view contrib/mq.el @ 36426:23d12524a202

http: drop custom http client logic

Eight and a half years ago, as my starter bug on code.google.com, I
investigated a mysterious "broken pipe" error from seemingly random
clients[0]. That investigation revealed a tragic story: the Python
standard library's httplib was (and remains) barely functional. During
large POSTs, if a server responds early with an error (even a
permission denied error!) the client only notices that the server
closed the connection and everything breaks. Such server behavior is
implicitly legal under RFC 2616 (the latest HTTP RFC as of when I was
last working on this), and my understanding is that later RFCs have
made it explicitly legal to respond early with any status code outside
the 2xx range.

I embarked, probably foolishly, on a journey to write a new http
library with better overall behavior. The http library appears to work
well in most cases, but it can get confused in the presence of
proxies, and it depends on select(2) which limits its utility if a lot
of file descriptors are open. I haven't touched the http library in
almost two years, and in the interim the Python community has
discovered a better way[1] of writing network code. In theory some day
urllib3 will have its own home-grown http library built on h11[2], or
we could do that. Either way, it's time to declare our current
confusingly-named "http2" client logic and move on. I do hope to
revisit this some day: it's still garbage that we can't even respond
with a 401 or 403 without reading the entire POST body from the
client, but the goalposts on writing a new http client library have
moved substantially. We're almost certainly better off just switching
to requests and eventually picking up their http fixes than trying to
live with something that realistically only we'll ever use. Another
approach would be to write an adapter so that Mercurial can use pycurl
if it's installed. Neither of those approaches seem like they should
be investigated prior to a release of Mercurial that works on Python
3: that's where the mindshare is going to be for any improvements to
the state of the http client art.

0: http://web.archive.org/web/20130501031801/http://code.google.com/p/support/issues/detail?id=2716
1: http://sans-io.readthedocs.io/
2: https://github.com/njsmith/h11

Differential Revision: https://phab.mercurial-scm.org/D2444

;;; mq.el --- Emacs support for Mercurial Queues

;; Copyright (C) 2006 Bryan O'Sullivan

;; Author: Bryan O'Sullivan <[e-mail]>

;; 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: