lib/tevent/tevent_timed.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    common events code for timed events
   5
   6    Copyright (C) Andrew Tridgell        2003-2006
   7    Copyright (C) Stefan Metzmacher      2005-2009
   8
   9      ** NOTE! The following LGPL license applies to the tevent
  10      ** library. This does NOT imply that all of Samba is released
  11      ** under the LGPL
  12
  13    This library is free software; you can redistribute it and/or
  14    modify it under the terms of the GNU Lesser General Public
  15    License as published by the Free Software Foundation; either
  16    version 3 of the License, or (at your option) any later version.
  17
  18    This library is distributed in the hope that it will be useful,
  19    but WITHOUT ANY WARRANTY; without even the implied warranty of
  20    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  21    Lesser General Public License for more details.
  22
  23    You should have received a copy of the GNU Lesser General Public
  24    License along with this library; if not, see <http://www.gnu.org/licenses/>.
  25 */
  26
  27 #include "replace.h"
  28 #include "system/time.h"
  29 #include "tevent.h"
  30 #include "tevent_internal.h"
  31 #include "tevent_util.h"
  32
  33 /**
  34   compare two timeval structures.
  35   Return -1 if tv1 < tv2
  36   Return 0 if tv1 == tv2
  37   Return 1 if tv1 > tv2
  38 */
  39 int tevent_timeval_compare(const struct timeval *tv1, const struct timeval *tv2)
  40 {
  41         if (tv1->tv_sec  > tv2->tv_sec)  return 1;
  42         if (tv1->tv_sec  < tv2->tv_sec)  return -1;
  43         if (tv1->tv_usec > tv2->tv_usec) return 1;
  44         if (tv1->tv_usec < tv2->tv_usec) return -1;
  45         return 0;
  46 }
  47
  48 /**
  49   return a zero timeval
  50 */
  51 struct timeval tevent_timeval_zero(void)
  52 {
  53         struct timeval tv;
  54         tv.tv_sec = 0;
  55         tv.tv_usec = 0;
  56         return tv;
  57 }
  58
  59 /**
  60   return a timeval for the current time
  61 */
  62 struct timeval tevent_timeval_current(void)
  63 {
  64         struct timeval tv;
  65         gettimeofday(&tv, NULL);
  66         return tv;
  67 }
  68
  69 /**
  70   return a timeval struct with the given elements
  71 */
  72 struct timeval tevent_timeval_set(uint32_t secs, uint32_t usecs)
  73 {
  74         struct timeval tv;
  75         tv.tv_sec = secs;
  76         tv.tv_usec = usecs;
  77         return tv;
  78 }
  79
  80 /**
  81   return the difference between two timevals as a timeval
  82   if tv1 comes after tv2, then return a zero timeval
  83   (this is *tv2 - *tv1)
  84 */
  85 struct timeval tevent_timeval_until(const struct timeval *tv1,
  86                                     const struct timeval *tv2)
  87 {
  88         struct timeval t;
  89         if (tevent_timeval_compare(tv1, tv2) >= 0) {
  90                 return tevent_timeval_zero();
  91         }
  92         t.tv_sec = tv2->tv_sec - tv1->tv_sec;
  93         if (tv1->tv_usec > tv2->tv_usec) {
  94                 t.tv_sec--;
  95                 t.tv_usec = 1000000 - (tv1->tv_usec - tv2->tv_usec);
  96         } else {
  97                 t.tv_usec = tv2->tv_usec - tv1->tv_usec;
  98         }
  99         return t;
 100 }
 101
 102 /**
 103   return true if a timeval is zero
 104 */
 105 bool tevent_timeval_is_zero(const struct timeval *tv)
 106 {
 107         return tv->tv_sec == 0 && tv->tv_usec == 0;
 108 }
 109
 110 struct timeval tevent_timeval_add(const struct timeval *tv, uint32_t secs,
 111                                   uint32_t usecs)
 112 {
 113         struct timeval tv2 = *tv;
 114         tv2.tv_sec += secs;
 115         tv2.tv_usec += usecs;
 116         tv2.tv_sec += tv2.tv_usec / 1000000;
 117         tv2.tv_usec = tv2.tv_usec % 1000000;
 118
 119         return tv2;
 120 }
 121
 122 /**
 123   return a timeval in the future with a specified offset
 124 */
 125 struct timeval tevent_timeval_current_ofs(uint32_t secs, uint32_t usecs)
 126 {
 127         struct timeval tv = tevent_timeval_current();
 128         return tevent_timeval_add(&tv, secs, usecs);
 129 }
 130
 131 /*
 132   destroy a timed event
 133 */
 134 static int tevent_common_timed_destructor(struct tevent_timer *te)
 135 {
 136         if (te->event_ctx == NULL) {
 137                 return 0;
 138         }
 139
 140         tevent_debug(te->event_ctx, TEVENT_DEBUG_TRACE,
 141                      "Destroying timer event %p \"%s\"\n",
 142                      te, te->handler_name);
 143
