[bpt/emacs.git] / src / atimer.c

/* Asynchronous timers.
   Copyright (C) 2000 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs 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, or (at your option)
any later version.

GNU Emacs 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 GNU Emacs; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

#include <config.h>
#include <lisp.h>
#include <signal.h>
#include <syssignal.h>
#include <systime.h>
#include <blockinput.h>
#include <atimer.h>
#include <stdio.h>

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif

/* The ubiquitous min/max macros.  */

#define max(X, Y) ((X) > (Y) ? (X) : (Y))
#define min(X, Y) ((X) < (Y) ? (X) : (Y))

/* Free-list of atimer structures.  */

static struct atimer *free_atimers;

/* List of currently not running timers due to a call to
   lock_atimer.  */

static struct atimer *stopped_atimers;

/* List of active atimers, sorted by expiration time.  The timer that
   will become ripe next is always at the front of this list.  */

static struct atimer *atimers;

/* Non-zero means alarm_signal_handler has found ripe timers but
   interrupt_input_blocked was non-zero.  In this case, timer
   functions are not called until the next UNBLOCK_INPUT because timer
   functions are expected to call X, and X cannot be assumed to be
   reentrant.  */

int pending_atimers;

/* Block/unblock SIGALRM.. */

#define BLOCK_ATIMERS   sigblock (sigmask (SIGALRM))
#define UNBLOCK_ATIMERS sigunblock (sigmask (SIGALRM))

/* Function prototypes.  */

static void set_alarm P_ ((void));
static void schedule_atimer P_ ((struct atimer *));
static struct atimer *append_atimer_lists P_ ((struct atimer *,
					       struct atimer *));
SIGTYPE alarm_signal_handler ();


/* Start a new atimer of type TYPE.  TIME specifies when the timer is
   ripe.  FN is the function to call when the timer fires.
   CLIENT_DATA is stored in the client_data member of the atimer
   structure returned and so made available to FN when it is called.

   If TYPE is ATIMER_ABSOLUTE, TIME is the absolute time at which the
   timer fires.

   If TYPE is ATIMER_RELATIVE, the timer is ripe TIME s/us in the
   future.

   In both cases, the timer is automatically freed after it has fired.

   If TYPE is ATIMER_CONTINUOUS, the timer fires every TIME s/us.

   Value is a pointer to the atimer started.  It can be used in calls
   to cancel_atimer; don't free it yourself.  */

struct atimer *
start_atimer (type, time, fn, client_data)
     enum atimer_type type;
     EMACS_TIME time;
     atimer_callback fn;
     void *client_data;
{
  struct atimer *t;

  /* Round TIME up to the next full second if we don't have
     itimers.  */
#ifndef HAVE_SETITIMER
  if (EMACS_USECS (time) != 0)
    {
      EMACS_SET_USECS (time, 0);
      EMACS_SET_SECS (time, EMACS_SECS (time) + 1);
    }
#endif /* not HAVE_SETITIMER */

  /* Get an atimer structure from the free-list, or allocate
     a new one.  */
  if (free_atimers)
    {
      t = free_atimers;
      free_atimers = t->next;
    }
  else
    t = (struct atimer *) xmalloc (sizeof *t);

  /* Fill the atimer structure.  */
  bzero (t, sizeof *t);
  t->type = type;
  t->fn = fn;
  t->client_data = client_data;

  BLOCK_ATIMERS;

  /* Compute the timer's expiration time.  */
  switch (type)
    {
    case ATIMER_ABSOLUTE:
      t->expiration = time;
      break;
      
    case ATIMER_RELATIVE:
      EMACS_GET_TIME (t->expiration);
      EMACS_ADD_TIME (t->expiration, t->expiration, time);
      break;
      
    case ATIMER_CONTINUOUS:
      EMACS_GET_TIME (t->expiration);
      EMACS_ADD_TIME (t->expiration, t->expiration, time);
      t->interval = time;
      break;
    }

  /* Insert the timer in the list of active atimers.  */
  schedule_atimer (t);
  UNBLOCK_ATIMERS;

