Method contiguous_appender

src/include/buffer.h:761–766

      size_t out_of_band_offset = 0;

      contiguous_appender(bufferlist& bl, size_t len, bool d)
	: bl(bl),
	  space(bl.obtain_contiguous_space(len)),
	  pos(space.bp_data),
	  deep(d) {
      }

      void flush_and_continue() {
	const size_t l = pos - space.bp_data;