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[emacs.git] / src / atimer.c
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1 /* Asynchronous timers.
2 Copyright (C) 2000 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 <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>
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 /* The ubiquitous min/max macros. */
40 #define max(X, Y) ((X) > (Y) ? (X) : (Y))
41 #define min(X, Y) ((X) < (Y) ? (X) : (Y))
43 /* Free-list of atimer structures. */
45 static struct atimer *free_atimers;
47 /* List of currently not running timers due to a call to
48 lock_atimer. */
50 static struct atimer *stopped_atimers;
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. */
55 static struct atimer *atimers;
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. */
63 int pending_atimers;
65 /* Block/unblock SIGALRM.. */
67 #define BLOCK_ATIMERS sigblock (sigmask (SIGALRM))
68 #define UNBLOCK_ATIMERS sigunblock (sigmask (SIGALRM))
70 /* Function prototypes. */
72 static void set_alarm P_ ((void));
73 static void schedule_atimer P_ ((struct atimer *));
74 static struct atimer *append_atimer_lists P_ ((struct atimer *,
75 struct atimer *));
76 SIGTYPE alarm_signal_handler ();
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.
84 If TYPE is ATIMER_ABSOLUTE, TIME is the absolute time at which the
85 timer fires.
87 If TYPE is ATIMER_RELATIVE, the timer is ripe TIME s/us in the
88 future.
90 In both cases, the timer is automatically freed after it has fired.
92 If TYPE is ATIMER_CONTINUOUS, the timer fires every TIME s/us.
94 Value is a pointer to the atimer started. It can be used in calls
95 to cancel_atimer; don't free it yourself. */
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;
104 struct atimer *t;
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)
111 EMACS_SET_USECS (time, 0);
112 EMACS_SET_SECS (time, EMACS_SECS (time) + 1);
114 #endif /* not HAVE_SETITIMER */
116 /* Get an atimer structure from the free-list, or allocate
117 a new one. */
118 if (free_atimers)
120 t = free_atimers;
121 free_atimers = t->next;
123 else
124 t = (struct atimer *) xmalloc (sizeof *t);
126 /* Fill the atimer structure. */
127 bzero (t, sizeof *t);
128 t->type = type;
129 t->fn = fn;
130 t->client_data = client_data;
132 BLOCK_ATIMERS;
134 /* Compute the timer's expiration time. */
135 switch (type)
137 case ATIMER_ABSOLUTE:
138 t->expiration = time;
139 break;
141 case ATIMER_RELATIVE:
142 EMACS_GET_TIME (t->expiration);
143 EMACS_ADD_TIME (t->expiration, t->expiration, time);
144 break;
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;
153 /* Insert the timer in the list of active atimers. */
154 schedule_atimer (t);
155 UNBLOCK_ATIMERS;
157 /* Arrange for a SIGALRM at the time the next atimer is ripe. */
158 set_alarm ();
160 return t;
164 /* Cancel and free atimer TIMER. */
166 void
167 cancel_atimer (timer)
168 struct atimer *timer;
170 int i;
172 BLOCK_ATIMERS;
174 for (i = 0; i < 2; ++i)
176 struct atimer *t, *prev;
177 struct atimer **list = i ? &stopped_atimers : &atimers;
179 /* See if TIMER is active or stopped. */
180 for (t = *list, prev = NULL; t && t != timer; prev = t, t = t->next)
183 /* If it is, take it off the its list, and put in on the
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)
188 if (prev)
189 prev->next = t->next;
190 else
191 *list = t->next;
193 t->next = free_atimers;
194 free_atimers = t;
195 break;
199 UNBLOCK_ATIMERS;
203 /* Append two lists of atimers LIST1 and LIST2 and return the
204 result list. */
206 static struct atimer *
207 append_atimer_lists (list1, list2)
208 struct atimer *list1, *list2;
