the user.
+		{Bucket: string(metaBucketName), Key: string(consistentIndexKeyName)}: {},
+	}
+}
+
+func (s *store) Commit() {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	tx := s.b.BatchTx()
+	tx.Lock()
+	s.saveIndex(tx)
+	tx.Unlock()
+	s.b.ForceCommit()
+}
+
+func (s *store) Restore(b backend.Backend) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	close(s.stopc)
+	s.fifoSched.Stop()
+
+	atomic.StoreUint64(&s.consistentIndex, 0)
+	s.b = b
+	s.kvindex = newTreeIndex(s.lg)
+	s.currentRev = 1
+	s.compactMainRev = -1
+	s.fifoSched = schedule.NewFIFOScheduler()
+	s.stopc = make(chan struct{})
+
+	return s.restore()
+}
+
+func (s *store) restore() error {
+	s.setupMetricsReporter()
+
+	min, max := newRevBytes(), newRevBytes()
+	revToBytes(revision{main: 1}, min)
+	revToBytes(revision{main: math.MaxInt64, sub: math.MaxInt64}, max)
+
+	keyToLease := make(map[string]lease.LeaseID)
+
+	// restore index
+	tx := s.b.BatchTx()
+	tx.Lock()
+
+	_, finishedCompactBytes := tx.UnsafeRange(metaBucketName, finishedCompactKeyName, nil, 0)
+	if len(finishedCompactBytes) != 0 {
+		s.compactMainRev = bytesToRev(finishedCompactBytes[0]).main
+
+		if s.lg != nil {
+			s.lg.Info(
+				"restored last compact revision",
+				zap.String("meta-bucket-name", string(metaBucketName)),
+				zap.String("meta-bucket-name-key", string(finishedCompactKeyName)),
+				zap.Int64("restored-compact-revision", s.compactMainRev),
+			)
+		} else {
+			plog.Printf("restore compact to %d", s.compactMainRev)
+		}
+	}
+	_, scheduledCompactBytes := tx.UnsafeRange(metaBucketName, scheduledCompactKeyName, nil, 0)
+	scheduledCompact := int64(0)
+	if len(scheduledCompactBytes) != 0 {
+		scheduledCompact = bytesToRev(scheduledCompactBytes[0]).main
+	}
+
+	// index keys concurrently as they're loaded in from tx
+	keysGauge.Set(0)
+	rkvc, revc := restoreIntoIndex(s.lg, s.kvindex)
+	for {
+		keys, vals := tx.UnsafeRange(keyBucketName, min, max, int64(restoreChunkKeys))
+		if len(keys) == 0 {
+			break
+		}
+		// rkvc blocks if the total pending keys exceeds the restore
+		// chunk size to keep keys from consuming too much memory.
+		restoreChunk(s.lg, rkvc, keys, vals, keyToLease)
+		if len(keys) < restoreChunkKeys {
+			// partial set implies final set
+			break
+		}
+		// next set begins after where this one ended
+		newMin := bytesToRev(keys[len(keys)-1][:revBytesLen])
+		newMin.sub++
+		revToBytes(newMin, min)
+	}
+	close(rkvc)
+	s.currentRev = <-revc
+
+	// keys in the range [compacted revision -N, compaction] might all be deleted due to compaction.
+	// the correct revision should be set to compaction revision in the case, not the largest revision
+	// we have seen.
+	if s.currentRev < s.compactMainRev {
+		s.currentRev = s.compactMainRev
+	}
+	if scheduledCompact <= s.compactMainRev {
+		scheduledCompact = 0
+	}
+
+	for key, lid := range keyToLease {
+		if s.le == nil {
+			panic("no lessor to attach lease")
+		}
+		err := s.le.Attach(lid, []lease.LeaseItem{{Key: key}})
+		if err != nil {
+			if s.lg != nil {
+				s.lg.Warn(
+					"failed to attach a lease",
+					zap.String("lease-id", fmt.Sprintf("%016x", lid)),
+					zap.Error(err),
+				)
+			} else {
+				plog.Errorf("unexpected Attach error: %v", err)
+			}
+		}
+	}
+
+	tx.Unlock()
+
+	if scheduledCompact != 0 {
+		s.compactLockfree(scheduledCompact)
+
+		if s.lg != nil {
+			s.lg.Info(
+				"resume scheduled compaction",
+				zap.String("meta-bucket-name", string(metaBucketName)),
+				zap.String("meta-bucket-name-key", string(scheduledCompactKeyName)),
+				zap.Int64("scheduled-compact-revision", scheduledCompact),
+			)
+		} else {
+			plog.Printf("resume scheduled compaction at %d", scheduledCompact)
+		}
+	}
+
+	return nil
+}
+
+type revKeyValue struct {
+	key  []byte
+	kv   mvccpb.KeyValue
+	kstr string
+}
+
+func restoreIntoIndex(lg *zap.Logger, idx index) (chan<- revKeyValue, <-chan int64) {
+	rkvc, revc := make(chan revKeyValue, restoreChunkKeys), make(chan int64, 1)
+	go func() {
+		currentRev := int64(1)
+		defer func() { revc <- currentRev }()
+		// restore the tree index from streaming the unordered index.
