sched.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2010, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 * Russell Bryant <russell@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief Scheduler Routines (from cheops-NG)
 *
 * \author Mark Spencer <markster@digium.com>
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 369013 $")

#ifdef DEBUG_SCHEDULER
#define DEBUG(a) do { \
   if (option_debug) \
      DEBUG_M(a) \
   } while (0)
#else
#define DEBUG(a)
#endif

#include <sys/time.h>

#include "asterisk/sched.h"
#include "asterisk/channel.h"
#include "asterisk/lock.h"
#include "asterisk/utils.h"
#include "asterisk/linkedlists.h"
#include "asterisk/dlinkedlists.h"
#include "asterisk/hashtab.h"
#include "asterisk/heap.h"
#include "asterisk/threadstorage.h"

/*!
 * \brief Max num of schedule structs
 *
 * \note The max number of schedule structs to keep around
 * for use.  Undefine to disable schedule structure
 * caching. (Only disable this on very low memory
 * machines)
 */
#define SCHED_MAX_CACHE 128

AST_THREADSTORAGE(last_del_id);

struct sched {
   AST_LIST_ENTRY(sched) list;
   int id;                       /*!< ID number of event */
   struct timeval when;          /*!< Absolute time event should take place */
   int resched;                  /*!< When to reschedule */
   int variable;                 /*!< Use return value from callback to reschedule */
   const void *data;             /*!< Data */
   ast_sched_cb callback;        /*!< Callback */
   ssize_t __heap_index;
};

struct sched_thread {
   pthread_t thread;
   ast_cond_t cond;
   unsigned int stop:1;
};

struct ast_sched_context {
   ast_mutex_t lock;
   unsigned int eventcnt;                  /*!< Number of events processed */
   unsigned int schedcnt;                  /*!< Number of outstanding schedule events */
   unsigned int highwater;             /*!< highest count so far */
   struct ast_hashtab *schedq_ht;             /*!< hash table for fast searching */
   struct ast_heap *sched_heap;
   struct sched_thread *sched_thread;

#ifdef SCHED_MAX_CACHE
   AST_LIST_HEAD_NOLOCK(, sched) schedc;   /*!< Cache of unused schedule structures and how many */
   unsigned int schedccnt;
#endif
};

static void *sched_run(void *data)
{
   struct ast_sched_context *con = data;

   while (!con->sched_thread->stop) {
      int ms;
      struct timespec ts = {
         .tv_sec = 0,
      };

      ast_mutex_lock(&con->lock);

      if (con->sched_thread->stop) {
         ast_mutex_unlock(&con->lock);
         return NULL;
      }

      ms = ast_sched_wait(con);

      if (ms == -1) {
         ast_cond_wait(&con->sched_thread->cond, &con->lock);
      } else {
         struct timeval tv;
         tv = ast_tvadd(ast_tvnow(), ast_samp2tv(ms, 1000));
         ts.tv_sec = tv.tv_sec;
         ts.tv_nsec = tv.tv_usec * 1000;
         ast_cond_timedwait(&con->sched_thread->cond, &con->lock, &ts);
      }

      ast_mutex_unlock(&con->lock);

      if (con->sched_thread->stop) {
         return NULL;
      }

      ast_sched_runq(con);
   }

   return NULL;
}

static void sched_thread_destroy(struct ast_sched_context *con)
{
   if (!con->sched_thread) {
      return;
   }

   if (con->sched_thread->thread != AST_PTHREADT_NULL) {
      ast_mutex_lock(&con->lock);
      con->sched_thread->stop = 1;
      ast_cond_signal(&con->sched_thread->cond);
      ast_mutex_unlock(&con->lock);
      pthread_join(con->sched_thread->thread, NULL);
      con->sched_thread->thread = AST_PTHREADT_NULL;
   }

   ast_cond_destroy(&con->sched_thread->cond);

   ast_free(con->sched_thread);

   con->sched_thread = NULL;
}

int ast_sched_start_thread(struct ast_sched_context *con)
{
   struct sched_thread *st;

   if (con->sched_thread) {
      ast_log(LOG_ERROR, "Thread already started on this scheduler context\n");
      return -1;
   }

   if (!(st = ast_calloc(1, sizeof(*st)))) {
      return -1;
   }

   ast_cond_init(&st->cond, NULL);

   st->thread = AST_PTHREADT_NULL;

   con->sched_thread = st;

   if (ast_pthread_create_background(&st->thread, NULL, sched_run, con)) {
      ast_log(LOG_ERROR, "Failed to create scheduler thread\n");
      sched_thread_destroy(con);
      return -1;
   }

