Method labelNamesCommon

pkg/ingester/ingester.go:2047–2104

labelNamesCommon return all the label names. this should be used by LabelNames and LabelNamesStream. the cleanup function should be called in order to close the querier

(ctx context.Context, req *client.LabelNamesRequest)

// this should be used by LabelNames and LabelNamesStream.
// the cleanup function should be called in order to close the querier
func (i *Ingester) labelNamesCommon(ctx context.Context, req *client.LabelNamesRequest) (*client.LabelNamesResponse, func(), error) {
	cleanup := func() {}
	if err := i.checkRunning(); err != nil {
		return nil, cleanup, err
	}

	startTimestampMs, endTimestampMs, limit, matchers, err := client.FromLabelNamesRequest(i.matchersCache, req)
	if err != nil {
		return nil, cleanup, err
	}

	userID, err := users.TenantID(ctx)
	if err != nil {
		return nil, cleanup, err
	}

	db, err := i.getTSDB(userID)
	if err != nil || db == nil {
		return &client.LabelNamesResponse{}, cleanup, nil
	}

	if err := db.acquireReadLock(); err != nil {
		return &client.LabelNamesResponse{}, cleanup, nil
	}
	defer db.releaseReadLock()

	mint, maxt, err := metadataQueryRange(startTimestampMs, endTimestampMs, db, i.cfg.QueryIngestersWithin)
	if err != nil {
		return nil, cleanup, err
	}

	q, err := db.Querier(mint, maxt)
	if err != nil {
		return nil, cleanup, err
	}

	cleanup = func() {
		q.Close()
	}

	c, err := i.trackInflightQueryRequest()
	if err != nil {
		return nil, cleanup, err
	}
	defer c()
	names, _, err := q.LabelNames(ctx, &storage.LabelHints{Limit: limit}, matchers...)
	if err != nil {
		return nil, cleanup, err
	}

	if limit > 0 && len(names) > limit {
		names = names[:limit]
	}

	return &client.LabelNamesResponse{
		LabelNames: names,
	}, cleanup, nil
}