C++ qunlock函数代码示例

void
waitforkick(Round *r)
{
	int n;

	qlock(&r->lock);
	r->last = r->current;
	assert(r->current+1 == r->next);
	rwakeupall(&r->finish);
	while(!r->doanother)
		rsleep(&r->start);
	n = r->next++;
	r->current = n;
	r->doanother = 0;
	qunlock(&r->lock);
}

void
unbreak(Proc *p)
{
	int b;

	qlock(&broken);
	for(b=0; b < broken.n; b++)
		if(broken.p[b] == p) {
			broken.n--;
			memmove(&broken.p[b], &broken.p[b+1],
					sizeof(Proc*)*(NBROKEN-(b+1)));
			ready(p);
			break;
		}
	qunlock(&broken);
}

void
putbuf(Iobuf *p)
{

	if(canqlock(p))
		print("buffer not locked %Z(%lld)\n", p->dev, (Wideoff)p->addr);
	if(p->flags & Bimm) {
		if(!(p->flags & Bmod))
			print("imm and no mod %Z(%lld)\n",
				p->dev, (Wideoff)p->addr);
		if(!devwrite(p->dev, p->addr, p->iobuf))
			p->flags &= ~(Bmod|Bimm);
	}
	iobufunmap(p);
	qunlock(p);
}

/*
 * main filesystem server loop.
 * entered by many processes.
 * they wait for message buffers and
 * then process them.
 */
void
serve(void *)
{
	int i;
	Chan *cp;
	Msgbuf *mb;

	for (;;) {
		qlock(&reflock);
		/* read 9P request from a network input process */
		mb = fs_recv(serveq, 0);
		assert(mb->magic == Mbmagic);
		/* fs kernel sets chan in /sys/src/fs/ip/il.c:/^getchan */
		cp = mb->chan;
		if (cp == nil)
			panic("serve: nil mb->chan");
		rlock(&cp->reflock);
		qunlock(&reflock);

		rlock(&mainlock);

		if (mb->data == nil)
			panic("serve: nil mb->data");
		/* better sniffing code in /sys/src/cmd/disk/kfs/9p12.c */
		if(cp->protocol == nil){
			/* do we recognise the protocol in this packet? */
			/* better sniffing code: /sys/src/cmd/disk/kfs/9p12.c */
			for(i = 0; fsprotocol[i] != nil; i++)
				if(fsprotocol[i](mb) != 0) {
					cp->protocol = fsprotocol[i];
					break;
				}
			if(cp->protocol == nil){
				print("no protocol for message\n");
				for(i = 0; i < 12; i++)
					print(" %2.2X", mb->data[i]);
				print("\n");
			}
		} else
			/* process the request, generate an answer and reply */
			cp->protocol(mb);

		mbfree(mb);
		runlock(&mainlock);
		runlock(&cp->reflock);
	}
}

/*
 * allocate rest of mem
 * for io buffers.
 */
#define	HWIDTH	5	/* buffers per hash */
void
iobufinit(void)
{
	int32_t i;
	Iobuf *p, *q;
	Hiob *hp;

	i = conf.niobuf*RBUFSIZE;
	niob = i / (sizeof(Iobuf) + RBUFSIZE + sizeof(Hiob)/HWIDTH);
	nhiob = niob / HWIDTH;
	while(!prime(nhiob))
		nhiob++;
	if(chat)
		print("	%ld buffers; %ld hashes\n", niob, nhiob);
	hiob = ialloc(nhiob * sizeof(Hiob));
	hp = hiob;
	for(i=0; i<nhiob; i++) {
		lock(hp);
		unlock(hp);
		hp++;
	}
	p = ialloc(niob * sizeof(Iobuf));
	hp = hiob;
	for(i=0; i<niob; i++) {
		qlock(p);
		qunlock(p);
		if(hp == hiob)
			hp = hiob + nhiob;
		hp--;
		q = hp->link;
		if(q) {
			p->fore = q;
			p->back = q->back;
			q->back = p;
			p->back->fore = p;
		} else {
			hp->link = p;
			p->fore = p;
			p->back = p;
		}
		p->dev = devnone;
		p->addr = -1;
		p->xiobuf = ialloc(RBUFSIZE);
		p->iobuf = (char*)-1;
		p++;
	}
}