  /* Arrange for a SIGALRM at the time the next atimer is ripe.  */
  set_alarm ();
  
  return t;
}


/* Cancel and free atimer TIMER.  */

void
cancel_atimer (timer)
     struct atimer *timer;
{
  int i;
  
  BLOCK_ATIMERS;

  for (i = 0; i < 2; ++i)
    {
      struct atimer *t, *prev;
      struct atimer **list = i ? &stopped_atimers : &atimers;
      
      /* See if TIMER is active or stopped.  */
      for (t = *list, prev = NULL; t && t != timer; prev = t, t = t->next)
	;

      /* If it is, take it off the its list, and put in on the
	 free-list.  We don't bother to arrange for setting a
	 different alarm time, since a too early one doesn't hurt.  */
      if (t)
	{
	  if (prev)
	    prev->next = t->next;
	  else
	    *list = t->next;
	  
	  t->next = free_atimers;
	  free_atimers = t;
	  break;
	}
    }

  UNBLOCK_ATIMERS;
}


/* Append two lists of atimers LIST1 and LIST2 and return the
   result list.  */

static struct atimer *
append_atimer_lists (list1, list2)
     struct atimer *list1, *list2;
{
  if (list1 == NULL)
    return list2;
  else if (list2 == NULL)
    return list1;
  else
    {
      struct atimer *p;
      
      for (p = list1; p->next; p = p->next)
	;
      p->next = list2;
      return list1;
    }
}


/* Stop all timers except timer T.  T null means stop all timers.  */

void
stop_other_atimers (t)
     struct atimer *t;
{
  BLOCK_ATIMERS;
  
  if (t)
    {
      struct atimer *p, *prev;
      
      /* See if T is active.  */
      for (p = atimers, prev = 0; p && p != t; p = p->next)
	;

      if (p == t)
	{
	  if (prev)
	    prev->next = t->next;
	  else
	    atimers = t->next;
	  t->next = NULL;
	}
      else
	/* T is not active.  Let's handle this like T == 0.  */
	t = NULL;
    }
  
  stopped_atimers = append_atimer_lists (atimers, stopped_atimers);
  atimers = t;
  UNBLOCK_ATIMERS;
}


/* Run all timers again, if some have been stopped with a call to
   stop_other_atimers.  */

void
run_all_atimers ()
{
  if (stopped_atimers)
    {
      struct atimer *t = atimers;
      struct atimer *next;
      
      BLOCK_ATIMERS;
      atimers = stopped_atimers;
      stopped_atimers = NULL;
      
      while (t)
	{
	  next = t->next;
	  schedule_atimer (t);
	  t = next;
	}
      
      UNBLOCK_ATIMERS;
    }
}


/* A version of run_all_timers suitable for a record_unwind_protect.  */

Lisp_Object
unwind_stop_other_atimers (dummy)
     Lisp_Object dummy;
{
  run_all_atimers ();
  return Qnil;
}


/* Arrange for a SIGALRM to arrive when the next timer is ripe.  */

static void
set_alarm ()
{
#if defined (USG) && !defined (POSIX_SIGNALS)
  /* USG systems forget handlers when they are used;
     must reestablish each time.  */
  signal (SIGALRM, alarm_signal_handler);
#endif /* USG */
  
  if (atimers)
    {
      EMACS_TIME now, time;
#ifdef HAVE_SETITIMER
      struct itimerval it;
#endif

      /* Determine s/us till the next timer is ripe.  */
      EMACS_GET_TIME (now);
      EMACS_SUB_TIME (time, atimers->expiration, now);

#ifdef HAVE_SETITIMER
      /* Don't set the interval to 0; this disables the timer.  */
      if (EMACS_TIME_LE (atimers->expiration, now))
	{
	  EMACS_SET_SECS (time, 0);
	  EMACS_SET_USECS (time, 1000);
	}
      
      bzero (&it, sizeof it);
      it.it_value = time;
      setitimer (ITIMER_REAL, &it, 0);
#else /* not HAVE_SETITIMER */
      alarm (max (EMACS_SECS (time), 1));
#endif /* not HAVE_SETITIMER */
    }
}


