empserver/include/lost.h
Markus Armbruster 2fa5f65257 Generation numbers to catch write back of stale copies
Oops when a stale copy is written back, i.e. the processor was yielded
since the copy was made.  Such bugs are difficult to spot.  Sequence
numbers catch them when they do actual harm (they also catch different
bugs).  Generation numbers catch them even when they don't.

New ef_generation to count generations.  Call new ef_make_stale() to
increment it whenever the processor may be yielded.

New struct emptypedstr member generation.  To conserve space, make it
a bit-field of twelve bits, i.e. generations are only recorded modulo
2^12.  Make sure all members of unit empobj_storage share it.  It is
only used in copies; its value on disk and in the cache is
meaningless.  Copies with generation other than ef_generation are
stale.  Stale copies that are a multiple of 2^12 generations old can't
be detected, but that is sufficiently improbable.

Set generation to ef_generation by calling new ef_mark_fresh() when
making copies in ef_read() and ef_blank().  nav_ship() and
fltp_to_list() make copies without going through ef_read(), and
therefore need to call ef_mark_fresh() as well.  Also call it in
obj_changed() to make check_sect_ok() & friends freshen their argument
when it is unchanged.

New must_be_fresh() oopses when its argument is stale.  Call it in
ef_write() to catch write back of stale copies.
2010-01-19 08:36:01 +01:00

64 lines
2.1 KiB
C

/*
* Empire - A multi-player, client/server Internet based war game.
* Copyright (C) 1986-2009, Dave Pare, Jeff Bailey, Thomas Ruschak,
* Ken Stevens, Steve McClure
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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
*
* ---
*
* See files README, COPYING and CREDITS in the root of the source
* tree for related information and legal notices. It is expected
* that future projects/authors will amend these files as needed.
*
* ---
*
* lost.h: Definitions for lost items
*
* Known contributors to this file:
* Steve McClure, 1997
*/
#ifndef LOST_H
#define LOST_H
#include <time.h>
#include "types.h"
struct loststr {
/* initial part must match struct empobj */
signed ef_type: 8;
unsigned lost_seqno: 12;
unsigned lost_generation: 12;
int lost_uid;
time_t lost_timestamp; /* When it was lost */
natid lost_owner; /* Who lost it */
/* end of part matching struct empobj */
short lost_type; /* Type of thing (ship, plane, nuke, land, sector) */
int lost_id; /* uid of lost thing (0 for sector)*/
coord lost_x;
coord lost_y;
};
#define getlost(n, p) ef_read(EF_LOST, (n), (p))
#define putlost(n, p) ef_write(EF_LOST, (n), (p))
/* src/lib/subs/lostsub.c */
extern void lost_and_found(int, natid, natid, int, coord, coord);
extern void makelost(int, natid, int, coord, coord);
extern void makenotlost(int, natid, int, coord, coord);
extern void delete_old_lostitems(void);
#endif