remove useless function

pkg/costattribution/manager.go

@@ -217,10 +217,7 @@ func (m *Manager) purgeInactiveAttributionsUntil(deadline time.Time) error {
 			continue
 		}
 
-		invalidKeys := st.inactiveObservations(deadline)
-		for _, key := range invalidKeys {
-			st.cleanupTrackerAttribution(key)
-		}
+		st.cleanupInactiveObservations(deadline)
 
 		// only sample tracker can recovered from overflow, the activeseries tracker after the cooldown would just be deleted and recreated
 		if st.recoveredFromOverflow(deadline) {

pkg/costattribution/sample_tracker.go

@@ -87,12 +87,6 @@ var bufferPool = sync.Pool{
 	},
 }
 
-func (st *SampleTracker) cleanupTrackerAttribution(key string) {
-	st.observedMtx.Lock()
-	defer st.observedMtx.Unlock()
-	delete(st.observed, key)
-}
-
 func (st *SampleTracker) Collect(out chan<- prometheus.Metric) {
 	// We don't know the performance of out receiver, so we don't want to hold the lock for too long
 	var prometheusMetrics []prometheus.Metric
@@ -304,16 +298,20 @@ func (st *SampleTracker) recoveredFromOverflow(deadline time.Time) bool {
 	return false
 }
 
-func (st *SampleTracker) inactiveObservations(deadline time.Time) []string {
+func (st *SampleTracker) cleanupInactiveObservations(deadline time.Time) {
 	// otherwise, we need to check all observations and clean up the ones that are inactive
 	var invalidKeys []string
 	st.observedMtx.RLock()
-	defer st.observedMtx.RUnlock()
 	for labkey, ob := range st.observed {
 		if ob != nil && ob.lastUpdate.Load() <= deadline.Unix() {
 			invalidKeys = append(invalidKeys, labkey)
 		}
 	}
+	st.observedMtx.RUnlock()
 
-	return invalidKeys
+	st.observedMtx.Lock()
+	for _, key := range invalidKeys {
+		delete(st.observed, key)
+	}
+	st.observedMtx.Unlock()
 }

pkg/costattribution/sample_tracker_test.go

@@ -108,18 +108,17 @@ func TestSampleTracker_inactiveObservations(t *testing.T) {
 	require.Len(t, st.observed, 3)
 
 	// Purge observations that haven't been updated in the last 10 seconds.
-	purged := st.inactiveObservations(time.Unix(0, 0))
-	require.Len(t, purged, 0)
+	st.cleanupInactiveObservations(time.Unix(0, 0))
+	require.Len(t, st.observed, 3)
 
-	purged = st.inactiveObservations(time.Unix(10, 0))
-	assert.ElementsMatch(t, []string{"foo"}, purged)
+	st.cleanupInactiveObservations(time.Unix(10, 0))
+	assert.Len(t, st.observed, 2)
 
-	purged = st.inactiveObservations(time.Unix(15, 0))
-	assert.ElementsMatch(t, []string{"foo", "bar"}, purged)
+	st.cleanupInactiveObservations(time.Unix(15, 0))
+	assert.Len(t, st.observed, 1)
 
-	// Check that the purged observation matches the expected details.
-	purged = st.inactiveObservations(time.Unix(25, 0))
-	assert.ElementsMatch(t, []string{"foo", "bar", "baz"}, purged)
+	st.cleanupInactiveObservations(time.Unix(25, 0))
+	assert.Len(t, st.observed, 0)
 }
 
 func TestSampleTracker_Concurrency(t *testing.T) {