/*

 * Copyright (c) 2013 Nicira, Inc.

 *

 * 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 "guarded-list.h"

void

guarded_list_init(struct guarded_list *list)

{

    ovs_mutex_init(&list->mutex);

    ovs_list_init(&list->list);

    list->n = 0;

}

void

guarded_list_destroy(struct guarded_list *list)

{

    ovs_mutex_destroy(&list->mutex);

}

bool

guarded_list_is_empty(const struct guarded_list *list)

{

    bool empty;

    ovs_mutex_lock(&list->mutex);

    empty = list->n == 0;

    ovs_mutex_unlock(&list->mutex);

    return empty;

}

/* If 'list' has fewer than 'max' elements, adds 'node' at the end of the list

 * and returns the number of elements now on the list.

 *

 * If 'list' already has at least 'max' elements, returns 0 without modifying

 * the list. */

size_t

guarded_list_push_back(struct guarded_list *list,

                       struct ovs_list *node, size_t max)

{

    size_t retval = 0;

    ovs_mutex_lock(&list->mutex);

    if (list->n < max) {

        ovs_list_push_back(&list->list, node);

        retval = ++list->n;

    }

    ovs_mutex_unlock(&list->mutex);

    return retval;

}

struct ovs_list *

guarded_list_pop_front(struct guarded_list *list)

{

    struct ovs_list *node = NULL;

    ovs_mutex_lock(&list->mutex);

    if (list->n) {

        node = ovs_list_pop_front(&list->list);

        list->n--;

    }

    ovs_mutex_unlock(&list->mutex);

    return node;

}

size_t

guarded_list_pop_all(struct guarded_list *list, struct ovs_list *elements)

{

    size_t n;

    ovs_mutex_lock(&list->mutex);

    ovs_list_move(elements, &list->list);

    n = list->n;

    ovs_list_init(&list->list);

    list->n = 0;

    ovs_mutex_unlock(&list->mutex);

    return n;

}