@Override
  public String toString() {
    return toStringHelper(this)
        .add("lastPollRequestTimestamp", lastPollRequestTimestamp)
        .add("pollRate", pollRate())
        .add("missingRate", missingRate())
        .add("disorderCause", disorderCauseCounter.getCount())
        .toString();
  }
The {@link SubscriptionPrefetchingQueueStates} manages the state of a {@link
SubscriptionPrefetchingQueue}. It determines whether prefetching should occur based on memory
availability, poll request rates, and missing prefetch rates.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/subscription/broker/SubscriptionPrefetchingQueueStates.java