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

[Sam Vilain]

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;

(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?