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[emacs.git] / src / atimer.c
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1 /* Asynchronous timers.
2 Copyright (C) 2000, 2004 Free Software Foundation, Inc.
4 This file is part of GNU Emacs.
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.
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.
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. */
21 #include <config.h>
22 #include <signal.h>
23 #include <stdio.h>
24 #include <lisp.h>
25 #include <syssignal.h>
26 #include <systime.h>
27 #include <blockinput.h>
28 #include <atimer.h>
30 #ifdef HAVE_UNISTD_H
31 #include <unistd.h>
32 #endif
34 #ifdef HAVE_SYS_TIME_H
35 #include <sys/time.h>
36 #endif
38 /* Free-list of atimer structures. */
40 static struct atimer *free_atimers;
42 /* List of currently not running timers due to a call to
43 lock_atimer. */
45 static struct atimer *stopped_atimers;
47 /* List of active atimers, sorted by expiration time. The timer that
48 will become ripe next is always at the front of this list. */
50 static struct atimer *atimers;
52 /* Non-zero means alarm_signal_handler has found ripe timers but
53 interrupt_input_blocked was non-zero. In this case, timer
54 functions are not called until the next UNBLOCK_INPUT because timer
55 functions are expected to call X, and X cannot be assumed to be
56 reentrant. */
58 int pending_atimers;
60 /* Block/unblock SIGALRM. */
62 #define BLOCK_ATIMERS sigblock (sigmask (SIGALRM))
63 #define UNBLOCK_ATIMERS sigunblock (sigmask (SIGALRM))
65 /* Function prototypes. */
67 static void set_alarm P_ ((void));
68 static void schedule_atimer P_ ((struct atimer *));
69 static struct atimer *append_atimer_lists P_ ((struct atimer *,
70 struct atimer *));
71 SIGTYPE alarm_signal_handler ();
74 /* Start a new atimer of type TYPE. TIME specifies when the timer is
75 ripe. FN is the function to call when the timer fires.
76 CLIENT_DATA is stored in the client_data member of the atimer
77 structure returned and so made available to FN when it is called.
79 If TYPE is ATIMER_ABSOLUTE, TIME is the absolute time at which the
80 timer fires.
82 If TYPE is ATIMER_RELATIVE, the timer is ripe TIME s/us in the
83 future.
85 In both cases, the timer is automatically freed after it has fired.
87 If TYPE is ATIMER_CONTINUOUS, the timer fires every TIME s/us.
89 Value is a pointer to the atimer started. It can be used in calls
90 to cancel_atimer; don't free it yourself. */
92 struct atimer *
93 start_atimer (type, time, fn, client_data)
94 enum atimer_type type;
95 EMACS_TIME time;
96 atimer_callback fn;
97 void *client_data;
99 struct atimer *t;
101 /* Round TIME up to the next full second if we don't have
102 itimers. */
103 #ifndef HAVE_SETITIMER
104 if (EMACS_USECS (time) != 0)
106 EMACS_SET_USECS (time, 0);
107 EMACS_SET_SECS (time, EMACS_SECS (time) + 1);
109 #endif /* not HAVE_SETITIMER */
111 /* Get an atimer structure from the free-list, or allocate
112 a new one. */
113 if (free_atimers)
115 t = free_atimers;
116 free_atimers = t->next;
118 else
119 t = (struct atimer *) xmalloc (sizeof *t);
121 /* Fill the atimer structure. */
122 bzero (t, sizeof *t);
123 t->type = type;
124 t->fn = fn;
125 t->client_data = client_data;
127 BLOCK_ATIMERS;
129 /* Compute the timer's expiration time. */
130 switch (type)
132 case ATIMER_ABSOLUTE:
133 t->expiration = time;
134 break;
136 case ATIMER_RELATIVE:
137 EMACS_GET_TIME (t->expiration);
138 EMACS_ADD_TIME (t->expiration, t->expiration, time);
139 break;
141 case ATIMER_CONTINUOUS:
142 EMACS_GET_TIME (t->expiration);
143 EMACS_ADD_TIME (t->expiration, t->expiration, time);
144 t->interval = time;
145 break;
148 /* Insert the timer in the list of active atimers. */
149 schedule_atimer (t);
150 UNBLOCK_ATIMERS;
152 /* Arrange for a SIGALRM at the time the next atimer is ripe. */
153 set_alarm ();
155 return t;
159 /* Cancel and free atimer TIMER. */
161 void
162 cancel_atimer (timer)
163 struct atimer *timer;
165 int i;
167 BLOCK_ATIMERS;
169 for (i = 0; i < 2; ++i)
171 struct atimer *t, *prev;
172 struct atimer **list = i ? &stopped_atimers : &atimers;
174 /* See if TIMER is active or stopped. */
175 for (t = *list, prev = NULL; t && t != timer; prev = t, t = t->next)
178 /* If it is, take it off the its list, and put in on the
179 free-list. We don't bother to arrange for setting a
180 different alarm time, since a too early one doesn't hurt. */
181 if (t)
183 if (prev)
184 prev->next = t->next;
185 else
186 *list = t->next;
188 t->next = free_atimers;
189 free_atimers = t;
190 break;
