public Pair<ByteBuffer, InsertNode> getByteBufferOrInsertNode(final WALEntryPosition position) {
    hasPipeRunning = true;

    final Pair<ByteBuffer, InsertNode> pair = lruCache.get(position);

    if (pair == null) {
      throw new IllegalStateException();
    }

    return pair;
  }
This cache is used by {@link WALEntryPosition}.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/wal/utils/WALInsertNodeCache.java