210 if (list1 == NULL)
211 return list2;
212 else if (list2 == NULL)
213 return list1;
214 else
216 struct atimer *p;
218 for (p = list1; p->next; p = p->next)
220 p->next = list2;
221 return list1;
226 /* Stop all timers except timer T. T null means stop all timers. */
228 void
229 stop_other_atimers (t)
230 struct atimer *t;
232 BLOCK_ATIMERS;
234 if (t)
236 struct atimer *p, *prev;
238 /* See if T is active. */
239 for (p = atimers, prev = 0; p && p != t; p = p->next)
242 if (p == t)
244 if (prev)
245 prev->next = t->next;
246 else
247 atimers = t->next;
248 t->next = NULL;
250 else
251 /* T is not active. Let's handle this like T == 0. */
252 t = NULL;
255 stopped_atimers = append_atimer_lists (atimers, stopped_atimers);
256 atimers = t;
257 UNBLOCK_ATIMERS;
261 /* Run all timers again, if some have been stopped with a call to
262 stop_other_atimers. */
264 void
265 run_all_atimers ()
267 if (stopped_atimers)
269 struct atimer *t = atimers;
270 struct atimer *next;
272 BLOCK_ATIMERS;
273 atimers = stopped_atimers;
274 stopped_atimers = NULL;
276 while (t)
278 next = t->next;
279 schedule_atimer (t);
280 t = next;
283 UNBLOCK_ATIMERS;
288 /* A version of run_all_timers suitable for a record_unwind_protect. */
290 Lisp_Object
291 unwind_stop_other_atimers (dummy)
292 Lisp_Object dummy;
294 run_all_atimers ();
295 return Qnil;
299 /* Arrange for a SIGALRM to arrive when the next timer is ripe. */
301 static void
302 set_alarm ()
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 */
310 if (atimers)
312 EMACS_TIME now, time;
313 #ifdef HAVE_SETITIMER
314 struct itimerval it;
315 #endif
317 /* Determine s/us till the next timer is ripe. */
318 EMACS_GET_TIME (now);
319 EMACS_SUB_TIME (time, atimers->expiration, now);
321 #ifdef HAVE_SETITIMER
322 /* Don't set the interval to 0; this disables the timer. */
323 if (EMACS_TIME_LE (atimers->expiration, now))
325 EMACS_SET_SECS (time, 0);
326 EMACS_SET_USECS (time, 1000);
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 */
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. */
343 static void
344 schedule_atimer (t)
345 struct atimer *t;
347 struct atimer *a = atimers, *prev = NULL;
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;
353 /* Insert T in front of the atimer found, if any. */
354 if (prev)
355 prev->next = t;
356 else
357 atimers = t;
359 t->next = a;
363 /* Signal handler for SIGALRM. SIGNO is the signal number, i.e.
364 SIGALRM. */
366 SIGTYPE
367 alarm_signal_handler (signo)
368 int signo;
370 EMACS_TIME now;
372 EMACS_GET_TIME (now);
373 pending_atimers = 0;
375 while (atimers
376 && (pending_atimers = interrupt_input_blocked) == 0
377 && EMACS_TIME_LE (atimers->expiration, now))
379 struct atimer *t;
381 t = atimers;
382 atimers = atimers->next;
383 t->fn (t);
385 if (t->type == ATIMER_CONTINUOUS)
387 EMACS_ADD_TIME (t->expiration, now, t->interval);
388 schedule_atimer (t);
390 else
392 t->next = free_atimers;
393 free_atimers = t;
396 EMACS_GET_TIME (now);
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 */
405 set_alarm ();
409 /* Call alarm_signal_handler for pending timers. */
411 void
412 do_pending_atimers ()
414 if (pending_atimers)
416 BLOCK_ATIMERS;
417 alarm_signal_handler (SIGALRM);
418 UNBLOCK_ATIMERS;
423 /* Turn alarms on/off. This seems to be temporarily necessary on
424 some systems like HPUX (see process.c). */
426 void
427 turn_on_atimers (on)
428 int on;
430 if (on)
432 signal (SIGALRM, alarm_signal_handler);
433 set_alarm ();
435 else
436 alarm (0);
440 void
441 init_atimer ()
443 free_atimers = atimers = NULL;
444 pending_atimers = 0;
445 signal (SIGALRM, alarm_signal_handler);