@Override
  public PrepareBulkLoadResponse prepareBulkLoad(RpcController controller,
    PrepareBulkLoadRequest request) throws ServiceException {
    try {
      checkOpen();
      requestCount.increment();

      HRegion region = getRegion(request.getRegion());

      String bulkToken = server.getSecureBulkLoadManager().prepareBulkLoad(region, request);
      PrepareBulkLoadResponse.Builder builder = PrepareBulkLoadResponse.newBuilder();
      builder.setBulkToken(bulkToken);
      return builder.build();
    } catch (IOException ie) {
      throw new ServiceException(ie);
    }
  }
Atomically bulk load several HFiles into an open region
@return true if successful, false is failed but recoverably (no action)
@throws ServiceException if failed unrecoverably
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java