| /* gsm_timer.cpp |
| * |
| * Copyright (C) 2012 Ivan Klyuchnikov |
| * |
| * 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. |
| */ |
| |
| /* These store the amount of frame number that we wait until next timer expires. */ |
| static int nearest; |
| static int *nearest_p; |
| |
| /*! \addtogroup gsm_timer |
| * @{ |
| */ |
| |
| /*! \file gsm_timer.cpp |
| */ |
| |
| #include <assert.h> |
| #include <string.h> |
| #include <limits.h> |
| #include <gsm_timer.h> |
| #include <pcu_l1_if.h> |
| #include <bts.h> |
| |
| |
| static struct rb_root timer_root = RB_ROOT; |
| |
| /* |
| * TODO: make this depend on the BTS. This means that |
| * all time functions schedule based on the BTS they |
| * are scheduled on. |
| */ |
| static int get_current_fn() |
| { |
| return BTS::main_bts()->current_frame_number(); |
| } |
| |
| static void __add_gsm_timer(struct osmo_gsm_timer_list *timer) |
| { |
| struct rb_node **new_node = &(timer_root.rb_node); |
| struct rb_node *parent = NULL; |
| |
| while (*new_node) { |
| struct osmo_gsm_timer_list *this_timer; |
| |
| this_timer = container_of(*new_node, struct osmo_gsm_timer_list, node); |
| |
| parent = *new_node; |
| if (timer->fn < this_timer->fn) |
| new_node = &((*new_node)->rb_left); |
| else |
| new_node = &((*new_node)->rb_right); |
| } |
| |
| rb_link_node(&timer->node, parent, new_node); |
| rb_insert_color(&timer->node, &timer_root); |
| } |
| |
| /*! \brief add a new timer to the timer management |
| * \param[in] timer the timer that should be added |
| */ |
| void osmo_gsm_timer_add(struct osmo_gsm_timer_list *timer) |
| { |
| osmo_gsm_timer_del(timer); |
| timer->active = 1; |
| INIT_LLIST_HEAD(&timer->list); |
| __add_gsm_timer(timer); |
| } |
| |
| /*! \brief schedule a gsm timer at a given future relative time |
| * \param[in] timer the to-be-added timer |
| * \param[in] number of frames from now |
| * |
| * This function can be used to (re-)schedule a given timer at a |
| * specified number of frames in the future. It will |
| * internally add it to the timer management data structures, thus |
| * osmo_timer_add() is automatically called. |
| */ |
| void |
| osmo_gsm_timer_schedule(struct osmo_gsm_timer_list *timer, int fn) |
| { |
| int current_fn; |
| |
| current_fn = get_current_fn(); |
| timer->fn = current_fn + fn; |
| osmo_gsm_timer_add(timer); |
| } |
| |
| /*! \brief delete a gsm 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_gsm_timer_del(struct osmo_gsm_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); |
| } |
| } |
| |
| /*! \brief 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_gsm_timer_pending(struct osmo_gsm_timer_list *timer) |
| { |
| return timer->active; |
| } |
| |
| /* |
| * if we have a nearest frame number return the delta between the current |
| * FN and the FN of the nearest timer. |
| * If the nearest timer timed out return NULL and then we will |
| * dispatch everything after the select |
| */ |
| int *osmo_gsm_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(int *cand, int *current) |
| { |
| if (*cand != LONG_MAX) { |
| if (*cand > *current) |
| nearest = *cand - *current; |
| else { |
| /* loop again inmediately */ |
| nearest = 0; |
| } |
| nearest_p = &nearest; |
| } else { |
| nearest_p = NULL; |
| } |
| } |
| |
| /* |
| * Find the nearest FN and update s_nearest_time |
| */ |
| void osmo_gsm_timers_prepare(void) |
| { |
| struct rb_node *node; |
| int current_fn; |
| |
| current_fn = get_current_fn(); |
| |
| node = rb_first(&timer_root); |
| if (node) { |
| struct osmo_gsm_timer_list *this_timer; |
| this_timer = container_of(node, struct osmo_gsm_timer_list, node); |
| update_nearest(&this_timer->fn, ¤t_fn); |
| } else { |
| nearest_p = NULL; |
| } |
| } |
| |
| /* |
| * fire all timers... and remove them |
| */ |
| int osmo_gsm_timers_update(void) |
| { |
| int current_fn; |
| struct rb_node *node; |
| struct llist_head timer_eviction_list; |
| struct osmo_gsm_timer_list *this_timer; |
| int work = 0; |
| |
| current_fn = get_current_fn(); |
| |
| INIT_LLIST_HEAD(&timer_eviction_list); |
| for (node = rb_first(&timer_root); node; node = rb_next(node)) { |
| this_timer = container_of(node, struct osmo_gsm_timer_list, node); |
| |
| if (this_timer->fn > current_fn) |
| break; |
| |
| llist_add(&this_timer->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_gsm_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, &timer_eviction_list, list) { |
| osmo_gsm_timer_del(this_timer); |
| this_timer->cb(this_timer->data); |
| work = 1; |
| goto restart; |
| } |
| |
| return work; |
| } |
| |
| int osmo_gsm_timers_check(void) |
| { |
| struct rb_node *node; |
| int i = 0; |
| |
| for (node = rb_first(&timer_root); node; node = rb_next(node)) { |
| i++; |
| } |
| return i; |
| } |
| |
| /*! }@ */ |
| |