Harald Welte | 987f59a | 2017-02-04 12:34:35 +0100 | [diff] [blame] | 1 | /* |
| 2 | * (C) 2008,2009 by Holger Hans Peter Freyther <zecke@selfish.org> |
| 3 | * (C) 2011 by Harald Welte <laforge@gnumonks.org> |
| 4 | * All Rights Reserved |
| 5 | * |
| 6 | * Authors: Holger Hans Peter Freyther <zecke@selfish.org> |
| 7 | * Harald Welte <laforge@gnumonks.org> |
| 8 | * Pablo Neira Ayuso <pablo@gnumonks.org> |
| 9 | * |
| 10 | * This program is free software; you can redistribute it and/or modify |
| 11 | * it under the terms of the GNU General Public License as published by |
| 12 | * the Free Software Foundation; either version 2 of the License, or |
| 13 | * (at your option) any later version. |
| 14 | * |
| 15 | * This program is distributed in the hope that it will be useful, |
| 16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 18 | * GNU General Public License for more details. |
| 19 | * |
| 20 | * You should have received a copy of the GNU General Public License along |
| 21 | * with this program; if not, write to the Free Software Foundation, Inc., |
| 22 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| 23 | * |
| 24 | */ |
| 25 | |
| 26 | |
| 27 | /*! \addtogroup timer |
| 28 | * @{ |
| 29 | */ |
| 30 | |
| 31 | /*! \file timer.c |
| 32 | */ |
| 33 | |
| 34 | #include <assert.h> |
| 35 | #include <limits.h> |
| 36 | #include "osmocom/core/linuxlist.h" |
| 37 | #include "osmocom/core/timer.h" |
| 38 | |
| 39 | /* These store the amount of time that we wait until next timer expires. */ |
| 40 | static struct osmo_timeval nearest; |
| 41 | static struct osmo_timeval *nearest_p; |
| 42 | |
| 43 | static struct rb_root timer_root = RB_ROOT; |
| 44 | |
| 45 | static void __add_timer(struct osmo_timer_list *timer) |
| 46 | { |
| 47 | struct rb_node **new = &(timer_root.rb_node); |
| 48 | struct rb_node *parent = NULL; |
| 49 | |
| 50 | while (*new) { |
| 51 | struct osmo_timer_list *this; |
| 52 | |
| 53 | this = container_of(*new, struct osmo_timer_list, node); |
| 54 | |
| 55 | parent = *new; |
| 56 | if (timercmp(&timer->timeout, &this->timeout, <)) |
| 57 | new = &((*new)->rb_left); |
| 58 | else |
| 59 | new = &((*new)->rb_right); |
| 60 | } |
| 61 | |
| 62 | rb_link_node(&timer->node, parent, new); |
| 63 | rb_insert_color(&timer->node, &timer_root); |
| 64 | } |
| 65 | |
| 66 | /*! \brief add a new timer to the timer management |
| 67 | * \param[in] timer the timer that should be added |
| 68 | */ |
| 69 | void osmo_timer_add(struct osmo_timer_list *timer) |
| 70 | { |
| 71 | osmo_timer_del(timer); |
| 72 | timer->active = 1; |
| 73 | INIT_LLIST_HEAD(&timer->list); |
| 74 | __add_timer(timer); |
| 75 | } |
| 76 | |
| 77 | /*! \brief schedule a timer at a given future relative time |
| 78 | * \param[in] timer the to-be-added timer |
| 79 | * \param[in] seconds number of seconds from now |
| 80 | * \param[in] microseconds number of microseconds from now |
| 81 | * |
| 82 | * This function can be used to (re-)schedule a given timer at a |
| 83 | * specified number of seconds+microseconds in the future. It will |
| 84 | * internally add it to the timer management data structures, thus |
| 85 | * osmo_timer_add() is automatically called. |
| 86 | */ |
| 87 | void |
| 88 | osmo_timer_schedule(struct osmo_timer_list *timer, int seconds, int microseconds) |
| 89 | { |
