timerqueue.c

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/*
 *  Generic Timer-queue
 *
 *  Manages a simple queue of timers, ordered by expiration time.
 *  Uses rbtrees for quick list adds and expiration.
 *
 *  NOTE: All of the following functions need to be serialized
 *  to avoid races. No locking is done by this library code.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/bug.h>
#include <linux/timerqueue.h>
#include <linux/rbtree.h>
#include <linux/export.h>

void timerqueue_add(struct timerqueue_head *head, struct timerqueue_node *node)
{
    struct rb_node **p = &head->head.rb_node;
    struct rb_node *parent = NULL;
    struct timerqueue_node  *ptr;

    /* Make sure we don't add nodes that are already added */
    WARN_ON_ONCE(!RB_EMPTY_NODE(&node->node));

    while (*p) {
        parent = *p;
        ptr = rb_entry(parent, struct timerqueue_node, node);
        if (node->expires.tv64 < ptr->expires.tv64)
            p = &(*p)->rb_left;
        else
            p = &(*p)->rb_right;
    }
    rb_link_node(&node->node, parent, p);
    rb_insert_color(&node->node, &head->head);

    if (!head->next || node->expires.tv64 < head->next->expires.tv64)
        head->next = node;
}
EXPORT_SYMBOL_GPL(timerqueue_add);

void timerqueue_del(struct timerqueue_head *head, struct timerqueue_node *node)
{
    WARN_ON_ONCE(RB_EMPTY_NODE(&node->node));

    /* update next pointer */
    if (head->next == node) {
        struct rb_node *rbn = rb_next(&node->node);

        head->next = rbn ?
            rb_entry(rbn, struct timerqueue_node, node) : NULL;
    }
    rb_erase(&node->node, &head->head);
    RB_CLEAR_NODE(&node->node);
}
EXPORT_SYMBOL_GPL(timerqueue_del);

struct timerqueue_node *timerqueue_iterate_next(struct timerqueue_node *node)
{
    struct rb_node *next;

    if (!node)
        return NULL;
    next = rb_next(&node->node);
    if (!next)
        return NULL;
    return container_of(next, struct timerqueue_node, node);
}
EXPORT_SYMBOL_GPL(timerqueue_iterate_next);