194 UNBLOCK_ATIMERS;
198 /* Append two lists of atimers LIST1 and LIST2 and return the
199 result list. */
201 static struct atimer *
202 append_atimer_lists (list1, list2)
203 struct atimer *list1, *list2;
205 if (list1 == NULL)
206 return list2;
207 else if (list2 == NULL)
208 return list1;
209 else
211 struct atimer *p;
213 for (p = list1; p->next; p = p->next)
215 p->next = list2;
216 return list1;
221 /* Stop all timers except timer T. T null means stop all timers. */
223 void
224 stop_other_atimers (t)
225 struct atimer *t;
227 BLOCK_ATIMERS;
229 if (t)
231 struct atimer *p, *prev;
233 /* See if T is active. */
234 for (p = atimers, prev = 0; p && p != t; p = p->next)
237 if (p == t)
239 if (prev)
240 prev->next = t->next;
241 else
242 atimers = t->next;
243 t->next = NULL;
245 else
246 /* T is not active. Let's handle this like T == 0. */
247 t = NULL;
250 stopped_atimers = append_atimer_lists (atimers, stopped_atimers);
251 atimers = t;
252 UNBLOCK_ATIMERS;
256 /* Run all timers again, if some have been stopped with a call to
257 stop_other_atimers. */
259 void
260 run_all_atimers ()
262 if (stopped_atimers)
264 struct atimer *t = atimers;
265 struct atimer *next;
267 BLOCK_ATIMERS;
268 atimers = stopped_atimers;
269 stopped_atimers = NULL;
271 while (t)
273 next = t->next;
274 schedule_atimer (t);
275 t = next;
278 UNBLOCK_ATIMERS;
283 /* A version of run_all_timers suitable for a record_unwind_protect. */
285 Lisp_Object
286 unwind_stop_other_atimers (dummy)
287 Lisp_Object dummy;
289 run_all_atimers ();
290 return Qnil;
294 /* Arrange for a SIGALRM to arrive when the next timer is ripe. */
296 static void
297 set_alarm ()
299 #if defined (USG) && !defined (POSIX_SIGNALS)
300 /* USG systems forget handlers when they are used;
301 must reestablish each time. */
302 signal (SIGALRM, alarm_signal_handler);
303 #endif /* USG */
305 if (atimers)
307 EMACS_TIME now, time;
308 #ifdef HAVE_SETITIMER
309 struct itimerval it;
310 #endif
312 /* Determine s/us till the next timer is ripe. */
313 EMACS_GET_TIME (now);
314 EMACS_SUB_TIME (time, atimers->expiration, now);
316 #ifdef HAVE_SETITIMER
317 /* Don't set the interval to 0; this disables the timer. */
318 if (EMACS_TIME_LE (atimers->expiration, now))
320 EMACS_SET_SECS (time, 0);
321 EMACS_SET_USECS (time, 1000);
324 bzero (&it, sizeof it);
325 it.it_value = time;
326 setitimer (ITIMER_REAL, &it, 0);
327 #else /* not HAVE_SETITIMER */
328 alarm (max (EMACS_SECS (time), 1));
329 #endif /* not HAVE_SETITIMER */
334 /* Insert timer T into the list of active atimers `atimers', keeping
335 the list sorted by expiration time. T must not be in this list
336 already. */
338 static void
339 schedule_atimer (t)
340 struct atimer *t;
342 struct atimer *a = atimers, *prev = NULL;
344 /* Look for the first atimer that is ripe after T. */
345 while (a && EMACS_TIME_GT (t->expiration, a->expiration))
346 prev = a, a = a->next;
348 /* Insert T in front of the atimer found, if any. */
349 if (prev)
350 prev->next = t;
351 else
352 atimers = t;
354 t->next = a;
358 /* Signal handler for SIGALRM. SIGNO is the signal number, i.e.
359 SIGALRM. */
361 SIGTYPE
362 alarm_signal_handler (signo)
363 int signo;
365 EMACS_TIME now;
367 SIGNAL_THREAD_CHECK (signo);
369 EMACS_GET_TIME (now);
370 pending_atimers = 0;
372 while (atimers
373 && (pending_atimers = interrupt_input_blocked) == 0
374 && EMACS_TIME_LE (atimers->expiration, now))
376 struct atimer *t;
378 t = atimers;
379 atimers = atimers->next;
380 #ifndef MAC_OSX
381 t->fn (t);
382 #endif
384 if (t->type == ATIMER_CONTINUOUS)
386 EMACS_ADD_TIME (t->expiration, now, t->interval);
387 schedule_atimer (t);
389 else
391 t->next = free_atimers;
392 free_atimers = t;
394 #ifdef MAC_OSX
395 /* Fix for Ctrl-G. Perhaps this should apply to all platforms. */
396 t->fn (t);
397 #endif
399 EMACS_GET_TIME (now);
402 if (! pending_atimers)
403 set_alarm ();
407 /* Call alarm_signal_handler for pending timers. */
409 void
410 do_pending_atimers ()
412 if (pending_atimers)
414 BLOCK_ATIMERS;
415 alarm_signal_handler (SIGALRM);
416 UNBLOCK_ATIMERS;
421 /* Turn alarms on/off. This seems to be temporarily necessary on
422 some systems like HPUX (see process.c). */
424 void
425 turn_on_atimers (on)
426 int on;
428 if (on)
430 signal (SIGALRM, alarm_signal_handler);
431 set_alarm ();
433 else
434 alarm (0);
438 void
439 init_atimer ()
441 free_atimers = atimers = NULL;
442 pending_atimers = 0;
443 signal (SIGALRM, alarm_signal_handler);
446 /* arch-tag: e6308261-eec6-404b-89fb-6e5909518d70
447 (do not change this comment) */