/* Insert timer T into the list of active atimers `atimers', keeping
   the list sorted by expiration time.  T must not be in this list
   already.  */

static void
schedule_atimer (t)
     struct atimer *t;
{
  struct atimer *a = atimers, *prev = NULL;

  /* Look for the first atimer that is ripe after T.  */
  while (a && EMACS_TIME_GT (t->expiration, a->expiration))
    prev = a, a = a->next;

  /* Insert T in front of the atimer found, if any.  */
  if (prev)
    prev->next = t;
  else
    atimers = t;
  
  t->next = a;
}


/* Signal handler for SIGALRM.  SIGNO is the signal number, i.e.
   SIGALRM.  */

SIGTYPE
alarm_signal_handler (signo)
     int signo;
{
  EMACS_TIME now;
  
  EMACS_GET_TIME (now);
  pending_atimers = 0;
  
  while (atimers
	 && (pending_atimers = interrupt_input_blocked) == 0
	 && EMACS_TIME_LE (atimers->expiration, now))
    {
      struct atimer *t;
      
      t = atimers;
      atimers = atimers->next;
      t->fn (t);
      
      if (t->type == ATIMER_CONTINUOUS)
	{
	  EMACS_ADD_TIME (t->expiration, now, t->interval);
	  schedule_atimer (t);
	}
      else
	{
	  t->next = free_atimers;
	  free_atimers = t;
	}
      
      EMACS_GET_TIME (now);
    }
  
#if defined (USG) && !defined (POSIX_SIGNALS)
  /* USG systems forget handlers when they are used;
     must reestablish each time.  */
  signal (SIGALRM, alarm_signal_handler);
#endif /* USG */
  
  set_alarm ();
}


/* Call alarm_signal_handler for pending timers.  */

void
do_pending_atimers ()
{
  if (pending_atimers)
    {
      BLOCK_ATIMERS;
      alarm_signal_handler (SIGALRM);
      UNBLOCK_ATIMERS;
    }
}


/* Turn alarms on/off.  This seems to be temporarily necessary on
   some systems like HPUX (see process.c).  */

void
turn_on_atimers (on)
     int on;
{
  if (on)
    {
      signal (SIGALRM, alarm_signal_handler);
      set_alarm ();
    }
  else
    alarm (0);
}


