private ScanInfo preCompactScannerOpen(CompactionRequestImpl request, ScanType scanType,
    User user) throws IOException {
    if (store.getCoprocessorHost() == null) {
      return store.getScanInfo();
    }
    return store.getCoprocessorHost().preCompactScannerOpen(store, scanType, request.getTracker(),
      request, user);
  }
Creates a writer for a new file.
@param fd The file details.
@return Writer for a new StoreFile
@throws IOException if creation failed
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/compactions/Compactor.java