Function newHistogram

prometheus/histogram.go:535–611

(desc *Desc, opts HistogramOpts, labelValues ...string)

}

func newHistogram(desc *Desc, opts HistogramOpts, labelValues ...string) Histogram {
	if len(desc.variableLabels.names) != len(labelValues) {
		panic(makeInconsistentCardinalityError(desc.fqName, desc.variableLabels.names, labelValues))
	}

	for _, n := range desc.variableLabels.names {
		if n == bucketLabel {
			panic(errBucketLabelNotAllowed)
		}
	}
	for _, lp := range desc.constLabelPairs {
		if lp.GetName() == bucketLabel {
			panic(errBucketLabelNotAllowed)
		}
	}

	if opts.now == nil {
		opts.now = time.Now
	}
	if opts.afterFunc == nil {
		opts.afterFunc = time.AfterFunc
	}

	h := &histogram{
		desc:                            desc,
		upperBounds:                     opts.Buckets,
		labelPairs:                      MakeLabelPairs(desc, labelValues),
		nativeHistogramMaxBuckets:       opts.NativeHistogramMaxBucketNumber,
		nativeHistogramMaxZeroThreshold: opts.NativeHistogramMaxZeroThreshold,
		nativeHistogramMinResetDuration: opts.NativeHistogramMinResetDuration,
		lastResetTime:                   opts.now(),
		now:                             opts.now,
		afterFunc:                       opts.afterFunc,
	}
	if len(h.upperBounds) == 0 && opts.NativeHistogramBucketFactor <= 1 {
		h.upperBounds = DefBuckets
	}
	if opts.NativeHistogramBucketFactor <= 1 {
		h.nativeHistogramSchema = math.MinInt32 // To mark that there are no sparse buckets.
	} else {
		switch {
		case opts.NativeHistogramZeroThreshold > 0:
			h.nativeHistogramZeroThreshold = opts.NativeHistogramZeroThreshold
		case opts.NativeHistogramZeroThreshold == 0:
			h.nativeHistogramZeroThreshold = DefNativeHistogramZeroThreshold
		} // Leave h.nativeHistogramZeroThreshold at 0 otherwise.
		h.nativeHistogramSchema = pickSchema(opts.NativeHistogramBucketFactor)
		h.nativeExemplars = makeNativeExemplars(opts.NativeHistogramExemplarTTL, opts.NativeHistogramMaxExemplars)
	}
	for i, upperBound := range h.upperBounds {
		if i < len(h.upperBounds)-1 {
			if upperBound >= h.upperBounds[i+1] {
				panic(fmt.Errorf(
					"histogram buckets must be in increasing order: %f >= %f",
					upperBound, h.upperBounds[i+1],
				))
			}
		} else {