Ejemplo n.º 1
0
Archivo: sema.c Proyecto: sindoc/racket
static Scheme_Object *make_sema_repost(int n, Scheme_Object **p)
{
  if (!SCHEME_SEMAP(p[0]))
    scheme_wrong_contract("semaphore-peek-evt", "semaphore?", 0, n, p);
 
  return scheme_make_sema_repost(p[0]);
}
Ejemplo n.º 2
0
Archivo: sema.c Proyecto: sindoc/racket
static Scheme_Object *hit_sema(int n, Scheme_Object **p)
{
  if (!SCHEME_SEMAP(p[0]))
    scheme_wrong_contract("semaphore-post", "semaphore?", 0, n, p);

  scheme_post_sema(p[0]);

  return scheme_void;
}
Ejemplo n.º 3
0
Archivo: sema.c Proyecto: sindoc/racket
static void get_outof_line(Scheme_Sema *sema, Scheme_Channel_Syncer *w)
{
  Scheme_Channel_Syncer *last, *first;

  if (!w->in_line)
    return;
  w->in_line = 0;

  if (SAME_TYPE(SCHEME_TYPE(sema), scheme_never_evt_type)) {
    return; /* !!!! skip everything else */
  } else if (SCHEME_SEMAP(sema)) {
    last = sema->last;
    first = sema->first;
  } else if (SCHEME_CHANNELP(sema)) {
    last = ((Scheme_Channel *)sema)->get_last;
    first = ((Scheme_Channel *)sema)->get_first;
  } else {
    last = ((Scheme_Channel_Put *)sema)->ch->put_last;
    first = ((Scheme_Channel_Put *)sema)->ch->put_first;
  }

  if (w->prev)
    w->prev->next = w->next;
  else
    first = w->next;
  if (w->next)
    w->next->prev = w->prev;
  else
    last = w->prev;

  if (SCHEME_SEMAP(sema)) {
    sema->last = last;
    sema->first = first;
  } else if (SCHEME_CHANNELP(sema)) {
    ((Scheme_Channel *)sema)->get_last = last;
    ((Scheme_Channel *)sema)->get_first = first;
  } else {
    ((Scheme_Channel_Put *)sema)->ch->put_last = last;
    ((Scheme_Channel_Put *)sema)->ch->put_first = first;
  }
}
Ejemplo n.º 4
0
Archivo: sema.c Proyecto: sindoc/racket
static void get_into_line(Scheme_Sema *sema, Scheme_Channel_Syncer *w)
  /* Can be called multiple times. */
{
  Scheme_Channel_Syncer *last, *first;
  
  w->in_line = 1;
  w->picked = 0;

  if (SAME_TYPE(SCHEME_TYPE(sema), scheme_never_evt_type)) {
    return; /* !!!! skip everything else */
  } else if (SCHEME_SEMAP(sema)) {
    last = sema->last;
    first = sema->first;
  } else if (SCHEME_CHANNELP(sema)) {
    last = ((Scheme_Channel *)sema)->get_last;
    first = ((Scheme_Channel *)sema)->get_first;
  } else {
    last = ((Scheme_Channel_Put *)sema)->ch->put_last;
    first = ((Scheme_Channel_Put *)sema)->ch->put_first;
  }

  w->prev = last;
  if (last)
    last->next = w;
  else
    first = w;
  last = w;
  w->next = NULL;

  if (SCHEME_SEMAP(sema)) {
    sema->last = last;
    sema->first = first;
  } else if (SCHEME_CHANNELP(sema)) {
    ((Scheme_Channel *)sema)->get_last = last;
    ((Scheme_Channel *)sema)->get_first = first;
  } else {
    ((Scheme_Channel_Put *)sema)->ch->put_last = last;
    ((Scheme_Channel_Put *)sema)->ch->put_first = first;
  }
}
Ejemplo n.º 5
0
Archivo: sema.c Proyecto: sindoc/racket
static Scheme_Object *semap(int n, Scheme_Object **p)
{
  return SCHEME_SEMAP(p[0]) ? scheme_true : scheme_false;
}
Ejemplo n.º 6
0
Archivo: sema.c Proyecto: edmore/racket
int scheme_wait_semas_chs(int n, Scheme_Object **o, int just_try, Syncing *syncing)
     /* When syncing is supplied, o can contain Scheme_Channel_Syncer
	and never-evt values, and just_try must be 0. */
{
  Scheme_Sema **semas = (Scheme_Sema **)o;
  int v, i, ii;

  if (just_try) {
    /* assert: n == 1, !syncing */
    Scheme_Sema *sema = semas[0];
    if (just_try > 0) {
      if (sema->so.type == scheme_sema_type) {
        v = scheme_try_plain_sema((Scheme_Object *)sema);
      } else {
	v = try_channel(sema, syncing, 0, NULL);
      }
    } else {
      Scheme_Cont_Frame_Data cframe;

      scheme_push_break_enable(&cframe, 1, 1);

      scheme_wait_sema((Scheme_Object *)sema, 0);

      scheme_pop_break_enable(&cframe, 0);

      return 1;
    }
  } else {
    int start_pos;

