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/*
* Copyright (c) 2008, 2009 Nicira Networks.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <config.h>
#include "queue.h"
#include <assert.h>
#include "compiler.h"
#include "leak-checker.h"
#include "ofpbuf.h"
static void check_queue(struct ovs_queue *q);
/* Initializes 'q' as an empty packet queue. */
void
queue_init(struct ovs_queue *q)
{
q->n = 0;
q->head = NULL;
q->tail = NULL;
}
/* Destroys 'q' and all of the packets that it contains. */
void
queue_destroy(struct ovs_queue *q)
{
struct ofpbuf *cur, *next;
for (cur = q->head; cur != NULL; cur = next) {
next = cur->next;
ofpbuf_delete(cur);
}
}
/* Removes and destroys all of the packets in 'q', rendering it empty. */
void
queue_clear(struct ovs_queue *q)
{
queue_destroy(q);
queue_init(q);
}
/* Advances the first packet in 'q' from 'q->head' to 'next', which should be
* the second packet in the queue.
*
* The odd, unsafe interface here allows the first packet in the queue to be
* passed to a function for possible consumption (and destruction) and only
* dropped from the queue if that function actually accepts it. */
void
queue_advance_head(struct ovs_queue *q, struct ofpbuf *next)
{
assert(q->n);
assert(q->head);
q->head = next;
if (q->head == NULL) {
q->tail = NULL;
}
q->n--;
}
/* Appends 'b' to the tail of 'q'. */
void
queue_push_tail(struct ovs_queue *q, struct ofpbuf *b)
{
check_queue(q);
leak_checker_claim(b);
b->next = NULL;
if (q->n++) {
q->tail->next = b;
} else {
q->head = b;
}
q->tail = b;
check_queue(q);
}
/* Removes the first buffer from 'q', which must not be empty, and returns
* it. The caller must free the buffer (with ofpbuf_delete()) when it is no
* longer needed. */
struct ofpbuf *
queue_pop_head(struct ovs_queue *q)
{
struct ofpbuf *head = q->head;
queue_advance_head(q, head->next);
return head;
}
/* Checks the internal integrity of 'q'. For use in debugging. */
static void
check_queue(struct ovs_queue *q UNUSED)
{
#if 0
struct ofpbuf *iter;
size_t n;
assert(q->n == 0
? q->head == NULL && q->tail == NULL
: q->head != NULL && q->tail != NULL);
n = 0;
for (iter = q->head; iter != NULL; iter = iter->next) {
n++;
assert((iter->next != NULL) == (iter != q->tail));
}
assert(n == q->n);
#endif
}
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