bundle2: increase payload part chunk size to 32kb
Bundle2 payload parts are framed chunks. Esentially, we obtain
data in equal size chunks of size `preferedchunksize` and emit those
to a generator. That generator is fed into a compressor (which can
be the no-op compressor, which just re-emits the generator). And
the output from the compressor likely goes to a file descriptor
or socket.
What this means is that small chunk sizes create more Python objects
and Python function calls than larger chunk sizes. And as we know,
Python object and function call overhead in performance sensitive
code matters (at least with CPython).
This commit increases the bundle2 part payload chunk size from 4k
to 32k. Practically speaking, this means that the chunks we feed
into a compressor (implemented in C code) or feed directly into a
file handle or socket write() are larger. It's possible the chunks
might be larger than what the receiver can handle in one logical
operation. But at that point, we're in C code, which is much more
efficient at dealing with splitting up the chunk and making multiple
function calls than Python is.
A downside to larger chunks is that the receiver has to wait for that
much data to arrive (either raw or from a decompressor) before it
can process the chunk. But 32kb still feels like a small buffer to
have to wait for. And in many cases, the client will convert from
8 read(4096) to 1 read(32768). That's happening in Python land. So
we cut down on the number of Python objects and function calls,
making the client faster as well. I don't think there are any
significant concerns to increasing the payload chunk size to 32kb.
The impact of this change on performance significant. Using `curl`
to obtain a stream clone bundle2 payload from a server on localhost
serving the mozilla-unified repository:
before: 20.78 user; 7.71 system; 80.5 MB/s
after: 13.90 user; 3.51 system; 132 MB/s
legacy: 9.72 user; 8.16 system; 132 MB/s
bundle2 stream clone generation is still more resource intensive than
legacy stream clone (that's likely because of the use of a
util.chunkbuffer). But the throughput is the same. We might
be in territory we're this is effectively a benchmark of the
networking stack or Python's syscall throughput.
From the client perspective, `hg clone -U --stream`:
before: 33.50 user; 7.95 system; 53.3 MB/s
after: 22.82 user; 7.33 system; 72.7 MB/s
legacy: 29.96 user; 7.94 system; 58.0 MB/s
And for `hg clone --stream` with a working directory update of
~230k files:
after: 119.55 user; 26.47 system; 0:57.08 wall
legacy: 126.98 user; 26.94 system; 1:05.56 wall
So, it appears that bundle2's stream clone is now definitively faster
than legacy stream clone!
Differential Revision: https://phab.mercurial-scm.org/D1932
;;; mq.el --- Emacs support for Mercurial Queues
;; Copyright (C) 2006 Bryan O'Sullivan
;; Author: Bryan O'Sullivan <bos@serpentine.com>
;; mq.el is free software; you can redistribute it and/or modify it
;; under the terms of the GNU General Public License version 2 or any
;; later version.
;; mq.el is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;; General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with mq.el, GNU Emacs, or XEmacs; see the file COPYING (`C-h
;; C-l'). If not, see <http://www.gnu.org/licenses/>.
(eval-when-compile (require 'cl))
(require 'mercurial)
(defcustom mq-mode-hook nil
"Hook run when a buffer enters mq-mode."
:type 'sexp
:group 'mercurial)
(defcustom mq-global-prefix "\C-cq"
"The global prefix for Mercurial Queues keymap bindings."
:type 'sexp
:group 'mercurial)
(defcustom mq-edit-mode-hook nil
"Hook run after a buffer is populated to edit a patch description."
:type 'sexp
:group 'mercurial)
(defcustom mq-edit-finish-hook nil
"Hook run before a patch description is finished up with."
:type 'sexp
:group 'mercurial)
(defcustom mq-signoff-address nil
"Address with which to sign off on a patch."
:type 'string
:group 'mercurial)
;;; Internal variables.
(defvar mq-mode nil
"Is this file managed by MQ?")
