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 <pthread.h>
  25
  26 #include <asterisk/sched.h>
  27 #include <asterisk/logger.h>
  28 #include <asterisk/channel.h>
  29
  30 /* Determine if a is sooner than b */
  31 #define SOONER(a,b) (((b).tv_sec > (a).tv_sec) || \
  32                                          (((b).tv_sec == (a).tv_sec) && ((b).tv_usec > (a).tv_usec)))
  33
  34 struct sched {
  35         struct sched *next;                             /* Next event in the list */
  36         int id;                                                 /* ID number of event */
  37         struct timeval when;                    /* Absolute time event should take place */
  38         int resched;                                    /* When to reschedule */
  39         void *data;                                     /* Data */
  40         ast_sched_cb callback;          /* Callback */
  41 };
  42
  43 struct sched_context {
  44         ast_mutex_t lock;
  45         /* Number of events processed */
  46         int eventcnt;
  47
  48         /* Number of outstanding schedule events */
  49         int schedcnt;
  50
  51         /* Schedule entry and main queue */
  52         struct sched *schedq;
  53
  54 #ifdef SCHED_MAX_CACHE
  55         /* Cache of unused schedule structures and how many */
  56         struct sched *schedc;
  57         int schedccnt;
  58 #endif
  59 };
  60
  61 struct sched_context *sched_context_create(void)
  62 {
  63         struct sched_context *tmp;
  64         tmp = malloc(sizeof(struct sched_context));
  65         if (tmp) {
  66                 ast_mutex_init(&tmp->lock);
  67                 tmp->eventcnt = 1;
  68                 tmp->schedcnt = 0;
  69                 tmp->schedq = NULL;
  70 #ifdef SCHED_MAX_CACHE
  71                 tmp->schedc = NULL;
  72                 tmp->schedccnt = 0;
  73 #endif
  74         }
  75         return tmp;
  76 }
  77
  78 void sched_context_destroy(struct sched_context *con)
  79 {
  80         struct sched *s, *sl;
  81         ast_mutex_lock(&con->lock);
  82 #ifdef SCHED_MAX_CACHE
  83         /* Eliminate the cache */
  84         s = con->schedc;
  85         while(s) {
  86                 sl = s;
  87                 s = s->next;
  88                 free(sl);
  89         }
  90 #endif
  91         /* And the queue */
  92         s = con->schedq;
  93         while(s) {
  94                 sl = s;
  95                 s = s->next;
  96                 free(sl);
  97         }
  98         /* And the context */
  99         ast_mutex_unlock(&con->lock);
 100         free(con);
 101 }
 102
 103 static struct sched *sched_alloc(struct sched_context *con)
 104 {
 105         /*
 106          * We keep a small cache of schedule entries
 107          * to minimize the number of necessary malloc()'s
 108          */
 109         struct sched *tmp;
 110 #ifdef SCHED_MAX_CACHE
 111         if (con->schedc) {
 112                 tmp = con->schedc;
 113                 con->schedc = con->schedc->next;
 114                 con->schedccnt--;
 115         } else
 116 #endif
 117                 tmp = malloc(sizeof(struct sched));
 118         return tmp;
 119 }
 120
 121 static void sched_release(struct sched_context *con, struct sched *tmp)
 122 {
 123         /*
 124          * Add to the cache, or just free() if we
 125          * already have too many cache entries
 126          */
 127
 128 #ifdef SCHED_MAX_CACHE
 129         if (con->schedccnt < SCHED_MAX_CACHE) {
 130                 tmp->next = con->schedc;
 131                 con->schedc = tmp;
 132                 con->schedccnt++;
 133         } else
 134 #endif
 135                 free(tmp);
 136 }
 137
 138 int ast_sched_wait(struct sched_context *con)
 139 {
 140         /*
 141          * Return the number of milliseconds
 142          * until the next scheduled event
 143          */
 144         struct timeval tv;
 145         int ms;
 146         DEBUG(ast_log(LOG_DEBUG, "ast_sched_wait()\n"));
 147         ast_mutex_lock(&con->lock);
 148         if (!con->schedq) {
 149                 ms = -1;
 150         } else if (gettimeofday(&tv, NULL) < 0) {
 151                 /* This should never happen */
 152                 ms = 0;
 153         } else {
 154                 ms = (con->schedq->when.tv_sec - tv.tv_sec) * 1000;
 155                 ms += (con->schedq->when.tv_usec - tv.tv_usec) / 1000;
 156                 if (ms < 0)
 157                         ms = 0;
 158         }
 159         ast_mutex_unlock(&con->lock);
 160         return ms;
 161
 162 }
 163
 164
 165 static void schedule(struct sched_context *con, struct sched *s)
 166 {
 167         /*
 168          * Take a sched structure and put it in the
 169          * queue, such that the soonest event is
 170          * first in the list.
