Function mysql_ha_read

sql/sql_handler.cc:768–1024

*/
 
bool mysql_ha_read(THD *thd, TABLE_LIST *tables,
                   enum enum_ha_read_modes mode, const char *keyname,
                   List<Item> *key_expr,
                   enum ha_rkey_function ha_rkey_mode, Item *cond,
                   ha_rows select_limit_cnt, ha_rows offset_limit_cnt)
{
  SQL_HANDLER   *handler;
  TABLE         *table;
  Protocol	*protocol= thd->protocol;
  char		buff[MAX_FIELD_WIDTH];
  String	buffer(buff, sizeof(buff), system_charset_info);
  int           error, keyno;
  uint          num_rows;
  uchar		*UNINIT_VAR(key);
  MDL_deadlock_and_lock_abort_error_handler sql_handler_lock_error;
  DBUG_ENTER("mysql_ha_read");
  DBUG_PRINT("enter",("'%s'.'%s' as '%s'",
                      tables->db.str, tables->table_name.str, tables->alias.str));

  if (thd->locked_tables_mode)
  {
    my_error(ER_LOCK_OR_ACTIVE_TRANSACTION, MYF(0));
    DBUG_RETURN(TRUE);
  }

retry:
  if (!(handler= mysql_ha_find_handler(thd, &tables->alias)))
    goto err0;

  if (thd->transaction->xid_state.check_has_uncommitted_xa())
    goto err0;

  table= handler->table;
  tables->table= table;                         // This is used by fix_fields
  table->pos_in_table_list= tables;

  if (handler->lock->table_count > 0)
  {
    int lock_error;

    THR_LOCK_DATA **pos,**end;
    for (pos= handler->lock->locks,
           end= handler->lock->locks + handler->lock->lock_count;
         pos < end;
         pos++)
    {
      pos[0]->type= pos[0]->org_type;
    }

    /* save open_tables state */
    TABLE* backup_open_tables= thd->open_tables;
    /* Always a one-element list, see mysql_ha_open(). */
    DBUG_ASSERT(table->next == NULL || table->s->tmp_table);
    /*
      mysql_lock_tables() needs thd->open_tables to be set correctly to
      be able to handle aborts properly.
    */
    thd->set_open_tables(table);