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WebSVN – planix.SVN – Blame – /os/branches/planix-v0/sys/src/libventi/queue.c – Rev 2

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