*LockedFile
	mutex sync.Mutex
	refs  int // Holds read lock refs.
}

// IsClosed - Check if the rlocked file is already closed.
func (r *RLockedFile) IsClosed() bool {
	r.mutex.Lock()
	defer r.mutex.Unlock()
	return r.refs == 0
}

// IncLockRef - is used by called to indicate lock refs.
func (r *RLockedFile) IncLockRef() {
	r.mutex.Lock()
	r.refs++
	r.mutex.Unlock()
}

func (m *bucketMeasurement) updateExponentialMovingAverage(endTime time.Time) {
	// Calculate aggregate avg bandwidth and exp window avg
	m.lock.Lock()
	defer func() {
		m.startTime = endTime
		m.lock.Unlock()
	}()

	if m.startTime.IsZero() {
		return
	}

	if endTime.Before(m.startTime) {
		return
	}

	duration := endTime.Sub(m.startTime)

	// Attempt all calls.
	_, err = lkClient.RLock(context.Background(), dsync.LockArgs{})
	if err == nil {
		t.Fatal("Expected for Rlock to fail")
	}

	_, err = lkClient.Lock(context.Background(), dsync.LockArgs{})
	if err == nil {
		t.Fatal("Expected for Lock to fail")
	}

	_, err = lkClient.RUnlock(context.Background(), dsync.LockArgs{})
	if err == nil {
		t.Fatal("Expected for RUnlock to fail")
	}

	}
}

func (restClient *ReconnectRESTClient) RLock(ctx context.Context, args LockArgs) (status bool, err error) {
	return restClient.Call("/v1/rlock", args)
}

func (restClient *ReconnectRESTClient) Lock(ctx context.Context, args LockArgs) (status bool, err error) {
	return restClient.Call("/v1/lock", args)
}

func (restClient *ReconnectRESTClient) RUnlock(ctx context.Context, args LockArgs) (status bool, err error) {

	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

	if !ok {
		t.Fatalf("should assign PreparedStatement Manager back to database when using PrepareStmt mode")
	}

	pdb.Mux.Lock()
	if len(pdb.Stmts) == 0 {
		pdb.Mux.Unlock()
		t.Fatalf("prepared stmt can not be empty")
	}
	pdb.Mux.Unlock()

	pdb.Reset()
	pdb.Mux.Lock()
	defer pdb.Mux.Unlock()
	if len(pdb.Stmts) != 0 {
		t.Fatalf("prepared stmt should be empty")
	}

func SystemTargets() []Target {
	swapSystemMuRW.RLock()
	defer swapSystemMuRW.RUnlock()

	res := systemTargets
	return res
}

// AuditTargets returns active audit targets.
// Returned slice may not be modified in any way.
func AuditTargets() []Target {
	swapAuditMuRW.RLock()
	defer swapAuditMuRW.RUnlock()

	res := auditTargets
	return res
}

	r  io.Reader
	mu sync.Mutex
}

func (d *disconnectReader) Read(p []byte) (n int, err error) {
	d.mu.Lock()
	defer d.mu.Unlock()
	if d.r != nil {
		return d.r.Read(p)
	}
	return 0, errors.New("reader closed")
}

func (d *disconnectReader) Close() error {
	d.mu.Lock()
	d.r = nil
	d.mu.Unlock()
	return nil
}

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()

func (r *lockedRandSource) Int63() (n int64) {
	r.lk.Lock()
	n = r.src.Int63()
	r.lk.Unlock()
	return
}

// Seed uses the provided seed value to initialize the generator to a
// deterministic state.
func (r *lockedRandSource) Seed(seed int64) {
	r.lk.Lock()
	r.src.Seed(seed)
	r.lk.Unlock()