sched.c

   1 /*
   2  * Asterisk
   3  *
   4  * Mark Spencer <markster@marko.net>
   5  *
   6  * Copyright(C) Mark Spencer
   7  *
   8  * Distributed under the terms of the GNU General Public License (GPL) Version 2
   9  *
  10  * Scheduler Routines (form cheops-NG)
  11  *
  12  */
  13
  14 #ifdef DEBUG_SCHEDULER
  15 #define DEBUG(a) DEBUG_M(a)
  16 #else
  17 #define DEBUG(a)
  18 #endif
  19
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <sys/time.h>
  23 #include <unistd.h>
  24 #include <asterisk/sched.h>
  25 #include <asterisk/logger.h>
  26 #include <asterisk/channel.h>
  27
  28 /* Determine if a is sooner than b */
  29 #define SOONER(a,b) (((b).tv_sec > (a).tv_sec) || \
  30                                          (((b).tv_sec == (a).tv_sec) && ((b).tv_usec > (a).tv_usec)))
  31
  32 struct sched {
  33         struct sched *next;                             /* Next event in the list */
  34         int id;                                                 /* ID number of event */
  35         struct timeval when;                    /* Absolute time event should take place */
  36         int resched;                                    /* When to reschedule */
  37         void *data;                                     /* Data */
  38         ast_sched_cb callback;          /* Callback */
  39 };
  40
  41 struct sched_context {
  42         /* Number of events processed */
  43         int eventcnt;
  44
  45         /* Number of outstanding schedule events */
  46         int schedcnt;
  47
  48         /* Schedule entry and main queue */
  49         struct sched *schedq;
  50
  51 #ifdef SCHED_MAX_CACHE
  52         /* Cache of unused schedule structures and how many */
  53         struct sched *schedc;
  54         int schedccnt;
  55 #endif
  56 };
  57
  58 struct sched_context *sched_context_create(void)
  59 {
  60         struct sched_context *tmp;
  61         tmp = malloc(sizeof(struct sched_context));
  62         if (tmp) {
  63                 tmp->eventcnt = 1;
  64                 tmp->schedcnt = 0;
  65                 tmp->schedq = NULL;
  66 #ifdef SCHED_MAX_CACHE
  67                 tmp->schedc = NULL;
  68                 tmp->schedccnt = 0;
  69 #endif
  70         }
  71         return tmp;
  72 }
  73
  74 void sched_context_destroy(struct sched_context *con)
  75 {
  76         struct sched *s, *sl;
  77 #ifdef SCHED_MAX_CACHE
  78         /* Eliminate the cache */
  79         s = con->schedc;
  80         while(s) {
  81                 sl = s;
  82                 s = s->next;
  83                 free(sl);
  84         }
  85 #endif
  86         /* And the queue */
  87         s = con->schedq;
  88         while(s) {
  89                 sl = s;
  90                 s = s->next;
  91                 free(sl);
  92         }
  93         /* And the context */
  94         free(con);
  95 }
  96
  97 static struct sched *sched_alloc(struct sched_context *con)
  98 {
  99         /*
 100          * We keep a small cache of schedule entries
 101          * to minimize the number of necessary malloc()'s
 102          */
 103         struct sched *tmp;
 104 #ifdef SCHED_MAX_CACHE
 105         if (con->schedc) {
 106                 tmp = con->schedc;
 107                 con->schedc = con->schedc->next;
 108                 con->schedccnt--;
 109         } else
 110 #endif
 111                 tmp = malloc(sizeof(struct sched));
 112         return tmp;
 113 }
 114
 115 static void sched_release(struct sched_context *con, struct sched *tmp)
 116 {
 117         /*
 118          * Add to the cache, or just free() if we
 119          * already have too many cache entries
 120          */
 121
 122 #ifdef SCHED_MAX_CACHE
 123         if (con->schedccnt < SCHED_MAX_CACHE) {
 124                 tmp->next = con->schedc;
 125                 con->schedc = tmp;
 126                 con->schedccnt++;
 127         } else
 128 #endif
 129                 free(tmp);
 130 }
 131
 132 int ast_sched_wait(struct sched_context *con)
 133 {
 134         /*
 135          * Return the number of milliseconds
 136          * until the next scheduled event
 137          */
 138         struct timeval tv;
 139         int ms;
 140         DEBUG(ast_log(LOG_DEBUG, "ast_sched_wait()\n"));
 141         if (!con->schedq)
 142                 return -1;
 143         if (gettimeofday(&tv, NULL) < 0) {
 144                 /* This should never happen */
 145                 return 0;
 146         };
 147         ms = (con->schedq->when.tv_sec - tv.tv_sec) * 1000;
 148         ms += (con->schedq->when.tv_usec - tv.tv_usec) / 1000;
 149         if (ms < 0)
 150                 ms = 0;
 151         return ms;
 152
 153 }
 154
 155
 156 static void schedule(struct sched_context *con, struct sched *s)
 157 {
 158         /*
 159          * Take a sched structure and put it in the
 160          * queue, such that the soonest event is
 161          * first in the list.
