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bug#64735: 29.0.92; find invocations are ~15x slower because of ignores
From: |
Ihor Radchenko |
Subject: |
bug#64735: 29.0.92; find invocations are ~15x slower because of ignores |
Date: |
Fri, 21 Jul 2023 13:17:17 +0000 |
Eli Zaretskii <eliz@gnu.org> writes:
>> > The question is: what is more costly
>> > (a) matching complex regexp && call function or
>> > (b) call function (lambda (fn) (when (and foo (match-string- ... fn)) ...))
>>
>> (benchmark-run-compiled 10000000 (string-match-p (caar
>> file-name-handler-alist) "/path/to/very/deep/file"))
>> ;; => (1.495432981 0 0.0)
>> (benchmark-run-compiled 10000000 (funcall (lambda (fn) (and nil
>> (string-match-p (caar file-name-handler-alist) fn)))
>> "/path/to/very/deep/file"))
>> ;; => (0.42053276500000003 0 0.0)
>>
>> Looks like even funcall overheads are not as bad as invoking regexp search.
>
> But "nil" is not a faithful emulation of the real test which will have
> to be put there, is it?
It is, at least in some cases. In other cases, it is list lookup, which
is also faster:
(benchmark-run-compiled 10000000 (funcall (lambda (fn) (and (get 'foo
'jka-compr) (string-match-p (caar file-name-handler-alist) fn)))
"/path/to/very/deep/file"))
;; => (0.5831819149999999 0 0.0)
Let me go through default handlers one by one:
file-name-handler-alist is a variable defined in fileio.c.
Value
(("..." . jka-compr-handler)
(".." . epa-file-handler)
("..." . tramp-archive-file-name-handler)
("..." . tramp-completion-file-name-handler)
("..." . tramp-file-name-handler)
("\\`/:" . file-name-non-special))
---- 1 -----
(defun jka-compr-handler (operation &rest args)
(save-match-data
(let ((jka-op (get operation 'jka-compr)))
(if (and jka-op (not jka-compr-inhibit))
(apply jka-op args)
(jka-compr-run-real-handler operation args)))))
skips when `get' fails, and also puts unnecessary `save-match-data'
call, which would better be inside if.
---- 2 -----
(defun epa-file-handler (operation &rest args)
(save-match-data
(let ((op (get operation 'epa-file)))
(if (and op (not epa-inhibit))
(apply op args)
(epa-file-run-real-handler operation args)))))
again checks `get' and also epa-inhitbit. (and again,
`save-match-data' only needed for (apply op args)).
Side note: These handlers essentially force double handler lookup
without skipping already processed handlers when they decide that they
need to delegate to defaults.
---- 3 -----
(if (not tramp-archive-enabled)
;; Unregister `tramp-archive-file-name-handler'.
(progn
(tramp-register-file-name-handlers)
(tramp-archive-run-real-handler operation args))
<...>
Note how this tries to remove itself from handler list, by testing a
boolean variable (nil by default!). However, this "self-removal" will
never happen unless we happen to query a file with matching regexp. If
no archive file is accessed during Emacs session (as it is the case for
me), this branch of code will never be executed and I am doomed to have
Emacs checking for regexp in front of this handler forever.
------ 4 ------
(defun tramp-completion-file-name-handler (operation &rest args)
"Invoke Tramp file name completion handler for OPERATION and ARGS.
Falls back to normal file name handler if no Tramp file name handler exists."
(if-let
((fn (and tramp-mode minibuffer-completing-file-name
(assoc operation tramp-completion-file-name-handler-alist))))
(save-match-data (apply (cdr fn) args))
(tramp-run-real-handler operation args)))
is checking for tramp-mode (t by default) and
minibuffer-completing-file-name (often nil).
-------- 5 --------
(defun tramp-file-name-handler (operation &rest args)
"Invoke Tramp file name handler for OPERATION and ARGS.
Fall back to normal file name handler if no Tramp file name handler exists."
(let ((filename (apply #'tramp-file-name-for-operation operation args))
<...>
(if (tramp-tramp-file-p filename) ;; <<--- always nil when tramp-mode is nil
<do staff>
;; When `tramp-mode' is not enabled, or the file name is quoted,
;; we don't do anything.
(tramp-run-real-handler operation args))
this one is more complex, but does nothing when tramp-mode is nil.
--------- 6 -------
file-name-non-special is complex.
The only thing I noticed is that it binds tramp-mode as
(let ((tramp-mode (and tramp-mode (eq method 'local-copy))))
So, other handlers checking for tramp-mode variable early would benefit
if they were able to do so.
--
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, (continued)
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Ihor Radchenko, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Eli Zaretskii, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Ihor Radchenko, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Michael Albinus, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Eli Zaretskii, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Michael Albinus, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Eli Zaretskii, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Spencer Baugh, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Eli Zaretskii, 2023/07/22
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Michael Albinus, 2023/07/22
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores,
Ihor Radchenko <=
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Michael Albinus, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Ihor Radchenko, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Michael Albinus, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Ihor Radchenko, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Michael Albinus, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Ihor Radchenko, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Eli Zaretskii, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Michael Albinus, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Dmitry Gutov, 2023/07/21
- bug#64735: 29.0.92; find invocations are ~15x slower because of ignores, Spencer Baugh, 2023/07/20