(make-variable-buffer-local 'mq-mode)
(put 'mq-mode 'permanent-local t)
(defvar mq-patch-history nil)
(defvar mq-top-patch '(nil))
(defvar mq-prev-buffer nil)
(make-variable-buffer-local 'mq-prev-buffer)
(put 'mq-prev-buffer 'permanent-local t)
(defvar mq-top nil)
(make-variable-buffer-local 'mq-top)
(put 'mq-top 'permanent-local t)
;;; Global keymap.
(defvar mq-global-map
(let ((map (make-sparse-keymap)))
(define-key map "." 'mq-push)
(define-key map ">" 'mq-push-all)
(define-key map "," 'mq-pop)
(define-key map "<" 'mq-pop-all)
(define-key map "=" 'mq-diff)
(define-key map "r" 'mq-refresh)
(define-key map "e" 'mq-refresh-edit)
(define-key map "i" 'mq-new)
(define-key map "n" 'mq-next)
(define-key map "o" 'mq-signoff)
(define-key map "p" 'mq-previous)
(define-key map "s" 'mq-edit-series)
(define-key map "t" 'mq-top)
map))
(global-set-key mq-global-prefix mq-global-map)
(add-minor-mode 'mq-mode 'mq-mode)
;;; Refresh edit mode keymap.
(defvar mq-edit-mode-map
(let ((map (make-sparse-keymap)))
(define-key map "\C-c\C-c" 'mq-edit-finish)
(define-key map "\C-c\C-k" 'mq-edit-kill)
(define-key map "\C-c\C-s" 'mq-signoff)
map))
;;; Helper functions.
(defun mq-read-patch-name (&optional source prompt force)
"Read a patch name to use with a command.
May return nil, meaning \"use the default\"."
(let ((patches (split-string
(hg-chomp (hg-run0 (or source "qseries"))) "\n")))
(when force
(completing-read (format "Patch%s: " (or prompt ""))
(mapcar (lambda (x) (cons x x)) patches)
nil
nil
nil
'mq-patch-history))))
(defun mq-refresh-buffers (root)
(save-excursion
(dolist (buf (hg-buffers-visiting-repo root))
(when (not (verify-visited-file-modtime buf))
(set-buffer buf)
(let ((ctx (hg-buffer-context)))
(message "Refreshing %s..." (buffer-name))
(revert-buffer t t t)
(hg-restore-context ctx)
(message "Refreshing %s...done" (buffer-name))))))
(hg-update-mode-lines root)
(mq-update-mode-lines root))
(defun mq-last-line ()
(goto-char (point-max))
(beginning-of-line)
(when (looking-at "^$")
(forward-line -1))
(let ((bol (point)))
(end-of-line)
(let ((line (buffer-substring bol (point))))
(when (> (length line) 0)
line))))
(defun mq-push (&optional patch)
"Push patches until PATCH is reached.
If PATCH is nil, push at most one patch."
(interactive (list (mq-read-patch-name "qunapplied" " to push"
current-prefix-arg)))
(let ((root (hg-root))
(prev-buf (current-buffer))
last-line ok)
(unless root
(error "Cannot push outside a repository!"))
(hg-sync-buffers root)
(let ((buf-name (format "MQ: Push %s" (or patch "next patch"))))
(kill-buffer (get-buffer-create buf-name))
(split-window-vertically)
(other-window 1)
(switch-to-buffer (get-buffer-create buf-name))
(cd root)
(message "Pushing...")
(setq ok (= 0 (apply 'call-process (hg-binary) nil t t "qpush"
(if patch (list patch))))
last-line (mq-last-line))
(let ((lines (count-lines (point-min) (point-max))))
(if (or (<= lines 1)
(and (equal lines 2) (string-match "Now at:" last-line)))
(progn
(kill-buffer (current-buffer))
(delete-window))
(hg-view-mode prev-buf))))
(mq-refresh-buffers root)
(sit-for 0)
(when last-line
(if ok
(message "Pushing... %s" last-line)
(error "Pushing... %s" last-line)))))
(defun mq-push-all ()
"Push patches until all are applied."
(interactive)
(mq-push "-a"))
(defun mq-pop (&optional patch)
"Pop patches until PATCH is reached.
