X-Git-Url: https://code.delx.au/gnu-emacs/blobdiff_plain/2ab329f3b5d52a39f0a45c3d9c129f1c19560142..aac6be13316f360bb2df46d6708ad9eea6059dc5:/src/atimer.c

diff --git a/src/atimer.c b/src/atimer.c
index 5dbd807872..ce782f6adb 100644
--- a/src/atimer.c
+++ b/src/atimer.c
@@ -1,5 +1,5 @@
 /* Asynchronous timers.
-   Copyright (C) 2000-2012  Free Software Foundation, Inc.
+   Copyright (C) 2000-2014 Free Software Foundation, Inc.
 
 This file is part of GNU Emacs.
 
@@ -26,6 +26,11 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "atimer.h"
 #include <unistd.h>
 
+#ifdef HAVE_TIMERFD
+#include <errno.h>
+# include <sys/timerfd.h>
+#endif
+
 /* Free-list of atimer structures.  */
 
 static struct atimer *free_atimers;
@@ -40,33 +45,35 @@ static struct atimer *stopped_atimers;
 
 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;
+#ifdef HAVE_ITIMERSPEC
+/* The alarm timer and whether it was properly initialized, if
+   POSIX timers are available.  */
+static timer_t alarm_timer;
+static bool alarm_timer_ok;
+
+# ifdef HAVE_TIMERFD
+/* File descriptor for timer, or -1 if it could not be created.  */
+static int timerfd;
+# else
+enum { timerfd = -1 };
+# endif
+#endif
 
 /* Block/unblock SIGALRM.  */
 
 static void
-sigmask_atimers (int how)
+block_atimers (sigset_t *oldset)
 {
   sigset_t blocked;
   sigemptyset (&blocked);
   sigaddset (&blocked, SIGALRM);
-  pthread_sigmask (how, &blocked, 0);
+  sigaddset (&blocked, SIGINT);
+  pthread_sigmask (SIG_BLOCK, &blocked, oldset);
 }
 static void
-block_atimers (void)
+unblock_atimers (sigset_t const *oldset)
 {
-  sigmask_atimers (SIG_BLOCK);
-}
-static void
-unblock_atimers (void)
-{
-  sigmask_atimers (SIG_UNBLOCK);
+  pthread_sigmask (SIG_SETMASK, oldset, 0);
 }
 
 /* Function prototypes.  */
@@ -76,36 +83,35 @@ 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
+/* Start a new atimer of type TYPE.  TIMESTAMP 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
+   If TYPE is ATIMER_ABSOLUTE, TIMESTAMP is the absolute time at which the
    timer fires.
 
-   If TYPE is ATIMER_RELATIVE, the timer is ripe TIME s/us in the
+   If TYPE is ATIMER_RELATIVE, the timer is ripe TIMESTAMP seconds 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.
+   If TYPE is ATIMER_CONTINUOUS, the timer fires every TIMESTAMP seconds.
 
    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)
+start_atimer (enum atimer_type type, struct timespec timestamp,
+	      atimer_callback fn, void *client_data)
 {
   struct atimer *t;
+  sigset_t oldset;
 
-  /* Round TIME up to the next full second if we don't have
-     itimers.  */
+  /* Round TIMESTAMP 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);
+  if (timestamp.tv_nsec != 0 && timestamp.tv_sec < TYPE_MAXIMUM (time_t))
+    timestamp = make_timespec (timestamp.tv_sec + 1, 0);
 #endif /* not HAVE_SETITIMER */
 
   /* Get an atimer structure from the free-list, or allocate
@@ -124,7 +130,7 @@ start_atimer (enum atimer_type type, EMACS_TIME timestamp, atimer_callback fn,
   t->fn = fn;
   t->client_data = client_data;
 
-  block_atimers ();
+  block_atimers (&oldset);
 
