add metric numbers of overwritten object

incubator/hnc/internal/reconcilers/object.go

@@ -377,7 +377,7 @@ func (r *ObjectReconciler) getTopSourceToPropagate(log logr.Logger, inst *unstru
 	for _, obj := range objs {
 		// If the source cannot propagate, ignore it.
 		// TODO: add a webhook rule to prevent e.g. removing a source finalizer that
-		//  would cause overwrting the source objects in the descendents.
+		//  would cause overwriting the source objects in the descendents.
 		//  See https://github.com/kubernetes-sigs/multi-tenancy/issues/1120
 		if !r.shouldPropagateSource(log, obj, inst.GetNamespace()) {
 			continue
@@ -394,6 +394,7 @@ func (r *ObjectReconciler) syncPropagated(log logr.Logger, inst, srcInst *unstru
 	// Delete this local source object from the forest if it exists. (This could
 	// only happen when we are trying to overwrite a conflicting source).
 	ns.DeleteSourceObject(r.GVK, inst.GetName())
+	stats.OverwriteObject(r.GVK)
 
 	// If no source object exists, delete this object. This can happen when the source was deleted by
 	// users or the admin decided this type should no longer be propagated.

incubator/hnc/internal/stats/metrics.go

@@ -31,6 +31,7 @@ var (
 	objectReconcileConcurrent     = ocstats.Int64("object_reconcile_concurrent_peak", "The peak concurrent object reconciliations happened in the last reporting period", "reconciliations")
 	objectWritesTotal             = ocstats.Int64("object_writes_total", "The number of object writes happened during object reconciliations", "writes")
 	namespaceConditions           = ocstats.Int64("namespace_conditions", "The number of namespaces with conditions", "conditions")
+	objectOverwritesTotal         = ocstats.Int64("object_overwrites_total", "The number of overwritten objects", "overwrites")
 )
 
 // Create Tags. Tags are used to group and filter collected metrics later on.
@@ -93,7 +94,7 @@ var (
 	}
 
 	objectWritesView = &ocview.View{
-		Name:        "hnc/reconcilers/object/object_writes_total",
+		Name:        "hnc/reconcilers/object/writes_total",
 		Measure:     objectWritesTotal,
 		Description: "The number of object writes happened during object reconciliations",
 		Aggregation: ocview.LastValue(),
@@ -107,6 +108,14 @@ var (
 		Aggregation: ocview.LastValue(),
 		TagKeys:     []tag.Key{KeyNamespaceConditionType, KeyNamespaceConditionReason},
 	}
+
+	objectOverwritesTotalView = &ocview.View{
+		Name:        "hnc/reconcilers/object/overwrites_total",
+		Measure:     objectOverwritesTotal,
+		Description: "The number of overwritten objects",
+		Aggregation: ocview.LastValue(),
+		TagKeys:     []tag.Key{KeyGroupKind},
+	}
 )
 
 // periodicPeak contains periodic peaks for concurrent reconciliations.
@@ -133,6 +142,7 @@ func startRecordingMetrics() {
 		objectReconcileConcurrentView,
 		objectWritesView,
 		namespaceConditionsView,
+		objectOverwritesTotalView,
 	); err != nil {
 		log.Error(err, "Failed to register the views")
 	}

incubator/hnc/internal/stats/stats.go

@@ -14,6 +14,7 @@ type object struct {
 	totalReconciles counter
 	curReconciles   counter
 	apiWrites       counter
+	totalOverwrites counter
 }
 
 type objects map[schema.GroupKind]*object
@@ -106,6 +107,14 @@ func WriteObject(gvk schema.GroupVersionKind) {
 	recordObjectMetric(stats.objects[gk].apiWrites, objectWritesTotal, gk)
 }
 
+// OverwriteObject updates the object stats by GK when writing the object.
+func OverwriteObject(gvk schema.GroupVersionKind) {
+	gk := gvk.GroupKind()
+	stats.objects[gk].totalOverwrites.incr()
+
+	recordObjectMetric(stats.objects[gk].totalOverwrites, objectOverwritesTotal, gk)
+}
+
 func init() {
 	objects := make(map[schema.GroupKind]*object)
 	peak = periodicPeak{
@@ -166,7 +175,8 @@ func logActivity(log logr.Logger, status string) {
 		"TotalHierConfigReconciles", stats.totalHierConfigReconciles,
 		"CurHierConfigReconciles", stats.curHierConfigReconciles,
 		"TotalObjReconciles", getTotalObjReconciles(),
-		"CurObjReconciles", getCurObjReconciles())
+		"CurObjReconciles", getCurObjReconciles(),
+		"ObjectOverwrites", getObjOverwrites())
 }
 
 func getTotalObjReconciles() counter {
@@ -193,6 +203,14 @@ func getObjWrites() counter {
 	return writes
 }
 
+func getObjOverwrites() counter {
+	var overwrites counter
+	for _, obj := range stats.objects {
+		overwrites += obj.totalOverwrites
+	}
+	return overwrites
+}
+
 func max(a counter, b counter) counter {
 	return counter(math.Max(float64(a), float64(b)))
 }