If PATCH is nil, pop at most one patch."
(interactive (list (mq-read-patch-name "qapplied" " to pop to"
current-prefix-arg)))
(let ((root (hg-root))
last-line ok)
(unless root
(error "Cannot pop outside a repository!"))
(hg-sync-buffers root)
(set-buffer (generate-new-buffer "qpop"))
(cd root)
(message "Popping...")
(setq ok (= 0 (apply 'call-process (hg-binary) nil t t "qpop"
(if patch (list patch))))
last-line (mq-last-line))
(kill-buffer (current-buffer))
(mq-refresh-buffers root)
(sit-for 0)
(when last-line
(if ok
(message "Popping... %s" last-line)
(error "Popping... %s" last-line)))))
(defun mq-pop-all ()
"Push patches until none are applied."
(interactive)
(mq-pop "-a"))
(defun mq-refresh-internal (root &rest args)
(hg-sync-buffers root)
(let ((patch (mq-patch-info "qtop")))
(message "Refreshing %s..." patch)
(let ((ret (apply 'hg-run "qrefresh" args)))
(if (equal (car ret) 0)
(message "Refreshing %s... done." patch)
(error "Refreshing %s... %s" patch (hg-chomp (cdr ret)))))))
(defun mq-refresh (&optional git)
"Refresh the topmost applied patch.
With a prefix argument, generate a git-compatible patch."
(interactive "P")
(let ((root (hg-root)))
(unless root
(error "Cannot refresh outside of a repository!"))
(apply 'mq-refresh-internal root (if git '("--git")))))
(defun mq-patch-info (cmd &optional msg)
(let* ((ret (hg-run cmd))
(info (hg-chomp (cdr ret))))
(if (equal (car ret) 0)
(if msg
(message "%s patch: %s" msg info)
info)
(error "%s" info))))
(defun mq-top ()
"Print the name of the topmost applied patch."
(interactive)
(mq-patch-info "qtop" "Top"))
(defun mq-next ()
"Print the name of the next patch to be pushed."
(interactive)
(mq-patch-info "qnext" "Next"))
(defun mq-previous ()
"Print the name of the first patch below the topmost applied patch.
This would become the active patch if popped to."
(interactive)
(mq-patch-info "qprev" "Previous"))
(defun mq-edit-finish ()
"Finish editing the description of this patch, and refresh the patch."
(interactive)
(unless (equal (mq-patch-info "qtop") mq-top)
(error "Topmost patch has changed!"))
(hg-sync-buffers hg-root)
(run-hooks 'mq-edit-finish-hook)
(mq-refresh-internal hg-root "-m" (buffer-substring (point-min) (point-max)))
(let ((buf mq-prev-buffer))
(kill-buffer nil)
(switch-to-buffer buf)))
(defun mq-edit-kill ()
"Kill the edit currently being prepared."
(interactive)
(when (or (not (buffer-modified-p)) (y-or-n-p "Really kill this edit? "))
(let ((buf mq-prev-buffer))
(kill-buffer nil)
(switch-to-buffer buf))))
(defun mq-get-top (root)
(let ((entry (assoc root mq-top-patch)))
(if entry
(cdr entry))))
(defun mq-set-top (root patch)
(let ((entry (assoc root mq-top-patch)))
(if entry
(if patch
(setcdr entry patch)
(setq mq-top-patch (delq entry mq-top-patch)))
(setq mq-top-patch (cons (cons root patch) mq-top-patch)))))
(defun mq-update-mode-lines (root)
(let ((cwd default-directory))
(cd root)
(condition-case nil
(mq-set-top root (mq-patch-info "qtop"))
(error (mq-set-top root nil)))
(cd cwd))
(let ((patch (mq-get-top root)))
(save-excursion
(dolist (buf (hg-buffers-visiting-repo root))
(set-buffer buf)
(if mq-mode
(setq mq-mode (or (and patch (concat " MQ:" patch)) " MQ")))))))
(defun mq-mode (&optional arg)
"Minor mode for Mercurial repositories with an MQ patch queue"
(interactive "i")
(cond ((hg-root)
(setq mq-mode (if (null arg) (not mq-mode)
arg))
(mq-update-mode-lines (hg-root))))
(run-hooks 'mq-mode-hook))
(defun mq-edit-mode ()
"Mode for editing the description of a patch.