void
init_atimer ()
{
  free_atimers = atimers = NULL;
  pending_atimers = 0;
  signal (SIGALRM, alarm_signal_handler);
}
Commit	Line	Data
e12489f9 GM	1	/* Asynchronous timers.
	2	Copyright (C) 2000 Free Software Foundation, Inc.
	3
	4	This file is part of GNU Emacs.
	5
	6	GNU Emacs is free software; you can redistribute it and/or modify
	7	it under the terms of the GNU General Public License as published by
	8	the Free Software Foundation; either version 2, or (at your option)
	9	any later version.
	10
	11	GNU Emacs is distributed in the hope that it will be useful,
	12	but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	GNU General Public License for more details.
	15
	16	You should have received a copy of the GNU General Public License
	17	along with GNU Emacs; see the file COPYING. If not, write to
	18	the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	19	Boston, MA 02111-1307, USA. */
	20
	21	#include <config.h>
	22	#include <lisp.h>
	23	#include <signal.h>
	24	#include <syssignal.h>
	25	#include <systime.h>
	26	#include <blockinput.h>
	27	#include <atimer.h>
	28	#include <stdio.h>
	29
	30	#ifdef HAVE_UNISTD_H
	31	#include <unistd.h>
	32	#endif
	33
	34	#ifdef HAVE_SYS_TIME_H
	35	#include <sys/time.h>
	36	#endif
	37
	38	/* The ubiquitous min/max macros. */
	39
	40	#define max(X, Y) ((X) > (Y) ? (X) : (Y))
	41	#define min(X, Y) ((X) < (Y) ? (X) : (Y))
	42
	43	/* Free-list of atimer structures. */
	44
	45	static struct atimer *free_atimers;
	46
9c2e3e8d GM	47	/* List of currently not running timers due to a call to
	48	lock_atimer. */
	49
	50	static struct atimer *stopped_atimers;
	51
e12489f9 GM	52	/* List of active atimers, sorted by expiration time. The timer that
	53	will become ripe next is always at the front of this list. */
	54
	55	static struct atimer *atimers;
	56
	57	/* Non-zero means alarm_signal_handler has found ripe timers but
	58	interrupt_input_blocked was non-zero. In this case, timer
	59	functions are not called until the next UNBLOCK_INPUT because timer
	60	functions are expected to call X, and X cannot be assumed to be
	61	reentrant. */
	62
	63	int pending_atimers;
	64
	65	/* Block/unblock SIGALRM.. */
	66
	67	#define BLOCK_ATIMERS sigblock (sigmask (SIGALRM))
	68	#define UNBLOCK_ATIMERS sigunblock (sigmask (SIGALRM))
	69
	70	/* Function prototypes. */
	71
	72	static void set_alarm P_ ((void));
	73	static void schedule_atimer P_ ((struct atimer *));
50b1039f GM	74	static struct atimer append_atimer_lists P_ ((struct atimer ,
50b1039f GM	75	struct atimer *));
a3aca278	76	SIGTYPE alarm_signal_handler ();
e12489f9 GM	77
	78
	79	/* Start a new atimer of type TYPE. TIME specifies when the timer is
	80	ripe. FN is the function to call when the timer fires.
	81	CLIENT_DATA is stored in the client_data member of the atimer
	82	structure returned and so made available to FN when it is called.
	83
	84	If TYPE is ATIMER_ABSOLUTE, TIME is the absolute time at which the
	85	timer fires.
	86
	87	If TYPE is ATIMER_RELATIVE, the timer is ripe TIME s/us in the
	88	future.
	89
	90	In both cases, the timer is automatically freed after it has fired.
	91
	92	If TYPE is ATIMER_CONTINUOUS, the timer fires every TIME s/us.
	93
	94	Value is a pointer to the atimer started. It can be used in calls
	95	to cancel_atimer; don't free it yourself. */
	96
	97	struct atimer *
	98	start_atimer (type, time, fn, client_data)
	99	enum atimer_type type;
	100	EMACS_TIME time;
	101	atimer_callback fn;
	102	void *client_data;
	103	{
	104	struct atimer *t;
	105
	106	/* Round TIME up to the next full second if we don't have
	107	itimers. */
	108	#ifndef HAVE_SETITIMER
	109	if (EMACS_USECS (time) != 0)
	110	{
4ce94f99 EZ	111	EMACS_SET_USECS (time, 0);
