sys/src/libventi/queue.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <venti.h>
   4 #include "queue.h"
   5
   6 typedef struct Qel Qel;
   7 struct Qel
   8 {
   9         Qel *next;
  10         void *p;
  11 };
  12
  13 struct Queue
  14 {
  15         int ref;
  16         int hungup;
  17         QLock lk;
  18         Rendez r;
  19         Qel *head;
  20         Qel *tail;
  21 };
  22
  23 Queue*
  24 _vtqalloc(void)
  25 {
  26         Queue *q;
  27
  28         q = vtmallocz(sizeof(Queue));
  29         q->r.l = &q->lk;
  30         q->ref = 1;
  31         return q;
  32 }
  33
  34 Queue*
  35 _vtqincref(Queue *q)
  36 {
  37         qlock(&q->lk);
  38         q->ref++;
  39         qunlock(&q->lk);
  40         return q;
  41 }
  42
  43 void
  44 _vtqdecref(Queue *q)
  45 {
  46         Qel *e;
  47
  48         qlock(&q->lk);
  49         if(--q->ref > 0){
  50                 qunlock(&q->lk);
  51                 return;
  52         }
  53         assert(q->ref == 0);
  54         qunlock(&q->lk);
  55
  56         /* Leaks the pointers e->p! */
  57         while(q->head){
  58                 e = q->head;
  59                 q->head = e->next;
  60                 free(e);
  61         }
  62         free(q);
  63 }
  64
  65 int
  66 _vtqsend(Queue *q, void *p)
  67 {
  68         Qel *e;
  69
  70         e = vtmalloc(sizeof(Qel));
  71         qlock(&q->lk);
  72         if(q->hungup){
  73                 werrstr("hungup queue");
  74                 qunlock(&q->lk);
  75                 return -1;
  76         }
  77         e->p = p;
  78         e->next = nil;
  79         if(q->head == nil)
  80                 q->head = e;
  81         else
  82                 q->tail->next = e;
  83         q->tail = e;
  84         rwakeup(&q->r);
  85         qunlock(&q->lk);
  86         return 0;
  87 }
  88
  89 void*
  90 _vtqrecv(Queue *q)
  91 {
  92         void *p;
  93         Qel *e;
  94
  95         qlock(&q->lk);
  96         while(q->head == nil && !q->hungup)
  97                 rsleep(&q->r);
  98         if(q->hungup){
  99                 qunlock(&q->lk);
 100                 return nil;
 101         }
 102         e = q->head;
 103         q->head = e->next;
 104         qunlock(&q->lk);
 105         p = e->p;
 106         vtfree(e);
 107         return p;
 108 }
 109
 110 void*
 111 _vtnbqrecv(Queue *q)
 112 {
 113         void *p;
 114         Qel *e;
 115
 116         qlock(&q->lk);
 117         if(q->head == nil){
 118                 qunlock(&q->lk);
 119                 return nil;
 120         }
 121         e = q->head;
 122         q->head = e->next;
 123         qunlock(&q->lk);
 124         p = e->p;
 125         vtfree(e);
 126         return p;
 127 }
 128
 129 void
 130 _vtqhangup(Queue *q)
 131 {
 132         qlock(&q->lk);
 133         q->hungup = 1;
 134         rwakeupall(&q->r);
 135         qunlock(&q->lk);
 136 }