[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 *));


/* 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 = 0; t && t != timer; 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;
	}
    }

  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 *));
e12489f9 GM	76
	77
	78	/* Start a new atimer of type TYPE. TIME specifies when the timer is
	79	ripe. FN is the function to call when the timer fires.
	80	CLIENT_DATA is stored in the client_data member of the atimer
	81	structure returned and so made available to FN when it is called.
	82
	83	If TYPE is ATIMER_ABSOLUTE, TIME is the absolute time at which the
	84	timer fires.
	85
	86	If TYPE is ATIMER_RELATIVE, the timer is ripe TIME s/us in the
	87	future.
	88
	89	In both cases, the timer is automatically freed after it has fired.
	90
	91	If TYPE is ATIMER_CONTINUOUS, the timer fires every TIME s/us.
	92
	93	Value is a pointer to the atimer started. It can be used in calls
	94	to cancel_atimer; don't free it yourself. */
	95
	96	struct atimer *
	97	start_atimer (type, time, fn, client_data)
	98	enum atimer_type type;
	99	EMACS_TIME time;
	100	atimer_callback fn;
	101	void *client_data;
	102	{
	103	struct atimer *t;
	104
	105	/* Round TIME up to the next full second if we don't have
	106	itimers. */
	107	#ifndef HAVE_SETITIMER
	108	if (EMACS_USECS (time) != 0)
	109	{
4ce94f99 EZ	110	EMACS_SET_USECS (time, 0);
4ce94f99 EZ	111	EMACS_SET_SECS (time, EMACS_SECS (time) + 1);
e12489f9 GM	112	}
	113	#endif /* not HAVE_SETITIMER */
	114
	115	/* Get an atimer structure from the free-list, or allocate
	116	a new one. */
	117	if (free_atimers)
	118	{
	119	t = free_atimers;
	120	free_atimers = t->next;
	121	}
	122	else
	123	t = (struct atimer ) xmalloc (sizeof t);
	124
	125	/* Fill the atimer structure. */
	126	bzero (t, sizeof *t);
	127	t->type = type;
	128	t->fn = fn;
	129	t->client_data = client_data;
	130
	131	BLOCK_ATIMERS;
	132
	133	/* Compute the timer's expiration time. */
	134	switch (type)
	135	{
	136	case ATIMER_ABSOLUTE:
	137	t->expiration = time;
	138	break;
	139
	140	case ATIMER_RELATIVE:
	141	EMACS_GET_TIME (t->expiration);
	142	EMACS_ADD_TIME (t->expiration, t->expiration, time);
	143	break;
	144
	145	case ATIMER_CONTINUOUS:
	146	EMACS_GET_TIME (t->expiration);
	147	EMACS_ADD_TIME (t->expiration, t->expiration, time);
	148	t->interval = time;
	149	break;
	150	}
	151
	152	/* Insert the timer in the list of active atimers. */
	153	schedule_atimer (t);
	154	UNBLOCK_ATIMERS;
	155
	156	/* Arrange for a SIGALRM at the time the next atimer is ripe. */
	157	set_alarm ();
	158
	159	return t;
	160	}
	161
	162
	163	/* Cancel and free atimer TIMER. */
	164
	165	void
	166	cancel_atimer (timer)
	167	struct atimer *timer;
	168	{
50b1039f GM	169	int i;
50b1039f GM	170
e12489f9 GM	171	BLOCK_ATIMERS;
e12489f9 GM	172
50b1039f	173	for (i = 0; i < 2; ++i)
94870977	174	{
50b1039f GM	175	struct atimer t, prev;
	176	struct atimer **list = i ? &stopped_atimers : &atimers;
	177
94870977	178	/* See if TIMER is active or stopped. */
94870977 GM	179	for (t = *list, prev = 0; t && t != timer; t = t->next)
	180	;
	181
50b1039f	182	/* If it is, take it off the its list, and put in on the
94870977 GM	183	free-list. We don't bother to arrange for setting a
	184	different alarm time, since a too early one doesn't hurt. */
	185	if (t)
	186	{
	187	if (prev)
	188	prev->next = t->next;
	189	else
	190	*list = t->next;
	191
	192	t->next = free_atimers;
	193	free_atimers = t;
	194	}
e12489f9 GM	195	}
	196
	197	UNBLOCK_ATIMERS;
	198	}
	199
	200
50b1039f GM	201	/* Append two lists of atimers LIST1 and LIST2 and return the
	202	result list. */
	203
	204	static struct atimer *
	205	append_atimer_lists (list1, list2)
	206	struct atimer list1, list2;
	207	{
	208	if (list1 == NULL)
	209	return list2;
	210	else if (list2 == NULL)
	211	return list1;
	212	else
	213	{
	214	struct atimer *p;
	215
	216	for (p = list1; p->next; p = p->next)
	217	;
	218	p->next = list2;
	219	return list1;
	220	}
	221	}
	222
	223
	224	/* Stop all timers except timer T. T null means stop all timers. */
9c2e3e8d GM	225
	226	void
	227	stop_other_atimers (t)
	228	struct atimer *t;
	229	{
	230	BLOCK_ATIMERS;
	231
9c2e3e8d GM	232	if (t)
9c2e3e8d GM	233	{
2503c8b1 GM	234	struct atimer p, prev;
	235
	236	/* See if T is active. */
	237	for (p = atimers, prev = 0; p && p != t; p = p->next)
	238	;
	239
	240	if (p == t)
	241	{
	242	if (prev)
