wg     *sync.WaitGroup
	buffer map[int64][]byte
	err    error

	nextOffset int64
	m          sync.Mutex
}

func (w *writerAt) WriteAt(b []byte, offset int64) (n int, err error) {
	w.m.Lock()
	defer w.m.Unlock()

	if w.nextOffset == offset {
		n, err = w.w.Write(b)
		w.nextOffset += int64(n)
	} else {
		if offset > w.nextOffset+ftpMaxWriteOffset {

		VersionID: versionID,
		DiskCount: len(storageDisks),
	}

	if !opts.NoLock {
		lk := er.NewNSLock(bucket, object)
		lkctx, err := lk.GetLock(ctx, globalOperationTimeout)
		if err != nil {
			return result, err
		}
		ctx = lkctx.Context()
		defer lk.Unlock(lkctx)
	}

	// Re-read when we have lock...
	partsMetadata, errs := readAllFileInfo(ctx, storageDisks, "", bucket, object, versionID, true, true)

				nil,
			)
			resultsMu.Lock()
			results.NodeResults = append(results.NodeResults, result)
			resultsMu.Unlock()
		}()
	}
	wg.Wait()
	return results, err
}

// GetClusterInfo - returns site replication information.
func (c *SiteReplicationSys) GetClusterInfo(ctx context.Context) (info madmin.SiteReplicationInfo, err error) {
	c.RLock()
	defer c.RUnlock()
	if !c.enabled {
		return info, nil

				if _, ok := err.(BucketExists); !ok {
					t.Logf("unexpected error: %T: %v", err, err)
					return
				}
				mu.Lock()
				errs++
				mu.Unlock()
				return
			}
			mu.Lock()
			ok++
			mu.Unlock()
		}()
	}
	close(start)
	wg.Wait()
	if ok != 1 {
		t.Fatalf("want 1 ok, got %d", ok)
	}
	if errs != n-1 {

// returns true if the node changed state from online to offline
func (c *Client) MarkOffline(err error) bool {
	c.Lock()
	c.lastErr = err
	c.lastErrTime = time.Now()
	atomic.StoreInt64(&c.lastConn, time.Now().UnixNano())
	c.Unlock()

	return c.runHealthCheck()

			old := e.cached.Swap(newAcc)
			var a AccElem
			a.Size = atomic.LoadInt64(&old.Size)
			a.Total = atomic.LoadInt64(&old.Total)
			a.N = atomic.LoadInt64(&old.N)
			e.mu.Lock()
			e.addAll(t-1, a)
			e.mu.Unlock()
			acc = newAcc
		} else {
			// We may be able to grab the new accumulator by yielding.
			runtime.Gosched()
			acc = e.cached.Load()
		}
	}
	atomic.AddInt64(&acc.N, 1)

}

// Returns current profile data, returns error if there is no active
// profiling in progress. Stops an active profile.
func getProfileData() (map[string][]byte, error) {
	globalProfilerMu.Lock()
	defer globalProfilerMu.Unlock()

	if len(globalProfiler) == 0 {
		return nil, errors.New("profiler not enabled")
	}

	dst := make(map[string][]byte, len(globalProfiler))
	for typ, prof := range globalProfiler {

		if globalIsDistErasure {
			// Top locks
			adminRouter.Methods(http.MethodGet).Path(adminVersion + "/top/locks").HandlerFunc(adminMiddleware(adminAPI.TopLocksHandler))
			// Force unlocks paths
			adminRouter.Methods(http.MethodPost).Path(adminVersion+"/force-unlock").
				Queries("paths", "{paths:.*}").HandlerFunc(adminMiddleware(adminAPI.ForceUnlockHandler))
		}

     * error-prone code like:
     *
     * Striped<Lock> stripedLock = Striped.lazyWeakXXX(...)'
     * Iterable<Lock> locks = stripedLock.bulkGet(keys);
     * for (Lock lock : locks) {
     *   lock.lock();
     * }
     * operation();
     * for (Lock lock : locks) {
     *   lock.unlock();
     * }
     *

func (s *xlStorage) GetDiskID() (string, error) {
	s.RLock()
	diskID := s.diskID
	fileInfo := s.formatFileInfo
	lastCheck := s.formatLastCheck

	// check if we have a valid disk ID that is less than 1 seconds old.
	if fileInfo != nil && diskID != "" && time.Since(lastCheck) <= 1*time.Second {
		s.RUnlock()
		return diskID, nil
	}
	s.RUnlock()

	fi, err := s.checkFormatJSON()
	if err != nil {