Use the new upcoming iterator style instead of our custom Range()

internal/exp/metrics/staleness/staleness.go

@@ -22,9 +22,9 @@ type Map[T any] interface {
 	LoadOrStore(key identity.Stream, value T) (T, bool)
 	// Remove the value at key from the map
 	Delete(key identity.Stream)
-	// Range calls f sequentially for each key and value present in the map.
-	// If f returns false, range stops the iteration.
-	Range(f func(key identity.Stream, value T) bool)
+	// Items returns an iterator function that in future go version can be used with range
+	// See: https://go.dev/wiki/RangefuncExperiment
+	Items() func(yield func(identity.Stream, T) bool) bool
 }
 
 type Staleness[T any] struct {

internal/exp/metrics/staleness/staleness_test.go

@@ -37,11 +37,14 @@ func (rm *RawMap[K, V]) Delete(key K) {
 	delete(*rm, key)
 }
 
-func (rm *RawMap[K, V]) Range(f func(key K, value V) bool) {
-	for key, value := range *rm {
-		if !f(key, value) {
-			return
+func (rm *RawMap[K, V]) Items() func(yield func(K, V) bool) bool {
+	return func(yield func(K, V) bool) bool {
+		for k, v := range *rm {
+			if !yield(k, v) {
+				break
+			}
 		}
+		return false
 	}
 }
 
@@ -122,10 +125,9 @@ func TestStaleness(t *testing.T) {
 func validateStalenessMapEntries(t *testing.T, expected map[identity.Stream]int, sm *Staleness[int]) {
 	actual := map[identity.Stream]int{}
 
-	sm.Range(func(key identity.Stream, value int) bool {
+	sm.Items()(func(key identity.Stream, value int) bool {
 		actual[key] = value
 		return true
 	})
-
 	require.Equal(t, expected, actual)
 }