/* Copyright (C) 2006 MySQL AB & MySQL Finland AB & TCX DataKonsult AB

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/*
  WL#3234 Maria control file
  First version written by Guilhem Bichot on 2006-04-27.
*/

#define CONTROL_FILE_BASE_NAME "maria_control"
/*
  indicate absence of the log file number; first log is always number 1, 0 is
  impossible.
*/
#define CONTROL_FILE_IMPOSSIBLE_FILENO 0
/* logs always have a header */
#define CONTROL_FILE_IMPOSSIBLE_LOG_OFFSET 0
/* indicate absence of LSN.  */
#define CONTROL_FILE_IMPOSSIBLE_LSN ((LSN)0)

/* Here is the interface of this module */

/*
  LSN of the last checkoint
  (if last_checkpoint_lsn == CONTROL_FILE_IMPOSSIBLE_LSN
  then there was never a checkpoint)
*/
extern LSN last_checkpoint_lsn;
/*
  Last log number (if last_logno ==
  CONTROL_FILE_IMPOSSIBLE_FILENO then there is no log file yet)
*/
extern uint32 last_logno;

typedef enum enum_control_file_error {
  CONTROL_FILE_OK= 0,
  CONTROL_FILE_TOO_SMALL,
  CONTROL_FILE_TOO_BIG,
  CONTROL_FILE_BAD_MAGIC_STRING,
  CONTROL_FILE_BAD_CHECKSUM,
  CONTROL_FILE_UNKNOWN_ERROR /* any other error */
} CONTROL_FILE_ERROR;

#define CONTROL_FILE_UPDATE_ALL 0
#define CONTROL_FILE_UPDATE_ONLY_LSN 1
#define CONTROL_FILE_UPDATE_ONLY_LOGNO 2


/*
  Looks for the control file. If absent, it's a fresh start, create file.
  If present, read it to find out last checkpoint's LSN and last log.
  Called at engine's start.
*/
CONTROL_FILE_ERROR ma_control_file_create_or_open();
/*
  Write information durably to the control file.
  Called when we have created a new log (after syncing this log's creation)
  and when we have written a checkpoint (after syncing this log record).
*/
int ma_control_file_write_and_force(const LSN checkpoint_lsn, uint32 logno,
                                    uint objs_to_write);


/* Free resources taken by control file subsystem */
int ma_control_file_end();