   return 0;
}

static int sched_cmp(const void *a, const void *b)
{
   const struct sched *as = a;
   const struct sched *bs = b;
   return as->id != bs->id; /* return 0 on a match like strcmp would */
}

static unsigned int sched_hash(const void *obj)
{
   const struct sched *s = obj;
   unsigned int h = s->id;
   return h;
}

static int sched_time_cmp(void *a, void *b)
{
   return ast_tvcmp(((struct sched *) b)->when, ((struct sched *) a)->when);
}

struct ast_sched_context *ast_sched_context_create(void)
{
   struct ast_sched_context *tmp;

   if (!(tmp = ast_calloc(1, sizeof(*tmp)))) {
      return NULL;
   }

   ast_mutex_init(&tmp->lock);
   tmp->eventcnt = 1;

   tmp->schedq_ht = ast_hashtab_create(23, sched_cmp, ast_hashtab_resize_java, ast_hashtab_newsize_java, sched_hash, 1);

   if (!(tmp->sched_heap = ast_heap_create(8, sched_time_cmp,
         offsetof(struct sched, __heap_index)))) {
      ast_sched_context_destroy(tmp);
      return NULL;
   }

   return tmp;
}

void ast_sched_context_destroy(struct ast_sched_context *con)
{
   struct sched *s;

   sched_thread_destroy(con);
   con->sched_thread = NULL;

   ast_mutex_lock(&con->lock);

#ifdef SCHED_MAX_CACHE
   while ((s = AST_LIST_REMOVE_HEAD(&con->schedc, list))) {
      ast_free(s);
   }
#endif

   if (con->sched_heap) {
      while ((s = ast_heap_pop(con->sched_heap))) {
         ast_free(s);
      }
      ast_heap_destroy(con->sched_heap);
      con->sched_heap = NULL;
   }

   ast_hashtab_destroy(con->schedq_ht, NULL);
   con->schedq_ht = NULL;

   ast_mutex_unlock(&con->lock);
   ast_mutex_destroy(&con->lock);

   ast_free(con);
}

static struct sched *sched_alloc(struct ast_sched_context *con)
{
   struct sched *tmp;

   /*
    * We keep a small cache of schedule entries
    * to minimize the number of necessary malloc()'s
    */
#ifdef SCHED_MAX_CACHE
   if ((tmp = AST_LIST_REMOVE_HEAD(&con->schedc, list)))
      con->schedccnt--;
   else
#endif
      tmp = ast_calloc(1, sizeof(*tmp));

   return tmp;
}

static void sched_release(struct ast_sched_context *con, struct sched *tmp)
{
   /*
    * Add to the cache, or just free() if we
    * already have too many cache entries
    */

#ifdef SCHED_MAX_CACHE
   if (con->schedccnt < SCHED_MAX_CACHE) {
      AST_LIST_INSERT_HEAD(&con->schedc, tmp, list);
      con->schedccnt++;
   } else
#endif
      ast_free(tmp);
}

/*! \brief
 * Return the number of milliseconds
 * until the next scheduled event
 */
int ast_sched_wait(struct ast_sched_context *con)
{
   int ms;
   struct sched *s;

   DEBUG(ast_debug(1, "ast_sched_wait()\n"));

   ast_mutex_lock(&con->lock);
   if ((s = ast_heap_peek(con->sched_heap, 1))) {
      ms = ast_tvdiff_ms(s->when, ast_tvnow());
      if (ms < 0) {
         ms = 0;
      }
   } else {
      ms = -1;
   }
   ast_mutex_unlock(&con->lock);

   return ms;
}


/*! \brief
 * Take a sched structure and put it in the
 * queue, such that the soonest event is
 * first in the list.
 */
static void schedule(struct ast_sched_context *con, struct sched *s)
{
   ast_heap_push(con->sched_heap, s);

   if (!ast_hashtab_insert_safe(con->schedq_ht, s)) {
      ast_log(LOG_WARNING,"Schedule Queue entry %d is already in table!\n", s->id);
   }

   con->schedcnt++;

   if (con->schedcnt > con->highwater) {
      con->highwater = con->schedcnt;
   }
}

/*! \brief
 * given the last event *tv and the offset in milliseconds 'when',
 * computes the next value,
 */
static int sched_settime(struct timeval *t, int when)
{
   struct timeval now = ast_tvnow();

   /*ast_debug(1, "TV -> %lu,%lu\n", tv->tv_sec, tv->tv_usec);*/
   if (ast_tvzero(*t))  /* not supplied, default to now */
      *t = now;
   *t = ast_tvadd(*t, ast_samp2tv(when, 1000));
   if (ast_tvcmp(*t, now) < 0) {
      *t = now;
   }
   return 0;
}

int ast_sched_replace_variable(int old_id, struct ast_sched_context *con, int when, ast_sched_cb callback, const void *data, int variable)
{
   /* 0 means the schedule item is new; do not delete */
   if (old_id > 0) {
      AST_SCHED_DEL(con, old_id);
   }
   return ast_sched_add_variable(con, when, callback, data, variable);
}

