Import sources from 2011-03-30 iso image

1 files changed, 223 insertions, 0 deletions

diff --git a/sys/src/9/port/qlock.c b/sys/src/9/port/qlock.c
new file mode 100755
index 000000000..3d666516d
--- /dev/null
+++ b/sys/src/9/port/qlock.c
@@ -0,0 +1,223 @@
+#include "u.h"
+#include "../port/lib.h"
+#include "mem.h"
+#include "dat.h"
+#include "fns.h"
+
+struct {
+	ulong rlock;
+	ulong rlockq;
+	ulong wlock;
+	ulong wlockq;
+	ulong qlock;
+	ulong qlockq;
+} rwstats;
+
+void
+qlock(QLock *q)
+{
+	Proc *p;
+
+	if(m->ilockdepth != 0)
+		print("qlock: %#p: ilockdepth %d\n", getcallerpc(&q), m->ilockdepth);
+	if(up != nil && up->nlocks.ref)
+		print("qlock: %#p: nlocks %lud\n", getcallerpc(&q), up->nlocks.ref);
+
+	if(q->use.key == 0x55555555)
+		panic("qlock: q %#p, key 5*\n", q);
+	lock(&q->use);
+	rwstats.qlock++;
+	if(!q->locked) {
+		q->locked = 1;
+		unlock(&q->use);
+		return;
+	}
+	if(up == 0)
+		panic("qlock");
+	rwstats.qlockq++;
+	p = q->tail;
+	if(p == 0)
+		q->head = up;
+	else
+		p->qnext = up;
+	q->tail = up;
+	up->qnext = 0;
+	up->state = Queueing;
+	up->qpc = getcallerpc(&q);
+	unlock(&q->use);
+	sched();
+}
+
+int
+canqlock(QLock *q)
+{
+	if(!canlock(&q->use))
+		return 0;
+	if(q->locked){
+		unlock(&q->use);
+		return 0;
+	}
+	q->locked = 1;
+	unlock(&q->use);
+	return 1;
+}
+
+void
+qunlock(QLock *q)
+{
+	Proc *p;
+
+	lock(&q->use);
+	if (q->locked == 0)
+		print("qunlock called with qlock not held, from %#p\n",
+			getcallerpc(&q));
+	p = q->head;
+	if(p){
+		q->head = p->qnext;
+		if(q->head == 0)
+			q->tail = 0;
+		unlock(&q->use);
+		ready(p);
+		return;
+	}
+	q->locked = 0;
+	unlock(&q->use);
+}
+
+void
+rlock(RWlock *q)
+{
+	Proc *p;
+
+	lock(&q->use);
+	rwstats.rlock++;
+	if(q->writer == 0 && q->head == nil){
+		/* no writer, go for it */
+		q->readers++;
+		unlock(&q->use);
+		return;
+	}
+
+	rwstats.rlockq++;
+	p = q->tail;
+	if(up == nil)
+		panic("rlock");
+	if(p == 0)
+		q->head = up;
+	else
+		p->qnext = up;
+	q->tail = up;
+	up->qnext = 0;
+	up->state = QueueingR;
+	unlock(&q->use);
+	sched();
+}
+
+void
+runlock(RWlock *q)
+{
+	Proc *p;
+
+	lock(&q->use);
+	p = q->head;
+	if(--(q->readers) > 0 || p == nil){
+		unlock(&q->use);
+		return;
+	}
+
+	/* start waiting writer */
+	if(p->state != QueueingW)
+		panic("runlock");
+	q->head = p->qnext;
+	if(q->head == 0)
+		q->tail = 0;
+	q->writer = 1;
+	unlock(&q->use);
+	ready(p);
+}
+
+void
+wlock(RWlock *q)
+{
+	Proc *p;
+
+	lock(&q->use);
+	rwstats.wlock++;
+	if(q->readers == 0 && q->writer == 0){
+		/* noone waiting, go for it */
+		q->wpc = getcallerpc(&q);
+		q->wproc = up;
+		q->writer = 1;
+		unlock(&q->use);
+		return;
+	}
+
+	/* wait */
+	rwstats.wlockq++;
+	p = q->tail;
+	if(up == nil)
+		panic("wlock");
+	if(p == nil)
+		q->head = up;
+	else
+		p->qnext = up;
+	q->tail = up;
+	up->qnext = 0;
+	up->state = QueueingW;
+	unlock(&q->use);
+	sched();
+}
+
+void
+wunlock(RWlock *q)
+{
+	Proc *p;
+
+	lock(&q->use);
+	p = q->head;
+	if(p == nil){
+		q->writer = 0;
+		unlock(&q->use);
+		return;
+	}
+	if(p->state == QueueingW){
+		/* start waiting writer */
+		q->head = p->qnext;
+		if(q->head == nil)
+			q->tail = nil;
+		unlock(&q->use);
+		ready(p);
+		return;
+	}
+
+	if(p->state != QueueingR)
+		panic("wunlock");
+
+	/* waken waiting readers */
+	while(q->head != nil && q->head->state == QueueingR){
+		p = q->head;
+		q->head = p->qnext;
+		q->readers++;
+		ready(p);
+	}
+	if(q->head == nil)
+		q->tail = nil;
+	q->writer = 0;
+	unlock(&q->use);
+}
+
+/* same as rlock but punts if there are any writers waiting */
+int
+canrlock(RWlock *q)
+{
+	lock(&q->use);
+	rwstats.rlock++;
+	if(q->writer == 0 && q->head == nil){
+		/* no writer, go for it */
+		q->readers++;
+		unlock(&q->use);
+		return 1;
+	}
+	unlock(&q->use);
+	return 0;
+}