71e0f98825
(empth_select, empth_sleep, empth_wait_for_signal) (empth_sem_wait) [EMPTH_W32]: Add the ability to wait additional event in loc_RunThread() when acquiring the hThread mutex. (empth_rwlock_t, empth_rwlock_create, empth_rwlock_destroy) (empth_rwlock_wrlock, empth_rwlock_rdlock, empth_rwlock_unlock): New. (empth_rwlock_t, empth_rwlock_create, empth_rwlock_destroy) (empth_rwlock_wrlock, empth_rwlock_rdlock, empth_rwlock_unlock) [EMPTH_W32]: WIN32 implementation. (empth_rwlock_t, empth_rwlock_create, empth_rwlock_destroy) (empth_rwlock_wrlock, empth_rwlock_rdlock, empth_rwlock_unlock) (lwp_rwlock, lwp_rwlock_create, lwp_rwlock_destroy) (lwp_rwlock_wrlock, lwp_rwlock_rdlock, lwp_rwlock_unlock) [EMPTH_LWP]: LWP implementation. (empth_rwlock_t, empth_rwlock_create, empth_rwlock_destroy) (empth_rwlock_wrlock, empth_rwlock_rdlock, empth_rwlock_unlock) [EMPTH_POSIX]: pthread implementation.
134 lines
3.5 KiB
C
134 lines
3.5 KiB
C
/*
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* Empire - A multi-player, client/server Internet based war game.
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* Copyright (C) 1994-2007, Dave Pare, Jeff Bailey, Thomas Ruschak,
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* Ken Stevens, Steve McClure
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* Copyright (C) 1991-3 Stephen Crane
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* ---
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*
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* See files README, COPYING and CREDITS in the root of the source
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* tree for related information and legal notices. It is expected
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* that future projects/authors will amend these files as needed.
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*
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* ---
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*
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* rwlock.c: Read-write locks
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*
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* Known contributors to this file:
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* Ron Koenderink, 2007
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* Markus Armbruster, 2007
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*/
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#include <config.h>
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#include <stdlib.h>
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#include <string.h>
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#include "lwp.h"
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#include "lwpint.h"
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struct lwp_rwlock {
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/*
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* Lock counter
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* 0: unlocked
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* -1: locked for writing
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* >0: locked for reading that many times
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*/
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int count;
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struct lwpQueue rq; /* read lock sleepers */
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struct lwpQueue wq; /* write lock sleepers */
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char *name;
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};
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struct lwp_rwlock *
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lwp_rwlock_create(char *name)
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{
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struct lwp_rwlock *rwlock;
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rwlock = malloc(sizeof(*rwlock));
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if (!rwlock)
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return NULL;
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memset(rwlock, 0, sizeof(*rwlock));
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rwlock->name = strdup(name);
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return rwlock;
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}
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void
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lwp_rwlock_destroy(struct lwp_rwlock *rwlock)
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{
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if (CANT_HAPPEN(rwlock->count))
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return;
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free(rwlock);
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}
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void
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lwp_rwlock_wrlock(struct lwp_rwlock *rwlock)
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{
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if (rwlock->count) {
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lwpAddTail(&rwlock->wq, LwpCurrent);
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lwpStatus(LwpCurrent, "blocked to acquire rwlock %s for writing",
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rwlock->name);
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lwpReschedule();
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}
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CANT_HAPPEN(rwlock->count != 0);
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rwlock->count = -1;
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lwpStatus(LwpCurrent, "acquired rwlock %s for writing", rwlock->name);
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}
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void
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lwp_rwlock_rdlock(struct lwp_rwlock *rwlock)
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{
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if (rwlock->count < 0 || rwlock->wq.head) {
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lwpStatus(LwpCurrent, "blocked to acquire rwlock %s for reading",
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rwlock->name);
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lwpAddTail(&rwlock->rq, LwpCurrent);
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lwpReschedule();
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}
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CANT_HAPPEN(rwlock->count < 0);
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rwlock->count++;
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lwpStatus(LwpCurrent, "acquired rwlock %s for reading", rwlock->name);
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}
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void
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lwp_rwlock_unlock(struct lwp_rwlock *rwlock)
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{
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struct lwpProc *p;
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lwpStatus(LwpCurrent, "unlocking rwlock %s", rwlock->name);
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if (CANT_HAPPEN(rwlock->count == 0))
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return;
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if (rwlock->count < 0)
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rwlock->count = 0;
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else
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rwlock->count--;
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if (rwlock->count == 0 && rwlock->wq.head) {
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p = lwpGetFirst(&rwlock->wq);
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lwpStatus(p, "wake up next writer of rwlock %s", rwlock->name);
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} else if (rwlock->count >= 0 && rwlock->rq.head && !rwlock->wq.head) {
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p = lwpGetFirst(&rwlock->rq);
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lwpStatus(p, "wake up next reader of rwlock %s", rwlock->name);
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} else
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return;
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lwpReady(p);
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if (LwpCurrent->pri < p->pri) {
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lwpStatus(LwpCurrent, "yielding to thread with higher priority");
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lwpYield();
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}
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}
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