// Buffers sent on out can not be referenced once sent.
	StreamHandlerFn func(ctx context.Context, payload []byte, in <-chan []byte, out chan<- []byte) *RemoteErr

	// StreamHandler handles fully bidirectional streams,
	// There is flow control in both directions.
	StreamHandler struct {
		// Handle an incoming request. Initial payload is sent.
		// Additional input packets (if any) are streamed to request.

		if testCase.expectedResult != actualResult {
			t.Errorf("Test %d: Expected the result to `%v`, but instead got `%v`", i+1, testCase.expectedResult, actualResult)
		}
	}
}

// Provides a fully populated http request instance, fails otherwise.
func mustNewRequest(method string, urlStr string, contentLength int64, body io.ReadSeeker, t *testing.T) *http.Request {
	req, err := newTestRequest(method, urlStr, contentLength, body)

		// the client offline in such situations.
		// generally all implementations should simply return
		// 403, but in situations where there is a dependency
		// with the caller to take the client offline purpose
		// fully it should make sure to respond with '412'
		// instead, see cmd/storage-rest-server.go for ideas.
		if c.HealthCheckFn != nil && resp.StatusCode == http.StatusPreconditionFailed {

	FilePath   string             `msg:"fp"`
	UpdateOpts UpdateMetadataOpts `msg:"uo"`
	FI         FileInfo           `msg:"fi"`
}

// UpdateMetadataOpts provides an optional input to indicate if xl.meta updates need to be fully synced to disk.
type UpdateMetadataOpts struct {
	NoPersistence bool `msg:"np"`
}

// CheckPartsHandlerParams are parameters for CheckPartsHandler
type CheckPartsHandlerParams struct {

}

// returns "https" if the tls boolean is true, "http" otherwise.
func getURLScheme(tls bool) string {
	if tls {
		return httpsScheme
	}
	return httpScheme
}

// getObjectLocation gets the fully qualified URL of an object.
func getObjectLocation(r *http.Request, domains []string, bucket, object string) string {
	// unit tests do not have host set.
	if r.Host == "" {
		return path.Clean(r.URL.Path)
	}

		}
	case size >= fi.Erasure.BlockSize:
		buffer = globalBytePoolCap.Load().Get()
		defer globalBytePoolCap.Load().Put(buffer)
	case size < fi.Erasure.BlockSize:
		// No need to allocate fully fi.Erasure.BlockSize buffer if the incoming data is smaller.
		buffer = make([]byte, size, 2*size+int64(fi.Erasure.ParityBlocks+fi.Erasure.DataBlocks-1))
	}

	if len(buffer) > int(fi.Erasure.BlockSize) {

// returns error if it find extra or superfluous keys.
func CheckValidKeys(subSys string, kv KVS, validKVS KVS, deprecatedKeys ...string) error {
	nkv := KVS{}
	for _, kv := range kv {
		// Comment is a valid key, its also fully optional
		// ignore it since it is a valid key for all
		// sub-systems.
		if kv.Key == Comment {
			continue
		}
		var skip bool
		for _, deprecatedKey := range deprecatedKeys {

		if shouldHealObjectOnDisk(errs[i], dataErrs[i], partsMetadata[i], latestMeta) {
			outDatedDisks[i] = storageDisks[i]
			disksToHealCount++
			continue
		}
	}

	if isAllNotFound(errs) {
		// File is fully gone, fileInfo is empty.
		err := errFileNotFound
		if versionID != "" {
			err = errFileVersionNotFound
		}
		return er.defaultHealResult(FileInfo{}, storageDisks, storageEndpoints, errs,

func (mg *MetricsGroup) LockAndSetBuckets(buckets []string) func() {
	mg.bucketsLock.Lock()
	mg.buckets = buckets
	return func() {
		mg.bucketsLock.Unlock()
	}
}

// MetricFQN - returns the fully qualified name for the given metric name.
func (mg *MetricsGroup) MetricFQN(name MetricName) string {
	v, ok := mg.descriptorMap[name]
	if !ok {
		// This should never happen.
		return ""
	}