master 452f46d366 2/2: Allow fractional values of `polling-period'

[Po Lu]

branch: master
commit 452f46d3665e1bfab93ec14003484ce57b636471
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Allow fractional values of `polling-period'
    
    This allows C-g to be handled faster in the NS port at the cost
    of some extra CPU time on slow machines.
    
    * etc/NEWS: Announce new feature.
    * src/keyboard.c (start_polling):
    (bind_polling_period): Handle floating point values of
    `polling-period'.
    (syms_of_keyboard): Make `polling-period' a Lisp variable
    instead of an int variable.
---
 etc/NEWS       |  5 +++++
 src/keyboard.c | 45 +++++++++++++++++++++++++++++++++------------
 2 files changed, 38 insertions(+), 12 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index c6d9c32a82..ae4bf7e4d3 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -967,6 +967,11 @@ functions.
 
 * Lisp Changes in Emacs 29.1
 
+--
+** The variable 'polling-period' now accepts floating point values
+Setting it to a floating-point value means that Emacs will poll for
+input every so many fractions of a second.
+
 --
 ** New function 'bidi-string-strip-control-characters'.
 This utility function is meant for displaying strings when it's
diff --git a/src/keyboard.c b/src/keyboard.c
index a9f3257282..6f1614a7df 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -1895,6 +1895,9 @@ int poll_suppress_count;
 
 static struct atimer *poll_timer;
 
+/* The poll period that constructed this timer.  */
+static Lisp_Object poll_timer_time;
+
 #if defined CYGWIN || defined DOS_NT
 /* Poll for input, so that we catch a C-g if it comes in.  */
 void
@@ -1936,17 +1939,18 @@ start_polling (void)
 
       /* If poll timer doesn't exist, or we need one with
         a different interval, start a new one.  */
-      if (poll_timer == NULL
-         || poll_timer->interval.tv_sec != polling_period)
+      if (NUMBERP (Vpolling_period)
+         && (poll_timer == NULL
+             || !Fequal (Vpolling_period, poll_timer_time)))
        {
-         time_t period = max (1, min (polling_period, TYPE_MAXIMUM (time_t)));
-         struct timespec interval = make_timespec (period, 0);
+         struct timespec interval = dtotimespec (XFLOATINT (Vpolling_period));
 
          if (poll_timer)
            cancel_atimer (poll_timer);
 
          poll_timer = start_atimer (ATIMER_CONTINUOUS, interval,
                                     poll_for_input, NULL);
+         poll_timer_time = Vpolling_period;
        }
 
       /* Let the timer's callback function poll for input
@@ -2014,14 +2018,28 @@ void
 bind_polling_period (int n)
 {
 #ifdef POLL_FOR_INPUT
-  intmax_t new = polling_period;
+  if (FIXNUMP (Vpolling_period))
+    {
+      intmax_t new = XFIXNUM (Vpolling_period);
+
+      if (n > new)
+       new = n;
+
+      stop_other_atimers (poll_timer);
+      stop_polling ();
+      specbind (Qpolling_period, make_int (new));
+    }
+  else if (FLOATP (Vpolling_period))
+    {
+      double new = XFLOAT_DATA (Vpolling_period);
 
-  if (n > new)
-    new = n;
+      stop_other_atimers (poll_timer);
+      stop_polling ();
+      specbind (Qpolling_period, (n > new
+                                 ? make_int (n)
+                                 : Vpolling_period));
+    }
 
-  stop_other_atimers (poll_timer);
-  stop_polling ();
-  specbind (Qpolling_period, make_int (new));
   /* Start a new alarm with the new period.  */
   start_polling ();
 #endif
@@ -12064,6 +12082,9 @@ syms_of_keyboard (void)
   help_form_saved_window_configs = Qnil;
   staticpro (&help_form_saved_window_configs);
 
+  poll_timer_time = Qnil;
+  staticpro (&poll_timer_time);
+
   defsubr (&Scurrent_idle_time);
   defsubr (&Sevent_symbol_parse_modifiers);
   defsubr (&Sevent_convert_list);
@@ -12221,12 +12242,12 @@ The value may be integer or floating point.
 If the value is zero, don't echo at all.  */);
   Vecho_keystrokes = make_fixnum (1);
 
-  DEFVAR_INT ("polling-period", polling_period,
+  DEFVAR_LISP ("polling-period", Vpolling_period,
              doc: /* Interval between polling for input during Lisp execution.
 The reason for polling is to make C-g work to stop a running program.
 Polling is needed only when using X windows and SIGIO does not work.
 Polling is automatically disabled in all other cases.  */);
-  polling_period = 2;
+  Vpolling_period = make_float (2.0);
 
   DEFVAR_LISP ("double-click-time", Vdouble_click_time,
               doc: /* Maximum time between mouse clicks to make a double-click.