jit-lock timer etc.

[Richard Stallman]

Here's my patch to make the jit-lock timer reschedule itself
instead of waiting.  It uses current-idle-time, which I have tested
and checked in, but I can't easily tell whether steath fontification
is working.  So I would like someone to test this before I check it in.

I have not yet tried to read the other proposed change to this code.
I was too tired when I saw it.

*** jit-lock.el 17 Aug 2006 11:21:10 -0400      1.54
--- jit-lock.el 18 Aug 2006 07:57:36 -0400      
***************
*** 171,176 ****
--- 171,180 ----
  
  (defvar jit-lock-stealth-timer nil
    "Timer for stealth fontification in Just-in-time Lock mode.")
+ (defvar jit-lock-stealth-resume-timer nil
+   "Timer for resuming stealth fontification in Just-in-time Lock mode.
+ When time stealth fontification finishes one batch, it reschedules
+ itself using this timer.")
  (defvar jit-lock-context-timer nil
    "Timer for context fontification in Just-in-time Lock mode.")
  (defvar jit-lock-defer-timer nil
***************
*** 225,230 ****
--- 229,241 ----
                 (run-with-idle-timer jit-lock-stealth-time t
                                      'jit-lock-stealth-fontify)))
  
+        ;; Set up an idle timer for stealth fontification to resume,
+        ;; but don't activate it now.
+        (when (and jit-lock-stealth-time (null jit-lock-stealth-timer))
+          (setq jit-lock-stealth-resume-timer (timer-create))
+          (timer-set-function jit-lock-stealth-resume-timer
+                              'jit-lock-stealth-fontify))
+ 
         ;; Init deferred fontification timer.
         (when (and jit-lock-defer-time (null jit-lock-defer-timer))
           (setq jit-lock-defer-timer
***************
*** 449,454 ****
--- 460,466 ----
  This functions is called after Emacs has been idle for
  `jit-lock-stealth-time' seconds."
    ;; I used to check `inhibit-read-only' here, but I can't remember why.  
-stef
+   (cancel-timer jit-lock-stealth-resume-timer)
    (unless (or executing-kbd-macro
              memory-full
              (window-minibuffer-p (selected-window)))
***************
*** 457,512 ****
          minibuffer-auto-raise
          message-log-max)
        (with-local-quit
!       (while (and buffers (not (input-pending-p)))
          (with-current-buffer (pop buffers)
!           (when jit-lock-mode
!             ;; This is funny.  Calling sit-for with 3rd arg non-nil
!             ;; so that it doesn't redisplay, internally calls
!             ;; wait_reading_process_input also with a parameter
!             ;; saying "don't redisplay."  Since this function here
!             ;; is called periodically, this effectively leads to
!             ;; process output not being redisplayed at all because
!             ;; redisplay_internal is never called.  (That didn't
!             ;; work in the old redisplay either.)  So, we learn that
!             ;; we mustn't call sit-for that way here.  But then, we
!             ;; have to be cautious not to call sit-for in a widened
!             ;; buffer, since this could display hidden parts of that
!             ;; buffer.  This explains the seemingly weird use of
!             ;; save-restriction/widen here.
! 
!             (with-temp-message (if jit-lock-stealth-verbose
!                                    (concat "JIT stealth lock "
!                                            (buffer-name)))
! 
!               ;; In the following code, the `sit-for' calls cause a
!               ;; redisplay, so it's required that the
!               ;; buffer-modified flag of a buffer that is displayed
!               ;; has the right value---otherwise the mode line of
!               ;; an unmodified buffer would show a `*'.
!               (let (start
!                     (nice (or jit-lock-stealth-nice 0))
!                     (point (point-min)))
!                 (while (and (setq start
!                                   (jit-lock-stealth-chunk-start point))
!                             ;; In case sit-for runs any timers,
!                             ;; give them the expected current buffer.
!                             (with-current-buffer outer-buffer
!                               (sit-for nice)))
! 
!                   ;; fontify a block.
!                   (jit-lock-fontify-now start (+ start jit-lock-chunk-size))
!                   ;; If stealth jit-locking is done backwards, this leads to
!                   ;; excessive O(n^2) refontification.   -stef
!                   ;; (when (>= jit-lock-context-unfontify-pos start)
!                   ;;   (setq jit-lock-context-unfontify-pos end))
! 
!                   ;; Wait a little if load is too high.
!                   (when (and jit-lock-stealth-load
!                              (> (car (load-average)) jit-lock-stealth-load))
!                     ;; In case sit-for runs any timers,
!                     ;; give them the expected current buffer.
!                     (with-current-buffer outer-buffer
!                       (sit-for (or jit-lock-stealth-time 30))))))))))))))
  
  
  
--- 469,527 ----
          minibuffer-auto-raise
          message-log-max)
        (with-local-quit
!       (when (and jit-lock-mode buffers (not (input-pending-p)))
          (with-current-buffer (pop buffers)
!           ;; This is funny.  Calling sit-for with 3rd arg non-nil
!           ;; so that it doesn't redisplay, internally calls
!           ;; wait_reading_process_input also with a parameter
!           ;; saying "don't redisplay."  Since this function here
!           ;; is called periodically, this effectively leads to
!           ;; process output not being redisplayed at all because
!           ;; redisplay_internal is never called.  (That didn't
!           ;; work in the old redisplay either.)  So, we learn that
!           ;; we mustn't call sit-for that way here.  But then, we
!           ;; have to be cautious not to call sit-for in a widened
!           ;; buffer, since this could display hidden parts of that
!           ;; buffer.  This explains the seemingly weird use of
!           ;; save-restriction/widen here.
! 
!           (with-temp-message (if jit-lock-stealth-verbose
!                                  (concat "JIT stealth lock "
!                                          (buffer-name)))
! 
!             ;; In the following code, the `sit-for' calls cause a
!             ;; redisplay, so it's required that the
!             ;; buffer-modified flag of a buffer that is displayed
!             ;; has the right value---otherwise the mode line of
!             ;; an unmodified buffer would show a `*'.
!             (let (start
!                   (nice (or jit-lock-stealth-nice 0))
!                   (point (point-min)))
!               (while (and (setq start
!                                 (jit-lock-stealth-chunk-start point))
!                           ;; In case sit-for runs any timers,
!                           ;; give them the expected current buffer.
!                           (with-current-buffer outer-buffer
!                             (sit-for nice)))
! 
!                 ;; fontify a block.
!                 (jit-lock-fontify-now start (+ start jit-lock-chunk-size))
!                 ;; If stealth jit-locking is done backwards, this leads to
!                 ;; excessive O(n^2) refontification.   -stef
!                 ;; (when (>= jit-lock-context-unfontify-pos start)
!                 ;;   (setq jit-lock-context-unfontify-pos end))
! 
!                 ;; Wait a little if load is too high.
!                 (when (and jit-lock-stealth-load
!                            (> (car (load-average)) jit-lock-stealth-load))
!                   ;; Make this timer resume jit-lock in a few
!                   ;; seconds.  Compute an idleness time suitably
!                   ;; larger than the current one.
!                   (timer-set-idle-time jit-lock-stealth-resume-timer
!                                        (current-idle-time))
!                   (timer-inc-time (or jit-lock-stealth-time 30))
!                   (timer-activate-when-idle
!                    jit-lock-stealth-resume-timer t)))))))))))