From cdbd39ba26481b3bced7f8bf180e00723742f2e8 Mon Sep 17 00:00:00 2001
From: Henrik Lissner <henrik@lissner.net>
Date: Mon, 12 Jul 2021 21:57:44 -0400
Subject: [PATCH] emacs/undo: increase undo-outer-limit

Was missing a 0 (a typo), which meant it was less than its default
value, thus having the opposite effect and making data loss *more*
likely.

Also got rid of outdated comments; I think those have been around since
the sub-v2.0 days of Doom.
---
 modules/emacs/undo/config.el | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/modules/emacs/undo/config.el b/modules/emacs/undo/config.el
index 2c84ba4c6..bfa98f4a7 100644
--- a/modules/emacs/undo/config.el
+++ b/modules/emacs/undo/config.el
@@ -4,10 +4,10 @@
   :unless (featurep! +tree)
   :hook (doom-first-buffer . undo-fu-mode)
   :config
-  ;; Store more undo history to prevent loss of data
-  (setq undo-limit 400000
-        undo-strong-limit 3000000
-        undo-outer-limit 3000000)
+  ;; Increase undo history limits to reduce likelihood of data loss
+  (setq undo-limit 400000           ; 400kb (default is 160kb)
+        undo-strong-limit 3000000   ; 3mb   (default is 240kb)
+        undo-outer-limit 48000000)  ; 48mb  (default is 24mb)
 
   (define-minor-mode undo-fu-mode
     "Enables `undo-fu' for the current session."
@@ -60,12 +60,14 @@
   (setq undo-tree-visualizer-diff t
         undo-tree-auto-save-history t
         undo-tree-enable-undo-in-region t
-        ;; Increase undo-limits by a factor of ten to avoid emacs prematurely
-        ;; truncating the undo history and corrupting the tree. See
-        ;; https://github.com/syl20bnr/spacemacs/issues/12110
-        undo-limit 800000
-        undo-strong-limit 12000000
-        undo-outer-limit 120000000)
+        ;; Increase undo limits to avoid emacs prematurely truncating the undo
+        ;; history and corrupting the tree. This is larger than the undo-fu
+        ;; defaults because undo-tree trees consume exponentially more space,
+        ;; and then some when `undo-tree-enable-undo-in-region' is involved. See
+        ;; syl20bnr/spacemacs#12110
+        undo-limit 800000           ; 800kb (default is 160kb)
+        undo-strong-limit 12000000  ; 12mb  (default is 240kb)
+        undo-outer-limit 128000000) ; 128mb (default is 24mb)
 
   ;; Compress undo-tree history files with zstd, if available. File size isn't
   ;; the (only) concern here: the file IO barrier is slow for Emacs to cross;