1 /* Copyright (C) 2003 Russ Cox, Massachusetts Institute of Technology */
2 /* See COPYRIGHT */
3 
4 #include <u.h>
5 #include <libc.h>
6 #include <mux.h>
7 
8 typedef struct Qel Qel;
9 struct Qel
10 {
11 	Qel *next;
12 	void *p;
13 };
14 
15 struct Muxqueue
16 {
17 	int hungup;
18 	QLock lk;
19 	Rendez r;
20 	Qel *head;
21 	Qel *tail;
22 };
23 
24 Muxqueue*
25 _muxqalloc(void)
26 {
27 	Muxqueue *q;
28 
29 	q = mallocz(sizeof(Muxqueue), 1);
30 	if(q == nil)
31 		return nil;
32 	q->r.l = &q->lk;
33 	return q;
34 }
35 
36 int
37 _muxqsend(Muxqueue *q, void *p)
38 {
39 	Qel *e;
40 
41 	e = malloc(sizeof(Qel));
42 	if(e == nil)
43 		return -1;
44 	qlock(&q->lk);
45 	if(q->hungup){
46 		werrstr("hungup queue");
47 		qunlock(&q->lk);
48 		free(e);
49 		return -1;
50 	}
51 	e->p = p;
52 	e->next = nil;
53 	if(q->head == nil)
54 		q->head = e;
55 	else
56 		q->tail->next = e;
57 	q->tail = e;
58 	rwakeup(&q->r);
59 	qunlock(&q->lk);
60 	return 0;
61 }
62 
63 void*
64 _muxqrecv(Muxqueue *q)
65 {
66 	void *p;
67 	Qel *e;
68 
69 	qlock(&q->lk);
70 	while(q->head == nil && !q->hungup)
71 		rsleep(&q->r);
72 	if(q->hungup){
73 		qunlock(&q->lk);
74 		return nil;
75 	}
76 	e = q->head;
77 	q->head = e->next;
78 	qunlock(&q->lk);
79 	p = e->p;
80 	free(e);
81 	return p;
82 }
83 
84 int
85 _muxnbqrecv(Muxqueue *q, void **vp)
86 {
87 	void *p;
88 	Qel *e;
89 
90 	qlock(&q->lk);
91 	if(q->head == nil){
92 		qunlock(&q->lk);
93 		*vp = nil;
94 		return q->hungup;
95 	}
96 	e = q->head;
97 	q->head = e->next;
98 	qunlock(&q->lk);
99 	p = e->p;
100 	free(e);
101 	*vp = p;
102 	return 1;
103 }
104 
105 void
106 _muxqhangup(Muxqueue *q)
107 {
108 	qlock(&q->lk);
109 	q->hungup = 1;
110 	rwakeupall(&q->r);
111 	qunlock(&q->lk);
112 }