Optimize deprioritized policy preemption logic

Use the priorityequeue to sort the listed policies to avoid multiple preemption.

Signed-off-by: whitewindmills <[email protected]>

Author: whitewindmills

pkg/detector/preemption.go

@@ -17,6 +17,8 @@ limitations under the License.
 package detector
 
 import (
+	pq "github.com/emirpasic/gods/queues/priorityqueue"
+	godsutils "github.com/emirpasic/gods/utils"
 	corev1 "k8s.io/api/core/v1"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
@@ -33,6 +35,13 @@ import (
 	"github.com/karmada-io/karmada/pkg/util/names"
 )
 
+// PriorityKey is the unique propagation policy key with priority.
+type PriorityKey struct {
+	util.QueueKey
+	// Priority is the priority of the propagation policy.
+	Priority int32
+}
+
 // preemptionEnabled checks if preemption is enabled.
 func preemptionEnabled(preemption policyv1alpha1.PreemptionBehavior) bool {
 	if preemption != policyv1alpha1.PreemptAlways {
@@ -257,10 +266,10 @@ func (d *ResourceDetector) HandleDeprioritizedPropagationPolicy(oldPolicy policy
 		return
 	}
 
-	// TODO(@RainbowMango): Should sort the listed policies to ensure the
+	// Use the priority queue to sort the listed policies to ensure the
 	// higher priority PropagationPolicy be process first to avoid possible
 	// multiple preemption.
-
+	var sortedPotentialKeys *pq.Queue
 	for i := range policies {
 		var potentialPolicy policyv1alpha1.PropagationPolicy
 		if err = helper.ConvertToTypedObject(policies[i], &potentialPolicy); err != nil {
@@ -277,35 +286,43 @@ func (d *ResourceDetector) HandleDeprioritizedPropagationPolicy(oldPolicy policy
 			potentialPolicy.Spec.Preemption == policyv1alpha1.PreemptAlways &&
 			potentialPolicy.ExplicitPriority() > newPolicy.ExplicitPriority() &&
 			potentialPolicy.ExplicitPriority() < oldPolicy.ExplicitPriority() {
-			var potentialKey util.QueueKey
-			potentialKey, err = ClusterWideKeyFunc(&potentialPolicy)
+			potentialKey, err := ClusterWideKeyFunc(&potentialPolicy)
 			if err != nil {
-				return
+				klog.Errorf("Failed to convert PropagationPolicy to queued key: %v", err)
+				continue
 			}
+
 			klog.Infof("Enqueuing PropagationPolicy(%s/%s) in case of PropagationPolicy(%s/%s) priority changes", potentialPolicy.GetNamespace(), potentialPolicy.GetName(), newPolicy.GetNamespace(), newPolicy.GetName())
-			d.policyReconcileWorker.Add(potentialKey)
+			if sortedPotentialKeys == nil {
+				sortedPotentialKeys = pq.NewWith(priorityDescendingComparator)
+			}
+
+			sortedPotentialKeys.Enqueue(&PriorityKey{
+				QueueKey: potentialKey,
+				Priority: potentialPolicy.ExplicitPriority(),
+			})
 		}
 	}
+	requeuePotentialKeys(sortedPotentialKeys, d.policyReconcileWorker)
 }
 
