main/sched.c

   1 /*
   2  * Asterisk -- An open source telephony toolkit.
   3  *
   4  * Copyright (C) 1999 - 2005, Digium, Inc.
   5  *
   6  * Mark Spencer <markster@digium.com>
   7  *
   8  * See http://www.asterisk.org for more information about
   9  * the Asterisk project. Please do not directly contact
  10  * any of the maintainers of this project for assistance;
  11  * the project provides a web site, mailing lists and IRC
  12  * channels for your use.
  13  *
  14  * This program is free software, distributed under the terms of
  15  * the GNU General Public License Version 2. See the LICENSE file
  16  * at the top of the source tree.
  17  */
  18
  19 /*! \file
  20  *
  21  * \brief Scheduler Routines (from cheops-NG)
  22  *
  23  * \author Mark Spencer <markster@digium.com>
  24  */
  25
  26 #include "asterisk.h"
  27
  28 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
  29
  30 #ifdef DEBUG_SCHEDULER
  31 #define DEBUG(a) do { \
  32         if (option_debug) \
  33                 DEBUG_M(a) \
  34         } while (0)
  35 #else
  36 #define DEBUG(a)
  37 #endif
  38
  39 #include <sys/time.h>
  40
  41 #include "asterisk/sched.h"
  42 #include "asterisk/channel.h"
  43 #include "asterisk/lock.h"
  44 #include "asterisk/utils.h"
  45 #include "asterisk/linkedlists.h"
  46 #include "asterisk/dlinkedlists.h"
  47 #include "asterisk/hashtab.h"
  48
  49 struct sched {
  50         AST_DLLIST_ENTRY(sched) list;
  51         int id;                       /*!< ID number of event */
  52         struct timeval when;          /*!< Absolute time event should take place */
  53         int resched;                  /*!< When to reschedule */
  54         int variable;                 /*!< Use return value from callback to reschedule */
  55         const void *data;             /*!< Data */
  56         ast_sched_cb callback;        /*!< Callback */
  57 };
  58
  59 struct sched_context {
  60         ast_mutex_t lock;
  61         unsigned int eventcnt;                  /*!< Number of events processed */
  62         unsigned int schedcnt;                  /*!< Number of outstanding schedule events */
  63         unsigned int highwater;                                 /*!< highest count so far */
  64         AST_DLLIST_HEAD_NOLOCK(, sched) schedq;   /*!< Schedule entry and main queue */
  65         struct ast_hashtab *schedq_ht;             /*!< hash table for fast searching */
  66
  67 #ifdef SCHED_MAX_CACHE
  68         AST_LIST_HEAD_NOLOCK(, sched) schedc;   /*!< Cache of unused schedule structures and how many */
  69         unsigned int schedccnt;
  70 #endif
  71 };
  72
  73
  74 /* hash routines for sched */
  75
  76 static int sched_cmp(const void *a, const void *b)
  77 {
  78         const struct sched *as = a;
  79         const struct sched *bs = b;
  80         return as->id != bs->id; /* return 0 on a match like strcmp would */
  81 }
  82
  83 static unsigned int sched_hash(const void *obj)
  84 {
  85         const struct sched *s = obj;
  86         unsigned int h = s->id;
  87         return h;
  88 }
  89
  90 struct sched_context *sched_context_create(void)
  91 {
  92         struct sched_context *tmp;
  93
  94         if (!(tmp = ast_calloc(1, sizeof(*tmp))))
  95                 return NULL;
  96
  97         ast_mutex_init(&tmp->lock);
  98         tmp->eventcnt = 1;
  99
 100         tmp->schedq_ht = ast_hashtab_create(23, sched_cmp, ast_hashtab_resize_java, ast_hashtab_newsize_java, sched_hash, 1);
 101
 102         return tmp;
 103 }
 104
 105 void sched_context_destroy(struct sched_context *con)
 106 {
 107         struct sched *s;
 108
 109         ast_mutex_lock(&con->lock);
 110
 111 #ifdef SCHED_MAX_CACHE
 112         /* Eliminate the cache */
 113         while ((s = AST_LIST_REMOVE_HEAD(&con->schedc, list)))
 114                 ast_free(s);
 115 #endif
 116
 117         /* And the queue */
 118         while ((s = AST_DLLIST_REMOVE_HEAD(&con->schedq, list)))
 119                 ast_free(s);
 120
 121         ast_hashtab_destroy(con->schedq_ht, NULL);
 122         con->schedq_ht = NULL;
 123
 124         /* And the context */
 125         ast_mutex_unlock(&con->lock);
 126         ast_mutex_destroy(&con->lock);
 127         ast_free(con);
 128 }
 129
 130 static struct sched *sched_alloc(struct sched_context *con)
 131 {
 132         struct sched *tmp;
 133
 134         /*
 135          * We keep a small cache of schedule entries
 136          * to minimize the number of necessary malloc()'s
 137          */
 138 #ifdef SCHED_MAX_CACHE
 139         if ((tmp = AST_LIST_REMOVE_HEAD(&con->schedc, list)))
 140                 con->schedccnt--;
 141         else
 142 #endif
 143                 tmp = ast_calloc(1, sizeof(*tmp));
 144
 145         return tmp;
 146 }
 147
 148 static void sched_release(struct sched_context *con, struct sched *tmp)
 149 {
 150         /*
 151          * Add to the cache, or just free() if we
 152          * already have too many cache entries
 153          */
 154
 155 #ifdef SCHED_MAX_CACHE
 156         if (con->schedccnt < SCHED_MAX_CACHE) {
 157                 AST_LIST_INSERT_HEAD(&con->schedc, tmp, list);
 158                 con->schedccnt++;
 159         } else
 160 #endif
 161                 ast_free(tmp);
 162 }
 163
 164 /*! \brief
 165  * Return the number of milliseconds
 166  * until the next scheduled event
 167  */
 168 int ast_sched_wait(struct sched_context *con)
 169 {
 170         int ms;
 171
 172         DEBUG(ast_debug(1, "ast_sched_wait()\n"));
 173
 174         ast_mutex_lock(&con->lock);
 175         if (AST_DLLIST_EMPTY(&con->schedq)) {
 176                 ms = -1;
 177         } else {
 178                 ms = ast_tvdiff_ms(AST_DLLIST_FIRST(&con->schedq)->when, ast_tvnow());
 179                 if (ms < 0)
 180                         ms = 0;
 181         }
 182         ast_mutex_unlock(&con->lock);
 183
 184         return ms;
 185 }
 186
 187
 188 /*! \brief
 189  * Take a sched structure and put it in the
 190  * queue, such that the soonest event is
 191  * first in the list.
 192  */
 193 static void schedule(struct sched_context *con, struct sched *s)
 194 {
 195         struct sched *cur = NULL;
 196         int ret;
 197         int df = 0;
 198         int de = 0;
 199         struct sched *first = AST_DLLIST_FIRST(&con->schedq);
 200         struct sched *last = AST_DLLIST_LAST(&con->schedq);
 201
 202         if (first)
 203                 df = ast_tvdiff_us(s->when, first->when);
 204         if (last)
 205                 de = ast_tvdiff_us(s->when, last->when);
 206
 207         if (df < 0)
 208                 df = -df;
 209         if (de < 0)
 210                 de = -de;
 211
 212         if (df < de) {
 213                 AST_DLLIST_TRAVERSE(&con->schedq, cur, list) {
 214                         if (ast_tvcmp(s->when, cur->when) == -1) {
 215                                 AST_DLLIST_INSERT_BEFORE(&con->schedq, cur, s, list);
 216                                 break;
 217                         }
 218                 }
 219                 if (!cur) {
 220                         AST_DLLIST_INSERT_TAIL(&con->schedq, s, list);
 221                 }
 222         } else {
 223                 AST_DLLIST_TRAVERSE_BACKWARDS(&con->schedq, cur, list) {
 224                         if (ast_tvcmp(s->when, cur->when) == 1) {
 225                                 AST_DLLIST_INSERT_AFTER(&con->schedq, cur, s, list);
 226                                 break;
 227                         }
 228                 }
 229                 if (!cur) {
 230                         AST_DLLIST_INSERT_HEAD(&con->schedq, s, list);
