emacs ltstat,readlink on slow filesyste.

emacs ltstat,readlink on slow filesyste.

[kenneth johansson]

I'm using emacs to edit files on a sshfs filesystem but have a problem
whith emacs doing lstat and readlink for files that do not exist. And on a
slow network this creates interruptions to scrolling in emacs since the lstat
and readlink is taking so long to complete.

I have been trying to figure out what in emacs is doing this but have so
far failed to find a way around it. 

to see what is happening do the following.

cd /tmp
num=0; while [ $num -lt 1000 ] ;do echo "line $num" ; num=$((num +1)) ; done   >test_file.c
strace -f -etrace=lstat,readlink  emacs -Q test_file.c 


then just move around in the file and you should see the lstats and readlink calls. 

anyone know a way to configure emacs so this is not happening ???

Re: emacs ltstat,readlink on slow filesyste.

[Stefan Monnier]

> strace -f -etrace=lstat,readlink  emacs -Q test_file.c 

> then just move around in the file and you should see the lstats and
> readlink calls. 

The patch below should fix this problem.  Thanks for reporting it.
Note that using M-x report-emacs-bug would have made it even better,


        Stefan


--- jit-lock.el.~1.66.~	2009-01-12 15:41:49.000000000 -0500
+++ jit-lock.el	2009-02-14 16:37:04.000000000 -0500
@@ -45,14 +45,16 @@
     "Execute BODY in current buffer, overriding several variables.
 Preserves the `buffer-modified-p' state of the current buffer."
     (declare (debug t))
-    `(with-buffer-unmodified
-      (let ((buffer-undo-list t)
+    `(let ((buffer-undo-list t)
 	    (inhibit-read-only t)
 	    (inhibit-point-motion-hooks t)
 	    (inhibit-modification-hooks t)
 	    deactivate-mark
 	    buffer-file-name
 	    buffer-file-truename)
+       ;; Do reset the modification status from within the let, since
+       ;; otherwise set-buffer-modified-p may try to unlock the file.
+       (with-buffer-unmodified
 	,@body))))