public double getCacheHitRate() {
    return Objects.nonNull(lruCache) ? lruCache.stats().hitRate() : 0;
  }
This cache is used by {@link WALEntryPosition}.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/wal/utils/WALInsertNodeCache.java