 231                 }
 232         }
 233
 234         ret = ast_hashtab_insert_safe(con->schedq_ht, s);
 235         if (!ret)
 236                 ast_log(LOG_WARNING,"Schedule Queue entry %d is already in table!\n",s->id);
 237
 238         con->schedcnt++;
 239
 240         if (con->schedcnt > con->highwater)
 241                 con->highwater = con->schedcnt;
 242 }
 243
 244 /*! \brief
 245  * given the last event *tv and the offset in milliseconds 'when',
 246  * computes the next value,
 247  */
 248 static int sched_settime(struct timeval *tv, int when)
 249 {
 250         struct timeval now = ast_tvnow();
 251
 252         /*ast_debug(1, "TV -> %lu,%lu\n", tv->tv_sec, tv->tv_usec);*/
 253         if (ast_tvzero(*tv))    /* not supplied, default to now */
 254                 *tv = now;
 255         *tv = ast_tvadd(*tv, ast_samp2tv(when, 1000));
 256         if (ast_tvcmp(*tv, now) < 0) {
 257                 ast_debug(1, "Request to schedule in the past?!?!\n");
 258                 *tv = now;
 259         }
 260         return 0;
 261 }
 262
 263 int ast_sched_replace_variable(int old_id, struct sched_context *con, int when, ast_sched_cb callback, const void *data, int variable)
 264 {
 265         /* 0 means the schedule item is new; do not delete */
 266         if (old_id > 0) {
 267                 AST_SCHED_DEL(con, old_id);
 268         }
 269         return ast_sched_add_variable(con, when, callback, data, variable);
 270 }
 271
 272 /*! \brief
 273  * Schedule callback(data) to happen when ms into the future
 274  */
 275 int ast_sched_add_variable(struct sched_context *con, int when, ast_sched_cb callback, const void *data, int variable)
 276 {
 277         struct sched *tmp;
 278         int res = -1;
 279         DEBUG(ast_debug(1, "ast_sched_add()\n"));
 280         if (!when) {
 281                 ast_log(LOG_NOTICE, "Scheduled event in 0 ms?\n");
 282                 return -1;
 283         }
 284         ast_mutex_lock(&con->lock);
 285         if ((tmp = sched_alloc(con))) {
 286                 tmp->id = con->eventcnt++;
 287                 tmp->callback = callback;
 288                 tmp->data = data;
 289                 tmp->resched = when;
 290                 tmp->variable = variable;
 291                 tmp->when = ast_tv(0, 0);
 292                 if (sched_settime(&tmp->when, when)) {
 293                         sched_release(con, tmp);
 294                 } else {
 295                         schedule(con, tmp);
 296                         res = tmp->id;
 297                 }
 298         }
 299 #ifdef DUMP_SCHEDULER
 300         /* Dump contents of the context while we have the lock so nothing gets screwed up by accident. */
 301         if (option_debug)
 302                 ast_sched_dump(con);
 303 #endif
 304         ast_mutex_unlock(&con->lock);
 305         return res;
 306 }
 307
 308 int ast_sched_replace(int old_id, struct sched_context *con, int when, ast_sched_cb callback, const void *data)
 309 {
 310         if (old_id > -1) {
 311                 AST_SCHED_DEL(con, old_id);
 312         }
 313         return ast_sched_add(con, when, callback, data);
 314 }
 315
 316 int ast_sched_add(struct sched_context *con, int when, ast_sched_cb callback, const void *data)
 317 {
 318         return ast_sched_add_variable(con, when, callback, data, 0);
 319 }
 320
 321 const void *ast_sched_find_data(struct sched_context *con, int id)
 322 {
 323         struct sched tmp,*res;
 324         tmp.id = id;
 325         res = ast_hashtab_lookup(con->schedq_ht, &tmp);
 326         if (res)
 327                 return res->data;
 328         return NULL;
 329 }
 330
 331 /*! \brief
 332  * Delete the schedule entry with number
 333  * "id".  It's nearly impossible that there
 334  * would be two or more in the list with that
 335  * id.
