Function fill

3rd/asio-1.24.0/include/asio/buffered_stream.hpp:191–194

Fill the buffer with some data. Returns the number of bytes placed in the buffer as a result of the operation. Throws an exception on failure.

  /// Fill the buffer with some data. Returns the number of bytes placed in the
  /// buffer as a result of the operation. Throws an exception on failure.
  std::size_t fill()
  {
    return stream_impl_.fill();
  }

  /// Fill the buffer with some data. Returns the number of bytes placed in the
  /// buffer as a result of the operation, or 0 if an error occurred.