Optimize deprioritized policy preemption logic

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

pkg/detector/preemption.go

@@ -17,6 +17,7 @@ limitations under the License.
 package detector
 
 import (
+	rbt "github.com/emirpasic/gods/trees/redblacktree"
 	corev1 "k8s.io/api/core/v1"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
@@ -257,10 +258,10 @@ func (d *ResourceDetector) HandleDeprioritizedPropagationPolicy(oldPolicy policy
 		return
 	}
 
-	// TODO(@RainbowMango): Should sort the listed policies to ensure the
+	// Use red-black tree to sort the listed policies to ensure the
 	// higher priority PropagationPolicy be process first to avoid possible
 	// multiple preemption.
-
+	var sortedPotentialKeys *rbt.Tree
 	for i := range policies {
 		var potentialPolicy policyv1alpha1.PropagationPolicy
 		if err = helper.ConvertToTypedObject(policies[i], &potentialPolicy); err != nil {
@@ -283,6 +284,15 @@ func (d *ResourceDetector) HandleDeprioritizedPropagationPolicy(oldPolicy policy
 				return
 			}
 			klog.Infof("Enqueuing PropagationPolicy(%s/%s) in case of PropagationPolicy(%s/%s) priority changes", potentialPolicy.GetNamespace(), potentialPolicy.GetName(), newPolicy.GetNamespace(), newPolicy.GetName())
+			if sortedPotentialKeys == nil {
+				sortedPotentialKeys = rbt.NewWith(int32DescendingComparator)
+			}
+			sortedPotentialKeys.Put(potentialPolicy.ExplicitPriority(), potentialKey)
+		}
+	}
+
+	if sortedPotentialKeys != nil {
+		for _, potentialKey := range sortedPotentialKeys.Values() {
 			d.policyReconcileWorker.Add(potentialKey)
 		}
 	}
@@ -293,19 +303,18 @@ func (d *ResourceDetector) HandleDeprioritizedPropagationPolicy(oldPolicy policy
 // 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 red-black tree to sort the listed policies to ensure the
 	// higher priority ClusterPropagationPolicy be process first to avoid possible
 	// multiple preemption.
-
+	var sortedPotentialKeys *rbt.Tree
 	for i := range policies {
 		var potentialPolicy policyv1alpha1.ClusterPropagationPolicy
 		if err = helper.ConvertToTypedObject(policies[i], &potentialPolicy); err != nil {
@@ -329,7 +338,30 @@ func (d *ResourceDetector) HandleDeprioritizedClusterPropagationPolicy(oldPolicy
 			}
 			klog.Infof("Enqueuing ClusterPropagationPolicy(%s/%s) in case of ClusterPropagationPolicy(%s/%s) priority changes",
 				potentialPolicy.GetNamespace(), potentialPolicy.GetName(), newPolicy.GetNamespace(), newPolicy.GetName())
+			if sortedPotentialKeys == nil {
+				sortedPotentialKeys = rbt.NewWith(int32DescendingComparator)
+			}
+			sortedPotentialKeys.Put(potentialPolicy.ExplicitPriority(), potentialKey)
+		}
+	}
+
+	if sortedPotentialKeys != nil {
+		for _, potentialKey := range sortedPotentialKeys.Values() {
 			d.clusterPolicyReconcileWorker.Add(potentialKey)
 		}
 	}
 }
+
+// int32DescendingComparator provides a basic descending comparison on int32.
+func int32DescendingComparator(a, b interface{}) int {
+	aAsserted := a.(int32)
+	bAsserted := b.(int32)
+	switch {
+	case aAsserted > bAsserted:
+		return -1
+	case aAsserted < bAsserted:
+		return 1
+	default:
+		return 0
+	}
+}