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/* Asynchronous timers.
Copyright (C) 2000-2013 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 3 of the License, 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. If not, see <http://www.gnu.org/licenses/>. */
#include <config.h>
#include <stdio.h>
#include "lisp.h"
#include "syssignal.h"
#include "systime.h"
#include "blockinput.h"
#include "atimer.h"
#include <unistd.h>
/* 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;
/* The alarm timer and whether it was properly initialized, if
POSIX timers are available. */
#ifdef HAVE_ITIMERSPEC
static timer_t alarm_timer;
static bool alarm_timer_ok;
#endif
/* Block/unblock SIGALRM. */
static void
sigmask_atimers (int how)
{
sigset_t blocked;
sigemptyset (&blocked);
sigaddset (&blocked, SIGALRM);
pthread_sigmask (how, &blocked, 0);
}
static void
block_atimers (void)
{
sigmask_atimers (SIG_BLOCK);
}
static void
unblock_atimers (void)
{
sigmask_atimers (SIG_UNBLOCK);
}
/* Function prototypes. */
static void set_alarm (void);
static void schedule_atimer (struct atimer *);
static struct atimer *append_atimer_lists (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 (enum atimer_type type, EMACS_TIME timestamp, 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_NSECS (timestamp) != 0
&& EMACS_SECS (timestamp) < TYPE_MAXIMUM (time_t))
timestamp = make_emacs_time (EMACS_SECS (timestamp) + 1, 0);
#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 = xmalloc (sizeof *t);
/* Fill the atimer structure. */
memset (t, 0, 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 = timestamp;
break;
case ATIMER_RELATIVE:
t->expiration = add_emacs_time (current_emacs_time (), timestamp);
break;
case ATIMER_CONTINUOUS:
t->expiration = add_emacs_time (current_emacs_time (), timestamp);
t->interval = timestamp;
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 (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 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 LIST_1 and LIST_2 and return the
result list. */
static struct atimer *
append_atimer_lists (struct atimer *list_1, struct atimer *list_2)
{
if (list_1 == NULL)
return list_2;
else if (list_2 == NULL)
return list_1;
else
{
struct atimer *p;
for (p = list_1; p->next; p = p->next)
;
p->next = list_2;
return list_1;
}
}
/* Stop all timers except timer T. T null means stop all timers. */
void
stop_other_atimers (struct atimer *t)
{
block_atimers ();
if (t)
{
struct atimer *p, *prev;
/* See if T is active. */
for (p = atimers, prev = NULL; p && p != t; prev = p, 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. */
static void
run_all_atimers (void)
{
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_atimers suitable for a record_unwind_protect. */
Lisp_Object
unwind_stop_other_atimers (Lisp_Object dummy)
{
run_all_atimers ();
return Qnil;
}
/* Arrange for a SIGALRM to arrive when the next timer is ripe. */
static void
set_alarm (void)
{
if (atimers)
{
#ifdef HAVE_SETITIMER
struct itimerval it;
#endif
EMACS_TIME now, interval;
#ifdef HAVE_ITIMERSPEC
if (alarm_timer_ok)
{
struct itimerspec ispec;
ispec.it_value = atimers->expiration;
ispec.it_interval.tv_sec = ispec.it_interval.tv_nsec = 0;
if (timer_settime (alarm_timer, 0, &ispec, 0) == 0)
return;
}
#endif
/* Determine interval till the next timer is ripe.
Don't set the interval to 0; this disables the timer. */
now = current_emacs_time ();
interval = (EMACS_TIME_LE (atimers->expiration, now)
? make_emacs_time (0, 1000 * 1000)
: sub_emacs_time (atimers->expiration, now));
#ifdef HAVE_SETITIMER
memset (&it, 0, sizeof it);
it.it_value = make_timeval (interval);
setitimer (ITIMER_REAL, &it, 0);
#else /* not HAVE_SETITIMER */
alarm (max (EMACS_SECS (interval), 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 (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;
}
static void
run_timers (void)
{
EMACS_TIME now = current_emacs_time ();
while (atimers && EMACS_TIME_LE (atimers->expiration, now))
{
struct atimer *t = atimers;
atimers = atimers->next;
#ifndef DARWIN_OS
t->fn (t);
#endif
if (t->type == ATIMER_CONTINUOUS)
{
t->expiration = add_emacs_time (now, t->interval);
schedule_atimer (t);
}
else
{
t->next = free_atimers;
free_atimers = t;
}
#ifdef DARWIN_OS
/* Fix for Ctrl-G. Perhaps this should apply to all platforms. */
t->fn (t);
#endif
}
set_alarm ();
}
/* Signal handler for SIGALRM. SIGNO is the signal number, i.e.
SIGALRM. */
static void
handle_alarm_signal (int sig)
{
pending_signals = 1;
}
/* Do pending timers. */
void
do_pending_atimers (void)
{
if (atimers)
{
block_atimers ();
run_timers ();
unblock_atimers ();
}
}
/* Turn alarms on/off. This seems to be temporarily necessary on
some systems like HPUX (see process.c). */
void
turn_on_atimers (bool on)
{
if (on)
set_alarm ();
else
alarm (0);
}
void
init_atimer (void)
{
struct sigaction action;
#ifdef HAVE_ITIMERSPEC
struct sigevent sigev;
sigev.sigev_notify = SIGEV_SIGNAL;
sigev.sigev_signo = SIGALRM;
sigev.sigev_value.sival_ptr = &alarm_timer;
alarm_timer_ok = timer_create (CLOCK_REALTIME, &sigev, &alarm_timer) == 0;
#endif
free_atimers = stopped_atimers = atimers = NULL;
/* pending_signals is initialized in init_keyboard.*/
emacs_sigaction_init (&action, handle_alarm_signal);
sigaction (SIGALRM, &action, 0);
}
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