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 (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) {

	defer func() {
		if unlockOnDefer {
			nsUnlocker()
		}
	}()

	// Acquire lock
	if !opts.NoLock {
		lock := z.NewNSLock(bucket, object)
		lkctx, err := lock.GetRLock(ctx, globalOperationTimeout)
		if err != nil {
			return nil, err
		}
		ctx = lkctx.Context()
		nsUnlocker = func() { lock.RUnlock(lkctx) }
		unlockOnDefer = true
	}

	checkPrecondFn := opts.CheckPrecondFn

		t.Fatal(err)
	}

	erasureDisks := xl.getDisks()
	z.serverPools[0].erasureDisksMu.Lock()
	xl.getDisks = func() []StorageAPI {
		for i := range erasureDisks[:6] {
			erasureDisks[i] = newNaughtyDisk(erasureDisks[i], nil, errFaultyDisk)
		}
		return erasureDisks
	}

	z.serverPools[0].erasureDisksMu.Unlock()
	_, err = obj.DeleteObject(ctx, bucket, object, ObjectOptions{})

	var funcReturnedMu sync.Mutex
	defer func() {
		funcReturnedMu.Lock()
		funcReturned = true
		funcReturnedMu.Unlock()
	}()
	// Write listing to results and saver.
	go func() {
		var returned bool
		for entry := range inCh {
			if !returned {
				funcReturnedMu.Lock()
				returned = funcReturned
				funcReturnedMu.Unlock()
				outCh <- entry
				if returned {
					xioutil.SafeClose(outCh)

				p.mu.RLock()
				workers := min(len(p.workers)+1, maxWorkers)
				existing := len(p.workers)
				p.mu.RUnlock()
				p.ResizeWorkers(workers, existing)
			}
			maxMRFWorkers := min(maxWorkers, MRFWorkerMaxLimit)
			if p.ActiveMRFWorkers() < maxMRFWorkers {
				p.mu.RLock()
				workers := min(p.mrfWorkerSize+1, maxMRFWorkers)
				p.mu.RUnlock()
				p.ResizeFailedWorkers(workers)

// LockArgs is minimal required values for any dsync compatible lock operation.
type LockArgs struct {
	// Unique ID of lock/unlock request.
	UID string

	// Resources contains single or multiple entries to be locked/unlocked.
	Resources []string

	// Source contains the line number, function and file name of the code
	// on the client node that requested the lock.
	Source string

	Endpoint string `json:"-"`
	// Secure is true if the replication target endpoint is secure
	Secure bool `json:"-"`
}

func (sr *SRStats) update(st replStat, dID string) {
	sr.lock.Lock()
	defer sr.lock.Unlock()
	srs, ok := sr.M[dID]
	if !ok {
		srs = &SRStatus{
			XferRateLrg: newXferStats(),
			XferRateSml: newXferStats(),
		}
	}
	srs.Endpoint = st.Endpoint
	srs.Secure = st.Secure

	globalObjLayerMutex.Lock()
	globalConsoleSrv = srv
	globalObjLayerMutex.Unlock()
}

func newObjectLayerFn() ObjectLayer {
	globalObjLayerMutex.RLock()
	defer globalObjLayerMutex.RUnlock()
	return globalObjectAPI
}

func setObjectLayer(o ObjectLayer) {
	globalObjLayerMutex.Lock()
	globalObjectAPI = o
	globalObjLayerMutex.Unlock()
}

// objectAPIHandler implements and provides http handlers for S3 API.