4ce94f99 EZ	112	EMACS_SET_SECS (time, EMACS_SECS (time) + 1);
e12489f9 GM	113	}
	114	#endif /* not HAVE_SETITIMER */
	115
	116	/* Get an atimer structure from the free-list, or allocate
	117	a new one. */
	118	if (free_atimers)
	119	{
	120	t = free_atimers;
	121	free_atimers = t->next;
	122	}
	123	else
	124	t = (struct atimer ) xmalloc (sizeof t);
	125
	126	/* Fill the atimer structure. */
	127	bzero (t, sizeof *t);
	128	t->type = type;
	129	t->fn = fn;
	130	t->client_data = client_data;
	131
	132	BLOCK_ATIMERS;
	133
	134	/* Compute the timer's expiration time. */
	135	switch (type)
	136	{
	137	case ATIMER_ABSOLUTE:
	138	t->expiration = time;
	139	break;
	140
	141	case ATIMER_RELATIVE:
	142	EMACS_GET_TIME (t->expiration);
	143	EMACS_ADD_TIME (t->expiration, t->expiration, time);
	144	break;
	145
	146	case ATIMER_CONTINUOUS:
	147	EMACS_GET_TIME (t->expiration);
	148	EMACS_ADD_TIME (t->expiration, t->expiration, time);
	149	t->interval = time;
	150	break;
	151	}
	152
	153	/* Insert the timer in the list of active atimers. */
	154	schedule_atimer (t);
	155	UNBLOCK_ATIMERS;
	156
	157	/* Arrange for a SIGALRM at the time the next atimer is ripe. */
	158	set_alarm ();
	159
	160	return t;
	161	}
	162
	163
	164	/* Cancel and free atimer TIMER. */
	165
	166	void
	167	cancel_atimer (timer)
	168	struct atimer *timer;
	169	{
50b1039f GM	170	int i;
50b1039f GM	171
e12489f9 GM	172	BLOCK_ATIMERS;
e12489f9 GM	173
50b1039f	174	for (i = 0; i < 2; ++i)
94870977	175	{
50b1039f GM	176	struct atimer t, prev;
	177	struct atimer **list = i ? &stopped_atimers : &atimers;
	178
94870977	179	/* See if TIMER is active or stopped. */
4ab1d4be	180	for (t = *list, prev = NULL; t && t != timer; prev = t, t = t->next)
94870977 GM	181	;
94870977 GM	182
50b1039f	183	/* If it is, take it off the its list, and put in on the
94870977 GM	184	free-list. We don't bother to arrange for setting a
	185	different alarm time, since a too early one doesn't hurt. */
	186	if (t)
	187	{
	188	if (prev)
	189	prev->next = t->next;
	190	else
	191	*list = t->next;
	192
	193	t->next = free_atimers;
	194	free_atimers = t;
4ab1d4be	195	break;
94870977	196	}
e12489f9 GM	197	}
	198
	199	UNBLOCK_ATIMERS;
	200	}
	201
	202
50b1039f GM	203	/* Append two lists of atimers LIST1 and LIST2 and return the
	204	result list. */
	205
	206	static struct atimer *
	207	append_atimer_lists (list1, list2)
	208	struct atimer list1, list2;
	209	{
	210	if (list1 == NULL)
	211	return list2;
	212	else if (list2 == NULL)
	213	return list1;
	214	else
	215	{
	216	struct atimer *p;
	217
	218	for (p = list1; p->next; p = p->next)
	219	;
	220	p->next = list2;
	221	return list1;
	222	}
	223	}
	224
	225
	226	/* Stop all timers except timer T. T null means stop all timers. */
9c2e3e8d GM	227
	228	void
	229	stop_other_atimers (t)
	230	struct atimer *t;
	231	{
	232	BLOCK_ATIMERS;
	233
9c2e3e8d GM	234	if (t)
9c2e3e8d GM	235	{
2503c8b1 GM	236	struct atimer p, prev;
	237
	238	/* See if T is active. */
	239	for (p = atimers, prev = 0; p && p != t; p = p->next)
	240	;
	241
	242	if (p == t)
	243	{
	244	if (prev)
	245	prev->next = t->next;
	246	else
	247	atimers = t->next;
	248	t->next = NULL;
	249	}
	250	else
	251	/* T is not active. Let's handle this like T == 0. */
	252	t = NULL;
9c2e3e8d GM	253	}
9c2e3e8d GM	254
50b1039f	255	stopped_atimers = append_atimer_lists (atimers, stopped_atimers);
9c2e3e8d GM	256	atimers = t;
	257	UNBLOCK_ATIMERS;
	258	}
	259
	260
	261	/* Run all timers again, if some have been stopped with a call to
	262	stop_other_atimers. */
	263
	264	void
	265	run_all_atimers ()
	266	{
	267	if (stopped_atimers)
	268	{
	269	struct atimer *t = atimers;
50b1039f GM	270	struct atimer *next;
50b1039f GM	271
9c2e3e8d GM	272	BLOCK_ATIMERS;
	273	atimers = stopped_atimers;