ulong
procalarm(ulong time)
{
	Proc **l, *f;
	ulong when, old;

	if(up->alarm)
		old = tk2ms(up->alarm - MACHP(0)->ticks);
	else
		old = 0;
	if(time == 0) {
		up->alarm = 0;
		return old;
	}
	when = ms2tk(time)+MACHP(0)->ticks;

	qlock(&alarms);
	l = &alarms.head;
	for(f = *l; f; f = f->palarm) {
		if(up == f){
			*l = f->palarm;
			break;
		}
		l = &f->palarm;
	}

	up->palarm = 0;
	if(alarms.head) {
		l = &alarms.head;
		for(f = *l; f; f = f->palarm) {
			if(f->alarm > when) {
				up->palarm = f;
				*l = up;
				goto done;
			}
			l = &f->palarm;
		}
		*l = up;
	}
	else
		alarms.head = up;
done:
	up->alarm = when;
	qunlock(&alarms);

	return old;
}

static void
pageouttext(int pgszi, int color)
{

	Proc *p;
	Pgsza *pa;
	int i, n, np, x;
	Segment *s;
	int prepaged;

	USED(color);
	pa = &pga.pgsza[pgszi];
	n = x = 0;
	prepaged = 0;

	/*
	 * Try first to steal text pages from non-prepaged processes,
	 * then from anyone.
	 */
Again:
	do{
		if((p = psincref(x)) == nil)
			break;
		np = 0;
		if(p->prepagemem == 0 || prepaged != 0)
		if(p->state != Dead && p->noswap == 0 && canqlock(&p->seglock)){
			for(i = 0; i < NSEG; i++){
				if((s = p->seg[i]) == nil)
					continue;
				if((s->type&SG_TYPE) == SG_TEXT)
					np = pageout(p, s);
			}
			qunlock(&p->seglock);
		}
		/*
		 * else process dead or locked or changing its segments
		 */
		psdecref(p);
		n += np;
		if(np > 0)
			DBG("pager: %d from proc #%d %#p\n", np, x, p);
		x++;
	}while(pa->freecount < Minpages);

	if(pa->freecount < Minpages && prepaged++ == 0)
		goto Again;
}

/*
 * always called with cp->flock locked
 */
File*
newfp(Chan *cp)
{
	File *f, *e;

retry:
	lock(&suballoc.flock);
	f = suballoc.ffree;
	if(f != nil){
		suballoc.ffree = f->list;
		unlock(&suballoc.flock);
		f->list = 0;
		f->cp = cp;
		f->next = cp->flist;
		f->wpath = 0;
		f->tlock = 0;
		f->dslot = 0;
		f->doffset = 0;
		f->uid = 0;
		f->cuid = 0;
		cp->flist = f;
		return f;
	}
	unlock(&suballoc.flock);

	if(conf.nfile > Fmax){
		print("%d: out of files\n", cp->chan);
		return 0;
	}

	/*
	 *  create a few new files
	 */
	f = malloc(Finc*sizeof(*f));
	memset(f, 0, Finc*sizeof(*f));
	lock(&suballoc.flock);
	for(e = f+Finc; f < e; f++){
		qlock(f);
		qunlock(f);
		f->list = suballoc.ffree;
		suballoc.ffree = f;
	}
	conf.nfile += Finc;
	unlock(&suballoc.flock);
	goto retry;
}

static Chan *
cecattach(char *spec)
{
	Chan *c;
	static QLock q;
	static int inited;