 162          */
 163
 164         struct sched *last=NULL;
 165         struct sched *current=con->schedq;
 166         while(current) {
 167                 if (SOONER(s->when, current->when))
 168                         break;
 169                 last = current;
 170                 current = current->next;
 171         }
 172         /* Insert this event into the schedule */
 173         s->next = current;
 174         if (last)
 175                 last->next = s;
 176         else
 177                 con->schedq = s;
 178         con->schedcnt++;
 179 }
 180
 181 static inline int sched_settime(struct timeval *tv, int when)
 182 {
 183         struct timeval tv_tmp;
 184         long error_sec, error_usec;
 185
 186         if (gettimeofday(&tv_tmp, NULL) < 0) {
 187                 /* This shouldn't ever happen, but let's be sure */
 188                 ast_log(LOG_NOTICE, "gettimeofday() failed!\n");
 189                 return -1;
 190         }
 191         /*ast_log(LOG_DEBUG, "TV -> %lu,%lu\n", tv->tv_sec, tv->tv_usec);*/
 192         if (((unsigned long)(tv->tv_sec) > 0)&&((unsigned long)(tv->tv_usec) > 0)) {
 193                 if ((unsigned long)(tv_tmp.tv_usec) < (unsigned long)(tv->tv_usec)) {
 194                         tv_tmp.tv_usec += 1000000;
 195                         tv_tmp.tv_sec -= 1;
 196                 }
 197                 error_sec = (unsigned long)(tv_tmp.tv_sec) - (unsigned long)(tv->tv_sec);
 198                 error_usec = (unsigned long)(tv_tmp.tv_usec) - (unsigned long)(tv->tv_usec);
 199         } else {
 200                 /*ast_log(LOG_DEBUG, "Initializing error\n");*/
 201                 error_sec = 0;
 202                 error_usec = 0;
 203         }
 204         /*ast_log(LOG_DEBUG, "ERROR -> %lu,%lu\n", error_sec, error_usec);*/
 205         if (error_sec * 1000 + error_usec / 1000 < when) {
 206                 tv->tv_sec = tv_tmp.tv_sec + (when/1000 - error_sec);
 207                 tv->tv_usec = tv_tmp.tv_usec + ((when % 1000) * 1000 - error_usec);
 208         } else {
 209                 ast_log(LOG_NOTICE, "Request to schedule in the past?!?!\n");
 210                 tv->tv_sec = tv_tmp.tv_sec;
 211                 tv->tv_usec = tv_tmp.tv_usec;
 212         }
 213         if (tv->tv_usec > 1000000) {
 214                 tv->tv_sec++;
 215                 tv->tv_usec-= 1000000;
 216         }
 217         return 0;
 218 }
 219
 220 int ast_sched_add(struct sched_context *con, int when, ast_sched_cb callback, void *data)
 221 {
 222         /*
 223          * Schedule callback(data) to happen when ms into the future
 224          */
 225         struct sched *tmp;
 226         DEBUG(ast_log(LOG_DEBUG, "ast_sched_add()\n"));
 227         if (!when) {
 228                 ast_log(LOG_NOTICE, "Scheduled event in 0 ms?");
 229                 return -1;
 230         }
 231         if ((tmp = sched_alloc(con))) {
 232                 tmp->id = con->eventcnt++;
 233                 tmp->callback = callback;
 234                 tmp->data = data;
 235                 tmp->resched = when;
 236                 tmp->when.tv_sec = 0;
 237                 tmp->when.tv_usec = 0;
 238                 if (sched_settime(&tmp->when, when)) {
 239                         sched_release(con, tmp);
 240                         return -1;
 241                 } else
 242                         schedule(con, tmp);
 243         } else
 244                 return -1;
 245         return tmp->id;
 246 }
 247
 248 int ast_sched_del(struct sched_context *con, int id)
 249 {
 250         /*
 251          * Delete the schedule entry with number
 252          * "id".  It's nearly impossible that there
 253          * would be two or more in the list with that
 254          * id.
