sync.RWMutex  // protects requestsCount only
	requestsCount map[string]struct {
		success int64
		failure int64
	}
	histogram *prometheus.HistogramVec
}

var globalTierMetrics = tierMetrics{
	requestsCount: make(map[string]struct {
		success int64
		failure int64
	}),
	histogram: prometheus.NewHistogramVec(prometheus.HistogramOpts{
		Name:    "tier_ttlb_seconds",

				t.Error("got objects", e.Objects, "want", w.objs)
			}
			if e.Versions != uint64(w.objs) {
				t.Error("got versions", e.Versions, "want", w.objs)
			}
			if e.ObjSizes != w.oSizes {
				t.Error("got histogram", e.ObjSizes, "want", w.oSizes)
			}
		})
	}

	files = []usageTestFile{
		{
			name: "newfolder/afile",
			size: 4,
		},
		{
			name: "newfolder/anotherone",
			size: 1,
		},

	{"GREATER_THAN_512_MB", humanize.MiByte * 512, math.MaxInt64},
}

// ObjectsHistogramIntervals is the list of all intervals
// of object sizes to be included in objects histogram.
// Note: this histogram expands 1024B-1MB to incl. 1024B-64KB, 64KB-256KB, 256KB-512KB and 512KB-1MiB
var ObjectsHistogramIntervals = [dataUsageBucketLen]objectHistogramInterval{
	{"LESS_THAN_1024_B", 0, humanize.KiByte - 1},

// dataUsageHash is the hash type used.
type dataUsageHash string

// sizeHistogramV1 is size histogram V1, which has fewer intervals esp. between
// 1024B and 1MiB.
type sizeHistogramV1 [dataUsageBucketLenV1]uint64

// sizeHistogram is a size histogram.
type sizeHistogram [dataUsageBucketLen]uint64

// versionsHistogram is a histogram of number of versions in an object.
type versionsHistogram [dataUsageVersionLen]uint64

		VariableLabels:       make(map[string]string, len(m.VariableLabels)),
		Histogram:            make(map[string]uint64, len(m.Histogram)),
	}
	maps.Copy(metric.StaticLabels, m.StaticLabels)
	maps.Copy(metric.VariableLabels, m.VariableLabels)
	maps.Copy(metric.Histogram, m.Histogram)
	return metric
}

// Get - returns cached value always upton the configured TTL,

    - `scheduler_async_api_call_execution_total`: tracks executed API calls by call type and result (success/error)
    - `scheduler_async_api_call_duration_seconds`: histogram of API call execution duration by call type and result

*   `tf.keras`:

    *   Changed the TensorBoard tag names produced by the
        `tf.keras.callbacks.TensorBoard` callback, so that summaries logged
        automatically for model weights now include either a `/histogram` or
        `/image` suffix in their tag names, in order to prevent tag name
        collisions across summary types.

*   When running on GPU (with cuDNN version 7.6.3 or