| 90 | struct osmo_timeval current_time; |
| 91 | |
| 92 | osmo_gettimeofday(¤t_time, NULL); |
| 93 | #if 0 |
| 94 | timer->timeout.tv_sec = seconds; |
| 95 | timer->timeout.tv_usec = microseconds; |
| 96 | #else |
| 97 | timer->timeout.expires = (seconds*1000) + (microseconds/1000); |
| 98 | #endif |
| 99 | timeradd(&timer->timeout, ¤t_time, &timer->timeout); |
| 100 | osmo_timer_add(timer); |
| 101 | } |
| 102 | |
| 103 | /*! \brief delete a timer from timer management |
| 104 | * \param[in] timer the to-be-deleted timer |
| 105 | * |
| 106 | * This function can be used to delete a previously added/scheduled |
| 107 | * timer from the timer management code. |
| 108 | */ |
| 109 | void osmo_timer_del(struct osmo_timer_list *timer) |
| 110 | { |
| 111 | if (timer->active) { |
| 112 | timer->active = 0; |
| 113 | rb_erase(&timer->node, &timer_root); |
| 114 | /* make sure this is not already scheduled for removal. */ |
| 115 | if (!llist_empty(&timer->list)) |
| 116 | llist_del_init(&timer->list); |
| 117 | } |
| 118 | } |
| 119 | |
| 120 | /*! \brief check if given timer is still pending |
| 121 | * \param[in] timer the to-be-checked timer |
| 122 | * \return 1 if pending, 0 otherwise |
| 123 | * |
| 124 | * This function can be used to determine whether a given timer |
| 125 | * has alredy expired (returns 0) or is still pending (returns 1) |
| 126 | */ |
| 127 | int osmo_timer_pending(struct osmo_timer_list *timer) |
| 128 | { |
| 129 | return timer->active; |
| 130 | } |
| 131 | |
| 132 | /*! \brief compute the remaining time of a timer |
| 133 | * \param[in] timer the to-be-checked timer |
| 134 | * \param[in] now the current time (NULL if not known) |
| 135 | * \param[out] remaining remaining time until timer fires |
| 136 | * \return 0 if timer has not expired yet, -1 if it has |
| 137 | * |
| 138 | * This function can be used to determine the amount of time |
| 139 | * remaining until the expiration of the timer. |
| 140 | */ |
| 141 | int osmo_timer_remaining(const struct osmo_timer_list *timer, |
| 142 | const struct osmo_timeval *now, |
| 143 | struct osmo_timeval *remaining) |
| 144 | { |
| 145 | struct osmo_timeval current_time; |
| 146 | |
| 147 | if (!now) |
| 148 | osmo_gettimeofday(¤t_time, NULL); |
| 149 | else |
| 150 | current_time = *now; |
| 151 | |
| 152 | timersub(&timer->timeout, ¤t_time, remaining); |
| 153 | |
| 154 | #if 0 |
| 155 | if (remaining->tv_sec < 0) |
| 156 | #else |
| 157 | if (remaining->expires < 0) |
| 158 | #endif |
| 159 | return -1; |
| 160 | |
| 161 | return 0; |
| 162 | } |
| 163 | |
| 164 | /*! \brief Determine time between now and the nearest timer |
| 165 | * \returns pointer to osmo_timeval of nearest timer, NULL if there is none |
| 166 | * |
| 167 | * if we have a nearest time return the delta between the current |
| 168 | * time and the time of the nearest timer. |
| 169 | * If the nearest timer timed out return NULL and then we will |
| 170 | * dispatch everything after the select |
| 171 | */ |
| 172 | struct osmo_timeval *osmo_timers_nearest(void) |
| 173 | { |
| 174 | /* nearest_p is exactly what we need already: NULL if nothing is |
| 175 | * waiting, {0,0} if we must dispatch immediately, and the correct |
| 176 | * delay if we need to wait */ |
| 177 | return nearest_p; |
| 178 | } |
| 179 | |
| 180 | static void update_nearest(struct osmo_timeval *cand, struct osmo_timeval *current) |
