Method recover

phx_percona/percona/sql/binlog.cc:7594–7695

MYSQLD server recovers from last crashed binlog. @param log IO_CACHE of the crashed binlog. @param fdle Format_description_log_event of the crashed binlog. @param valid_pos The position of the last valid transaction or event(non-transaction) of the crashed binlog. @retval 0 ok @retval 1 error */

    1                  error
*/
int MYSQL_BIN_LOG::recover(IO_CACHE *log, Format_description_log_event *fdle,
                            my_off_t *valid_pos)
{
  Log_event  *ev;
  HASH xids;
  MEM_ROOT mem_root;
  /*
    The flag is used for handling the case that a transaction
    is partially written to the binlog.
  */
  bool in_transaction= FALSE;

  if (! fdle->is_valid() ||
      my_hash_init(&xids, &my_charset_bin, TC_LOG_PAGE_SIZE/3, 0,
                   sizeof(my_xid), 0, 0, MYF(0)))
    goto err1;

  init_alloc_root(&mem_root, TC_LOG_PAGE_SIZE, TC_LOG_PAGE_SIZE);

  while ((ev= Log_event::read_log_event(log, 0, fdle, TRUE))
         && ev->is_valid())
  {
    if (ev->get_type_code() == QUERY_EVENT &&
        !strcmp(((Query_log_event*)ev)->query, "BEGIN"))
      in_transaction= TRUE;

    if (ev->get_type_code() == QUERY_EVENT &&
        !strcmp(((Query_log_event*)ev)->query, "COMMIT"))
    {
      DBUG_ASSERT(in_transaction == TRUE);
      in_transaction= FALSE;
    }
    else if (ev->get_type_code() == XID_EVENT)
    {
      DBUG_ASSERT(in_transaction == TRUE);
      in_transaction= FALSE;
      Xid_log_event *xev=(Xid_log_event *)ev;
      uchar *x= (uchar *) memdup_root(&mem_root, (uchar*) &xev->xid,
                                      sizeof(xev->xid));
      if (!x || my_hash_insert(&xids, x))
        goto err2;
    }

    /*
      Recorded valid position for the crashed binlog file
      which did not contain incorrect events. The following
      positions increase the variable valid_pos:

      1 -
        ...
        <---> HERE IS VALID <--->
        GTID 
        BEGIN
        ...
        COMMIT
        ...
         
      2 -