perf(clickhouse): P0 dashboard/observability query limits, cache, slower polling

internal/apps/openflare/dashboard/cache.go

@@ -0,0 +1,33 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package dashboard
+
+import (
+	"sync"
+	"time"
+)
+
+const overviewCacheTTL = 30 * time.Second
+
+var overviewCache struct {
+	mu        sync.Mutex
+	payload   *OverviewPayload
+	expiresAt time.Time
+}
+
+func getCachedOverview() (*OverviewPayload, bool) {
+	overviewCache.mu.Lock()
+	defer overviewCache.mu.Unlock()
+	if overviewCache.payload == nil || time.Now().After(overviewCache.expiresAt) {
+		return nil, false
+	}
+	return overviewCache.payload, true
+}
+
+func setCachedOverview(payload *OverviewPayload) {
+	overviewCache.mu.Lock()
+	defer overviewCache.mu.Unlock()
+	overviewCache.payload = payload
+	overviewCache.expiresAt = time.Now().Add(overviewCacheTTL)
+}

internal/apps/openflare/dashboard/helpers.go

@@ -18,6 +18,7 @@ const (
 	nodeStatusPending = "pending"
 
 	dashboardDistributionLimit       = 8
+	dashboardOverviewSnapshotLimit   = 500
 	highCPUUsagePercentThreshold     = 80
 	highMemoryUsagePercentThreshold  = 85
 	highStorageUsagePercentThreshold = 85

internal/apps/openflare/dashboard/logics.go

@@ -97,11 +97,16 @@ type trendsPayload struct {
 
 // GetOverview aggregates dashboard overview data from nodes and observability tables.
 func GetOverview(ctx context.Context) (*OverviewPayload, error) {
+	if payload, ok := getCachedOverview(); ok {
+		return payload, nil
+	}
 	view, err := buildOverviewView(ctx)
 	if err != nil {
 		return nil, err
 	}
-	return compressOverview(view), nil
+	payload := compressOverview(view)
+	setCachedOverview(payload)
+	return payload, nil
 }
 
 func buildOverviewView(ctx context.Context) (*OverviewView, error) {
@@ -112,11 +117,11 @@ func buildOverviewView(ctx context.Context) (*OverviewView, error) {
 	if err != nil {
 		return nil, err
 	}
-	snapshots, err := model.ListOpenFlareMetricSnapshotsSince(ctx, "", since, 0)
+	snapshots, err := model.ListOpenFlareMetricSnapshotsSince(ctx, "", since, dashboardOverviewSnapshotLimit)
 	if err != nil {
 		return nil, err
 	}
-	reports, err := model.ListOpenFlareRequestReportsSince(ctx, "", since, 0)
+	reports, err := model.ListOpenFlareRequestReportsSince(ctx, "", since, dashboardOverviewSnapshotLimit)
 	if err != nil {
 		return nil, err
 	}
@@ -128,7 +133,7 @@ func buildOverviewView(ctx context.Context) (*OverviewView, error) {
 	if err != nil {
 		return nil, err
 	}
-	openrestySnapshots, err := model.ListOpenFlareNodeObservationOpenresty(ctx, "", since, 0)
+	openrestySnapshots, err := model.ListOpenFlareNodeObservationOpenresty(ctx, "", since, dashboardOverviewSnapshotLimit)
 	if err != nil {
 		return nil, err
 	}