 171          */
 172
 173         struct sched *last=NULL;
 174         struct sched *current=con->schedq;
 175         while(current) {
 176                 if (SOONER(s->when, current->when))
 177                         break;
 178                 last = current;
 179                 current = current->next;
 180         }
 181         /* Insert this event into the schedule */
 182         s->next = current;
 183         if (last)
 184                 last->next = s;
 185         else
 186                 con->schedq = s;
 187         con->schedcnt++;
 188 }
 189
 190 static inline int sched_settime(struct timeval *tv, int when)
 191 {
 192         struct timeval tv_tmp;
 193         long error_sec, error_usec;
 194
 195         if (gettimeofday(&tv_tmp, NULL) < 0) {
 196                 /* This shouldn't ever happen, but let's be sure */
 197                 ast_log(LOG_NOTICE, "gettimeofday() failed!\n");
 198                 return -1;
 199         }
 200         /*ast_log(LOG_DEBUG, "TV -> %lu,%lu\n", tv->tv_sec, tv->tv_usec);*/
 201         if (((unsigned long)(tv->tv_sec) > 0)&&((unsigned long)(tv->tv_usec) > 0)) {
 202                 if ((unsigned long)(tv_tmp.tv_usec) < (unsigned long)(tv->tv_usec)) {
 203                         tv_tmp.tv_usec += 1000000;
 204                         tv_tmp.tv_sec -= 1;
 205                 }
 206                 error_sec = (unsigned long)(tv_tmp.tv_sec) - (unsigned long)(tv->tv_sec);
 207                 error_usec = (unsigned long)(tv_tmp.tv_usec) - (unsigned long)(tv->tv_usec);
 208         } else {
 209                 /*ast_log(LOG_DEBUG, "Initializing error\n");*/
 210                 error_sec = 0;
 211                 error_usec = 0;
 212         }
 213         /*ast_log(LOG_DEBUG, "ERROR -> %lu,%lu\n", error_sec, error_usec);*/
 214         if (error_sec * 1000 + error_usec / 1000 < when) {
 215                 tv->tv_sec = tv_tmp.tv_sec + (when/1000 - error_sec);
 216                 tv->tv_usec = tv_tmp.tv_usec + ((when % 1000) * 1000 - error_usec);
 217         } else {
 218                 ast_log(LOG_NOTICE, "Request to schedule in the past?!?!\n");
 219                 tv->tv_sec = tv_tmp.tv_sec;
 220                 tv->tv_usec = tv_tmp.tv_usec;
 221         }
 222         if (tv->tv_usec > 1000000) {
 223                 tv->tv_sec++;
 224                 tv->tv_usec-= 1000000;
 225         }
 226         return 0;
 227 }
 228
 229 int ast_sched_add(struct sched_context *con, int when, ast_sched_cb callback, void *data)
 230 {
 231         /*
 232          * Schedule callback(data) to happen when ms into the future
 233          */
 234         struct sched *tmp;
 235         int res = -1;
 236         DEBUG(ast_log(LOG_DEBUG, "ast_sched_add()\n"));
 237         if (!when) {
 238                 ast_log(LOG_NOTICE, "Scheduled event in 0 ms?\n");
 239                 return -1;
 240         }
 241         ast_mutex_lock(&con->lock);
 242         if ((tmp = sched_alloc(con))) {
 243                 tmp->id = con->eventcnt++;
 244                 tmp->callback = callback;
 245                 tmp->data = data;
 246                 tmp->resched = when;
 247                 tmp->when.tv_sec = 0;
 248                 tmp->when.tv_usec = 0;
 249                 if (sched_settime(&tmp->when, when)) {
 250                         sched_release(con, tmp);
 251                 } else {
 252                         schedule(con, tmp);
 253                         res = tmp->id;
 254                 }
 255         }
 256         ast_mutex_lock(&con->lock);
 257         return res;
 258 }
 259
 260 int ast_sched_del(struct sched_context *con, int id)
 261 {
 262         /*
 263          * Delete the schedule entry with number
 264          * "id".  It's nearly impossible that there
 265          * would be two or more in the list with that
 266          * id.
