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Synchronize commands and update properly with a lock (towards

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resolving #1458175 and #1504036):
(update_lock): New.
(update_shed): Initialize it.
(update_wait, dispatch): Take exclusive update_lock around the update,
shared update_lock around commands.  This makes the update block until
all aborted commands terminated and gave up their lock.  Remove the
cheesy and unsafe two second wait for commands to finish.  It also
makes player threads block before executing commands while the update
is pending, removing the need to fail commands then.  So don't.
This commit is contained in:
Markus Armbruster 2007-01-15 19:57:26 +00:00
parent 0c52f203c0
commit 6cbdd3e02a
3 changed files with 13 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

1
include/server.h
View file

@ -39,6 +39,7 @@
extern int shutdown_pending;
extern int update_pending;
extern empth_sem_t *update_sem;
extern empth_rwlock_t *update_lock;
extern time_t update_time;
extern int updating_mob;

6
src/lib/player/dispatch.c
View file

@ -88,10 +88,7 @@ dispatch(char *buf, char *redir)
pr("Command not implemented\n");
return 0;
}
if (update_pending) {
pr("Update in progress...command failed\n");
return 0;
}
empth_rwlock_rdlock(update_lock);
if (redir) {
prredir(redir);
uprnf(buf);
@ -113,6 +110,7 @@ dispatch(char *buf, char *redir)
logerror("%s: returned bad value", command->c_form);
break;
}
empth_rwlock_unlock(update_lock);
player->command = 0;
return 0;
}

20
src/server/update.c
View file

@ -48,6 +48,7 @@
#include "server.h"
empth_sem_t *update_sem;
empth_rwlock_t *update_lock;
time_t update_time;
static void update_wait(void *unused);
@ -61,9 +62,9 @@ update_sched(void *unused)
time_t now, delta;
update_sem = empth_sem_create("Update", 0);
update_lock = empth_rwlock_create("Update");
empth_create(PP_SCHED, update_wait, (50 * 1024), 0, "UpdateWait",
"Waits until players idle", 0);
time(&now);
if (s_p_etu <= 0) {
logerror("bad value for s_p_etu (%d)", s_p_etu);
s_p_etu = 2 * 60;
@ -116,15 +117,12 @@ static void
update_wait(void *unused)
{
struct player *p;
int running;
time_t now;
int stacksize;
struct player *dp;
while (1) {
empth_sem_wait(update_sem);
update_pending = 1;
running = 0;
for (p = player_next(0); p != 0; p = player_next(p)) {
if (p->state != PS_PLAYING)
continue;
@ -132,17 +130,13 @@ update_wait(void *unused)
pr_flash(p, "Update aborting command\n");
p->aborted = 1;
empth_wakeup(p->proc);
running++;
}
}
time(&now);
if (running) {
/* sleep a few, wait for aborts to take effect */
empth_sleep(now + 2);
}
empth_rwlock_wrlock(update_lock);
if (*pre_update_hook) {
if (run_hook(pre_update_hook, "pre-update")) {
update_pending = 0;
empth_rwlock_unlock(update_lock);
continue;
}
}
@ -154,6 +148,7 @@ update_wait(void *unused)
if (!dp) {
logerror("can't create dummy player for update");
update_pending = 0;
empth_rwlock_unlock(update_lock);
continue;
}
stacksize = 100000 +
@ -162,6 +157,11 @@ update_wait(void *unused)
empth_create(PP_UPDATE, update_main, stacksize, 0,
"UpdateRun", "Updates the world", dp);
while (update_pending)
empth_yield(); /* FIXME cheesy! */
update_pending = 0;
empth_rwlock_unlock(update_lock);
}
/*NOTREACHED*/
}