	qlock(&q);
	if(inited == 0){
		kproc("cectimer", cectimer, nil);
		inited++;
	}
	qunlock(&q);
	c = devattach(L'©', spec);
	c->qid.path = Qdir;
	return c;
}

static Walkqid*
loopbackwalk(Chan *c, Chan *nc, char **name, int nname)
{
	Walkqid *wq;
	Loop *lb;

	wq = devwalk(c, nc, name, nname, nil, 0, loopbackgen);
	if(wq != nil && wq->clone != nil && wq->clone != c){
		lb = c->aux;
		qlock(lb);
		lb->ref++;
		if((c->flag & COPEN) && TYPE(c->qid.path) == Qdata)
			lb->link[ID(c->qid.path)].ref++;
		qunlock(lb);
	}
	return wq;
}

void
addbroken(Proc *p)
{
	qlock(&broken);
	if(broken.n == NBROKEN) {
		ready(broken.p[0]);
		memmove(&broken.p[0], &broken.p[1], sizeof(Proc*)*(NBROKEN-1));
		--broken.n;
	}
	broken.p[broken.n++] = p;
	qunlock(&broken);

	edfstop(up);
	p->state = Broken;
	p->psstate = nil;
	sched();
}

void
usbfsdirdump(void)
{
	int i;

	qlock(&fslck);
	fprint(2, "%s: fs list: (%d used %d total)\n", argv0, fsused, nfs);
	for(i = 1; i < nfs; i++)
		if(fs[i] != nil) {
			if(fs[i]->dev != nil)
				fprint(2, "%s\t%s dev %#p refs %ld\n",
					argv0, fs[i]->name, fs[i]->dev, fs[i]->dev->Ref.ref);
			else
				fprint(2, "%s:\t%s\n", argv0, fs[i]->name);
		}
	qunlock(&fslck);
}

static void
aoeinit(void)
{
	static int init;
	static QLock l;

	if(!canqlock(&l))
		return;
	if(init == 0){
		fmtinstall(L'æ', fmtæ);
		events.rp = events.wp = events.buf;
		kproc("aoesweep", aoesweepproc, nil);
		aoecfg();
		init = 1;
	}
	qunlock(&l);
}

static int32_t
unionread(Chan *c, void *va, int32_t n)
{
	Proc *up = externup();
	int i;
	int32_t nr;
	Mhead *mh;
	Mount *mount;

	qlock(&c->umqlock);
	mh = c->umh;
	rlock(&mh->lock);
	mount = mh->mount;
	/* bring mount in sync with c->uri and c->umc */
	for(i = 0; mount != nil && i < c->uri; i++)
		mount = mount->next;

	nr = 0;
	while(mount != nil){
		/* Error causes component of union to be skipped */
		if(mount->to && !waserror()){
			if(c->umc == nil){
				c->umc = cclone(mount->to);
				c->umc = c->umc->dev->open(c->umc, OREAD);
			}

			nr = c->umc->dev->read(c->umc, va, n, c->umc->offset);
			c->umc->offset += nr;
			poperror();
		}
		if(nr > 0)
			break;

		/* Advance to next element */
		c->uri++;
		if(c->umc){
			cclose(c->umc);
			c->umc = nil;
		}
		mount = mount->next;
	}
	runlock(&mh->lock);
	qunlock(&c->umqlock);
	return nr;
}

/* called from icmp(v6) for unreachable hosts, time exceeded, etc. */
void
espadvise(Proto *esp, Block *bp, char *msg)
{
	Conv *c;
	Versdep vers;

	getverslens(pktipvers(esp->f, &bp), &vers);
	getpktspiaddrs(bp->rp, &vers);

	qlock(esp);
	c = convlookup(esp, vers.spi);
	if(c != nil) {
		qhangup(c->rq, msg);
		qhangup(c->wq, msg);
	}
	qunlock(esp);
	freeblist(bp);
}