mvcc/metrics.go
func ReportEventReceived(n int) {
	pendingEventsGauge.Sub(float64(n))
	totalEventsCounter.Add(float64(n))
}
func ReportEventReceived(n int) {
	pendingEventsGauge.Sub(float64(n))
	totalEventsCounter.Add(float64(n))
}
// ReportEventReceived reports that an event is received.
// This function should be called when the external systems received an
// event from mvcc.Watcher.