Server.java 文件源码

/**
 * Setup response for the IPC Call on Fatal Error from a 
 * client that is using old version of Hadoop.
 * The response is serialized using the previous protocol's response
 * layout.
 * 
 * @param response buffer to serialize the response into
 * @param call {@link Call} to which we are setting up the response
 * @param rv return value for the IPC Call, if the call was successful
 * @param errorClass error class, if the the call failed
 * @param error error message, if the call failed
 * @throws IOException
 */
private void setupResponseOldVersionFatal(ByteArrayOutputStream response, 
                           Call call,
                           Writable rv, String errorClass, String error) 
throws IOException {
  final int OLD_VERSION_FATAL_STATUS = -1;
  response.reset();
  DataOutputStream out = new DataOutputStream(response);
  out.writeInt(call.callId);                // write call id
  out.writeInt(OLD_VERSION_FATAL_STATUS);   // write FATAL_STATUS
  WritableUtils.writeString(out, errorClass);
  WritableUtils.writeString(out, error);

  if (call.connection.useWrap) {
    wrapWithSasl(response, call);
  }
  call.setResponse(ByteBuffer.wrap(response.toByteArray()));
}