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/*
* Copyright (c) 2008, 2009 Nicira Networks.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#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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