	274	stopped_atimers = NULL;
50b1039f GM	275
	276	while (t)
	277	{
	278	next = t->next;
	279	schedule_atimer (t);
	280	t = next;
	281	}
	282
9c2e3e8d GM	283	UNBLOCK_ATIMERS;
	284	}
	285	}
	286
	287
	288	/* A version of run_all_timers suitable for a record_unwind_protect. */
	289
	290	Lisp_Object
	291	unwind_stop_other_atimers (dummy)
	292	Lisp_Object dummy;
	293	{
	294	run_all_atimers ();
	295	return Qnil;
	296	}
	297
	298
e12489f9 GM	299	/* Arrange for a SIGALRM to arrive when the next timer is ripe. */
	300
	301	static void
	302	set_alarm ()
	303	{
e12489f9 GM	304	#if defined (USG) && !defined (POSIX_SIGNALS)
	305	/* USG systems forget handlers when they are used;
	306	must reestablish each time. */
	307	signal (SIGALRM, alarm_signal_handler);
	308	#endif /* USG */
	309
	310	if (atimers)
	311	{
	312	EMACS_TIME now, time;
	313	#ifdef HAVE_SETITIMER
	314	struct itimerval it;
	315	#endif
	316
	317	/* Determine s/us till the next timer is ripe. */
	318	EMACS_GET_TIME (now);
	319	EMACS_SUB_TIME (time, atimers->expiration, now);
	320
	321	#ifdef HAVE_SETITIMER
	322	/* Don't set the interval to 0; this disables the timer. */
	323	if (EMACS_TIME_LE (atimers->expiration, now))
	324	{
	325	EMACS_SET_SECS (time, 0);
	326	EMACS_SET_USECS (time, 1000);
	327	}
	328
	329	bzero (&it, sizeof it);
	330	it.it_value = time;
	331	setitimer (ITIMER_REAL, &it, 0);
	332	#else /* not HAVE_SETITIMER */
	333	alarm (max (EMACS_SECS (time), 1));
	334	#endif /* not HAVE_SETITIMER */
	335	}
	336	}
	337
	338
	339	/* Insert timer T into the list of active atimers `atimers', keeping
	340	the list sorted by expiration time. T must not be in this list
	341	already. */
	342
	343	static void
	344	schedule_atimer (t)
	345	struct atimer *t;
	346	{
	347	struct atimer a = atimers, prev = NULL;
	348
	349	/* Look for the first atimer that is ripe after T. */
	350	while (a && EMACS_TIME_GT (t->expiration, a->expiration))
	351	prev = a, a = a->next;
	352
	353	/* Insert T in front of the atimer found, if any. */
	354	if (prev)
	355	prev->next = t;
	356	else
	357	atimers = t;
	358
	359	t->next = a;
	360	}
	361
	362
	363	/* Signal handler for SIGALRM. SIGNO is the signal number, i.e.
	364	SIGALRM. */
	365
	366	SIGTYPE
	367	alarm_signal_handler (signo)
368	int signo;
369	{
370	EMACS_TIME now;
371
372	EMACS_GET_TIME (now);
373	pending_atimers = 0;
374
375	while (atimers
376	&& (pending_atimers = interrupt_input_blocked) == 0
377	&& EMACS_TIME_LE (atimers->expiration, now))
378	{
379	struct atimer *t;
380
381	t = atimers;
382	atimers = atimers->next;
383	t->fn (t);
384
385	if (t->type == ATIMER_CONTINUOUS)
386	{
387	EMACS_ADD_TIME (t->expiration, now, t->interval);
388	schedule_atimer (t);
389	}
390	else
391	{
392	t->next = free_atimers;
393	free_atimers = t;
394	}
395
396	EMACS_GET_TIME (now);
397	}
398
399	#if defined (USG) && !defined (POSIX_SIGNALS)
400	/* USG systems forget handlers when they are used;
401	must reestablish each time. */
402	signal (SIGALRM, alarm_signal_handler);
403	#endif /* USG */
404
405	set_alarm ();
406	}
407
408
409	/* Call alarm_signal_handler for pending timers. */
410
411	void
412	do_pending_atimers ()
413	{
414	if (pending_atimers)
415	{
416	BLOCK_ATIMERS;
417	alarm_signal_handler (SIGALRM);
418	UNBLOCK_ATIMERS;
419	}
420	}
421
422
423	/* Turn alarms on/off. This seems to be temporarily necessary on
424	some systems like HPUX (see process.c). */
425
426	void
427	turn_on_atimers (on)
428	int on;
429	{
430	if (on)
431	{
432	signal (SIGALRM, alarm_signal_handler);
433	set_alarm ();
434	}
435	else
436	alarm (0);
437	}
438
439
440	void
441	init_atimer ()
442	{
443	free_atimers = atimers = NULL;
444	pending_atimers = 0;
445	signal (SIGALRM, alarm_signal_handler);
446	}