#if 0
    /* Use the "immutable" flag bit on a semaphore to check for
       inconsistent use in atomic and non-atomic modes, which
       can lead to an attempt to suspend in atomic mode. */
    if ((n == 1) && SCHEME_SEMAP(o[0])) {
      if (!do_atomic) {
        SCHEME_SET_IMMUTABLE(o[0]);
      } else if (SCHEME_IMMUTABLEP(o[0])) {
        if (!on_atomic_timeout
            || (do_atomic > atomic_timeout_atomic_level)) {
          scheme_signal_error("using a seaphore in both atomic and non-atomic mode");
        }
      }
    }
#endif

    if (n > 1) {
      if (syncing)
	start_pos = syncing->start_pos;
      else {
	Scheme_Object *rand_state;
	rand_state = scheme_get_param(scheme_current_config(), MZCONFIG_SCHEDULER_RANDOM_STATE);
	start_pos = scheme_rand((Scheme_Random_State *)rand_state);
      }
    } else
      start_pos = 0;

    /* Initial poll */
    while (1) {
      i = 0;
      for (ii = 0; ii < n; ii++) {
        /* Randomized start position for poll ensures fairness: */
        i = (start_pos + ii) % n;

        if (semas[i]->so.type == scheme_sema_type) {
          if (semas[i]->value) {
            if ((semas[i]->value > 0) && (!syncing || !syncing->reposts || !syncing->reposts[i]))
              --semas[i]->value;
            if (syncing) {
	      syncing->result = i + 1;
	      if (syncing->accepts && syncing->accepts[i])
		scheme_accept_sync(syncing, i);
	    }
            break;
          }
        } else if (semas[i]->so.type == scheme_never_evt_type) {
          /* Never ready. */
        } else if (semas[i]->so.type == scheme_channel_syncer_type) {
          if (((Scheme_Channel_Syncer *)semas[i])->picked)
            break;
        } else if (try_channel(semas[i], syncing, i, NULL))
          break;
      }

      if (ii >= n) {
        if (!scheme_wait_until_suspend_ok()) {
          break;
        } else {
          /* there may have been some action on one of the waitables;
             try again, if no result, yet */
          if (syncing && syncing->result) {
            i = syncing->result - 1;
            ii = 0;
            break;
          }
        }
      } else
        break;
    }

    /* In the following, syncers get changed back to channels,
       and channel puts */
    if (ii >= n) {
      Scheme_Channel_Syncer **ws, *w;

      ws = MALLOC_N(Scheme_Channel_Syncer*, n);
      for (i = 0; i < n; i++) {
	if (semas[i]->so.type == scheme_channel_syncer_type) {
	  ws[i] = (Scheme_Channel_Syncer *)semas[i];
	  semas[i] = (Scheme_Sema *)ws[i]->obj;
	} else {
	  w = MALLOC_ONE_RT(Scheme_Channel_Syncer);
	  ws[i] = w;
	  w->so.type = scheme_channel_syncer_type;
	  w->p = scheme_current_thread;
	  w->syncing = syncing;
	  w->obj = (Scheme_Object *)semas[i];
	  w->syncing_i = i;
	}
      }
      
      while (1) {
	int out_of_a_line;

	/* Get into line */
	for (i = 0; i < n; i++) {
	  if (!ws[i]->in_line) {
	    get_into_line(semas[i], ws[i]);
	  }
	}

	if (!scheme_current_thread->next) {
	  void **a;

	  /* We're not allowed to suspend the main thread. Delay
	     breaks so we get a chance to clean up. */
	  scheme_current_thread->suspend_break++;

	  a = MALLOC_N(void*, 3);
	  a[0] = scheme_make_integer(n);
	  a[1] = ws;
	  a[2] = scheme_current_thread;
	  
	  scheme_main_was_once_suspended = 0;

	  scheme_block_until(out_of_line, NULL, (Scheme_Object *)a, (float)0.0);
	  
	  --scheme_current_thread->suspend_break;
	} else {
	  /* Mark the thread to indicate that we need to clean up
	     if the thread is killed. */
	  int old_nkc;
	  old_nkc = (scheme_current_thread->running & MZTHREAD_NEED_KILL_CLEANUP);
	  if (!old_nkc)
	    scheme_current_thread->running += MZTHREAD_NEED_KILL_CLEANUP;
	  scheme_weak_suspend_thread(scheme_current_thread);
	  if (!old_nkc && (scheme_current_thread->running & MZTHREAD_NEED_KILL_CLEANUP))
	    scheme_current_thread->running -= MZTHREAD_NEED_KILL_CLEANUP;
	}

	/* We've been resumed. But was it for the semaphore, or a signal? */
	out_of_a_line = 0;
	
	/* If we get the post, we must return WITHOUT BLOCKING. 
	   GRacket, for example, depends on this special property, which
	   ensures that the thread can't be broken or killed between
	   receiving the post and returning. */

	if (!syncing) {
	  /* Poster can't be sure that we really will get it,
	     so we have to decrement the sema count here. */
	  i = 0;
	  for (ii = 0; ii < n; ii++) {
	    i = (start_pos + ii) % n;
	    if (ws[i]->picked) {
	      out_of_a_line = 1;
	      if (semas[i]->value) {
		if (semas[i]->value > 0)
		  --(semas[i]->value);
		break;
	      }
	    }
	  }
	  if (ii >= n)
	    i = n;
	} else {
	  if (syncing->result) {
	    out_of_a_line = 1;
	    i = syncing->result - 1;
	  } else {
	    out_of_a_line = 0;
	    i = n;
	  }
	}

	if (!out_of_a_line) {
	  /* We weren't woken by any semaphore/channel. Get out of line, block once 
	     (to handle breaks/kills) and then loop to get back into line. */
	  for (i = 0; i < n; i++) {
	    if (ws[i]->in_line)
	      get_outof_line(semas[i], ws[i]);
	  }
	  
	  scheme_thread_block(0); /* ok if it returns multiple times */ 
	  scheme_current_thread->ran_some = 1;
	  /* [but why would it return multiple times?! there must have been a reason...] */
	} else {

	  if ((scheme_current_thread->running & MZTHREAD_KILLED)
	      || ((scheme_current_thread->running & MZTHREAD_USER_SUSPENDED)
		  && !(scheme_current_thread->running & MZTHREAD_NEED_SUSPEND_CLEANUP))) {
	    /* We've been killed or suspended! */
	    i = -1;
	  }

	  /* We got a post from semas[i], or we were killed. 
	     Did any (other) semaphore pick us?
	     (This only happens when syncing == NULL.) */
	  if (!syncing) {
	    int j;

	    for (j = 0; j < n; j++) {
	      if (j != i) {
		if (ws[j]->picked) {
		  if (semas[j]->value) {
		    /* Consume the value and repost, because no one else
		       has been told to go, and we're accepting a different post. */
		    if (semas[j]->value > 0)
		      --semas[j]->value;
		    scheme_post_sema((Scheme_Object *)semas[j]);
		  }
		}
	      }
	    }
	  }

	  /* If we're done, get out of all lines that we're still in. */
	  if (i < n) {
	    int j;
	    for (j = 0; j < n; j++) {
	      if (ws[j]->in_line)
		get_outof_line(semas[j], ws[j]);
	    }
	  }

	  if (i == -1) {
	    scheme_thread_block(0); /* dies or suspends */
	    scheme_current_thread->ran_some = 1;
	  }

	  if (i < n)
	    break;
	}

	/* Otherwise: !syncing and someone stole the post, or we were
	   suspended and we have to start over. Either way, poll then
	   loop to get back in line an try again. */
	for (ii = 0; ii < n; ii++) {
	  i = (start_pos + ii) % n;

	  if (semas[i]->so.type == scheme_sema_type) {
	    if (semas[i]->value) {
	      if ((semas[i]->value > 0) && (!syncing || !syncing->reposts || !syncing->reposts[i]))
		--semas[i]->value;
              if (syncing && syncing->accepts && syncing->accepts[i])
                scheme_accept_sync(syncing, i);
	      break;
	    }
	  }  else if (semas[i]->so.type == scheme_never_evt_type) {
	    /* Never ready. */
	  } else if (try_channel(semas[i], syncing, i, NULL))
	    break;
	}

	if (ii < n) {
	  /* Get out of any line that we still might be in: */
	  int j;
	  for (j = 0; j < n; j++) {
	    if (ws[j]->in_line)
	      get_outof_line(semas[j], ws[j]);
	  }

	  break;
	}

	if (!syncing) {
	  /* Looks like this thread is a victim of unfair semaphore access.
	     Go into fair mode by allocating a syncing: */
	  syncing = MALLOC_ONE_RT(Syncing);
#ifdef MZTAG_REQUIRED
	  syncing->type = scheme_rt_syncing;
#endif
	  syncing->start_pos = start_pos;

	  /* Get out of all lines, and set syncing field before we get back in line: */
	  {
	    int j;
	    for (j = 0; j < n; j++) {
	      if (ws[j]->in_line)
		get_outof_line(semas[j], ws[j]);
	      ws[j]->syncing = syncing;
	    }
	  }
	}
	/* Back to top of loop to sync again */
      }