public boolean hasNextSplit() throws IOException {
    if (nextUnseqFileIndex >= unseqFiles.size()) {
      return false;
    }
    return prepareNextSplit();
  }
CrossSpaceCompactionResource manages files and caches of readers to avoid unnecessary object
creations and file openings.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/compaction/selector/utils/CrossSpaceCompactionCandidate.java