+		kiCache := make(map[string]*keyIndex, restoreChunkKeys)
+		for rkv := range rkvc {
+			ki, ok := kiCache[rkv.kstr]
+			// purge kiCache if many keys but still missing in the cache
+			if !ok && len(kiCache) >= restoreChunkKeys {
+				i := 10
+				for k := range kiCache {
+					delete(kiCache, k)
+					if i--; i == 0 {
+						break
+					}
+				}
+			}
+			// cache miss, fetch from tree index if there
+			if !ok {
+				ki = &keyIndex{key: rkv.kv.Key}
+				if idxKey := idx.KeyIndex(ki); idxKey != nil {
+					kiCache[rkv.kstr], ki = idxKey, idxKey
+					ok = true
+				}
+			}
+			rev := bytesToRev(rkv.key)
+			currentRev = rev.main
+			if ok {
+				if isTombstone(rkv.key) {
+					ki.tombstone(lg, rev.main, rev.sub)
+					continue
+				}
+				ki.put(lg, rev.main, rev.sub)
+			} else if !isTombstone(rkv.key) {
+				ki.restore(lg, revision{rkv.kv.CreateRevision, 0}, rev, rkv.kv.Version)
+				idx.Insert(ki)
+				kiCache[rkv.kstr] = ki
+			}
+		}
+	}()
+	return rkvc, revc
+}
+
+func restoreChunk(lg *zap.Logger, kvc chan<- revKeyValue, keys, vals [][]byte, keyToLease map[string]lease.LeaseID) {
+	for i, key := range keys {
+		rkv := revKeyValue{key: key}
+		if err := rkv.kv.Unmarshal(vals[i]); err != nil {
+			if lg != nil {
+				lg.Fatal("failed to unmarshal mvccpb.KeyValue", zap.Error(err))
+			} else {
+				plog.Fatalf("cannot unmarshal event: %v", err)
+			}
+		}
+		rkv.kstr = string(rkv.kv.Key)
+		if isTombstone(key) {
+			delete(keyToLease, rkv.kstr)
+		} else if lid := lease.LeaseID(rkv.kv.Lease); lid != lease.NoLease {
+			keyToLease[rkv.kstr] = lid
+		} else {
+			delete(keyToLease, rkv.kstr)
+		}
+		kvc <- rkv
+	}
+}
+
+func (s *store) Close() error {
+	close(s.stopc)
+	s.fifoSched.Stop()
+	return nil
+}
+
+func (s *store) saveIndex(tx backend.BatchTx) {
+	if s.ig == nil {
+		return
+	}
+	bs := s.bytesBuf8
+	ci := s.ig.ConsistentIndex()
+	binary.BigEndian.PutUint64(bs, ci)
+	// put the index into the underlying backend
+	// tx has been locked in TxnBegin, so there is no need to lock it again
+	tx.UnsafePut(metaBucketName, consistentIndexKeyName, bs)
+	atomic.StoreUint64(&s.consistentIndex, ci)
+}
+
+func (s *store) ConsistentIndex() uint64 {
+	if ci := atomic.LoadUint64(&s.consistentIndex); ci > 0 {
+		return ci
+	}
+	tx := s.b.BatchTx()
+	tx.Lock()
+	defer tx.Unlock()
+	_, vs := tx.UnsafeRange(metaBucketName, consistentIndexKeyName, nil, 0)
+	if len(vs) == 0 {
+		return 0
+	}
+	v := binary.BigEndian.Uint64(vs[0])
+	atomic.StoreUint64(&s.consistentIndex, v)
+	return v
+}
+
+func (s *store) setupMetricsReporter() {
+	b := s.b
+	reportDbTotalSizeInBytesMu.Lock()
+	reportDbTotalSizeInBytes = func() float64 { return float64(b.Size()) }
+	reportDbTotalSizeInBytesMu.Unlock()
+	reportDbTotalSizeInBytesDebugMu.Lock()
+	reportDbTotalSizeInBytesDebug = func() float64 { return float64(b.Size()) }
+	reportDbTotalSizeInBytesDebugMu.Unlock()
+	reportDbTotalSizeInUseInBytesMu.Lock()
+	reportDbTotalSizeInUseInBytes = func() float64 { return float64(b.SizeInUse()) }
+	reportDbTotalSizeInUseInBytesMu.Unlock()
+	reportDbOpenReadTxNMu.Lock()
+	reportDbOpenReadTxN = func() float64 { return float64(b.OpenReadTxN()) }
+	reportDbOpenReadTxNMu.Unlock()
+	reportCurrentRevMu.Lock()
+	reportCurrentRev = func() float64 {
+		s.revMu.RLock()
+		defer s.revMu.RUnlock()
+		return float64(s.currentRev)
+	}
+	reportCurrentRevMu.Unlock()
+	reportCompactRevMu.Lock()
+	reportCompactRev = func() float64 {
+		s.revMu.RLock()
+		defer s.revMu.RUnlock()
+		return float64(s.compactMainRev)
+	}
+	reportCompactRevMu.Unlock()
+}
+
+// appendMarkTombstone appends tombstone mark to normal revision bytes.
+func appendMarkTombstone(lg *zap.Logger, b []byte) []byte {
+	if len(b) != revBytesLen {
+		if lg != nil {
+			lg.Panic(
+				"cannot append tombstone mark to non-normal revision bytes",
+				zap.Int("expected-revision-bytes-size", revBytesLen),
+				zap.Int("given-revision-bytes-size", len(b)),
+			)
+		} else {
+			plog.Panicf("cannot append mark to non normal revision bytes")
+		}
+	}
+	return append(b, markTombstone)
+}
+
+// isTombstone checks whether the revision bytes is a tombstone.
+func isTombstone(b []byte) bool {
+	return len(b) == markedRevBytesLen && b[markBytePosition] == markTombstone
+}