func()

in v1storage/storage.go [684:750]

• 59 lines of code
• 13 McCabe index (conditional complexity)

func (s *MemorySeriesStorage) candidateFPsForLabelMatchers(
	matchers ...*metric.LabelMatcher,
) (map[model.Fingerprint]struct{}, []*metric.LabelMatcher, error) {
	sort.Sort(metric.LabelMatchers(matchers))

	if len(matchers) == 0 || matchers[0].MatchesEmptyString() {
		// No matchers at all or even the best matcher matches the empty string.
		return nil, nil, nil
	}

	var (
		matcherIdx   int
		candidateFPs map[model.Fingerprint]struct{}
	)

	// Equal matchers.
	for ; matcherIdx < len(matchers) && (candidateFPs == nil || len(candidateFPs) > fpEqualMatchThreshold); matcherIdx++ {
		m := matchers[matcherIdx]
		if m.Type != metric.Equal || m.MatchesEmptyString() {
			break
		}
		candidateFPs = s.fingerprintsForLabelPair(
			model.LabelPair{
				Name:  m.Name,
				Value: m.Value,
			},
			nil,
			candidateFPs,
		)
		if len(candidateFPs) == 0 {
			return nil, nil, nil
		}
	}

	// Other matchers.
	for ; matcherIdx < len(matchers) && (candidateFPs == nil || len(candidateFPs) > fpOtherMatchThreshold); matcherIdx++ {
		m := matchers[matcherIdx]
		if m.MatchesEmptyString() {
			break
		}

		lvs, err := s.LabelValuesForLabelName(context.TODO(), m.Name)
		if err != nil {
			return nil, nil, err
		}
		lvs = m.Filter(lvs)
		if len(lvs) == 0 {
			return nil, nil, nil
		}
		fps := map[model.Fingerprint]struct{}{}
		for _, lv := range lvs {
			s.fingerprintsForLabelPair(
				model.LabelPair{
					Name:  m.Name,
					Value: lv,
				},
				fps,
				candidateFPs,
			)
		}
		candidateFPs = fps
		if len(candidateFPs) == 0 {
			return nil, nil, nil
		}
	}
	return candidateFPs, matchers[matcherIdx:], nil
}