1991/1030/port/qlock.c (diff list | history)

1991/1030/sys/src/9/port/qlock.c:1,96 – 1992/0321/sys/src/9/port/qlock.c:1,96 (short | long | prev | next)
Move lib.h to ../port. rsc Fri Mar 4 12:44:25 2005
1991/0428		#include "u.h" #include "lib.h"
1992/0321		#include "../port/lib.h"
1991/0428		#include "mem.h" #include "dat.h" #include "fns.h" void qlock(QLock *q) {
1991/1002		Proc *p, *mp;
1991/0428
1991/1002		lock(&q->use); if(!q->locked) { q->locked = 1; unlock(&q->use);
1991/0428		return; } p = q->tail;
1991/1002		mp = u->p;
1991/0428		if(p == 0)
1991/1002		q->head = mp;
1991/0428		else
1991/1002		p->qnext = mp; q->tail = mp; mp->qnext = 0; mp->state = Queueing; unlock(&q->use);
1991/0428		sched(); } int canqlock(QLock *q) {
1991/1002		lock(&q->use);
1991/1030		if(q->locked){
1991/1002		unlock(&q->use); return 0; } q->locked = 1; unlock(&q->use); return 1;
1991/0428		} void qunlock(QLock *q) { Proc *p;
1991/1002		lock(&q->use); p = q->head; if(p) {
1991/0428		q->head = p->qnext; if(q->head == 0) q->tail = 0; unlock(&q->use);
1991/1002		ready(p); return;
1991/0428		}
1991/1002		q->locked = 0; unlock(&q->use);
1991/0428		}
1991/1011		void rlock(RWlock *l) { qlock(&l->x); /* wait here for writers and exclusion */ lock(l); l->readers++; canqlock(&l->k); /* block writers if we are the first reader */ unlock(l); qunlock(&l->x); } void runlock(RWlock *l) { lock(l); if(--l->readers == 0) /* last reader out allows writers */ qunlock(&l->k); unlock(l); } void wlock(RWlock *l) { qlock(&l->x); /* wait here for writers and exclusion */ qlock(&l->k); /* wait here for last reader */ } void wunlock(RWlock *l) { qunlock(&l->x); qunlock(&l->k); }