/*! \brief
 * Schedule callback(data) to happen when ms into the future
 */
int ast_sched_add_variable(struct ast_sched_context *con, int when, ast_sched_cb callback, const void *data, int variable)
{
   struct sched *tmp;
   int res = -1;

   DEBUG(ast_debug(1, "ast_sched_add()\n"));

   ast_mutex_lock(&con->lock);
   if ((tmp = sched_alloc(con))) {
      tmp->id = con->eventcnt++;
      tmp->callback = callback;
      tmp->data = data;
      tmp->resched = when;
      tmp->variable = variable;
      tmp->when = ast_tv(0, 0);
      if (sched_settime(&tmp->when, when)) {
         sched_release(con, tmp);
      } else {
         schedule(con, tmp);
         res = tmp->id;
      }
   }
#ifdef DUMP_SCHEDULER
   /* Dump contents of the context while we have the lock so nothing gets screwed up by accident. */
   if (option_debug)
      ast_sched_dump(con);
#endif
   if (con->sched_thread) {
      ast_cond_signal(&con->sched_thread->cond);
   }
   ast_mutex_unlock(&con->lock);

   return res;
}

int ast_sched_replace(int old_id, struct ast_sched_context *con, int when, ast_sched_cb callback, const void *data)
{
   if (old_id > -1) {
      AST_SCHED_DEL(con, old_id);
   }
   return ast_sched_add(con, when, callback, data);
}

int ast_sched_add(struct ast_sched_context *con, int when, ast_sched_cb callback, const void *data)
{
   return ast_sched_add_variable(con, when, callback, data, 0);
}

const void *ast_sched_find_data(struct ast_sched_context *con, int id)
{
   struct sched tmp,*res;
   tmp.id = id;
   res = ast_hashtab_lookup(con->schedq_ht, &tmp);
   if (res)
      return res->data;
   return NULL;
}

/*! \brief
 * Delete the schedule entry with number
 * "id".  It's nearly impossible that there
 * would be two or more in the list with that
 * id.
 */
#ifndef AST_DEVMODE
int ast_sched_del(struct ast_sched_context *con, int id)
#else
int _ast_sched_del(struct ast_sched_context *con, int id, const char *file, int line, const char *function)
#endif
{
   struct sched *s, tmp = {
      .id = id,
   };
   int *last_id = ast_threadstorage_get(&last_del_id, sizeof(int));

   DEBUG(ast_debug(1, "ast_sched_del(%d)\n", id));

   if (id < 0) {
      return 0;
   }

   ast_mutex_lock(&con->lock);
   s = ast_hashtab_lookup(con->schedq_ht, &tmp);
   if (s) {
      if (!ast_heap_remove(con->sched_heap, s)) {
         ast_log(LOG_WARNING,"sched entry %d not in the sched heap?\n", s->id);
      }

      if (!ast_hashtab_remove_this_object(con->schedq_ht, s)) {
         ast_log(LOG_WARNING,"Found sched entry %d, then couldn't remove it?\n", s->id);
      }

      con->schedcnt--;

      sched_release(con, s);
   }

#ifdef DUMP_SCHEDULER
   /* Dump contents of the context while we have the lock so nothing gets screwed up by accident. */
   if (option_debug)
      ast_sched_dump(con);
#endif
   if (con->sched_thread) {
      ast_cond_signal(&con->sched_thread->cond);
   }
   ast_mutex_unlock(&con->lock);

   if (!s && *last_id != id) {
      ast_debug(1, "Attempted to delete nonexistent schedule entry %d!\n", id);
#ifndef AST_DEVMODE
      ast_assert(s != NULL);
#else
      {
      char buf[100];
      snprintf(buf, sizeof(buf), "s != NULL, id=%d", id);
      _ast_assert(0, buf, file, line, function);
      }
#endif
      *last_id = id;
      return -1;
   } else if (!s) {
      return -1;
   }

   return 0;
}

void ast_sched_report(struct ast_sched_context *con, struct ast_str **buf, struct ast_cb_names *cbnames)
{
   int i, x;
   struct sched *cur;
   int countlist[cbnames->numassocs + 1];
   size_t heap_size;

   memset(countlist, 0, sizeof(countlist));
   ast_str_set(buf, 0, " Highwater = %d\n schedcnt = %d\n", con->highwater, con->schedcnt);

