[PATCH] Include a bug from Nix we dropped on the floor
Was looking through Gmane, and came across this. Sorry about the delay, Nix.
See the discussion here: http://thread.gmane.org/gmane.lisp.emacs-cl/128 for
more info.
lisp/ChangeLog addition:
2004-06-28 Nix <nix(a)esperi.org.uk>
* cmdloop.el (truncate-command-history-for-gc): Delay
execution of all things that look up variable bindings,
via `enqueue-eval-event'.
XEmacs Trunk source patch:
Diff command: cvs -q diff -u
Files affected: lisp/cmdloop.el
===================================================================
RCS
Index: lisp/cmdloop.el
===================================================================
RCS file: /pack/xemacscvs/XEmacs/xemacs/lisp/cmdloop.el,v
retrieving revision 1.22
diff -u -r1.22 cmdloop.el
--- lisp/cmdloop.el 2006/06/25 13:58:03 1.22
+++ lisp/cmdloop.el 2006/11/24 13:38:29
＠＠ -183,11 +183,26 ＠＠
(defun truncate-command-history-for-gc ()
- (let ((tail (nthcdr 30 command-history)))
- (if tail (setcdr tail nil)))
- (let ((tail (nthcdr 30 values)))
- (if tail (setcdr tail nil)))
- )
+ ;; We should try to avoid accessing any bindings to speak of in this
+ ;; function; as this hook is called asynchronously, the search for
+ ;; those bindings might search local bindings from essentially
+ ;; arbitrary functions. We force the body of the function to run at
+ ;; command-loop level, where the danger of local bindings is much
+ ;; reduced; the code can still do its job because the command history
+ ;; and values list will not grow before then anyway.
+ ;;
+ ;; Nothing is done in batch mode, both because it is a waste of time
+ ;; (there is no command loop!) and because this any GCs during dumping
+ ;; will invoke this code, and if it were to enqueue an eval event,
+ ;; the portable dumper would try to dump it and fail.
+ (if (not (noninteractive))
+ (enqueue-eval-event
+ (lambda (arg)
+ (let ((tail (nthcdr 30 command-history)))
+ (if tail (setcdr tail nil)))
+ (let ((tail (nthcdr 30 values)))
+ (if tail (setcdr tail nil))))
+ nil)))
(add-hook 'pre-gc-hook 'truncate-command-history-for-gc)
--
Santa Maradona, priez pour moi!
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