	243	prev->next = t->next;
	244	else
	245	atimers = t->next;
	246	t->next = NULL;
	247	}
	248	else
	249	/* T is not active. Let's handle this like T == 0. */
	250	t = NULL;
9c2e3e8d GM	251	}
9c2e3e8d GM	252
50b1039f	253	stopped_atimers = append_atimer_lists (atimers, stopped_atimers);
9c2e3e8d GM	254	atimers = t;
	255	UNBLOCK_ATIMERS;
	256	}
	257
	258
	259	/* Run all timers again, if some have been stopped with a call to
	260	stop_other_atimers. */
	261
	262	void
	263	run_all_atimers ()
	264	{
	265	if (stopped_atimers)
	266	{
	267	struct atimer *t = atimers;
50b1039f GM	268	struct atimer *next;
50b1039f GM	269
9c2e3e8d GM	270	BLOCK_ATIMERS;
	271	atimers = stopped_atimers;
	272	stopped_atimers = NULL;
50b1039f GM	273
	274	while (t)
	275	{
	276	next = t->next;
	277	schedule_atimer (t);
	278	t = next;
	279	}
	280
9c2e3e8d GM	281	UNBLOCK_ATIMERS;
	282	}
	283	}
	284
	285
	286	/* A version of run_all_timers suitable for a record_unwind_protect. */
	287
	288	Lisp_Object
	289	unwind_stop_other_atimers (dummy)
	290	Lisp_Object dummy;
	291	{
	292	run_all_atimers ();
	293	return Qnil;
	294	}
	295
	296
e12489f9 GM	297	/* Arrange for a SIGALRM to arrive when the next timer is ripe. */
	298
	299	static void
	300	set_alarm ()
	301	{
e12489f9 GM	302	#if defined (USG) && !defined (POSIX_SIGNALS)
	303	/* USG systems forget handlers when they are used;
	304	must reestablish each time. */
	305	signal (SIGALRM, alarm_signal_handler);
	306	#endif /* USG */
	307
	308	if (atimers)
	309	{
	310	EMACS_TIME now, time;
	311	#ifdef HAVE_SETITIMER
	312	struct itimerval it;
	313	#endif
	314
	315	/* Determine s/us till the next timer is ripe. */
	316	EMACS_GET_TIME (now);
	317	EMACS_SUB_TIME (time, atimers->expiration, now);
	318
	319	#ifdef HAVE_SETITIMER
	320	/* Don't set the interval to 0; this disables the timer. */
	321	if (EMACS_TIME_LE (atimers->expiration, now))
	322	{
	323	EMACS_SET_SECS (time, 0);
	324	EMACS_SET_USECS (time, 1000);
	325	}
	326
	327	bzero (&it, sizeof it);
	328	it.it_value = time;
	329	setitimer (ITIMER_REAL, &it, 0);
	330	#else /* not HAVE_SETITIMER */
	331	alarm (max (EMACS_SECS (time), 1));
	332	#endif /* not HAVE_SETITIMER */
	333	}
	334	}
	335
	336
	337	/* Insert timer T into the list of active atimers `atimers', keeping
	338	the list sorted by expiration time. T must not be in this list
	339	already. */
	340
	341	static void
	342	schedule_atimer (t)
	343	struct atimer *t;
	344	{
	345	struct atimer a = atimers, prev = NULL;
	346
	347	/* Look for the first atimer that is ripe after T. */
	348	while (a && EMACS_TIME_GT (t->expiration, a->expiration))
	349	prev = a, a = a->next;
	350
	351	/* Insert T in front of the atimer found, if any. */
	352	if (prev)
	353	prev->next = t;
	354	else
	355	atimers = t;
	356
	357	t->next = a;
	358	}
	359
	360
	361	/* Signal handler for SIGALRM. SIGNO is the signal number, i.e.
	362	SIGALRM. */
	363
	364	SIGTYPE
	365	alarm_signal_handler (signo)
366	int signo;
367	{
368	EMACS_TIME now;
369
370	EMACS_GET_TIME (now);
371	pending_atimers = 0;
372
373	while (atimers
374	&& (pending_atimers = interrupt_input_blocked) == 0
375	&& EMACS_TIME_LE (atimers->expiration, now))
376	{
377	struct atimer *t;
378
379	t = atimers;
380	atimers = atimers->next;
381	t->fn (t);
382
383	if (t->type == ATIMER_CONTINUOUS)
384	{
385	EMACS_ADD_TIME (t->expiration, now, t->interval);
386	schedule_atimer (t);
387	}
388	else
389	{
390	t->next = free_atimers;
391	free_atimers = t;
392	}
393
394	EMACS_GET_TIME (now);
395	}
396
397	#if defined (USG) && !defined (POSIX_SIGNALS)
398	/* USG systems forget handlers when they are used;
399	must reestablish each time. */
400	signal (SIGALRM, alarm_signal_handler);
401	#endif /* USG */
402
403	set_alarm ();
404	}
405
406
407	/* Call alarm_signal_handler for pending timers. */
408
409	void
410	do_pending_atimers ()
411	{
412	if (pending_atimers)
413	{
414	BLOCK_ATIMERS;
415	alarm_signal_handler (SIGALRM);
416	UNBLOCK_ATIMERS;
417	}
418	}
419
420
421	/* Turn alarms on/off. This seems to be temporarily necessary on
422	some systems like HPUX (see process.c). */
423
424	void
425	turn_on_atimers (on)
426	int on;
427	{
428	if (on)
429	{
430	signal (SIGALRM, alarm_signal_handler);
431	set_alarm ();
432	}
433	else
434	alarm (0);
435	}
436
437
438	void
439	init_atimer ()
440	{
441	free_atimers = atimers = NULL;
442	pending_atimers = 0;
443	signal (SIGALRM, alarm_signal_handler);
444	}