public void updateFiles(Collection<HStoreFile> files) {
    this.filesToCompact = Preconditions.checkNotNull(files, "files for compaction can not null");
    recalculateSize();
  }
This class holds all logical details necessary to run a compaction.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/compactions/CompactionRequestImpl.java