Zappy Cider Eval Overlays
Cider eval overlays are a great technology of our time. Being able to use the hands and the eyes just in the place where I am thinking, right in the source code - just invaluable.
I want the The Quick Eval smooth and zappy. Yea. Pure coconut. It is my skates with which I ride the ice of the Clojure program.
How to get really fast cider eval overlays.
The Benchmark
- Make a
cider-eval-last-sexpafter this form:
(repeatedly 10000 random-uuid)
- is it zappy, or not zappy?
Numero Uno
The biggest gain - or pain, depending on how you want to think about it is the echo area message.
I set cider-use-overlays to t, not both.
(setq-default cider-use-overlays t)
Now we do not print the message anymore which is a night and day difference.
cider–make-result-overlay perf hacks
I still am not completely satisfied with those overlays.
You might think that fontifying the string takes long but it seems like in my perf investigation that did not seem to be an issue.
(Hence have cider-overlays-use-font-lock to t).
length instead of string-width
I went into cider--make-result-overlay and one of the performance bottlenecks was that we called string-width
on those large strings, which is an expensive computation.
It needs to calculate the actual string display width, which is different from the character count of the string.
I just changed this to a length call. Doesn't matter much to me. It's just about saying when to cut off the result-overlay.
This does another little speed up.
In case you don't know.
profiler-start- do the action you want to debug
profiler-stopprofiler-report
Truncate after 1 line, not 3 lines
I am fine with rendering less data in the preview overlay. I can use cider pretty print for bigger outputs. Instead of cutting off after (* 3 (window-width)) I just cut off after 1 window-width.
Here is the updated function that I use:
;;; cider-overlays.el --- Managing CIDER overlays -*- lexical-binding: t; -*- ;; Copyright © 2015-2023 Bozhidar Batsov, Artur Malabarba and CIDER contributors ;; Author: Artur Malabarba <bruce.connor.am@gmail.com> ;; This program is free software; you can redistribute it and/or modify ;; it under the terms of the GNU General Public License as published by ;; the Free Software Foundation, either version 3 of the License, or ;; (at your option) any later version. ;; This program 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 this program. If not, see <http://www.gnu.org/licenses/>. (cl-defun cider--make-result-overlay (value &rest props &key where duration (type 'result) (format (concat " " cider-eval-result-prefix "%s ")) (prepend-face 'cider-result-overlay-face) &allow-other-keys) "Place an overlay displaying VALUE at the position determined by WHERE. VALUE is used as the overlay's after-string property, meaning it is displayed at the end of the overlay. Return nil if the overlay was not placed or if it might not be visible, and return the overlay otherwise. Return the overlay if it was placed successfully, and nil if it failed. This function takes some optional keyword arguments: If WHERE is a number or a marker, apply the overlay as determined by `cider-result-overlay-position'. If it is a cons cell, the car and cdr determine the start and end of the overlay. DURATION takes the same possible values as the `cider-eval-result-duration' variable. TYPE is passed to `cider--make-overlay' (defaults to `result'). FORMAT is a string passed to `format'. It should have exactly one %s construct (for VALUE). All arguments beyond these (PROPS) are properties to be used on the overlay." (declare (indent 1)) (while (keywordp (car props)) (setq props (cdr (cdr props)))) ;; If the marker points to a dead buffer, don't do anything. (when-let ((buffer (cond ((markerp where) (marker-buffer where)) ((markerp (car-safe where)) (marker-buffer (car where))) (t (current-buffer))))) (with-current-buffer buffer (save-excursion (when (number-or-marker-p where) (goto-char where)) ;; Make sure the overlay is actually at the end of the sexp. (skip-chars-backward "\r\n[:blank:]") (let* ((beg (if (consp where) (car where) (save-excursion (clojure-backward-logical-sexp 1) (point)))) (end (if (consp where) (cdr where) (pcase cider-result-overlay-position ('at-eol (line-end-position)) ('at-point (point))))) ;; Specify `default' face, otherwise unformatted text will ;; inherit the face of the following text. (display-string (format (propertize format 'face 'default) value)) (o nil)) ;; Remove any overlay at the position we're creating a new one, if it ;; exists. (remove-overlays beg end 'category type) (funcall (if cider-overlays-use-font-lock #'font-lock-prepend-text-property #'put-text-property) 0 (length display-string) 'face prepend-face display-string) ;; If the display spans multiple lines or is very long, display it at ;; the beginning of the next line. (when (or (string-match "\n." display-string) (> (length display-string) (- (window-width) (current-column)))) (setq display-string (concat " \n" display-string))) ;; Put the cursor property only once we're done manipulating the ;; string, since we want it to be at the first char. (put-text-property 0 1 'cursor 0 display-string) (when (> (length display-string) (window-width)) (setq display-string (concat (substring display-string 0 (window-width)) (substitute-command-keys "...\nResult truncated. Type `\\[cider-inspect-last-result]' to inspect it.")))) ;; Create the result overlay. (setq o (apply #'cider--make-overlay beg end type 'after-string display-string props)) (pcase duration ((pred numberp) (run-at-time duration nil #'cider--delete-overlay o)) (`command ;; Since the previous overlay was already removed above, we should ;; remove the hook to remove all overlays after this function ;; ends. Otherwise, we would inadvertently remove the newly created ;; overlay too. (remove-hook 'post-command-hook 'cider--remove-result-overlay 'local) ;; If inside a command-loop, tell `cider--remove-result-overlay' ;; to only remove after the *next* command. (if this-command (add-hook 'post-command-hook #'cider--remove-result-overlay-after-command nil 'local) (cider--remove-result-overlay-after-command))) (`change (add-hook 'after-change-functions #'cider--remove-result-overlay nil 'local))) (when-let* ((win (get-buffer-window buffer))) ;; Left edge is visible. (when (and (<= (window-start win) (point) (window-end win)) ;; Right edge is visible. This is a little conservative ;; if the overlay contains line breaks. (or (< (+ (current-column) (length value)) (window-width win)) (not truncate-lines))) o)))))))