func (le *lessor) initAndRecover() {
	tx := le.b.BatchTx()
	tx.Lock()

	tx.UnsafeCreateBucket(leaseBucketName)
	_, vs := tx.UnsafeRange(leaseBucketName, int64ToBytes(0), int64ToBytes(math.MaxInt64), 0)
	// TODO: copy vs and do decoding outside tx lock if lock contention becomes an issue.
	for i := range vs {
		var lpb leasepb.Lease
		err := lpb.Unmarshal(vs[i])
		if err != nil {
			tx.Unlock()
			panic("failed to unmarshal lease proto item")
		}
		ID := LeaseID(lpb.ID)
		le.leaseMap[ID] = &Lease{
			ID:  ID,
			TTL: lpb.TTL,
			// itemSet will be filled in when recover key-value pairs
			// set expiry to forever, refresh when promoted
			itemSet: make(map[LeaseItem]struct{}),
			expiry:  forever,
		}
	}
	tx.Unlock()

	le.b.ForceCommit()
}

func (le *lessor) initAndRecover() {
	tx := le.b.BatchTx()
	tx.Lock()

	tx.UnsafeCreateBucket(leaseBucketName)
	_, vs := tx.UnsafeRange(leaseBucketName, int64ToBytes(0), int64ToBytes(math.MaxInt64), 0)
	// TODO: copy vs and do decoding outside tx lock if lock contention becomes an issue.
	for i := range vs {
		var lpb leasepb.Lease
		err := lpb.Unmarshal(vs[i])
		if err != nil {
			tx.Unlock()
			panic("failed to unmarshal lease proto item")
		}
		id := LeaseID(lpb.ID)
		le.leaseMap[id] = &lease{
			id:  id,
			ttl: lpb.TTL,

			// itemSet will be filled in when recover key-value pairs
			expiry: minExpiry(time.Now(), time.Now().Add(time.Second*time.Duration(lpb.TTL))),
		}
	}
	tx.Unlock()

	le.b.ForceCommit()
}

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()
}