func (l Lease) removeFrom(b backend.Backend) {
	key := int64ToBytes(int64(l.ID))

	b.BatchTx().Lock()
	b.BatchTx().UnsafeDelete(leaseBucketName, key)
	b.BatchTx().Unlock()
}

func mustSaveClusterVersionToBackend(be backend.Backend, ver *semver.Version) {
	ckey := backendClusterVersionKey()

	tx := be.BatchTx()
	tx.Lock()
	defer tx.Unlock()
	tx.UnsafePut(clusterBucketName, ckey, []byte(ver.String()))
}

func mustCreateBackendBuckets(be backend.Backend) {
	tx := be.BatchTx()
	tx.Lock()
	defer tx.Unlock()
	tx.UnsafeCreateBucket(membersBucketName)
	tx.UnsafeCreateBucket(membersRemovedBuckedName)
	tx.UnsafeCreateBucket(clusterBucketName)
}

func mustDeleteMemberFromBackend(be backend.Backend, id types.ID) {
	mkey := backendMemberKey(id)

	tx := be.BatchTx()
	tx.Lock()
	tx.UnsafeDelete(membersBucketName, mkey)
	tx.UnsafePut(membersRemovedBuckedName, mkey, []byte("removed"))
	tx.Unlock()
}

func NewAuthStore(be backend.Backend) *authStore {
	tx := be.BatchTx()
	tx.Lock()
	tx.UnsafeCreateBucket(authBucketName)
	tx.Unlock()
	be.ForceCommit()

	return &authStore{
		be: be,
	}
}

func mustSaveMemberToBackend(be backend.Backend, m *Member) {
	mkey := backendMemberKey(m.ID)
	mvalue, err := json.Marshal(m)
	if err != nil {
		plog.Panicf("marshal raftAttributes should never fail: %v", err)
	}

	tx := be.BatchTx()
	tx.Lock()
	tx.UnsafePut(membersBucketName, mkey, mvalue)
	tx.Unlock()
}

func (l Lease) persistTo(b backend.Backend) {
	key := int64ToBytes(int64(l.ID))

	lpb := leasepb.Lease{ID: int64(l.ID), TTL: int64(l.TTL)}
	val, err := lpb.Marshal()
	if err != nil {
		panic("failed to marshal lease proto item")
	}

	b.BatchTx().Lock()
	b.BatchTx().UnsafePut(leaseBucketName, key, val)
	b.BatchTx().Unlock()
}

func (s *store) Restore(b backend.Backend) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	close(s.stopc)
	s.fifoSched.Stop()

	s.b = b
	s.kvindex = newTreeIndex()
	s.currentRev = revision{main: 1}
	s.compactMainRev = -1
	s.tx = b.BatchTx()
	s.txnID = -1
	s.fifoSched = schedule.NewFIFOScheduler()
	s.stopc = make(chan struct{})

	return s.restore()
}

func (s *store) Restore(b backend.Backend) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	close(s.stopc)
	// TODO: restore without waiting for compaction routine to finish.
	// We need a way to notify that the store is finished using the old
	// backend though.
	s.wg.Wait()

	s.b = b
	s.kvindex = newTreeIndex()
	s.currentRev = revision{main: 1}
	s.compactMainRev = -1
	s.tx = b.BatchTx()
	s.txnID = -1
	s.stopc = make(chan struct{})

	return s.restore()
}

func cleanup(s KV, b backend.Backend, path string) {
	s.Close()
	b.Close()
	os.Remove(path)
}