[svk-devel] Re: "svk info" latency vs. vc-svk.el: pain vs. gain

[Chip Salzenberg]

On Sun, Aug 06, 2006 at 04:52:23PM +1200, Sam Vilain wrote:
> Chip Salzenberg wrote:
> > I'm using svk (thanks clkao!) and vc-svk.el (thanks Sam!) and I mostly enjoy
> > the combination.  Except: vc-svk.el uses 'svk info' to determine whether a
> > file is source-controlled, and that's a four-second latency for every file.
> 
> The version I wrote just did read .svk/config using e-lisp;

Hrm, looks like I confused vc-svk versions -- sorry about that, Chief;
AFAICT, your vc-svk-registered function still runs svk status on the file
(if it's in a checkout directory), so the svk startup penalty still applies.

> (defun vc-svk-registered (file)
>   "Return true if FILE is registered under SVK."
>   ;; First, a quick false positive test: is there a `.svk/entries' file?
>   (vc-svk-read-config)
>   (let ((dirname (or (replace-regexp-in-string "/\$" ""
>                                              (file-name-directory
>                                               (file-truename file))) ""))
>         ;; make sure that the file name is searched case-sensitively
>         (case-fold-search nil))
>     (let ((found nil))
>       (while (and (not found)
>                 (> (length dirname) 0))
>       (if (member dirname vc-svk-checkout-paths)
>           (setq found t)
>         )
>       (setf dirname (replace-regexp-in-string "/[^/]*$" "" dirname))
>       )
>         (and found (vc-svk-run-status file))))
>   )
> 
> ; This method assumes ~/.svk/config was saved with $YAML::indent = 2
> ; and that keys are only ever quoted with single quotes
> ; note - ph34r my ub3r lisp p0w3rs - mugwump.
> ;(defstruct checkoutpath path true)
> (defun vc-svk-read-config ()
>   "reads the SVK config file in and sets relevant variables"
>   (with-temp-buffer
>     (vc-insert-file "~/.svk/config")
>     (goto-char (point-min))
>     (re-search-forward "^checkout:")
>     (let ((start (re-search-forward "^  hash:.*$"))
>         (end (re-search-forward "^  [^ ]+:.*$")))
>       (setf vc-svk-checkout-paths ())
>     (goto-char start)
>     (while (< (point) end)
>       (if (or (looking-at "^    \\(.*\\):$")
>             (looking-at "^    '\\(.*\\)':$")
>             )
>         (setf vc-svk-checkout-paths (cons (match-string 1)
> vc-svk-checkout-paths))
>       )
>       (goto-char (+ (point) 1))
>       (if (re-search-forward "^    [^ ]" nil t)
>           (goto-char (- (point) 5))
>         (setf end (point)))
>       )
>     vc-svk-checkout-paths
>     )
>   ))
> 
> > When I 'emacs *.c', I have to wait a long time.
> > 
> > It's getting annoying.  So until I get Parrot working, I guess I'm stuck
> > with it being slow.  Ironically enough, this slowdown is a slight drag on
> > Parrot development.  :-(
> > 
> > I've strace'd 'svk info' and it spends most of those four seconds just
> > looking for and parsing Perl modules, so there's no easy fix.  Perhaps
> > SVK could make more extensive use of deferred loading, e.g. C<use autouse>?
> > 
> > An Emacs-specific wrapper around 'svk info' that caches answers could help.
> > It's a terrible hack, though.
> > 
> > Or, perhaps, a minimal 'tinysvk info' program could avoid all the extensive
> > module loads but knows enough to just say whether a file is controlled or
> > not.  For example, it could load only YAML, look in ~/.svk/config for the
> > current svn repo, and then (speculation begins) use 'svn' directly in some
> > way to find out whether the given file is currently controlled.
> > 
> > Thoughts?  Solutions?
> 
> 

-- 
Chip Salzenberg <chip at pobox.com>