perf(node-handler): use spec.nodeName field indexer instead of cluste…

pkg/handlers/resources/node_handler.go

@@ -7,7 +7,6 @@ import (
 	"sort"
 
 	"github.com/gin-gonic/gin"
-	"github.com/samber/lo"
 	"github.com/zxh326/kite/pkg/cluster"
 	"github.com/zxh326/kite/pkg/common"
 	"github.com/zxh326/kite/pkg/kube"
@@ -16,6 +15,7 @@ import (
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/klog/v2"
 	metricsv1 "k8s.io/metrics/pkg/apis/metrics/v1beta1"
+	"sigs.k8s.io/controller-runtime/pkg/client"
 )
 
 type NodeHandler struct {
@@ -262,44 +262,54 @@ func (h *NodeHandler) List(c *gin.Context) {
 		klog.Warningf("Failed to list node metrics: %v", err)
 	}
 
-	// Get all pods to calculate resource requests per node
-	var pods corev1.PodList
-	if err := cs.K8sClient.List(c.Request.Context(), &pods); err != nil {
-		klog.Warningf("Failed to list pods for node resource calculation: %v", err)
+	// Build node metrics lookup map
+	nodeMetricsMap := make(map[string]metricsv1.NodeMetrics, len(nodeMetrics.Items))
+	for _, nm := range nodeMetrics.Items {
+		nodeMetricsMap[nm.Name] = nm
 	}
 
-	// Group pods by node name and calculate resource requests
-	nodeResourceRequests := make(map[string]common.MetricsCell)
-	for _, pod := range pods.Items {
-		if pod.Spec.NodeName == "" {
-			continue // Skip pods not scheduled to any node
-		}
-
-		nodeName := pod.Spec.NodeName
-		if _, exists := nodeResourceRequests[nodeName]; !exists {
-			nodeResourceRequests[nodeName] = common.MetricsCell{}
-		}
-
-		metrics := nodeResourceRequests[nodeName]
-		metrics.Pods++
-
-		// Calculate CPU and memory requests for this pod
-		for _, container := range pod.Spec.Containers {
-			if cpuRequest := container.Resources.Requests.Cpu(); cpuRequest != nil {
-				metrics.CPURequest += cpuRequest.MilliValue()
+	// Calculate resource requests per node.
+	// When the informer cache is enabled, use the spec.nodeName field indexer for
+	// O(1) lookups per node. When cache is disabled (DISABLE_CACHE=true), fall back
+	// to a single cluster-wide pod list to avoid O(N) API server round-trips.
+	nodeResourceRequests := make(map[string]common.MetricsCell, len(nodes.Items))
+	if cs.K8sClient.CacheEnabled {
+		// Optimised path: per-node indexed query against the local informer cache.
+		for _, node := range nodes.Items {
+			var nodePods corev1.PodList
+			if err := cs.K8sClient.List(c.Request.Context(), &nodePods,
+				client.MatchingFields{"spec.nodeName": node.Name}); err != nil {
+				klog.Warningf("Failed to list pods for node %s: %v", node.Name, err)
+				continue
 			}
-			if memoryRequest := container.Resources.Requests.Memory(); memoryRequest != nil {
-				metrics.MemoryRequest += memoryRequest.Value()
+			nodeResourceRequests[node.Name] = sumPodResources(nodePods.Items)
+		}
+	} else {
+		// Fallback path: single cluster-wide list, then group in memory.
+		var allPods corev1.PodList
+		if err := cs.K8sClient.List(c.Request.Context(), &allPods); err != nil {
+			klog.Warningf("Failed to list pods: %v", err)
+		} else {
+			for i := range allPods.Items {
+				pod := &allPods.Items[i]
+				if pod.Spec.NodeName == "" {
+					continue
+				}
+				existing := nodeResourceRequests[pod.Spec.NodeName]
+				existing.Pods++
+				for _, container := range pod.Spec.Containers {
+					if cpuRequest := container.Resources.Requests.Cpu(); cpuRequest != nil {
+						existing.CPURequest += cpuRequest.MilliValue()
+					}
+					if memoryRequest := container.Resources.Requests.Memory(); memoryRequest != nil {
+						existing.MemoryRequest += memoryRequest.Value()
+					}
+				}
+				nodeResourceRequests[pod.Spec.NodeName] = existing
 			}
 		}
-
-		nodeResourceRequests[nodeName] = metrics
 	}
 
-	nodeMetricsMap := lo.KeyBy(nodeMetrics.Items, func(item metricsv1.NodeMetrics) string {
-		return item.Name
-	})
-
 	result := &common.NodeListWithMetrics{
 		TypeMeta: nodes.TypeMeta,
 		ListMeta: nodes.ListMeta,
@@ -343,3 +353,19 @@ func (h *NodeHandler) registerCustomRoutes(group *gin.RouterGroup) {
 	group.POST("/_all/:name/taint", h.TaintNode)
 	group.POST("/_all/:name/untaint", h.UntaintNode)
 }
+
+// sumPodResources aggregates pod count and resource requests from a slice of pods.
+func sumPodResources(pods []corev1.Pod) common.MetricsCell {
+	m := common.MetricsCell{Pods: int64(len(pods))}
+	for _, pod := range pods {
+		for _, container := range pod.Spec.Containers {
+			if cpuRequest := container.Resources.Requests.Cpu(); cpuRequest != nil {
+				m.CPURequest += cpuRequest.MilliValue()
+			}
+			if memoryRequest := container.Resources.Requests.Memory(); memoryRequest != nil {
+				m.MemoryRequest += memoryRequest.Value()
+			}
+		}
+	}
+	return m
+}