From 4e748b9cd8c269948b79d35e46d77bff66ced7cf Mon Sep 17 00:00:00 2001
From: Bryan Boreham <bjboreham@gmail.com>
Date: Tue, 10 Oct 2023 21:30:19 +0100
Subject: [PATCH] scraping: re-use labels Builder in scrape report metrics

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>
---
 scrape/scrape.go | 41 ++++++++++++++++++++++-------------------
 1 file changed, 22 insertions(+), 19 deletions(-)

diff --git a/scrape/scrape.go b/scrape/scrape.go
index 072f5f47be..ce581d71b8 100644
--- a/scrape/scrape.go
+++ b/scrape/scrape.go
@@ -1785,30 +1785,31 @@ func (sl *scrapeLoop) report(app storage.Appender, start time.Time, duration tim
 	if scrapeErr == nil {
 		health = 1
 	}
+	b := labels.NewBuilderWithSymbolTable(sl.symbolTable)
 
-	if err = sl.addReportSample(app, scrapeHealthMetricName, ts, health); err != nil {
+	if err = sl.addReportSample(app, scrapeHealthMetricName, ts, health, b); err != nil {
 		return
 	}
-	if err = sl.addReportSample(app, scrapeDurationMetricName, ts, duration.Seconds()); err != nil {
+	if err = sl.addReportSample(app, scrapeDurationMetricName, ts, duration.Seconds(), b); err != nil {
 		return
 	}
-	if err = sl.addReportSample(app, scrapeSamplesMetricName, ts, float64(scraped)); err != nil {
+	if err = sl.addReportSample(app, scrapeSamplesMetricName, ts, float64(scraped), b); err != nil {
 		return
 	}
-	if err = sl.addReportSample(app, samplesPostRelabelMetricName, ts, float64(added)); err != nil {
+	if err = sl.addReportSample(app, samplesPostRelabelMetricName, ts, float64(added), b); err != nil {
 		return
 	}
-	if err = sl.addReportSample(app, scrapeSeriesAddedMetricName, ts, float64(seriesAdded)); err != nil {
+	if err = sl.addReportSample(app, scrapeSeriesAddedMetricName, ts, float64(seriesAdded), b); err != nil {
 		return
 	}
 	if sl.reportExtraMetrics {
-		if err = sl.addReportSample(app, scrapeTimeoutMetricName, ts, sl.timeout.Seconds()); err != nil {
+		if err = sl.addReportSample(app, scrapeTimeoutMetricName, ts, sl.timeout.Seconds(), b); err != nil {
 			return
 		}
-		if err = sl.addReportSample(app, scrapeSampleLimitMetricName, ts, float64(sl.sampleLimit)); err != nil {
+		if err = sl.addReportSample(app, scrapeSampleLimitMetricName, ts, float64(sl.sampleLimit), b); err != nil {
 			return
 		}
-		if err = sl.addReportSample(app, scrapeBodySizeBytesMetricName, ts, float64(bytes)); err != nil {
+		if err = sl.addReportSample(app, scrapeBodySizeBytesMetricName, ts, float64(bytes), b); err != nil {
 			return
 		}
 	}
@@ -1819,37 +1820,38 @@ func (sl *scrapeLoop) reportStale(app storage.Appender, start time.Time) (err er
 	ts := timestamp.FromTime(start)
 
 	stale := math.Float64frombits(value.StaleNaN)
+	b := labels.NewBuilder(labels.EmptyLabels())
 
-	if err = sl.addReportSample(app, scrapeHealthMetricName, ts, stale); err != nil {
+	if err = sl.addReportSample(app, scrapeHealthMetricName, ts, stale, b); err != nil {
 		return
 	}
-	if err = sl.addReportSample(app, scrapeDurationMetricName, ts, stale); err != nil {
+	if err = sl.addReportSample(app, scrapeDurationMetricName, ts, stale, b); err != nil {
 		return
 	}
-	if err = sl.addReportSample(app, scrapeSamplesMetricName, ts, stale); err != nil {
+	if err = sl.addReportSample(app, scrapeSamplesMetricName, ts, stale, b); err != nil {
 		return
 	}
-	if err = sl.addReportSample(app, samplesPostRelabelMetricName, ts, stale); err != nil {
+	if err = sl.addReportSample(app, samplesPostRelabelMetricName, ts, stale, b); err != nil {
 		return
 	}
-	if err = sl.addReportSample(app, scrapeSeriesAddedMetricName, ts, stale); err != nil {
+	if err = sl.addReportSample(app, scrapeSeriesAddedMetricName, ts, stale, b); err != nil {
 		return
 	}
 	if sl.reportExtraMetrics {
-		if err = sl.addReportSample(app, scrapeTimeoutMetricName, ts, stale); err != nil {
+		if err = sl.addReportSample(app, scrapeTimeoutMetricName, ts, stale, b); err != nil {
 			return
 		}
-		if err = sl.addReportSample(app, scrapeSampleLimitMetricName, ts, stale); err != nil {
+		if err = sl.addReportSample(app, scrapeSampleLimitMetricName, ts, stale, b); err != nil {
 			return
 		}
-		if err = sl.addReportSample(app, scrapeBodySizeBytesMetricName, ts, stale); err != nil {
+		if err = sl.addReportSample(app, scrapeBodySizeBytesMetricName, ts, stale, b); err != nil {
 			return
 		}
 	}
 	return
 }
 
-func (sl *scrapeLoop) addReportSample(app storage.Appender, s []byte, t int64, v float64) error {
+func (sl *scrapeLoop) addReportSample(app storage.Appender, s []byte, t int64, v float64, b *labels.Builder) error {
 	ce, ok := sl.cache.get(s)
 	var ref storage.SeriesRef
 	var lset labels.Labels
@@ -1860,8 +1862,9 @@ func (sl *scrapeLoop) addReportSample(app storage.Appender, s []byte, t int64, v
 		// The constants are suffixed with the invalid \xff unicode rune to avoid collisions
 		// with scraped metrics in the cache.
 		// We have to drop it when building the actual metric.
-		lset = labels.FromStrings(labels.MetricName, string(s[:len(s)-1]))
-		lset = sl.reportSampleMutator(lset)
+		b.Reset(labels.EmptyLabels())
+		b.Set(labels.MetricName, string(s[:len(s)-1]))
+		lset = sl.reportSampleMutator(b.Labels())
 	}
 
 	ref, err := app.Append(ref, lset, t, v)