 336  */
 337 int ast_sched_del(struct sched_context *con, int id)
 338 {
 339         struct sched *s, tmp;
 340
 341         DEBUG(ast_debug(1, "ast_sched_del(%d)\n", id));
 342
 343         ast_mutex_lock(&con->lock);
 344
 345         /* OK, this is the heart of the sched performance upgrade.
 346            If we have 4700 peers, we can have 4700+ entries in the
 347            schedq list. searching this would take time. So, I add a
 348            hashtab to the context to keep track of each entry, by id.
 349            I also leave the linked list alone, almost, --  I implement
 350        a doubly-linked list instead, because it would do little good
 351            to look up the id in a hashtab, and then have to run thru
 352            a couple thousand entries to remove it from the schedq list! */
 353         tmp.id = id;
 354         s = ast_hashtab_lookup(con->schedq_ht, &tmp);
 355         if (s) {
 356                 struct sched *x = AST_DLLIST_REMOVE(&con->schedq, s, list);
 357
 358                 if (!x)
 359                         ast_log(LOG_WARNING,"sched entry %d not in the schedq list?\n", s->id);
 360
 361                 if (!ast_hashtab_remove_this_object(con->schedq_ht, s))
 362                         ast_log(LOG_WARNING,"Found sched entry %d, then couldn't remove it?\n", s->id);
 363                 con->schedcnt--;
 364                 sched_release(con, s);
 365         }
 366
 367 #ifdef DUMP_SCHEDULER
 368         /* Dump contents of the context while we have the lock so nothing gets screwed up by accident. */
 369         if (option_debug)
 370                 ast_sched_dump(con);
 371 #endif
 372         ast_mutex_unlock(&con->lock);
 373
 374         if (!s) {
 375                 ast_debug(1, "Attempted to delete nonexistent schedule entry %d!\n", id);
 376                 ast_assert(0);
 377                 return -1;
 378         }
 379
 380         return 0;
 381 }
 382
 383
 384 char *ast_sched_report(struct sched_context *con, char *buf, int bufsiz, struct ast_cb_names *cbnames)
 385 {
 386         int *countlist,i;
 387         struct sched *cur;
 388         char buf2[1200];
 389         ast_sched_cb xxx = NULL;
 390
 391         buf[0] = 0;
 392         sprintf(buf, " Highwater = %d\n schedcnt = %d\n", con->highwater, con->schedcnt);
 393         countlist = ast_calloc(sizeof(int),cbnames->numassocs+1);
 394
 395         AST_DLLIST_TRAVERSE(&con->schedq, cur, list) {
 396                 /* match the callback to the cblist */
 397                 for (i=0;i<cbnames->numassocs;i++) {
 398                         if (cur->callback == cbnames->cblist[i])
 399                                 break;
 400                 }
 401                 if (i < cbnames->numassocs)
 402                         countlist[i]++;
 403                 else {
 404                         xxx = cur->callback;
 405                         countlist[cbnames->numassocs]++;
 406                 }
 407         }
 408         for (i=0;i<cbnames->numassocs;i++) {
 409                 sprintf(buf2,"    %s : %d\n", cbnames->list[i], countlist[i]);
 410                 strcat(buf, buf2);
 411         }
 412         sprintf(buf2,"   <unknown:%p> : %d\n", xxx, countlist[cbnames->numassocs]);
 413         strcat( buf, buf2);
 414         return buf;
 415 }
 416
 417
 418
 419 /*! \brief Dump the contents of the scheduler to LOG_DEBUG */
 420 void ast_sched_dump(const struct sched_context *con)
 421 {
 422         struct sched *q;
 423         struct timeval tv = ast_tvnow();
 424 #ifdef SCHED_MAX_CACHE
 425         ast_debug(1, "Asterisk Schedule Dump (%d in Q, %d Total, %d Cache, %d high-water)\n", con->schedcnt, con->eventcnt - 1, con->schedccnt, con->highwater);
 426 #else
 427         ast_debug(1, "Asterisk Schedule Dump (%d in Q, %d Total, %d high-water)\n", con->schedcnt, con->eventcnt - 1, con->highwater);
 428 #endif
 429
 430         ast_debug(1, "=============================================================\n");
 431         ast_debug(1, "|ID    Callback          Data              Time  (sec:ms)   |\n");
 432         ast_debug(1, "+-----+-----------------+-----------------+-----------------+\n");
 433         AST_DLLIST_TRAVERSE(&con->schedq, q, list) {
 434                 struct timeval delta = ast_tvsub(q->when, tv);
 435
 436                 ast_debug(1, "|%.4d | %-15p | %-15p | %.6ld : %.6ld |\n",
 437                         q->id,
 438                         q->callback,
 439                         q->data,
 440                         delta.tv_sec,
 441                         (long int)delta.tv_usec);
 442         }
 443         ast_debug(1, "=============================================================\n");
 444
 445 }
 446
 447 /*! \brief
 448  * Launch all events which need to be run at this time.
