eventCount:         5,
			cacheCapacity:      5,
			lowerBoundCapacity: 5 / 2,
			upperBoundCapacity: 5 * 2,
			interval:           eventFreshDuration / 6,
			expectCapacity:     10,
			expectStartIndex:   0,
		},
		{
			name:               "[capacity not equals 4*n] events outside eventFreshDuration without change cache capacity",

// - decreases capacity by 2x when recent quarter of events occurred outside of eventFreshDuration(protect watchCache from flapping).
func (w *watchCache) resizeCacheLocked(eventTime time.Time) {
	if w.isCacheFullLocked() && eventTime.Sub(w.cache[w.startIndex%w.capacity].RecordTime) < eventFreshDuration {
		capacity := min(w.capacity*2, w.upperBoundCapacity)