Method floatHistogramSamplesV1

tsdb/record/record.go:717–760

floatHistogramSamplesV1 decodes V1 float-histogram records (BE64 baseRef/baseTime, varint deltas).

(dec *encoding.Decbuf, histograms []RefFloatHistogramSample)

// floatHistogramSamplesV1 decodes V1 float-histogram records (BE64 baseRef/baseTime, varint deltas).
func (d *Decoder) floatHistogramSamplesV1(dec *encoding.Decbuf, histograms []RefFloatHistogramSample) ([]RefFloatHistogramSample, error) {
	if dec.Len() == 0 {
		return histograms, nil
	}
	var (
		baseRef  = dec.Be64()
		baseTime = dec.Be64int64()
	)
	for len(dec.B) > 0 && dec.Err() == nil {
		dref := dec.Varint64()
		dtime := dec.Varint64()

		rh := RefFloatHistogramSample{
			Ref: chunks.HeadSeriesRef(baseRef + uint64(dref)),
			T:   baseTime + dtime,
			FH:  &histogram.FloatHistogram{},
		}

		DecodeFloatHistogram(dec, rh.FH)

		if !histogram.IsKnownSchema(rh.FH.Schema) {
			d.logger.Warn("skipping histogram with unknown schema in WAL record", "schema", rh.FH.Schema, "timestamp", rh.T)
			continue
		}
		if rh.FH.Schema > histogram.ExponentialSchemaMax && rh.FH.Schema <= histogram.ExponentialSchemaMaxReserved {
			// This is a very slow path, but it should only happen if the
			// record is from a newer Prometheus version that supports higher
			// resolution.
			if err := rh.FH.ReduceResolution(histogram.ExponentialSchemaMax); err != nil {
				return nil, fmt.Errorf("error reducing resolution of histogram #%d: %w", len(histograms)+1, err)
			}
		}

		histograms = append(histograms, rh)
	}

	if dec.Err() != nil {
		return nil, fmt.Errorf("decode error after %d histograms: %w", len(histograms), dec.Err())
	}
	if len(dec.B) > 0 {
		return nil, fmt.Errorf("unexpected %d bytes left in entry", len(dec.B))
	}
	return histograms, nil
}

// floatHistogramSamplesV2 decodes V2 float-histogram records.
func (d *Decoder) floatHistogramSamplesV2(dec *encoding.Decbuf, histograms []RefFloatHistogramSample) ([]RefFloatHistogramSample, error) {