   /* Compute the timer's expiration time.  */
   switch (type)
@@ -134,18 +140,18 @@ start_atimer (enum atimer_type type, EMACS_TIME timestamp, atimer_callback fn,
       break;
 
     case ATIMER_RELATIVE:
-      t->expiration = add_emacs_time (current_emacs_time (), timestamp);
+      t->expiration = timespec_add (current_timespec (), timestamp);
       break;
 
     case ATIMER_CONTINUOUS:
-      t->expiration = add_emacs_time (current_emacs_time (), timestamp);
+      t->expiration = timespec_add (current_timespec (), timestamp);
       t->interval = timestamp;
       break;
     }
 
   /* Insert the timer in the list of active atimers.  */
   schedule_atimer (t);
-  unblock_atimers ();
+  unblock_atimers (&oldset);
 
   /* Arrange for a SIGALRM at the time the next atimer is ripe.  */
   set_alarm ();
@@ -160,8 +166,9 @@ void
 cancel_atimer (struct atimer *timer)
 {
   int i;
+  sigset_t oldset;
 
-  block_atimers ();
+  block_atimers (&oldset);
 
   for (i = 0; i < 2; ++i)
     {
@@ -188,7 +195,7 @@ cancel_atimer (struct atimer *timer)
 	}
     }
 
-  unblock_atimers ();
+  unblock_atimers (&oldset);
 }
 
 
@@ -219,7 +226,8 @@ append_atimer_lists (struct atimer *list_1, struct atimer *list_2)
 void
 stop_other_atimers (struct atimer *t)
 {
-  block_atimers ();
+  sigset_t oldset;
+  block_atimers (&oldset);
 
   if (t)
     {
@@ -244,22 +252,23 @@ stop_other_atimers (struct atimer *t)
 
   stopped_atimers = append_atimer_lists (atimers, stopped_atimers);
   atimers = t;
-  unblock_atimers ();
+  unblock_atimers (&oldset);
 }
 
 
 /* Run all timers again, if some have been stopped with a call to
    stop_other_atimers.  */
 
-static void
+void
 run_all_atimers (void)
 {
   if (stopped_atimers)
     {
       struct atimer *t = atimers;
       struct atimer *next;
+      sigset_t oldset;
 
-      block_atimers ();
+      block_atimers (&oldset);
       atimers = stopped_atimers;
       stopped_atimers = NULL;
 
@@ -270,21 +279,11 @@ run_all_atimers (void)
 	  t = next;
 	}
 
-      unblock_atimers ();
+      unblock_atimers (&oldset);
     }
 }
 
 
-/* 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
@@ -295,14 +294,33 @@ set_alarm (void)
 #ifdef HAVE_SETITIMER
       struct itimerval it;
 #endif
+      struct timespec now, interval;
 
-      /* Determine s/us till the next timer is ripe.  */
-      EMACS_TIME now = current_emacs_time ();
+#ifdef HAVE_ITIMERSPEC
+      if (0 <= timerfd || alarm_timer_ok)
+	{
+	  struct itimerspec ispec;
+	  ispec.it_value = atimers->expiration;
+	  ispec.it_interval.tv_sec = ispec.it_interval.tv_nsec = 0;
+# ifdef HAVE_TIMERFD
+	  if (timerfd_settime (timerfd, TFD_TIMER_ABSTIME, &ispec, 0) == 0)
+	    {
+	      add_timer_wait_descriptor (timerfd);
+	      return;
+	    }
+# endif
+	  if (alarm_timer_ok
+	      && timer_settime (alarm_timer, TIMER_ABSTIME, &ispec, 0) == 0)
+	    return;
+	}
+#endif
 
-      /* Don't set the interval to 0; this disables the timer.  */
-      EMACS_TIME interval = (EMACS_TIME_LE (atimers->expiration, now)
-			     ? make_emacs_time (0, 1000 * 1000)
-			     : sub_emacs_time (atimers->expiration, now));
+      /* Determine interval till the next timer is ripe.
+	 Don't set the interval to 0; this disables the timer.  */
+      now = current_timespec ();
+      interval = (timespec_cmp (atimers->expiration, now) <= 0
+		  ? make_timespec (0, 1000 * 1000)
+		  : timespec_sub (atimers->expiration, now));
 