 449  */
 450 int ast_sched_runq(struct sched_context *con)
 451 {
 452         struct sched *current;
 453         struct timeval tv;
 454         int numevents;
 455         int res;
 456
 457         DEBUG(ast_debug(1, "ast_sched_runq()\n"));
 458
 459         ast_mutex_lock(&con->lock);
 460
 461         for (numevents = 0; !AST_DLLIST_EMPTY(&con->schedq); numevents++) {
 462                 /* schedule all events which are going to expire within 1ms.
 463                  * We only care about millisecond accuracy anyway, so this will
 464                  * help us get more than one event at one time if they are very
 465                  * close together.
 466                  */
 467                 tv = ast_tvadd(ast_tvnow(), ast_tv(0, 1000));
 468                 if (ast_tvcmp(AST_DLLIST_FIRST(&con->schedq)->when, tv) != -1)
 469                         break;
 470
 471                 current = AST_DLLIST_REMOVE_HEAD(&con->schedq, list);
 472                 if (!ast_hashtab_remove_this_object(con->schedq_ht, current))
 473                         ast_log(LOG_ERROR,"Sched entry %d was in the schedq list but not in the hashtab???\n", current->id);
 474
 475                 con->schedcnt--;
 476
 477                 /*
 478                  * At this point, the schedule queue is still intact.  We
 479                  * have removed the first event and the rest is still there,
 480                  * so it's permissible for the callback to add new events, but
 481                  * trying to delete itself won't work because it isn't in
 482                  * the schedule queue.  If that's what it wants to do, it
 483                  * should return 0.
 484                  */
 485
 486                 ast_mutex_unlock(&con->lock);
 487                 res = current->callback(current->data);
 488                 ast_mutex_lock(&con->lock);
 489
 490                 if (res) {
 491                         /*
 492                          * If they return non-zero, we should schedule them to be
 493                          * run again.
 494                          */
 495                         if (sched_settime(&current->when, current->variable? res : current->resched)) {
 496                                 sched_release(con, current);
 497                         } else
 498                                 schedule(con, current);
 499                 } else {
 500                         /* No longer needed, so release it */
 501                         sched_release(con, current);
 502                 }
 503         }
 504
 505         ast_mutex_unlock(&con->lock);
 506
 507         return numevents;
 508 }
 509
 510 long ast_sched_when(struct sched_context *con,int id)
 511 {
 512         struct sched *s, tmp;
 513         long secs = -1;
 514         DEBUG(ast_debug(1, "ast_sched_when()\n"));
 515
 516         ast_mutex_lock(&con->lock);
 517
 518         /* these next 2 lines replace a lookup loop */
 519         tmp.id = id;
 520         s = ast_hashtab_lookup(con->schedq_ht, &tmp);
 521
 522         if (s) {
 523                 struct timeval now = ast_tvnow();
 524                 secs = s->when.tv_sec - now.tv_sec;
 525         }
 526         ast_mutex_unlock(&con->lock);
 527
 528         return secs;
 529 }