func (ls *Stores) readBootstrapInfoLocked(bi *gossip.BootstrapInfo) error {
	latestTS := roachpb.ZeroTimestamp
	timestamps := map[roachpb.StoreID]roachpb.Timestamp{}

	// Find the most recent bootstrap info, collecting timestamps for
	// each store along the way.
	for id, s := range ls.storeMap {
		var storeBI gossip.BootstrapInfo
		ok, err := engine.MVCCGetProto(s.engine, keys.StoreGossipKey(), roachpb.ZeroTimestamp, true, nil, &storeBI)
		if err != nil {
			return err
		}
		timestamps[id] = storeBI.Timestamp
		if ok && latestTS.Less(storeBI.Timestamp) {
			latestTS = storeBI.Timestamp
			*bi = storeBI
		}
	}

	// Update all stores with an earlier timestamp.
	for id, s := range ls.storeMap {
		if timestamps[id].Less(latestTS) {
			if err := engine.MVCCPutProto(s.engine, nil, keys.StoreGossipKey(), roachpb.ZeroTimestamp, nil, bi); err != nil {
				return err
			}
			log.Infof("updated gossip bootstrap info to %s", s)
		}
	}

	ls.biLatestTS = latestTS
	return nil
}

// WriteBootstrapInfo implements the gossip.Storage interface. Write
// persists the supplied bootstrap info to every known store. Returns
// nil on success; otherwise returns first error encountered writing
// to the stores.
func (ls *Stores) WriteBootstrapInfo(bi *gossip.BootstrapInfo) error {
	ls.mu.RLock()
	defer ls.mu.RUnlock()
	ls.biLatestTS = ls.clock.Now()
	bi.Timestamp = ls.biLatestTS
	for _, s := range ls.storeMap {
		if err := engine.MVCCPutProto(s.engine, nil, keys.StoreGossipKey(), roachpb.ZeroTimestamp, nil, bi); err != nil {
			return err
		}
		log.Infof("wrote gossip bootstrap info to %s", s)
	}
	return nil
}

func (ls *Stores) updateBootstrapInfo(bi *gossip.BootstrapInfo) error {
	if bi.Timestamp.Less(ls.biLatestTS) {
		return nil
	}
	// Update the latest timestamp and set cached version.
	ls.biLatestTS = bi.Timestamp
	ls.latestBI = protoutil.Clone(bi).(*gossip.BootstrapInfo)
	// Update all stores.
	for _, s := range ls.storeMap {
		if err := engine.MVCCPutProto(context.Background(), s.engine, nil, keys.StoreGossipKey(), hlc.ZeroTimestamp, nil, bi); err != nil {
			return err
		}
	}
	return nil
}

// ReadBootstrapInfo implements the gossip.Storage interface. Read
// attempts to read gossip bootstrap info from every known store and
// finds the most recent from all stores to initialize the bootstrap
// info argument. Returns an error on any issues reading data for the
// stores (but excluding the case in which no data has been persisted
// yet).
func (ls *Stores) ReadBootstrapInfo(bi *gossip.BootstrapInfo) error {
	ls.mu.RLock()
	defer ls.mu.RUnlock()
	latestTS := hlc.ZeroTimestamp

	// Find the most recent bootstrap info.
	for _, s := range ls.storeMap {
		var storeBI gossip.BootstrapInfo
		ok, err := engine.MVCCGetProto(context.Background(), s.engine, keys.StoreGossipKey(), hlc.ZeroTimestamp, true, nil, &storeBI)
		if err != nil {
			return err
		}
		if ok && latestTS.Less(storeBI.Timestamp) {
			latestTS = storeBI.Timestamp
			*bi = storeBI
		}
	}
	log.Infof("read %d node addresses from persistent storage", len(bi.Addresses))
	return ls.updateBootstrapInfo(bi)
}