 144         if (te->event_ctx->last_zero_timer == te) {
 145                 te->event_ctx->last_zero_timer = DLIST_PREV(te);
 146         }
 147         DLIST_REMOVE(te->event_ctx->timer_events, te);
 148
 149         return 0;
 150 }
 151
 152 static int tevent_common_timed_deny_destructor(struct tevent_timer *te)
 153 {
 154         return -1;
 155 }
 156
 157 /*
 158   add a timed event
 159   return NULL on failure (memory allocation error)
 160 */
 161 static struct tevent_timer *tevent_common_add_timer_internal(
 162                                         struct tevent_context *ev,
 163                                         TALLOC_CTX *mem_ctx,
 164                                         struct timeval next_event,
 165                                         tevent_timer_handler_t handler,
 166                                         void *private_data,
 167                                         const char *handler_name,
 168                                         const char *location,
 169                                         bool optimize_zero)
 170 {
 171         struct tevent_timer *te, *prev_te, *cur_te;
 172
 173         te = talloc(mem_ctx?mem_ctx:ev, struct tevent_timer);
 174         if (te == NULL) return NULL;
 175
 176         te->event_ctx           = ev;
 177         te->next_event          = next_event;
 178         te->handler             = handler;
 179         te->private_data        = private_data;
 180         te->handler_name        = handler_name;
 181         te->location            = location;
 182         te->additional_data     = NULL;
 183
 184         if (ev->timer_events == NULL) {
 185                 ev->last_zero_timer = NULL;
 186         }
 187
 188         /* keep the list ordered */
 189         prev_te = NULL;
 190         if (optimize_zero && tevent_timeval_is_zero(&te->next_event)) {
 191                 /*
 192                  * Some callers use zero tevent_timer
 193                  * instead of tevent_immediate events.
 194                  *
 195                  * As these can happen very often,
 196                  * we remember the last zero timer
 197                  * in the list.
 198                  */
 199                 prev_te = ev->last_zero_timer;
 200                 ev->last_zero_timer = te;
 201         } else {
 202                 /*
 203                  * we traverse the list from the tail
 204                  * because it's much more likely that
 205                  * timers are added at the end of the list
 206                  */
 207                 for (cur_te = DLIST_TAIL(ev->timer_events);
 208                      cur_te != NULL;
 209                      cur_te = DLIST_PREV(cur_te))
 210                 {
 211                         int ret;
 212
 213                         /*
 214                          * if the new event comes before the current
 215                          * we continue searching
 216                          */
 217                         ret = tevent_timeval_compare(&te->next_event,
 218                                                      &cur_te->next_event);
 219                         if (ret < 0) {
 220                                 continue;
 221                         }
 222
 223                         break;
 224                 }
 225
 226                 prev_te = cur_te;
 227         }
 228
 229         DLIST_ADD_AFTER(ev->timer_events, te, prev_te);
 230
 231         talloc_set_destructor(te, tevent_common_timed_destructor);
 232
 233         tevent_debug(ev, TEVENT_DEBUG_TRACE,
 234                      "Added timed event \"%s\": %p\n",
 235                      handler_name, te);
 236         return te;
 237 }
 238
 239 struct tevent_timer *tevent_common_add_timer(struct tevent_context *ev,
 240                                              TALLOC_CTX *mem_ctx,
 241                                              struct timeval next_event,
 242                                              tevent_timer_handler_t handler,
 243                                              void *private_data,
 244                                              const char *handler_name,
 245                                              const char *location)
 246 {
 247         /*
 248          * do not use optimization, there are broken Samba
 249          * versions which use tevent_common_add_timer()
 250          * without using tevent_common_loop_timer_delay(),
 251          * it just uses DLIST_REMOVE(ev->timer_events, te)
 252          * and would leave ev->last_zero_timer behind.