 // HandleDeprioritizedClusterPropagationPolicy responses to priority change of a ClusterPropagationPolicy,
 // if the change is from high priority (e.g. 5) to low priority(e.g. 3), it will
 // check if there is another ClusterPropagationPolicy could preempt the targeted resource,
 // and put the ClusterPropagationPolicy in the queue to trigger preemption.
 func (d *ResourceDetector) HandleDeprioritizedClusterPropagationPolicy(oldPolicy policyv1alpha1.ClusterPropagationPolicy, newPolicy policyv1alpha1.ClusterPropagationPolicy) {
-	klog.Infof("ClusterPropagationPolicy(%s/%s) priority changed from %d to %d",
-		newPolicy.GetNamespace(), newPolicy.GetName(), *oldPolicy.Spec.Priority, *newPolicy.Spec.Priority)
-
-	policies, err := d.clusterPropagationPolicyLister.ByNamespace(newPolicy.GetNamespace()).List(labels.Everything())
+	klog.Infof("ClusterPropagationPolicy(%s) priority changed from %d to %d",
+		newPolicy.GetName(), *oldPolicy.Spec.Priority, *newPolicy.Spec.Priority)
+	policies, err := d.clusterPropagationPolicyLister.List(labels.Everything())
 	if err != nil {
-		klog.Errorf("Failed to list ClusterPropagationPolicy from namespace: %s, error: %v", newPolicy.GetNamespace(), err)
+		klog.Errorf("Failed to list ClusterPropagationPolicy, error: %v", err)
 		return
 	}
 
-	// TODO(@RainbowMango): Should sort the listed policies to ensure the
+	// Use the priority queue to sort the listed policies to ensure the
 	// higher priority ClusterPropagationPolicy be process first to avoid possible
 	// multiple preemption.
-
+	var sortedPotentialKeys *pq.Queue
 	for i := range policies {
 		var potentialPolicy policyv1alpha1.ClusterPropagationPolicy
 		if err = helper.ConvertToTypedObject(policies[i], &potentialPolicy); err != nil {
@@ -322,14 +339,47 @@ func (d *ResourceDetector) HandleDeprioritizedClusterPropagationPolicy(oldPolicy
 			potentialPolicy.Spec.Preemption == policyv1alpha1.PreemptAlways &&
 			potentialPolicy.ExplicitPriority() > newPolicy.ExplicitPriority() &&
 			potentialPolicy.ExplicitPriority() < oldPolicy.ExplicitPriority() {
-			var potentialKey util.QueueKey
-			potentialKey, err = ClusterWideKeyFunc(&potentialPolicy)
+			potentialKey, err := ClusterWideKeyFunc(&potentialPolicy)
 			if err != nil {
-				return
+				klog.Errorf("Failed to convert ClusterPropagationPolicy to queued key: %v", err)
+				continue
 			}
-			klog.Infof("Enqueuing ClusterPropagationPolicy(%s/%s) in case of ClusterPropagationPolicy(%s/%s) priority changes",
-				potentialPolicy.GetNamespace(), potentialPolicy.GetName(), newPolicy.GetNamespace(), newPolicy.GetName())
-			d.clusterPolicyReconcileWorker.Add(potentialKey)
+
+			klog.Infof("Enqueuing ClusterPropagationPolicy(%s) in case of ClusterPropagationPolicy(%s) priority changes",
+				potentialPolicy.GetName(), newPolicy.GetName())
+			if sortedPotentialKeys == nil {
+				sortedPotentialKeys = pq.NewWith(priorityDescendingComparator)
+			}
+
+			sortedPotentialKeys.Enqueue(&PriorityKey{
+				QueueKey: potentialKey,
+				Priority: potentialPolicy.ExplicitPriority(),
+			})
 		}
 	}
+	requeuePotentialKeys(sortedPotentialKeys, d.clusterPolicyReconcileWorker)
+}
+
+// requeuePotentialKeys re-queues potential policy keys.
+func requeuePotentialKeys(sortedPotentialKeys *pq.Queue, worker util.AsyncWorker) {
+	// No suitable policy key to re-queue.
+	if sortedPotentialKeys == nil {
+		return
+	}
+
+	for {
+		key, ok := sortedPotentialKeys.Dequeue()
+		if !ok {
+			break
+		}
+
+		worker.Add(key.(*PriorityKey).QueueKey)
+	}
+}
+
+// priorityDescendingComparator provides a basic descending comparison on policy priority.
+func priorityDescendingComparator(a, b interface{}) int {
+	aPriority := a.(*PriorityKey).Priority
+	bPriority := b.(*PriorityKey).Priority
+	return godsutils.Int32Comparator(bPriority, aPriority)
 }