code: func (whisper *Whisper) checkOverflow() {
  	queueSize := len(whisper.messageQueue)
  
  	if queueSize == messageQueueLimit {
  		if !whisper.Overflow() {
  			whisper.settings.Store(overflowIdx, true)
  			log.Warn("message queue overflow")
  		}
  	} else if queueSize <= messageQueueLimit/2 {
  		if whisper.Overflow() {
  			whisper.settings.Store(overflowIdx, false)
  			log.Warn("message queue overflow fixed (back to normal)")
  		}
  	}
  }
docs: // checkOverflow checks if message queue overflow occurs and reports it if necessary.