 267          */
 268         struct sched *last=NULL, *s;
 269         DEBUG(ast_log(LOG_DEBUG, "ast_sched_del()\n"));
 270         ast_mutex_lock(&con->lock);
 271         s = con->schedq;
 272         while(s) {
 273                 if (s->id == id) {
 274                         if (last)
 275                                 last->next = s->next;
 276                         else
 277                                 con->schedq = s->next;
 278                         con->schedcnt--;
 279                         sched_release(con, s);
 280                         break;
 281                 }
 282                 last = s;
 283                 s = s->next;
 284         }
 285         ast_mutex_unlock(&con->lock);
 286         if (!s) {
 287                 ast_log(LOG_NOTICE, "Attempted to delete non-existant schedule entry %d!\n", id);
 288 #ifdef DO_CRASH
 289                 CRASH;
 290 #endif
 291                 return -1;
 292         } else
 293                 return 0;
 294 }
 295
 296 void ast_sched_dump(struct sched_context *con)
 297 {
 298         /*
 299          * Dump the contents of the scheduler to
 300          * stderr
 301          */
 302         struct sched *q;
 303         struct timeval tv;
 304         time_t s, ms;
 305         gettimeofday(&tv, NULL);
 306 #ifdef SCHED_MAX_CACHE
 307         ast_log(LOG_DEBUG, "Asterisk Schedule Dump (%d in Q, %d Total, %d Cache)\n",
 308                                                         con-> schedcnt, con->eventcnt - 1, con->schedccnt);
 309 #else
 310         ast_log(LOG_DEBUG, "Asterisk Schedule Dump (%d in Q, %d Total)\n",
 311                                                         con-> schedcnt, con->eventcnt - 1);
 312 #endif
 313
 314         ast_log(LOG_DEBUG, "=================================================\n");
 315         ast_log(LOG_DEBUG, "|ID    Callback    Data        Time  (sec:ms)   |\n");
 316         ast_log(LOG_DEBUG, "+-----+-----------+-----------+-----------------+\n");
 317         q = con->schedq;
 318         while(q) {
 319                 s =  q->when.tv_sec - tv.tv_sec;
 320                 ms = q->when.tv_usec - tv.tv_usec;
 321                 if (ms < 0) {
 322                         ms += 1000000;
 323                         s--;
 324                 }
 325                 ast_log(LOG_DEBUG, "|%.4d | %p | %p | %.6ld : %.6ld |\n",
 326                                 q->id,
 327                                 q->callback,
 328                                 q->data,
 329                                 (long)s,
 330                                 (long)ms);
 331                 q=q->next;
 332         }
 333         ast_log(LOG_DEBUG, "=================================================\n");
 334
 335 }
 336
 337 int ast_sched_runq(struct sched_context *con)
 338 {
 339         /*
 340          * Launch all events which need to be run at this time.
 341          */
 342         struct sched *current;
 343         struct timeval tv;
 344         int x=0;
 345         DEBUG(ast_log(LOG_DEBUG, "ast_sched_runq()\n"));
 346
 347         ast_mutex_lock(&con->lock);
 348         for(;;) {
 349                 if (!con->schedq)
 350                         break;
 351                 if (gettimeofday(&tv, NULL)) {
 352                         /* This should never happen */
 353                         ast_log(LOG_NOTICE, "gettimeofday() failed!\n");
 354                         break;
 355                 }
 356                 /* We only care about millisecond accuracy anyway, so this will
 357                    help us get more than one event at one time if they are very
 358                    close together. */
 359                 tv.tv_usec += 1000;
 360                 if (SOONER(con->schedq->when, tv)) {
 361                         current = con->schedq;
 362                         con->schedq = con->schedq->next;
 363                         con->schedcnt--;
 364
 365                         /*
 366                          * At this point, the schedule queue is still intact.  We
 367                          * have removed the first event and the rest is still there,
 368                          * so it's permissible for the callback to add new events, but
 369                          * trying to delete itself won't work because it isn't in
 370                          * the schedule queue.  If that's what it wants to do, it
 371                          * should return 0.
 372                          */
 373                         if (current->callback(current->data)) {
 374                                 /*
 375                                  * If they return non-zero, we should schedule them to be
 376                                  * run again.
 377                                  */
 378                                 if (sched_settime(&current->when, current->resched)) {
 379                                         sched_release(con, current);
 380                                 } else
 381                                         schedule(con, current);
 382                         } else {
 383                                 /* No longer needed, so release it */
 384                                 sched_release(con, current);
 385                         }
 386                         x++;
 387                 } else
 388                         break;
 389         }
 390         ast_mutex_unlock(&con->lock);
 391         return x;
 392 }