Method append

scrape/scrape.go:1595–1903

(b []byte, contentType string, ts time.Time)

var _ scrapeLoopAppendAdapter = &scrapeLoopAppender{}

func (sl *scrapeLoopAppender) append(b []byte, contentType string, ts time.Time) (total, added, seriesAdded int, err error) {
	defTime := timestamp.FromTime(ts)

	if len(b) == 0 {
		// Empty scrape. Just update the stale makers and swap the cache (but don't flush it).
		err = sl.updateStaleMarkers(sl.Appender, defTime)
		sl.cache.iterDone(false)
		return total, added, seriesAdded, err
	}

	p, err := textparse.New(b, contentType, sl.symbolTable, textparse.ParserOptions{
		EnableTypeAndUnitLabels:                 sl.enableTypeAndUnitLabels,
		IgnoreNativeHistograms:                  !sl.enableNativeHistogramScraping,
		ConvertClassicHistogramsToNHCB:          sl.convertClassicHistToNHCB,
		KeepClassicOnClassicAndNativeHistograms: sl.alwaysScrapeClassicHist,
		OpenMetricsSkipSTSeries:                 sl.enableSTZeroIngestion,
		FallbackContentType:                     sl.fallbackScrapeProtocol,
	})
	if p == nil {
		sl.l.Error(
			"Failed to determine correct type of scrape target.",
			"content_type", contentType,
			"fallback_media_type", sl.fallbackScrapeProtocol,
			"err", err,
		)
		return total, added, seriesAdded, err
	}
	if err != nil {
		sl.l.Debug(
			"Invalid content type on scrape, using fallback setting.",
			"content_type", contentType,
			"fallback_media_type", sl.fallbackScrapeProtocol,
			"err", err,
		)
	}
	var (
		appErrs        = appendErrors{}
		sampleLimitErr error
		bucketLimitErr error
		lset           labels.Labels     // Escapes to heap so hoisted out of loop.
		e              exemplar.Exemplar // Escapes to heap so hoisted out of loop.
		lastMeta       *metaEntry
		lastMFName     []byte
	)

	exemplars := make([]exemplar.Exemplar, 0, 1)

	// Take an appender with limits.
	app := appenderWithLimits(sl.Appender, sl.sampleLimit, sl.bucketLimit, sl.maxSchema)

	defer func() {
		if err != nil {
			return
		}
		// Flush and swap the cache as the scrape was non-empty.
		sl.cache.iterDone(true)
	}()