timer_resched.c

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/*
** Copyright (C) 2005 by Kevin L. Mitchell <klmitch@mit.edu>
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
**
** @(#)$Id: timer_resched.c,v 1.2 2005/09/15 18:14:11 klmitch Exp $
*/
#include "engines_int.h"

RCSTAG("@(#)$Id: timer_resched.c,v 1.2 2005/09/15 18:14:11 klmitch Exp $");

ev_err_t
timer_resched(ev_ctx_t *ctx, ev_tim_t *tim, ev_timtype_t type,
              struct timeval *value)
{
  ev_engine_t *eng;
  ev_err_t err = 0;
  struct timeval ov;
  int tmp;

  ev_init(); /* make sure library is initialized... */

  /* sanity-check the arguments... */
  if (!ec_verify(ctx) || !ti_verify(tim) ||
      (type != TT_ABSOLUTE && type != TT_RELATIVE && type != TT_PERIODIC) ||
      !value || eg_context(tim) != ctx)
    ev_return(EINVAL);

  /* if the generator's been deleted, it's already been removed from the
   * engines and from the timer tree...
   */
  if (!(eg_flags(tim) & EV_GEN_DELETED))
    /* Walk through all the timer engines (last to first)... */
    for (eng = ctx->ec_timer.el_last; eng;
         eng = eng->eng_timer.eti_active.el_prev)
      if ((err = eng_tim_rem(ctx, eng, tim))) { /* remove the timer */
        for (; eng; eng = eng->eng_timer.eti_active.el_prev)
          eng_tim_rem(ctx, eng, tim); /* remove from remaining engines */

        _timer_untree(ctx, tim); /* remove timer from tree */

        eg_flags_set(tim, EV_GEN_DELETED); /* got to delete it... */

        eg_ref_dec(ctx, tim); /* decrement reference count */

        ev_return(err); /* Return the error */
      }

  ov = tim->ti_expire; /* save the old timer value... */

  /* Re-configure timer value and recompute expiration time */
  tim->ti_type = type;
  tim->ti_value = *value;
  ti_expire_comp(tim); /* compute expiration time */

  /* Re-add timer to all the engines... */
  for (eng = ctx->ec_timer.el_first; eng;
       eng = eng->eng_timer.eti_active.el_next)
    if ((err = eng_tim_add(ctx, eng, tim))) { /* add to engine */
      /* oops, error occurred.  Walk engines backwards and remove timer */
      for (; eng; eng = eng->eng_timer.eti_active.el_prev)
        eng_tim_rem(ctx, eng, tim);

      _timer_untree(ctx, tim); /* remove timer from tree */

      eg_flags_set(tim, EV_GEN_DELETED); /* got to delete it... */

      eg_ref_dec(ctx, tim); /* decrement reference count */

      ev_return(err); /* return the error */
    }

  /* Update the tree... */
  if (eg_flags(tim) & EV_GEN_DELETED) /* was timer deleted? */
    err = _timer_insert(ctx, tim); /* then re-insert the timer */
  else if ((tmp = tv_comp(&tim->ti_expire, &ov)) < 0)
    err = _timer_heapify_down(ctx, tim); /* new value is earlier time... */
  else if (tmp > 0) /* new value is later time... */
    err = _timer_heapify_up(ctx, tim);

  if (err) /* did an error occur? */
    timer_destroy(ctx, tim); /* OK, destroy the timer. */
  else
    eg_flags_clr(tim, EV_GEN_DELETED); /* clear the deleted flag */

  ev_return(err);
}

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