 #ifdef HAVE_SETITIMER
 
@@ -310,7 +328,7 @@ set_alarm (void)
       it.it_value = make_timeval (interval);
       setitimer (ITIMER_REAL, &it, 0);
 #else /* not HAVE_SETITIMER */
-      alarm (max (EMACS_SECS (interval), 1));
+      alarm (max (interval.tv_sec, 1));
 #endif /* not HAVE_SETITIMER */
     }
 }
@@ -326,7 +344,7 @@ 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))
+  while (a && timespec_cmp (a->expiration, t->expiration) < 0)
     prev = a, a = a->next;
 
   /* Insert T in front of the atimer found, if any.  */
@@ -341,22 +359,17 @@ schedule_atimer (struct atimer *t)
 static void
 run_timers (void)
 {
-  EMACS_TIME now;
+  struct timespec now = current_timespec ();
 
-  while (atimers
-	 && (pending_atimers = interrupt_input_blocked) == 0
-	 && (now = current_emacs_time (),
-	     EMACS_TIME_LE (atimers->expiration, now)))
+  while (atimers && timespec_cmp (atimers->expiration, now) <= 0)
     {
-      struct atimer *t;
-
-      t = atimers;
+      struct atimer *t = atimers;
       atimers = atimers->next;
       t->fn (t);
 
       if (t->type == ATIMER_CONTINUOUS)
 	{
-	  t->expiration = add_emacs_time (now, t->interval);
+	  t->expiration = timespec_add (now, t->interval);
 	  schedule_atimer (t);
 	}
       else
@@ -366,16 +379,7 @@ run_timers (void)
 	}
     }
 
-  if (! atimers)
-    pending_atimers = 0;
-
-  if (pending_atimers)
-    pending_signals = 1;
-  else
-    {
-      pending_signals = interrupt_input_pending;
-      set_alarm ();
-    }
+  set_alarm ();
 }
 
 
@@ -385,27 +389,52 @@ run_timers (void)
 static void
 handle_alarm_signal (int sig)
 {
-  pending_atimers = 1;
   pending_signals = 1;
 }
 
-static void
-deliver_alarm_signal (int sig)
+#ifdef HAVE_TIMERFD
+
+/* Called from wait_reading_process_output when FD, which
+   should be equal to TIMERFD, is available for reading.  */
+
+void
+timerfd_callback (int fd, void *arg)
 {
-  handle_on_main_thread (sig, handle_alarm_signal);
+  ptrdiff_t nbytes;
+  uint64_t expirations;
+
+  eassert (fd == timerfd);
+  nbytes = emacs_read (fd, &expirations, sizeof (expirations));
+
+  if (nbytes == sizeof (expirations))
+    {
+      /* Timer should expire just once.  */
+      eassert (expirations == 1);
+      do_pending_atimers ();
+    }
+  else if (nbytes < 0)
+    /* For some not yet known reason, we may get weird event and no
+       data on timer descriptor.  This can break Gnus at least, see:
+       http://lists.gnu.org/archive/html/emacs-devel/2014-07/msg00503.html.  */
+    eassert (errno == EAGAIN);
+  else
+    /* I don't know what else can happen with this descriptor.  */
+    emacs_abort ();
 }
 
+#endif /* HAVE_TIMERFD */
 
-/* Call alarm signal handler for pending timers.  */
+/* Do pending timers.  */
 
 void
 do_pending_atimers (void)
 {
-  if (pending_atimers)
+  if (atimers)
     {
-      block_atimers ();
+      sigset_t oldset;
+      block_atimers (&oldset);
       run_timers ();
-      unblock_atimers ();
+      unblock_atimers (&oldset);
     }
 }
 
