rc   io.ReadCloser
	done chan struct{}
}

func (c *closeNotifier) Read(p []byte) (n int, err error) {
	n, err = c.rc.Read(p)
	if err != nil {
		if c.done != nil {
			xioutil.SafeClose(c.done)
			c.done = nil
		}
	}
	return n, err
}

func (c *closeNotifier) Close() error {
	if c.done != nil {
		xioutil.SafeClose(c.done)
		c.done = nil
	}
	return c.rc.Close()
}

	ctx, done, err := p.TrackDiskHealth(ctx, storageMetricListVols, "/")
	if err != nil {
		return nil, err
	}
	defer done(&err)

	return p.storage.ListVols(ctx)
}

func (p *xlStorageDiskIDCheck) StatVol(ctx context.Context, volume string) (vol VolInfo, err error) {
	ctx, done, err := p.TrackDiskHealth(ctx, storageMetricStatVol, volume)
	if err != nil {
		return vol, err
	}
	defer done(&err)

	disks := er.getDisks()
	var wg sync.WaitGroup
	var mu sync.Mutex
	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	for _, i := range r.Perm(len(disks)) {
		i := i
		wg.Add(1)
		go func() {
			defer wg.Done()
			if disks[i] == nil {
				return
			}
			di, err := disks[i].DiskInfo(context.Background(), DiskInfoOptions{})
			if err != nil || di.Healing {
				// - Do not consume disks which are not reachable

		}
		if sizeS.tiers != nil {
			sizeS.tiers[storageclass.STANDARD] = tierStats{}
			sizeS.tiers[storageclass.RRS] = tierStats{}
		}

		done := globalScannerMetrics.time(scannerMetricApplyAll)
		objInfos, err := item.applyVersionActions(ctx, objAPI, fivs.Versions, globalExpiryState)
		done()

		if err != nil {
			res["err"] = err.Error()
			return sizeSummary{}, errSkipFile
		}

!!! info
    In Pydantic version 1 the configuration was done in an internal class `Config`, in Pydantic version 2 it's done in an attribute `model_config`. This attribute takes a `dict`, and to get autocompletion and inline errors you can import and use `SettingsConfigDict` to define that `dict`.

	})
	if err != nil {
		return cache, toStorageErr(err)
	}
	var final *dataUsageCache
	err = st.Results(func(resp *nsScannerResp) error {
		if resp.Update != nil {
			select {
			case <-ctx.Done():
			case updates <- *resp.Update:
			}
		}
		if resp.Final != nil {
			final = resp.Final
		}
		// We can't reuse the response since it is sent upstream.
		return nil
	})
	if err != nil {

		// Start metrics server
		monitoring.SetupMonitoring(cfg.InstallConfig.MonitoringPort, "/metrics", ctx.Done())

		// Start UDS log server
		udsLogger := udsLog.NewUDSLogger()
		if err = udsLogger.StartUDSLogServer(cfg.InstallConfig.LogUDSAddress, ctx.Done()); err != nil {
			log.Errorf("Failed to start up UDS Log Server: %v", err)
			return
		}

		defer cancel()

		wg := sync.WaitGroup{}
		for i, disk := range disks {
			if disk == nil {
				done <- false
				continue
			}
			if !disk.IsOnline() {
				done <- false
				continue
			}
			wg.Add(1)
			go func(i int, disk StorageAPI) {
				defer wg.Done()

				var (
					fi  FileInfo
					rfi RawFileInfo
					err error
				)

				if opts.VersionID != "" {

	if err != nil {
		return probeSet, err
	}
	probeSet.Flush()
	return probeSet, nil
}

func (s *Server) Start() {
	log.Info("CNI ambient server starting")
	s.kubeClient.RunAndWait(s.ctx.Done())
	log.Info("CNI ambient server kubeclient started")
	pods := s.handlers.GetAmbientPods()
	err := s.dataplane.ConstructInitialSnapshot(pods)
	if err != nil {
		log.Warnf("failed to construct initial snapshot: %v", err)

Then your API will (let's imagine):

* Send the invoice to some customer of the external developer.
* Collect the money.
* Send a notification back to the API user (the external developer).
    * This will be done by sending a POST request (from *your API*) to some *external API* provided by that external developer (this is the "callback").

## The normal **FastAPI** app