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#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 ref;
int hungup;
QLock lk;
Rendez r;
Qel *head;
Qel *tail;
};
Queue*
_vtqalloc(void)
{
Queue *q;
q = vtmallocz(sizeof(Queue));
q->r.l = &q->lk;
q->ref = 1;
return q;
}
Queue*
_vtqincref(Queue *q)
{
qlock(&q->lk);
q->ref++;
qunlock(&q->lk);
return q;
}
void
_vtqdecref(Queue *q)
{
Qel *e;
qlock(&q->lk);
if(--q->ref > 0){
qunlock(&q->lk);
return;
}
assert(q->ref == 0);
qunlock(&q->lk);
/* Leaks the pointers e->p! */
while(q->head){
e = q->head;
q->head = e->next;
free(e);
}
free(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);
}
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