From f146a4f9c9dd7efe891a96f3158fa4917583a46b Mon Sep 17 00:00:00 2001
From: Kenichi Kamiya <kachick1@gmail.com>
Date: Wed, 2 Aug 2023 17:04:53 +0900
Subject: [PATCH] Make zsh faster again ~ Yesterday Once More ~ (#237)

---
 home-manager/packages.nix                     |  4 +-
 home-manager/zsh.nix                          | 42 +++++++++++++++++--
 .../share/homemade/bin/bench_shells.bash      |  9 ++--
 3 files changed, 47 insertions(+), 8 deletions(-)

diff --git a/home-manager/packages.nix b/home-manager/packages.nix
index 4f0f1fd8..9a0159d0 100644
--- a/home-manager/packages.nix
+++ b/home-manager/packages.nix
@@ -23,6 +23,9 @@
     pkgs.zoxide
     pkgs.fzf
 
+    # Used in anywhere
+    pkgs.coreutils
+
     # asdf/rtx
     #
     # Prefer rtx now
@@ -42,7 +45,6 @@
     pkgs.shfmt
     pkgs.nixpkgs-fmt
 
-    pkgs.coreutils
     pkgs.tree
     pkgs.exa
     pkgs.curl
diff --git a/home-manager/zsh.nix b/home-manager/zsh.nix
index 3688dc7a..87af459f 100644
--- a/home-manager/zsh.nix
+++ b/home-manager/zsh.nix
@@ -1,4 +1,4 @@
-{ config, ... }:
+{ config, lib, pkgs, ... }:
 
 {
   programs.starship.enableZshIntegration = true;
@@ -37,7 +37,42 @@
     syntaxHighlighting.enable = true;
 
     enableAutosuggestions = true;
+
+    # NOTE: enabling without tuning makes much slower zsh as +100~200ms execution time
+    #       And the default path is not intended, so you SHOULD update `completionInit`
     enableCompletion = true;
+    # https://github.com/nix-community/home-manager/blob/8c731978f0916b9a904d67a0e53744ceff47882c/modules/programs/zsh.nix#L325C7-L329
+    # https://github.com/nix-community/home-manager/blob/8c731978f0916b9a904d67a0e53744ceff47882c/modules/programs/zsh.nix#L368-L372
+    # The default is "autoload -U compinit && compinit", I can not accept the path and speed
+    initExtraBeforeCompInit = ''
+      _elapsed_seconds_for() {
+        local -r target_path="$1"
+        echo "$(("$(${lib.getBin pkgs.coreutils}/bin/date +"%s")" - "$(${lib.getBin pkgs.coreutils}/bin/stat --format='%Y' "$target_path")"))"
+      }
+
+      # path - https://stackoverflow.com/a/48057649/1212807
+      # speed - https://gist.github.com/ctechols/ca1035271ad134841284
+      # both - https://github.com/kachick/dotfiles/pull/155
+      _compinit_with_interval() {
+        local -r dump_dir="${config.xdg.cacheHome}/zsh"
+        local -r dump_path="$dump_dir/zcompdump-$ZSH_VERSION"
+        # seconds * minutes * hours
+        local -r threshold="$((60 * 60 * 3))"
+
+        if [ -e "$dump_path" ] && [ "$(_elapsed_seconds_for "$dump_path")" -le "$threshold" ]; then
+          # https://zsh.sourceforge.io/Doc/Release/Completion-System.html#Use-of-compinit
+          # -C omit to check new functions
+          compinit -C -d "$dump_path"
+        else
+          mkdir -p "$dump_dir"
+          compinit -d "$dump_path"
+        fi
+      }
+    '';
+    completionInit = ''
+      # `autoload` enable to use compinit
+      autoload -Uz compinit && _compinit_with_interval
+    '';
 
     # Setting bindkey
     # https://github.com/nix-community/home-manager/blob/8c731978f0916b9a904d67a0e53744ceff47882c/modules/programs/zsh.nix#L28
@@ -46,9 +81,8 @@
 
     # home-manager path will set in `programs.home-manager.enable = true`;
     envExtra = ''
-      # https://wiki.archlinux.jp/index.php/XDG_Base_Directory
-      # https://www.reddit.com/r/zsh/comments/tpwx9t/zcompcache_vs_zcompdump/
-      zstyle ':completion:*' cache-path "$XDG_CACHE_HOME/zsh/zcompcache"
+      # https://gist.github.com/ctechols/ca1035271ad134841284?permalink_comment_id=3401477#gistcomment-3401477
+      skip_global_compinit=1
 
       if [ -e "$HOME/.nix-profile/etc/profile.d/nix.sh" ]; then . "$HOME/.nix-profile/etc/profile.d/nix.sh"; fi # added by Nix installer
     '';
diff --git a/home/.local/share/homemade/bin/bench_shells.bash b/home/.local/share/homemade/bin/bench_shells.bash
index a50bba9d..fce7657b 100755
--- a/home/.local/share/homemade/bin/bench_shells.bash
+++ b/home/.local/share/homemade/bin/bench_shells.bash
@@ -4,10 +4,13 @@ set -euxo pipefail
 
 # ~ my feeling ~
 # 50ms : blazing fast!
-# 120ms : acceptable
+# 110ms : acceptable
+# 150ms : slow
 # 200ms : 1980s?
-# 300ms : slow!
+# 300ms : much slow!
 
-hyperfine --warmup 1 'bash -i -c exit'
+# zsh should be first, because it often makes much slower with the completion
 hyperfine --warmup 1 'zsh --interactive -c exit'
+
+hyperfine --warmup 1 'bash -i -c exit'
 hyperfine --warmup 1 'fish --interactive --command exit'