new venti library.

src/libventi/queue.c

@@ -0,0 +1,103 @@
+#include <u.h>
+#include <libc.h>
+#include <venti.h>
+#include "queue.h"
+
+typedef struct Qel Qel;
+struct Qel
+{
+	Qel *next;
+	void *p;
+};
+
+struct Queue
+{
+	int hungup;
+	QLock lk;
+	Rendez r;
+	Qel *head;
+	Qel *tail;
+};
+
+Queue*
+_vtqalloc(void)
+{
+	Queue *q;
+
+	q = vtmallocz(sizeof(Queue));
+	q->r.l = &q->lk;
+	return q;
+}
+
+int
+_vtqsend(Queue *q, void *p)
+{
+	Qel *e;
+
+	e = vtmalloc(sizeof(Qel));
+	qlock(&q->lk);
+	if(q->hungup){
+		werrstr("hungup queue");
+		qunlock(&q->lk);
+		return -1;
+	}
+	e->p = p;
+	e->next = nil;
+	if(q->head == nil)
+		q->head = e;
+	else
+		q->tail->next = e;
+	q->tail = e;
+	rwakeup(&q->r);
+	qunlock(&q->lk);
+	return 0;
+}
+
+void*
+_vtqrecv(Queue *q)
+{
+	void *p;
+	Qel *e;
+
+	qlock(&q->lk);
+	while(q->head == nil && !q->hungup)
+		rsleep(&q->r);
+	if(q->hungup){
+		qunlock(&q->lk);
+		return nil;
+	}
+	e = q->head;
+	q->head = e->next;
+	qunlock(&q->lk);
+	p = e->p;
+	vtfree(e);
+	return p;
+}
+
+void*
+_vtnbqrecv(Queue *q)
+{
+	void *p;
+	Qel *e;
+
+	qlock(&q->lk);
+	if(q->head == nil){
+		qunlock(&q->lk);
+		return nil;
+	}
+	e = q->head;
+	q->head = e->next;
+	qunlock(&q->lk);
+	p = e->p;
+	vtfree(e);
+	return p;
+}
+
+void
+_vtqhangup(Queue *q)
+{
+	qlock(&q->lk);
+	q->hungup = 1;
+	rwakeupall(&q->r);
+	qunlock(&q->lk);
+}