implemented max-score picker

Signed-off-by: Maroon Ayoub <[email protected]>

Author: vMaroon

pkg/epp/scheduling/plugins/picker/max_score_picker.go

@@ -0,0 +1,55 @@
+package picker
+
+import (
+	"fmt"
+
+	"sigs.k8s.io/gateway-api-inference-extension/pkg/epp/scheduling/plugins"
+	"sigs.k8s.io/gateway-api-inference-extension/pkg/epp/scheduling/types"
+	logutil "sigs.k8s.io/gateway-api-inference-extension/pkg/epp/util/logging"
+)
+
+// MaxScorePicker picks the pod with the maximum score from the list of
+// candidates.
+type MaxScorePicker struct{}
+
+var _ plugins.Picker = &MaxScorePicker{}
+
+// Name returns the name of the picker.
+func (msp *MaxScorePicker) Name() string {
+	return "max_score"
+}
+
+// Pick selects the pod with the maximum score from the list of candidates.
+func (msp *MaxScorePicker) Pick(ctx *types.SchedulingContext, scoredPods []*types.ScoredPod) *types.Result {
+	debugLogger := ctx.Logger.V(logutil.DEBUG).WithName("max-score-picker")
+	debugLogger.Info(fmt.Sprintf("Selecting the pod with the max score from %d candidates: %+v",
+		len(scoredPods), scoredPods))
+
+	winners := make([]*types.ScoredPod, 0)
+
+	maxScore := 0.0
+	for _, pod := range scoredPods {
+		score := pod.Score
+		if score > maxScore {
+			maxScore = score
+			winners = []*types.ScoredPod{pod}
+		} else if score == maxScore {
+			winners = append(winners, pod)
+		}
+	}
+
+	if len(winners) == 0 {
+		return nil
+	}
+
+	if len(winners) > 1 {
+		debugLogger.Info(fmt.Sprintf("Multiple pods have the same max score (%f): %+v",
+			maxScore, winners))
+
+		randomPicker := RandomPicker{}
+		return randomPicker.Pick(ctx, winners)
+	}
+
+	debugLogger.Info(fmt.Sprintf("Selected pod with max score (%f): %+v", maxScore, winners[0]))
+	return &types.Result{TargetPod: winners[0]}
+}