Handle operating system sleep: check regularly the difference between the monotonic clock and the effective time difference

app.go

@@ -22,6 +22,7 @@ type App struct {
 	srv          *http.Server
 	nextAlarm    *time.Timer
 	nextPreAlarm *time.Timer
+	ticker       *time.Ticker
 }
 
 func NewApp(cfg *config.Config) *App {
@@ -61,6 +62,10 @@ func NewApp(cfg *config.Config) *App {
 }
 
 func (app *App) Start() {
+	if app.ticker != nil {
+		app.ticker.Stop()
+	}
+
 	app.srv = &http.Server{
 		Addr:    app.cfg.Bind,
 		Handler: app.router,
@@ -68,12 +73,28 @@ func (app *App) Start() {
 
 	app.ResetTimer()
 
+	go app.CheckTime()
+
 	log.Printf("Ready, listening on %s\n", app.cfg.Bind)
 	if err := app.srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
 		log.Fatalf("listen: %s\n", err)
 	}
 }
 
+func (app *App) CheckTime() {
+	app.ticker = time.NewTicker(time.Minute)
+
+	startTime := time.Now()
+
+	for range app.ticker.C {
+		if time.Since(startTime).Round(time.Second).Seconds() != time.Since(startTime.Round(0)).Round(time.Second).Seconds() {
+			app.ResetTimer()
+
+			startTime = time.Now()
+		}
+	}
+}
+
 func (app *App) ResetTimer() {
 	if app.nextAlarm != nil {
 		app.nextAlarm.Stop()
@@ -137,6 +158,10 @@ func (app *App) Stop() {
 		app.nextAlarm.Stop()
 	}
 
+	if app.ticker != nil {
+		app.ticker.Stop()
+	}
+
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()
 	if err := app.srv.Shutdown(ctx); err != nil {