| 181 | { |
| 182 | #if 0 |
| 183 | if (cand->tv_sec != LONG_MAX) { |
| 184 | #else |
| 185 | if (cand->expires != LONG_MAX) { |
| 186 | #endif |
| 187 | if (timercmp(cand, current, >)) |
| 188 | timersub(cand, current, &nearest); |
| 189 | else { |
| 190 | /* loop again inmediately */ |
| 191 | timerclear(&nearest); |
| 192 | } |
| 193 | nearest_p = &nearest; |
| 194 | } else { |
| 195 | nearest_p = NULL; |
| 196 | } |
| 197 | } |
| 198 | |
| 199 | /*! \brief Find the nearest time and update nearest_p */ |
| 200 | void osmo_timers_prepare(void) |
| 201 | { |
| 202 | struct rb_node *node; |
| 203 | struct osmo_timeval current; |
| 204 | |
| 205 | osmo_gettimeofday(¤t, NULL); |
| 206 | |
| 207 | node = rb_first(&timer_root); |
| 208 | if (node) { |
| 209 | struct osmo_timer_list *this; |
| 210 | this = container_of(node, struct osmo_timer_list, node); |
| 211 | update_nearest(&this->timeout, ¤t); |
| 212 | } else { |
| 213 | nearest_p = NULL; |
| 214 | } |
| 215 | } |
| 216 | |
| 217 | /*! \brief fire all timers... and remove them */ |
| 218 | int osmo_timers_update(void) |
| 219 | { |
| 220 | struct osmo_timeval current_time; |
| 221 | struct rb_node *node; |
| 222 | struct llist_head timer_eviction_list; |
| 223 | struct osmo_timer_list *this; |
| 224 | int work = 0; |
| 225 | |
| 226 | osmo_gettimeofday(¤t_time, NULL); |
| 227 | |
| 228 | INIT_LLIST_HEAD(&timer_eviction_list); |
| 229 | for (node = rb_first(&timer_root); node; node = rb_next(node)) { |
| 230 | this = container_of(node, struct osmo_timer_list, node); |
| 231 | |
| 232 | if (timercmp(&this->timeout, ¤t_time, >)) |
| 233 | break; |
| 234 | |
| 235 | llist_add(&this->list, &timer_eviction_list); |
| 236 | } |
| 237 | |
| 238 | /* |
| 239 | * The callbacks might mess with our list and in this case |
| 240 | * even llist_for_each_entry_safe is not safe to use. To allow |
| 241 | * osmo_timer_del to be called from within the callback we need |
| 242 | * to restart the iteration for each element scheduled for removal. |
| 243 | * |
| 244 | * The problematic scenario is the following: Given two timers A |
| 245 | * and B that have expired at the same time. Thus, they are both |
| 246 | * in the eviction list in this order: A, then B. If we remove |
| 247 | * timer B from the A's callback, we continue with B in the next |
| 248 | * iteration step, leading to an access-after-release. |
| 249 | */ |
| 250 | restart: |
| 251 | llist_for_each_entry(this, &timer_eviction_list, list) { |
| 252 | osmo_timer_del(this); |
| 253 | if (this->cb) |
| 254 | this->cb(this->data); |
| 255 | work = 1; |
| 256 | goto restart; |
| 257 | } |
| 258 | |
| 259 | return work; |
| 260 | } |
| 261 | |
| 262 | /*! \brief Check how many timers we have in the system |
| 263 | * \returns number of \ref osmo_timer_list registered */ |
| 264 | int osmo_timers_check(void) |
| 265 | { |
| 266 | struct rb_node *node; |
| 267 | int i = 0; |
| 268 | |
| 269 | for (node = rb_first(&timer_root); node; node = rb_next(node)) { |
| 270 | i++; |
| 271 | } |
| 272 | return i; |
| 273 | } |
| 274 | |
| 275 | extern volatile unsigned long jiffies; |
| 276 | int osmo_gettimeofday(struct osmo_timeval *tv, struct timezone *tz) |
| 277 | { |
| 278 | tv->expires = jiffies; |
| 279 | return 0; |
| 280 | } |
| 281 | |
| 282 | /*! @} */ |