@@ -417,24 +446,123 @@ void
 turn_on_atimers (bool on)
 {
   if (on)
+    set_alarm ();
+  else
     {
-      struct sigaction action;
-      emacs_sigaction_init (&action, deliver_alarm_signal);
-      sigaction (SIGALRM, &action, 0);
-      set_alarm ();
+#ifdef HAVE_ITIMERSPEC
+      struct itimerspec ispec;
+      memset (&ispec, 0, sizeof ispec);
+      if (alarm_timer_ok)
+	timer_settime (alarm_timer, TIMER_ABSTIME, &ispec, 0);
+# ifdef HAVE_TIMERFD
+      timerfd_settime (timerfd, TFD_TIMER_ABSTIME, &ispec, 0);
+# endif
+#endif
+      alarm (0);
+    }
+}
+
+/* This is intended to use from automated tests.  */
+
+#ifdef ENABLE_CHECKING
+
+#define MAXTIMERS 10
+
+struct atimer_result
+{
+  /* Time when we expect this timer to trigger.  */
+  struct timespec expected;
+
+  /* Timer status: -1 if not triggered, 0 if triggered
+     too early or too late, 1 if triggered timely.  */
+  int intime;
+};
+
+static void
+debug_timer_callback (struct atimer *t)
+{
+  struct timespec now = current_timespec ();
+  struct atimer_result *r = (struct atimer_result *) t->client_data;
+  int result = timespec_cmp (now, r->expected);
+
+  if (result < 0)
+    /* Too early.  */
+    r->intime = 0;
+  else if (result >= 0)
+    {
+#ifdef HAVE_SETITIMER
+      struct timespec delta = timespec_sub (now, r->expected);
+      /* Too late if later than expected + 0.01s.  FIXME:
+	 this should depend from system clock resolution.  */
+      if (timespec_cmp (delta, make_timespec (0, 10000000)) > 0)
+	r->intime = 0;
+      else
+#endif /* HAVE_SETITIMER */
+	r->intime = 1;
     }
-  else
-    alarm (0);
 }
 
+DEFUN ("debug-timer-check", Fdebug_timer_check, Sdebug_timer_check, 0, 0, 0,
+       doc: /* Run internal self-tests to check timers subsystem.
+Return t if all self-tests are passed, nil otherwise.  */)
+  (void)
+{
+  int i, ok;
+  struct atimer *timer;
+  struct atimer_result *results[MAXTIMERS];
+  struct timespec t = make_timespec (0, 0);
+
+  /* Arm MAXTIMERS relative timers to trigger with 0.1s intervals.  */
+  for (i = 0; i < MAXTIMERS; i++)
+    {
+      results[i] = xmalloc (sizeof (struct atimer_result));
+      t = timespec_add (t, make_timespec (0, 100000000));
+      results[i]->expected = timespec_add (current_timespec (), t);
+      results[i]->intime = -1;
+      timer = start_atimer (ATIMER_RELATIVE, t,
+			    debug_timer_callback, results[i]);
+    }
+
+  /* Wait for 1s but process timers.  */
+  wait_reading_process_output (1, 0, 0, false, Qnil, NULL, 0);
+  /* Shut up the compiler by "using" this variable.  */
+  (void) timer;
+
+  for (i = 0, ok = 0; i < MAXTIMERS; i++)
+    ok += results[i]->intime, xfree (results[i]);
+
+  return ok == MAXTIMERS ? Qt : Qnil;
+}
+
+#endif /* ENABLE_CHECKING */
 
 void
 init_atimer (void)
 {
-  struct sigaction action;
+#ifdef HAVE_ITIMERSPEC
+# ifdef HAVE_TIMERFD
+  /* Until this feature is considered stable, you can ask to not use it.  */
+  timerfd = (egetenv ("EMACS_IGNORE_TIMERFD") ? -1 :
+	     timerfd_create (CLOCK_REALTIME, TFD_NONBLOCK | TFD_CLOEXEC));
+# endif
+  if (timerfd < 0)
+    {
+      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_atimers = 0;
-  /* pending_signals is initialized in init_keyboard.*/
-  emacs_sigaction_init (&action, deliver_alarm_signal);
+
+  /* pending_signals is initialized in init_keyboard.  */
+  struct sigaction action;
+  emacs_sigaction_init (&action, handle_alarm_signal);
   sigaction (SIGALRM, &action, 0);
+
+#ifdef ENABLE_CHECKING
+  defsubr (&Sdebug_timer_check);
+#endif
 }