code: func (e *Engine) ShouldCompactCache(t time.Time) bool {
  	sz := e.Cache.Size()
  
  	if sz == 0 {
  		return false
  	}
  
  	if sz > e.CacheFlushMemorySizeThreshold {
  		return true
  	}
  
  	return t.Sub(e.Cache.LastWriteTime()) > e.CacheFlushWriteColdDuration
  }
docs: // ShouldCompactCache returns true if the Cache is over its flush threshold
  // or if the passed in lastWriteTime is older than the write cold threshold.