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/* $OpenBSD: uthread_priority_queue.c,v 1.1 1999/05/26 00:18:25 d Exp $ */
/*
* Copyright (c) 1998 Daniel Eischen <eischen@vigrid.com>.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Daniel Eischen.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY DANIEL EISCHEN AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
#include <stdlib.h>
#include <sys/queue.h>
#include <string.h>
#ifdef _THREAD_SAFE
#include <pthread.h>
#include "pthread_private.h"
/* Prototypes: */
static void pq_insert_prio_list(pq_queue_t *pq, int prio);
int
_pq_init(pq_queue_t *pq, int minprio, int maxprio)
{
int i, ret = 0;
int prioslots = maxprio - minprio + 1;
if (pq == NULL)
ret = -1;
/* Create the priority queue with (maxprio - minprio + 1) slots: */
else if ((pq->pq_lists =
(pq_list_t *) malloc(sizeof(pq_list_t) * prioslots)) == NULL)
ret = -1;
else {
/* Initialize the queue for each priority slot: */
for (i = 0; i < prioslots; i++) {
TAILQ_INIT(&pq->pq_lists[i].pl_head);
pq->pq_lists[i].pl_prio = i;
pq->pq_lists[i].pl_queued = 0;
}
/* Initialize the priority queue: */
TAILQ_INIT(&pq->pq_queue);
/* Remember the queue size: */
pq->pq_size = prioslots;
}
return (ret);
}
void
_pq_remove(pq_queue_t *pq, pthread_t pthread)
{
int prio = pthread->active_priority;
TAILQ_REMOVE(&pq->pq_lists[prio].pl_head, pthread, pqe);
}
void
_pq_insert_head(pq_queue_t *pq, pthread_t pthread)
{
int prio = pthread->active_priority;
TAILQ_INSERT_HEAD(&pq->pq_lists[prio].pl_head, pthread, pqe);
if (pq->pq_lists[prio].pl_queued == 0)
/* Insert the list into the priority queue: */
pq_insert_prio_list(pq, prio);
}
void
_pq_insert_tail(pq_queue_t *pq, pthread_t pthread)
{
int prio = pthread->active_priority;
TAILQ_INSERT_TAIL(&pq->pq_lists[prio].pl_head, pthread, pqe);
if (pq->pq_lists[prio].pl_queued == 0)
/* Insert the list into the priority queue: */
pq_insert_prio_list(pq, prio);
}
pthread_t
_pq_first(pq_queue_t *pq)
{
pq_list_t *pql;
pthread_t pthread = NULL;
while (((pql = TAILQ_FIRST(&pq->pq_queue)) != NULL) &&
(pthread == NULL)) {
if ((pthread = TAILQ_FIRST(&pql->pl_head)) == NULL) {
/*
* The priority list is empty; remove the list
* from the queue.
*/
TAILQ_REMOVE(&pq->pq_queue, pql, pl_link);
/* Mark the list as not being in the queue: */
pql->pl_queued = 0;
}
}
return (pthread);
}
static void
pq_insert_prio_list(pq_queue_t *pq, int prio)
{
pq_list_t *pql;
/*
* The priority queue is in descending priority order. Start at
* the beginning of the queue and find the list before which the
* new list should to be inserted.
*/
pql = TAILQ_FIRST(&pq->pq_queue);
while ((pql != NULL) && (pql->pl_prio > prio))
pql = TAILQ_NEXT(pql, pl_link);
/* Insert the list: */
if (pql == NULL)
TAILQ_INSERT_TAIL(&pq->pq_queue, &pq->pq_lists[prio], pl_link);
else
TAILQ_INSERT_BEFORE(pql, &pq->pq_lists[prio], pl_link);
/* Mark this list as being in the queue: */
pq->pq_lists[prio].pl_queued = 1;
}
#endif
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