[elpa] externals/elisp-benchmarks d9986d67b9: * benchmarks/elb-scroll.el: New benchmark

[Stefan Monnier]

branch: externals/elisp-benchmarks
commit d9986d67b92669993ddd553d6c3701614fac4e79
Author: Stefan Monnier <monnier@iro.umontreal.ca>
Commit: Stefan Monnier <monnier@iro.umontreal.ca>

    * benchmarks/elb-scroll.el: New benchmark
---
 benchmarks/elb-scroll.el | 61 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/benchmarks/elb-scroll.el b/benchmarks/elb-scroll.el
new file mode 100644
index 0000000000..73c48db788
--- /dev/null
+++ b/benchmarks/elb-scroll.el
@@ -0,0 +1,61 @@
+;;; elb-scroll.el --- Benchmark scrolling performance  -*- lexical-binding: t; 
-*-
+
+;; Copyright (C) 2022  Free Software Foundation, Inc.
+
+;; Author: Stefan Monnier <monnier@iro.umontreal.ca>
+
+;; 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 <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; Benchmarking the scrolling of a font-locked buffer.
+;; This is hard to do in a way that reflects real use because it
+;; requires drawing and such, which in turns requires an interactive
+;; session, whereas we usually want to run benchmarks in batch mode.
+;;
+;; We use `redisplay-skip-initial-frame' and (redisplay 'force) to
+;; get the redisplay to do its job when running in batch mode, but
+;; this benchmark will still give very different results in an interactive
+;; session.
+
+;;; Code:
+
+(unless (and noninteractive (not (boundp 'redisplay-skip-initial-frame)))
+  (defun elb-scroll-entry ()
+    ;; FIXME: This relies on `elb-smie.el' being compiled already which is
+    ;; not necessarily the case if we're only running some of the benchmarks.
+    (load (expand-file-name "elb-smie.elc" elb-bench-directory))
+    (setq redisplay-skip-initial-frame nil)
+    (with-temp-buffer
+      (rename-buffer (generate-new-buffer-name "elb-scroll"))
+      (switch-to-buffer (current-buffer))
+      (insert-file-contents (expand-file-name
+                             "../resources/xmenu.c" elb-bench-directory))
+      (redisplay 'force) ;; Refresh the window dimensions.
+      (enlarge-window (- 23 (window-height)))
+      (enlarge-window (- 80 (window-width)) 'horiz)
+      (redisplay 'force) ;; Refresh the window dimensions.
+      (message "Window size: %S x %S" (window-height) (window-width))
+      (unless (and (equal 23 (window-height))
+                   (equal 80 (window-width)))
+        (error "Window size not as stipulated by the benchmark"))
+      (dotimes (_ 10)
+        (elb-smie-mode)
+        (goto-char (point-min))
+        (condition-case nil
+            (while t (scroll-up nil) (redisplay 'force))
+          (end-of-buffer nil))))))
+
+(provide 'elb-scroll)
+;;; elb-scroll.el ends here