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/*
* (C) 2008,2009 by Holger Hans Peter Freyther <zecke@selfish.org>
* (C) 2011 by Harald Welte <laforge@gnumonks.org>
* All Rights Reserved
*
* Authors: Holger Hans Peter Freyther <zecke@selfish.org>
* Harald Welte <laforge@gnumonks.org>
* Pablo Neira Ayuso <pablo@gnumonks.org>
*
* SPDX-License-Identifier: GPL-2.0+
*
* 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.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
*/
/*! \addtogroup timer
* @{
* Osmocom timer abstraction; modelled after linux kernel timers
*
* \file timer.c */
#include <assert.h>
#include <string.h>
#include <limits.h>
#include <osmocom/core/timer.h>
#include <osmocom/core/timer_compat.h>
#include <osmocom/core/linuxlist.h>
/* These store the amount of time that we wait until next timer expires. */
static struct timeval nearest;
static struct timeval *nearest_p;
static struct rb_root timer_root = RB_ROOT;
static void __add_timer(struct osmo_timer_list *timer)
{
struct rb_node **new = &(timer_root.rb_node);
struct rb_node *parent = NULL;
while (*new) {
struct osmo_timer_list *this;
this = container_of(*new, struct osmo_timer_list, node);
parent = *new;
if (timercmp(&timer->timeout, &this->timeout, <))
new = &((*new)->rb_left);
else
new = &((*new)->rb_right);
}
rb_link_node(&timer->node, parent, new);
rb_insert_color(&timer->node, &timer_root);
}
/*! set up timer callback and data
* \param[in] timer the timer that should be added
* \param[in] cb function to be called when timer expires
* \param[in] data pointer to data that passed to the callback function
*/
void osmo_timer_setup(struct osmo_timer_list *timer, void (*cb)(void *data),
void *data)
{
timer->cb = cb;
timer->data = data;
}
/*! add a new timer to the timer management
* \param[in] timer the timer that should be added
*/
void osmo_timer_add(struct osmo_timer_list *timer)
{
osmo_timer_del(timer);
timer->active = 1;
INIT_LLIST_HEAD(&timer->list);
__add_timer(timer);
}
/*! schedule a timer at a given future relative time
* \param[in] timer the to-be-added timer
* \param[in] seconds number of seconds from now
* \param[in] microseconds number of microseconds from now
*
* This function can be used to (re-)schedule a given timer at a
* specified number of seconds+microseconds in the future. It will
* internally add it to the timer management data structures, thus
* osmo_timer_add() is automatically called.
*/
void
osmo_timer_schedule(struct osmo_timer_list *timer, int seconds, int microseconds)
{
struct timeval current_time;
osmo_gettimeofday(¤t_time, NULL);
timer->timeout.tv_sec = seconds;
timer->timeout.tv_usec = microseconds;
timeradd(&timer->timeout, ¤t_time, &timer->timeout);
osmo_timer_add(timer);
}
/*! delete a timer from timer management
* \param[in] timer the to-be-deleted timer
*
* This function can be used to delete a previously added/scheduled
* timer from the timer management code.
*/
void osmo_timer_del(struct osmo_timer_list *timer)
{
if (timer->active) {
timer->active = 0;
rb_erase(&timer->node, &timer_root);
/* make sure this is not already scheduled for removal. */
if (!llist_empty(&timer->list))
llist_del_init(&timer->list);
}
}
/*! check if given timer is still pending
* \param[in] timer the to-be-checked timer
* \return 1 if pending, 0 otherwise
*
* This function can be used to determine whether a given timer
* has alredy expired (returns 0) or is still pending (returns 1)
*/
int osmo_timer_pending(struct osmo_timer_list *timer)
{
return timer->active;
}
/*! compute the remaining time of a timer
* \param[in] timer the to-be-checked timer
* \param[in] now the current time (NULL if not known)
* \param[out] remaining remaining time until timer fires
* \return 0 if timer has not expired yet, -1 if it has
*
* This function can be used to determine the amount of time
* remaining until the expiration of the timer.
*/
int osmo_timer_remaining(const struct osmo_timer_list *timer,
const struct timeval *now,
struct timeval *remaining)
{
struct timeval current_time;
if (!now)
osmo_gettimeofday(¤t_time, NULL);
else
current_time = *now;
timersub(&timer->timeout, ¤t_time, remaining);
if (remaining->tv_sec < 0)
return -1;
return 0;
}
/*! Determine time between now and the nearest timer
* \returns pointer to timeval of nearest timer, NULL if there is none
*
* if we have a nearest time return the delta between the current
* time and the time of the nearest timer.
* If the nearest timer timed out return NULL and then we will
* dispatch everything after the select
*/
struct timeval *osmo_timers_nearest(void)
{
/* nearest_p is exactly what we need already: NULL if nothing is
* waiting, {0,0} if we must dispatch immediately, and the correct
* delay if we need to wait */
return nearest_p;
}
static void update_nearest(struct timeval *cand, struct timeval *current)
{
if (cand->tv_sec != LONG_MAX) {
if (timercmp(cand, current, >))
timersub(cand, current, &nearest);
else {
/* loop again inmediately */
timerclear(&nearest);
}
nearest_p = &nearest;
} else {
nearest_p = NULL;
}
}
/*! Find the nearest time and update nearest_p */
void osmo_timers_prepare(void)
{
struct rb_node *node;
struct timeval current;
osmo_gettimeofday(¤t, NULL);
node = rb_first(&timer_root);
if (node) {
struct osmo_timer_list *this;
this = container_of(node, struct osmo_timer_list, node);
update_nearest(&this->timeout, ¤t);
} else {
nearest_p = NULL;
}
}
/*! fire all timers... and remove them */
int osmo_timers_update(void)
{
struct timeval current_time;
struct rb_node *node;
struct llist_head timer_eviction_list;
struct osmo_timer_list *this;
int work = 0;
osmo_gettimeofday(¤t_time, NULL);
INIT_LLIST_HEAD(&timer_eviction_list);
for (node = rb_first(&timer_root); node; node = rb_next(node)) {
this = container_of(node, struct osmo_timer_list, node);
if (timercmp(&this->timeout, ¤t_time, >))
break;
llist_add(&this->list, &timer_eviction_list);
}
/*
* The callbacks might mess with our list and in this case
* even llist_for_each_entry_safe is not safe to use. To allow
* osmo_timer_del to be called from within the callback we need
* to restart the iteration for each element scheduled for removal.
*
* The problematic scenario is the following: Given two timers A
* and B that have expired at the same time. Thus, they are both
* in the eviction list in this order: A, then B. If we remove
* timer B from the A's callback, we continue with B in the next
* iteration step, leading to an access-after-release.
*/
restart:
llist_for_each_entry(this, &timer_eviction_list, list) {
osmo_timer_del(this);
if (this->cb)
this->cb(this->data);
work = 1;
goto restart;
}
return work;
}
/*! Check how many timers we have in the system
* \returns number of \ref osmo_timer_list registered */
int osmo_timers_check(void)
{
struct rb_node *node;
int i = 0;
for (node = rb_first(&timer_root); node; node = rb_next(node)) {
i++;
}
return i;
}
/*! @} */
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