   ast_mutex_lock(&con->lock);

   heap_size = ast_heap_size(con->sched_heap);
   for (x = 1; x <= heap_size; x++) {
      cur = ast_heap_peek(con->sched_heap, x);
      /* match the callback to the cblist */
      for (i = 0; i < cbnames->numassocs; i++) {
         if (cur->callback == cbnames->cblist[i]) {
            break;
         }
      }
      if (i < cbnames->numassocs) {
         countlist[i]++;
      } else {
         countlist[cbnames->numassocs]++;
      }
   }

   ast_mutex_unlock(&con->lock);

   for (i = 0; i < cbnames->numassocs; i++) {
      ast_str_append(buf, 0, "    %s : %d\n", cbnames->list[i], countlist[i]);
   }

   ast_str_append(buf, 0, "   <unknown> : %d\n", countlist[cbnames->numassocs]);
}

/*! \brief Dump the contents of the scheduler to LOG_DEBUG */
void ast_sched_dump(struct ast_sched_context *con)
{
   struct sched *q;
   struct timeval when = ast_tvnow();
   int x;
   size_t heap_size;
#ifdef SCHED_MAX_CACHE
   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);
#else
   ast_debug(1, "Asterisk Schedule Dump (%d in Q, %d Total, %d high-water)\n", con->schedcnt, con->eventcnt - 1, con->highwater);
#endif

   ast_debug(1, "=============================================================\n");
   ast_debug(1, "|ID    Callback          Data              Time  (sec:ms)   |\n");
   ast_debug(1, "+-----+-----------------+-----------------+-----------------+\n");
   ast_mutex_lock(&con->lock);
   heap_size = ast_heap_size(con->sched_heap);
   for (x = 1; x <= heap_size; x++) {
      struct timeval delta;
      q = ast_heap_peek(con->sched_heap, x);
      delta = ast_tvsub(q->when, when);
      ast_debug(1, "|%.4d | %-15p | %-15p | %.6ld : %.6ld |\n",
         q->id,
         q->callback,
         q->data,
         (long)delta.tv_sec,
         (long int)delta.tv_usec);
   }
   ast_mutex_unlock(&con->lock);
   ast_debug(1, "=============================================================\n");
}

/*! \brief
 * Launch all events which need to be run at this time.
 */
int ast_sched_runq(struct ast_sched_context *con)
{
   struct sched *current;
   struct timeval when;
   int numevents;
   int res;

   DEBUG(ast_debug(1, "ast_sched_runq()\n"));

   ast_mutex_lock(&con->lock);

   when = ast_tvadd(ast_tvnow(), ast_tv(0, 1000));
   for (numevents = 0; (current = ast_heap_peek(con->sched_heap, 1)); numevents++) {
      /* schedule all events which are going to expire within 1ms.
       * We only care about millisecond accuracy anyway, so this will
       * help us get more than one event at one time if they are very
       * close together.
       */
      if (ast_tvcmp(current->when, when) != -1) {
         break;
      }

      current = ast_heap_pop(con->sched_heap);

      if (!ast_hashtab_remove_this_object(con->schedq_ht, current)) {
         ast_log(LOG_ERROR,"Sched entry %d was in the schedq list but not in the hashtab???\n", current->id);
      }

      con->schedcnt--;

      /*
       * At this point, the schedule queue is still intact.  We
       * have removed the first event and the rest is still there,
       * so it's permissible for the callback to add new events, but
       * trying to delete itself won't work because it isn't in
       * the schedule queue.  If that's what it wants to do, it
       * should return 0.
       */

      ast_mutex_unlock(&con->lock);
      res = current->callback(current->data);
      ast_mutex_lock(&con->lock);

      if (res) {
         /*
          * If they return non-zero, we should schedule them to be
          * run again.
          */
         if (sched_settime(&current->when, current->variable? res : current->resched)) {
            sched_release(con, current);
         } else {
            schedule(con, current);
         }
      } else {
         /* No longer needed, so release it */
         sched_release(con, current);
      }
   }

   ast_mutex_unlock(&con->lock);

   return numevents;
}

long ast_sched_when(struct ast_sched_context *con,int id)
{
   struct sched *s, tmp;
   long secs = -1;
   DEBUG(ast_debug(1, "ast_sched_when()\n"));

   ast_mutex_lock(&con->lock);

   /* these next 2 lines replace a lookup loop */
   tmp.id = id;
   s = ast_hashtab_lookup(con->schedq_ht, &tmp);

   if (s) {
      struct timeval now = ast_tvnow();
      secs = s->when.tv_sec - now.tv_sec;
   }
   ast_mutex_unlock(&con->lock);

   return secs;
}