func (srv *Server) Shutdown() error {
	srv.listenerMutex.Lock()
	if srv.listener == nil {
		srv.listenerMutex.Unlock()
		return http.ErrServerClosed
	}
	srv.listenerMutex.Unlock()

	if atomic.AddUint32(&srv.inShutdown, 1) > 1 {
		// shutdown in progress
		return http.ErrServerClosed
	}

	// Close underneath HTTP listener.
	srv.listenerMutex.Lock()
	err := srv.listener.Close()
	srv.listenerMutex.Unlock()

		t.Fatalf("unexpected error: %v", err)
	}
	if err := ps.Subscribe(MaskAll, ch2, doneCh, nil); err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	ps.Lock()
	defer ps.Unlock()

	if len(ps.subs) != 2 || ps.NumSubscribers(MaskAll) != 2 || ps.Subscribers() != 2 {
		t.Fatalf("expected 2 subscribers")
	}
}

func TestNumSubscribersMask(t *testing.T) {
	ps := New[Maskable, Mask](2)

}

func (c *connMgr) addConn(conn *ZtunnelConnection) {
	log.Debug("ztunnel connected")
	c.mu.Lock()
	defer c.mu.Unlock()
	c.connectionSet[conn] = struct{}{}
	c.latestConn = conn
	ztunnelConnected.RecordInt(int64(len(c.connectionSet)))
}

func (c *connMgr) LatestConn() *ZtunnelConnection {
	c.mu.Lock()
	defer c.mu.Unlock()
	return c.latestConn
}

func (c *connMgr) deleteConn(conn *ZtunnelConnection) {

}

// Empty returns true if targetList is empty.
func (list *TargetList) Empty() bool {
	list.RLock()
	defer list.RUnlock()

	return len(list.targets) == 0
}

// List - returns available target IDs.
func (list *TargetList) List(region string) []ARN {
	list.RLock()
	defer list.RUnlock()

	keys := make([]ARN, 0, len(list.targets))
	for k := range list.targets {

// if it is not successful yet.
func (l *Init) Do(f func() error) error {
	if atomic.LoadUint32(&l.done) == 0 {
		return l.do(f)
	}
	return nil
}

func (l *Init) do(f func() error) error {
	l.m.Lock()
	defer l.m.Unlock()
	if atomic.LoadUint32(&l.done) == 0 {
		if err := f(); err != nil {
			return err
		}
		// Mark as done only when f() is successful
		atomic.StoreUint32(&l.done, 1)
	}
	return nil
}

func (evnot *EventNotifier) RemoveNotification(bucketName string) {
	evnot.Lock()
	defer evnot.Unlock()

	delete(evnot.bucketRulesMap, bucketName)
}

// RemoveAllBucketTargets - closes and removes all notification targets.
func (evnot *EventNotifier) RemoveAllBucketTargets() {
	evnot.Lock()
	defer evnot.Unlock()

	targetIDSet := event.NewTargetIDSet()
	for k := range evnot.targetList.TargetMap() {

	resp := lockRPCUnlock.NewResponse()
	_, err := l.ll.Unlock(context.Background(), *args)
	// Ignore the Unlock() "reply" return value because if err == nil, "reply" is always true
	// Consequently, if err != nil, reply is always false
	return l.makeResp(resp, err)
}

// RLockHandler - Acquires an RLock.
func (l *lockRESTServer) RLockHandler(args *dsync.LockArgs) (*dsync.LockResp, *grid.RemoteErr) {

	if r == nil {
		return nil
	}
	r.Lock()
	defer r.Unlock()
	r.tags = append(r.tags, KeyVal{key, val})
	return r
}

// SetTags - sets key/val to ReqInfo.tags
func (r *ReqInfo) SetTags(key string, val interface{}) *ReqInfo {
	if r == nil {
		return nil
	}
	r.Lock()
	defer r.Unlock()
	// Search of tag key already exists in tags
	var updated bool

		srQueueStats: newInQueueStats(r, "site"),
	}
}

func (q *queueCache) update() {
	q.Lock()
	defer q.Unlock()
	q.srQueueStats.update()
	for _, s := range q.bucketStats {
		s.update()
	}
}

func (q *queueCache) getBucketStats(bucket string) InQueueMetric {
	q.RLock()
	defer q.RUnlock()
	v, ok := q.bucketStats[bucket]
	if !ok {
		return InQueueMetric{}
	}
	return InQueueMetric{

					continue
				}

				if disk.IsLocal() && globalIsDistErasure {
					globalLocalDrivesMu.RLock()
					ldisk := globalLocalSetDrives[poolIdx][i][j]
					if ldisk == nil {
						globalLocalDrivesMu.RUnlock()
						continue
					}
					disk.Close()
					disk = ldisk
					globalLocalDrivesMu.RUnlock()
				}

				innerWg.Add(1)
				go func(disk StorageAPI, i, j int) {
					defer innerWg.Done()