 255          */
 256         struct sched *last=NULL, *s;
 257         DEBUG(ast_log(LOG_DEBUG, "ast_sched_del()\n"));
 258         s = con->schedq;
 259         while(s) {
 260                 if (s->id == id) {
 261                         if (last)
 262                                 last->next = s->next;
 263                         else
 264                                 con->schedq = s->next;
 265                         con->schedcnt--;
 266                         sched_release(con, s);
 267                         return 0;
 268                 }
 269                 last = s;
 270                 s = s->next;
 271         }
 272         ast_log(LOG_NOTICE, "Attempted to delete non-existant schedule entry %d!\n", id);
 273 #ifdef DO_CRASH
 274         CRASH;
 275 #endif
 276         return -1;
 277 }
 278
 279 void ast_sched_dump(struct sched_context *con)
 280 {
 281         /*
 282          * Dump the contents of the scheduler to
 283          * stderr
 284          */
 285         struct sched *q;
 286         struct timeval tv;
 287         time_t s, ms;
 288         gettimeofday(&tv, NULL);
 289 #ifdef SCHED_MAX_CACHE
 290         ast_log(LOG_DEBUG, "Asterisk Schedule Dump (%d in Q, %d Total, %d Cache)\n",
 291                                                         con-> schedcnt, con->eventcnt - 1, con->schedccnt);
 292 #else
 293         ast_log(LOG_DEBUG, "Asterisk Schedule Dump (%d in Q, %d Total)\n",
 294                                                         con-> schedcnt, con->eventcnt - 1);
 295 #endif
 296
 297         ast_log(LOG_DEBUG, "=================================================\n");
 298         ast_log(LOG_DEBUG, "|ID    Callback    Data        Time  (sec:ms)   |\n");
 299         ast_log(LOG_DEBUG, "+-----+-----------+-----------+-----------------+\n");
 300         q = con->schedq;
 301         while(q) {
 302                 s =  q->when.tv_sec - tv.tv_sec;
 303                 ms = q->when.tv_usec - tv.tv_usec;
 304                 if (ms < 0) {
 305                         ms += 1000000;
 306                         s--;
 307                 }
 308                 ast_log(LOG_DEBUG, "|%.4d | %p | %p | %.6ld : %.6ld |\n",
 309                                 q->id,
 310                                 q->callback,
 311                                 q->data,
 312                                 (long)s,
 313                                 (long)ms);
 314                 q=q->next;
 315         }
 316         ast_log(LOG_DEBUG, "=================================================\n");
 317
 318 }
 319
 320 int ast_sched_runq(struct sched_context *con)
 321 {
 322         /*
 323          * Launch all events which need to be run at this time.
 324          */
 325         struct sched *current;
 326         struct timeval tv;
 327         int x=0;
 328         DEBUG(ast_log(LOG_DEBUG, "ast_sched_runq()\n"));
 329
 330         for(;;) {
 331                 if (!con->schedq)
 332                         break;
 333                 if (gettimeofday(&tv, NULL)) {
 334                         /* This should never happen */
 335                         ast_log(LOG_NOTICE, "gettimeofday() failed!\n");
 336                         return 0;
 337                 }
 338                 /* We only care about millisecond accuracy anyway, so this will
 339                    help us get more than one event at one time if they are very
 340                    close together. */
 341                 tv.tv_usec += 1000;
 342                 if (SOONER(con->schedq->when, tv)) {
 343                         current = con->schedq;
 344                         con->schedq = con->schedq->next;
 345                         con->schedcnt--;
 346
 347                         /*
 348                          * At this point, the schedule queue is still intact.  We
 349                          * have removed the first event and the rest is still there,
 350                          * so it's permissible for the callback to add new events, but
 351                          * trying to delete itself won't work because it isn't in
 352                          * the schedule queue.  If that's what it wants to do, it
 353                          * should return 0.
 354                          */
 355                         if (current->callback(current->data)) {
 356                                 /*
 357                                  * If they return non-zero, we should schedule them to be
 358                                  * run again.
 359                                  */
 360                                 if (sched_settime(&current->when, current->resched)) {
 361                                         sched_release(con, current);
 362                                 } else
 363                                         schedule(con, current);
 364                         } else {
 365                                 /* No longer needed, so release it */
 366                                 sched_release(con, current);
 367                         }
 368                         x++;
 369                 } else
 370                         break;
 371         }
 372         return x;
 373 }