 253          */
 254         return tevent_common_add_timer_internal(ev, mem_ctx, next_event,
 255                                                 handler, private_data,
 256                                                 handler_name, location,
 257                                                 false);
 258 }
 259
 260 struct tevent_timer *tevent_common_add_timer_v2(struct tevent_context *ev,
 261                                                 TALLOC_CTX *mem_ctx,
 262                                                 struct timeval next_event,
 263                                                 tevent_timer_handler_t handler,
 264                                                 void *private_data,
 265                                                 const char *handler_name,
 266                                                 const char *location)
 267 {
 268         /*
 269          * Here we turn on last_zero_timer optimization
 270          */
 271         return tevent_common_add_timer_internal(ev, mem_ctx, next_event,
 272                                                 handler, private_data,
 273                                                 handler_name, location,
 274                                                 true);
 275 }
 276
 277 /*
 278   do a single event loop using the events defined in ev
 279
 280   return the delay until the next timed event,
 281   or zero if a timed event was triggered
 282 */
 283 struct timeval tevent_common_loop_timer_delay(struct tevent_context *ev)
 284 {
 285         struct timeval current_time = tevent_timeval_zero();
 286         struct tevent_timer *te = ev->timer_events;
 287
 288         if (!te) {
 289                 /* have a default tick time of 30 seconds. This guarantees
 290                    that code that uses its own timeout checking will be
 291                    able to proceed eventually */
 292                 return tevent_timeval_set(30, 0);
 293         }
 294
 295         /*
 296          * work out the right timeout for the next timed event
 297          *
 298          * avoid the syscall to gettimeofday() if the timed event should
 299          * be triggered directly
 300          *
 301          * if there's a delay till the next timed event, we're done
 302          * with just returning the delay
 303          */
 304         if (!tevent_timeval_is_zero(&te->next_event)) {
 305                 struct timeval delay;
 306
 307                 current_time = tevent_timeval_current();
 308
 309                 delay = tevent_timeval_until(&current_time, &te->next_event);
 310                 if (!tevent_timeval_is_zero(&delay)) {
 311                         return delay;
 312                 }
 313         }
 314
 315         /*
 316          * ok, we have a timed event that we'll process ...
 317          */
 318
 319         /* deny the handler to free the event */
 320         talloc_set_destructor(te, tevent_common_timed_deny_destructor);
 321
 322         /* We need to remove the timer from the list before calling the
 323          * handler because in a semi-async inner event loop called from the
 324          * handler we don't want to come across this event again -- vl */
 325         if (ev->last_zero_timer == te) {
 326                 ev->last_zero_timer = DLIST_PREV(te);
 327         }
 328         DLIST_REMOVE(ev->timer_events, te);
 329
 330         tevent_debug(te->event_ctx, TEVENT_DEBUG_TRACE,
 331                      "Running timer event %p \"%s\"\n",
 332                      te, te->handler_name);
 333
 334         /*
 335          * If the timed event was registered for a zero current_time,
 336          * then we pass a zero timeval here too! To avoid the
 337          * overhead of gettimeofday() calls.
 338          *
 339          * otherwise we pass the current time
 340          */
 341         te->handler(ev, te, current_time, te->private_data);
 342
 343         /* The destructor isn't necessary anymore, we've already removed the
 344          * event from the list. */
 345         talloc_set_destructor(te, NULL);
 346
 347         tevent_debug(te->event_ctx, TEVENT_DEBUG_TRACE,
 348                      "Ending timer event %p \"%s\"\n",
 349                      te, te->handler_name);
 350
 351         talloc_free(te);
 352
 353         return tevent_timeval_zero();
 354 }
 355