Method refill_from_index_reader

sql/multi_range_read.cc:957–1017

*/

int Mrr_ordered_rndpos_reader::refill_from_index_reader()
{
  range_id_t range_info;
  int res;
  DBUG_ENTER("Mrr_ordered_rndpos_reader::refill_from_index_reader");

  DBUG_ASSERT(rowid_buffer->is_empty());
  index_rowid= index_reader->get_rowid_ptr();
  rowid_buffer->reset();
  rowid_buffer->setup_writing(file->ref_length,
                              is_mrr_assoc? sizeof(range_id_t) : 0);

  last_identical_rowid= NULL;

  index_reader->resume_read();
  while (rowid_buffer->can_write())
  {
    res= index_reader->get_next(&range_info);

    if (res)
    {
      if (res != HA_ERR_END_OF_FILE)
        DBUG_RETURN(res);
      index_reader_needs_refill=TRUE;
      break;
    }

    index_reader->position();

    /*
      If the built rowid filter cannot be used at the engine level, use it here.
    */
    if (rowid_filter && !file->pushed_rowid_filter &&
        !rowid_filter->check((char *)index_rowid))
      continue;

    /* Put rowid, or {rowid, range_id} pair into the buffer */
    rowid_buffer->write_ptr1= index_rowid;
    rowid_buffer->write_ptr2= (uchar*)&range_info;
    rowid_buffer->write();
  }
  
  /*
    When index_reader_needs_refill=TRUE, this means we've got all of index
    tuples for lookups keys that index_reader had. We are not in the middle
    of an index read, so there is no need to call interrupt_read.

    Actually, we must not call interrupt_read(), because it could be that we
    haven't read a single row (because all index lookups returned
    HA_ERR_KEY_NOT_FOUND). In this case, interrupt_read() will cause [harmless]
    valgrind warnings when trying to save garbage from table->record[0].
  */
  if (!index_reader_needs_refill)
    index_reader->interrupt_read();
  /* Sort the buffer contents by rowid */
  rowid_buffer->sort(rowid_cmp_reverse, (void*)file);

  rowid_buffer->setup_reading(file->ref_length,