protected CompactionTaskInfo calculatingCompactionTaskInfo(List<TsFileResource> resources)
      throws IOException {
    List<FileInfo> fileInfoList = new ArrayList<>();
    for (TsFileResource resource : resources) {
      FileInfo fileInfo = getFileInfoFromCache(resource);
      fileInfoList.add(fileInfo);
    }
    return new CompactionTaskInfo(resources, fileInfoList);
  }
The size of global compaction estimation rough file info cahce.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/compaction/selector/estimator/AbstractCompactionEstimator.java