few tweaks

Signed-off-by: Nir Rozenbaum <[email protected]>

Author: nirrozenbaum

pkg/epp/scheduling/framework/plugins/picker/weighted_random_picker.go

@@ -22,6 +22,7 @@ import (
 	"fmt"
 	"math"
 	"math/rand"
+	"slices"
 	"sort"
 	"time"
 
@@ -104,52 +105,35 @@ func (p *WeightedRandomPicker) TypedName() plugins.TypedName {
 // Pick selects the pod(s) randomly from the list of candidates, where the probability of the pod to get picked is derived
 // from its weighted score.
 func (p *WeightedRandomPicker) Pick(ctx context.Context, cycleState *types.CycleState, scoredPods []*types.ScoredPod) *types.ProfileRunResult {
-	log.FromContext(ctx).V(logutil.DEBUG).Info(fmt.Sprintf("Selecting maximum '%d' pods from %d candidates using weighted random sampling: %+v",
-		p.maxNumOfEndpoints, len(scoredPods), scoredPods))
-
-	// Check if all weights are zero or negative
-	allZeroWeights := true
-	for _, scoredPod := range scoredPods {
-		if scoredPod.Score > 0 {
-			allZeroWeights = false
-			break
-		}
-	}
-
-	// Delegate to RandomPicker for uniform selection when all weights are zero
-	if allZeroWeights {
-		log.FromContext(ctx).V(logutil.DEBUG).Info("All weights are zero, delegating to RandomPicker for uniform selection")
+	// Check if there is at least one pod with Score > 0, if not let random picker run
+	if slices.IndexFunc(scoredPods, func(scoredPod *types.ScoredPod) bool { return scoredPod.Score > 0 }) == -1 {
+		log.FromContext(ctx).V(logutil.DEBUG).Info("All scores are zero, delegating to RandomPicker for uniform selection")
 		return p.randomPicker.Pick(ctx, cycleState, scoredPods)
 	}
 
+	log.FromContext(ctx).V(logutil.DEBUG).Info(fmt.Sprintf("Selecting maximum '%d' pods from %d candidates using weighted random sampling: %+v",
+		p.maxNumOfEndpoints, len(scoredPods), scoredPods))
+
 	randomGenerator := rand.New(rand.NewSource(time.Now().UnixNano()))
 
 	// A-Res algorithm: keyᵢ = Uᵢ^(1/wᵢ)
-	weightedPods := make([]weightedScoredPod, 0, len(scoredPods))
-
-	for _, scoredPod := range scoredPods {
-		weight := float64(scoredPod.Score)
-
-		// Handle zero or negative weights
-		if weight <= 0 {
-			// Assign very small key for zero-weight pods (effectively excludes them)
-			weightedPods = append(weightedPods, weightedScoredPod{
-				ScoredPod: scoredPod,
-				key:       0,
-			})
+	weightedPods := make([]weightedScoredPod, len(scoredPods))
+
+	for i, scoredPod := range scoredPods {
+		// Handle zero score
+		if scoredPod.Score <= 0 {
+			// Assign key=0 for zero-score pods (effectively excludes them from selection)
+			weightedPods[i] = weightedScoredPod{ScoredPod: scoredPod, key: 0}
 			continue
 		}
 
-		// Generate random number U in (0,1)
+		// If we're here the scoredPod.Score > 0. Generate a random number U in (0,1)
 		u := randomGenerator.Float64()
 		if u == 0 {
 			u = 1e-10 // Avoid log(0)
 		}
 
-		weightedPods = append(weightedPods, weightedScoredPod{
-			ScoredPod: scoredPod,
-			key:       math.Pow(u, 1.0/weight), // key = U^(1/weight)
-		})
+		weightedPods[i] = weightedScoredPod{ScoredPod: scoredPod, key: math.Pow(u, 1.0/scoredPod.Score)} // key = U^(1/weight)
 	}
 
 	// Sort by key in descending order (largest keys first)