/api/data now returns stale and server_time

main.go

@@ -35,7 +35,7 @@ import (
 //go:embed static
 var embeddedStaticFiles embed.FS
 
-const version = "1.0.2"
+const version = "1.0.3"
 
 // ---------------------------------------------------------------------------
 // Config structs
@@ -467,6 +467,8 @@ type APIState struct {
 	ImbalancePercent float32 `json:"imbalance_percent"`
 	BiasPercent      float32 `json:"bias_percent"`
 	LastUpdate       string  `json:"last_update"`
+	ServerTime       string  `json:"server_time"`
+	Stale            bool    `json:"stale"`
 	DroppedSamples   uint64  `json:"dropped_samples"`
 	DroppedEvents    uint64  `json:"dropped_events"`
 }
@@ -927,6 +929,18 @@ func getConfigSnapshot() Config {
 	return cfg
 }
 
+func staleThreshold() time.Duration {
+	pollMs := getConfigSnapshot().PLC.PollMs
+	if pollMs <= 0 {
+		pollMs = 500
+	}
+	staleMs := pollMs * 4
+	if staleMs < 2500 {
+		staleMs = 2500
+	}
+	return time.Duration(staleMs) * time.Millisecond
+}
+
 func hotReloadSectionsLocked(dst *Config, src Config) {
 	dst.Thresholds = src.Thresholds
 	dst.Trend = src.Trend
@@ -1092,10 +1106,17 @@ func snapshotState() APIState {
 	state.RLock()
 	defer state.RUnlock()
 
+	now := time.Now()
 	lastUpdate := ""
 	if !state.LastUpdate.IsZero() {
 		lastUpdate = state.LastUpdate.Format(time.RFC3339Nano)
 	}
+
+	stale := false
+	if state.Connected && !state.LastUpdate.IsZero() {
+		stale = now.Sub(state.LastUpdate) > staleThreshold()
+	}
+
 	return APIState{
 		Connected:        state.Connected,
 		SilaL:            state.SilaL,
@@ -1107,6 +1128,8 @@ func snapshotState() APIState {
 		ImbalancePercent: state.ImbalancePercent,
 		BiasPercent:      state.BiasPercent,
 		LastUpdate:       lastUpdate,
+		ServerTime:       now.Format(time.RFC3339Nano),
+		Stale:            stale,
 		DroppedSamples:   state.DroppedSamples,
 		DroppedEvents:    state.DroppedEvents,
 	}
@@ -2753,7 +2776,8 @@ func main() {
 		IdleTimeout:  60 * time.Second,
 	}
 
-	log.Printf("Listening on http://localhost%s", cfg.Server.ListenAddr)
+	log.Printf("Listening address: %s", cfg.Server.ListenAddr)
+	log.Printf("Open locally: http://localhost%s", cfg.Server.ListenAddr)
 	log.Printf("License API: GET /api/license/status | GET /api/license/request | POST /api/license/activate")
 
 	go func() {