docs(Emacs basic conf): better garbage collection

docs/emacs/basic-config.org

@@ -25,9 +25,54 @@ loaded, speeding Emacs up a bit.
 (set-fringe-mode 10)               ; give some breathing room
 (menu-bar-mode -1)                 ; disable menubar
 (blink-cursor-mode 0)              ; disable blinking cursor
-(setq gc-cons-threshold (* 1024 1024 1024))
 #+end_src
 
+*** Better garbage collection
+Emacs sometimes freezes up a bit when doing some garbage collection,
+which is not super. So, in order to fix that, I do two things:
+1. Set up a really high threshold (I have a lot of RAM to spare, so I
+   don’t really care),
+2. Hook garbage collection thirty seconds after Emacs loses focus and
+   every thirty seconds after that,
+3. Cancel garbage collection if Emacs gains focus back within this
+   thirty seconds window.
+
+With a garbage collection threshold, Emacs should never garbage
+collect on its own, and Emacs is free to freeze up for a few seconds
+when it loses focus since I’m looking away.
+#+begin_src emacs-lisp
+(setq garbage-collection-messages t            ;; tell me when garbage collecting
+      gc-cons-threshold (* 16 1024 1024 1024)) ;; 16GiB of RAM
+
+(defmacro my/time (&rest body)
+  `(let ((time (current-time)))
+     ,@body
+     (float-time (time-since time))))
+
+(defun my/garbage-collect ()
+  "Garbage collect and tell the user how much time it took."
+  (message "Garbage collector ran for %.06fs"
+           (my/time (garbage-collect))))
+
+(defvar my/gc-timer nil
+  "Timer for garbage collection. See
+`my/garbage-collect-on-focus-lost'.")
+
+(defun my/garbage-collect-on-focus-lost ()
+  "Garbage collect when Emacs loses focus.
+
+Garbage collection is only triggered thirty seconds after losing
+focus, and only once."
+  (if (frame-focus-state
+       (cancel-timer my/gc-timer))
+    (setq my/gc-timer (run-with-idle-timer 30 nil #'my/garbage-collect))))
+
+(add-function :after after-focus-change-function #'my/garbage-collect-on-focus-lost)
+#+end_src
+
+To write this, I mostly based myself on [[https://news.ycombinator.com/item?id=39190110][this HackerNews thread]] and [[https://akrl.sdf.org/#orgc15a10d][its
+related article]].
+
 ** Emacs Behavior
 *** Editing Text in Emacs
 I *never* want to keep trailing spaces in my files, which is why I’m