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/*
* Copyright (c) 1997-1999 University of Utah and the Flux Group.
* All rights reserved.
*
* This file is part of the Flux OSKit. The OSKit is free software, also known
* as "open source;" you can redistribute it and/or modify it under the terms
* of the GNU General Public License (GPL), version 2, as published by the Free
* Software Foundation (FSF). To explore alternate licensing terms, contact
* the University of Utah at csl-dist@cs.utah.edu or +1-801-585-3271.
*
* The OSKit is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GPL for more details. You should have
* received a copy of the GPL along with the OSKit; see the file COPYING. If
* not, write to the FSF, 59 Temple Place #330, Boston, MA 02111-1307, USA.
*/
/*
* a bounded queue implementation of the oskit_queue interface
*/
#include <oskit/com/queue.h>
#include <oskit/com/listener.h>
#include <oskit/c/assert.h>
#include <oskit/c/malloc.h>
#include <oskit/c/stdlib.h>
#include <oskit/c/string.h>
#include <oskit/c/assert.h>
typedef struct queue {
oskit_queue_t ioi;
unsigned count;
void *array;
int head, tail;
int itemsize;
int qlen, maxqlen;
int droplast;
oskit_listener_t *l;
} queue_t;
static OSKIT_COMDECL
queue_query(oskit_queue_t *s, const oskit_iid_t *iid, void **out_ihandle)
{
queue_t *q = (void *)s;
assert(q && q->count);
if (memcmp(iid, &oskit_iunknown_iid, sizeof(*iid)) == 0 ||
memcmp(iid, &oskit_queue_iid, sizeof(*iid)) == 0) {
*out_ihandle = &q->ioi;
++q->count;
return 0;
}
*out_ihandle = NULL;
return OSKIT_E_NOINTERFACE;
}
static OSKIT_COMDECL_U
queue_addref(oskit_queue_t *s)
{
queue_t *q = (void *)s;
assert(q->count);
return ++q->count;
}
static OSKIT_COMDECL_U
queue_release(oskit_queue_t *s)
{
queue_t *q = (void *)s;
unsigned newcount;
assert(q && q->count);
newcount = q->count - 1;
if (newcount == 0) {
if (q->l)
oskit_listener_release(q->l);
free(q->array);
free(q);
return 0;
}
return q->count = newcount;
}
static OSKIT_COMDECL_U
queue_dequeue(oskit_queue_t *s, void *item)
{
queue_t *q = (void *)s;
/* make sure queue is not empty... */
assert(q->head != q->tail);
memcpy(item, q->array + q->tail * q->itemsize, q->itemsize);
q->tail = (q->tail + 1) % (q->maxqlen + 1);
q->qlen--;
return q->itemsize;
}
static OSKIT_COMDECL
queue_enqueue(oskit_queue_t *s, const void *item, oskit_size_t size)
{
queue_t *q = (void *)s;
oskit_error_t rc = 0;
/* Is this queue is full -> tell listener
* that I'm about to dump an entry
*/
if (q->qlen == q->maxqlen) {
if (q->l)
oskit_listener_notify(q->l, (oskit_iunknown_t *)s);
/* if nothing has happened, then dump it, for christ's sake */
if (q->qlen == q->maxqlen) {
if (q->droplast) {
q->tail = (q->tail + 1) % (q->maxqlen + 1);
q->qlen--;
} else
return OSKIT_ENOMEM;
}
}
memcpy(q->array + q->head * q->itemsize, item,
q->itemsize < size ? q->itemsize : size);
q->head = (q->head + 1) % (q->maxqlen + 1);
q->qlen++;
return rc;
}
static OSKIT_COMDECL_U
queue_size(oskit_queue_t *s)
{
return ((queue_t *)s)->qlen;
}
static OSKIT_COMDECL_U
queue_front(oskit_queue_t *s, void *item)
{
return OSKIT_E_NOTIMPL;
}
static struct oskit_queue_ops oskit_queue_ops = {
queue_query,
queue_addref,
queue_release,
queue_enqueue,
queue_dequeue,
queue_size,
queue_front
};
oskit_queue_t *
create_bounded_queue_with_fixed_size_items(int qlen,
oskit_size_t itemsize,
oskit_listener_t *l,
int droplast)
{
queue_t *q = malloc(sizeof *q);
if (!q)
return NULL;
memset (q, 0, sizeof *q);
q->maxqlen = qlen;
q->itemsize = itemsize;
if ((q->l = l) != NULL)
oskit_listener_addref(l);
q->array = calloc(qlen + 1, itemsize);
q->ioi.ops = &oskit_queue_ops;
q->count = 1;
q->droplast = droplast;
return &q->ioi;
}
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