Key bindings
------------
\\[mq-edit-finish] use this description
\\[mq-edit-kill] abandon this description"
(interactive)
(use-local-map mq-edit-mode-map)
(set-syntax-table text-mode-syntax-table)
(setq local-abbrev-table text-mode-abbrev-table
major-mode 'mq-edit-mode
mode-name "MQ-Edit")
(set-buffer-modified-p nil)
(setq buffer-undo-list nil)
(run-hooks 'text-mode-hook 'mq-edit-mode-hook))
(defun mq-refresh-edit ()
"Refresh the topmost applied patch, editing the patch description."
(interactive)
(while mq-prev-buffer
(set-buffer mq-prev-buffer))
(let ((root (hg-root))
(prev-buffer (current-buffer))
(patch (mq-patch-info "qtop")))
(hg-sync-buffers root)
(let ((buf-name (format "*MQ: Edit description of %s*" patch)))
(switch-to-buffer (get-buffer-create buf-name))
(when (= (point-min) (point-max))
(set (make-local-variable 'hg-root) root)
(set (make-local-variable 'mq-top) patch)
(setq mq-prev-buffer prev-buffer)
(insert (hg-run0 "qheader"))
(goto-char (point-min)))
(mq-edit-mode)
(cd root)))
(message "Type `C-c C-c' to finish editing and refresh the patch."))
(defun mq-new (name)
"Create a new empty patch named NAME.
The patch is applied on top of the current topmost patch.
With a prefix argument, forcibly create the patch even if the working
directory is modified."
(interactive (list (mq-read-patch-name "qseries" " to create" t)))
(message "Creating patch...")
(let ((ret (if current-prefix-arg
(hg-run "qnew" "-f" name)
(hg-run "qnew" name))))
(if (equal (car ret) 0)
(progn
(hg-update-mode-lines (buffer-file-name))
(message "Creating patch... done."))
(error "Creating patch... %s" (hg-chomp (cdr ret))))))
(defun mq-edit-series ()
"Edit the MQ series file directly."
(interactive)
(let ((root (hg-root)))
(unless root
(error "Not in an MQ repository!"))
(find-file (concat root ".hg/patches/series"))))
(defun mq-diff (&optional git)
"Display a diff of the topmost applied patch.
With a prefix argument, display a git-compatible diff."
(interactive "P")
(hg-view-output ((format "MQ: Diff of %s" (mq-patch-info "qtop")))
(if git
(call-process (hg-binary) nil t nil "qdiff" "--git")
(call-process (hg-binary) nil t nil "qdiff"))
(diff-mode)
(font-lock-fontify-buffer)))
(defun mq-signoff ()
"Sign off on the current patch, in the style used by the Linux kernel.
If the variable mq-signoff-address is non-nil, it will be used, otherwise
the value of the ui.username item from your hgrc will be used."
(interactive)
(let ((was-editing (eq major-mode 'mq-edit-mode))
signed)
(unless was-editing
(mq-refresh-edit))
(save-excursion
(let* ((user (or mq-signoff-address
(hg-run0 "debugconfig" "ui.username")))
(signoff (concat "Signed-off-by: " user)))
(if (search-forward signoff nil t)
(message "You have already signed off on this patch.")
(goto-char (point-max))
(let ((case-fold-search t))
(if (re-search-backward "^Signed-off-by: " nil t)
(forward-line 1)
(insert "\n")))
(insert signoff)
(message "%s" signoff)
(setq signed t))))
(unless was-editing
(if signed
(mq-edit-finish)
(mq-edit-kill)))))
(provide 'mq)
;;; Local Variables:
;;; prompt-to-byte-compile: nil
;;; end: