scrape: remove unused member from cacheEntry (#11281)

Signed-off-by: Bogdan Drutu <bogdandrutu@gmail.com>

scrape/scrape.go

@@ -845,7 +845,6 @@ type cacheEntry struct {
 	lastIter uint64
 	hash     uint64
 	lset     labels.Labels
-	meta     metadata.Metadata
 }
 
 type scrapeLoop struct {
@@ -991,11 +990,11 @@ func (c *scrapeCache) get(met string) (*cacheEntry, bool) {
 	return e, true
 }
 
-func (c *scrapeCache) addRef(met string, ref storage.SeriesRef, lset labels.Labels, meta metadata.Metadata, hash uint64) {
+func (c *scrapeCache) addRef(met string, ref storage.SeriesRef, lset labels.Labels, hash uint64) {
 	if ref == 0 {
 		return
 	}
-	c.series[met] = &cacheEntry{ref: ref, lastIter: c.iter, lset: lset, meta: meta, hash: hash}
+	c.series[met] = &cacheEntry{ref: ref, lastIter: c.iter, lset: lset, hash: hash}
 }
 
 func (c *scrapeCache) addDropped(met string) {
@@ -1609,7 +1608,7 @@ loop:
 				// Bypass staleness logic if there is an explicit timestamp.
 				sl.cache.trackStaleness(hash, lset)
 			}
-			sl.cache.addRef(mets, ref, lset, meta, hash)
+			sl.cache.addRef(mets, ref, lset, hash)
 			if sampleAdded && sampleLimitErr == nil {
 				seriesAdded++
 			}
@@ -1835,7 +1834,7 @@ func (sl *scrapeLoop) addReportSample(app storage.Appender, s string, t int64, v
 	switch errors.Cause(err) {
 	case nil:
 		if !ok {
-			sl.cache.addRef(s, ref, lset, metadata.Metadata{}, lset.Hash())
+			sl.cache.addRef(s, ref, lset, lset.Hash())
 		}
 		return nil
 	case storage.ErrOutOfOrderSample, storage.ErrDuplicateSampleForTimestamp:

scrape/scrape_test.go

@@ -39,7 +39,6 @@ import (
 	"github.com/prometheus/prometheus/discovery/targetgroup"
 	"github.com/prometheus/prometheus/model/exemplar"
 	"github.com/prometheus/prometheus/model/labels"
-	"github.com/prometheus/prometheus/model/metadata"
 	"github.com/prometheus/prometheus/model/relabel"
 	"github.com/prometheus/prometheus/model/textparse"
 	"github.com/prometheus/prometheus/model/timestamp"
@@ -1556,13 +1555,12 @@ func TestScrapeLoopAppendCacheEntryButErrNotFound(t *testing.T) {
 	require.NoError(t, warning)
 
 	var lset labels.Labels
-	var meta metadata.Metadata
 	p.Next()
 	mets := p.Metric(&lset)
 	hash := lset.Hash()
 
 	// Create a fake entry in the cache
-	sl.cache.addRef(mets, fakeRef, lset, meta, hash)
+	sl.cache.addRef(mets, fakeRef, lset, hash)
 	now := time.Now()
 
 	slApp := sl.appender(context.Background())