From 9ef8e38aecd98a7c67f3e77492393ff146a016a3 Mon Sep 17 00:00:00 2001
From: Sami Samhuri <sami@samhuri.net>
Date: Mon, 16 Dec 2024 08:55:55 -0800
Subject: [PATCH] Speed up shell startup with evalcache

---
 zsh/functions/_evalcache |  50 ++++++++++++
 zsh/functions/_hub       | 160 ---------------------------------------
 zshrc                    |  16 ++--
 3 files changed, 60 insertions(+), 166 deletions(-)
 create mode 100755 zsh/functions/_evalcache
 delete mode 100644 zsh/functions/_hub

diff --git a/zsh/functions/_evalcache b/zsh/functions/_evalcache
new file mode 100755
index 0000000..ecbea7c
--- /dev/null
+++ b/zsh/functions/_evalcache
@@ -0,0 +1,50 @@
+# Caches the output of a binary initialization command, to avoid the time to
+# execute it in the future.
+#
+# Usage: _evalcache [NAME=VALUE]... COMMAND [ARG]...
+
+# default cache directory
+export ZSH_EVALCACHE_DIR=${ZSH_EVALCACHE_DIR:-"$HOME/.zsh-evalcache"}
+
+function _evalcache () {
+  local cmdHash="nohash" data="$*" name
+
+  # use the first non-variable argument as the name
+  for name in $@; do
+    if [ "${name}" = "${name#[A-Za-z_][A-Za-z0-9_]*=}" ]; then
+      break
+    fi
+  done
+
+  # if command is a function, include its definition in data
+  if typeset -f "${name}" > /dev/null; then
+    data=${data}$(typeset -f "${name}")
+  fi
+
+  if builtin command -v md5 > /dev/null; then
+    cmdHash=$(echo -n "${data}" | md5)
+  elif builtin command -v md5sum > /dev/null; then
+    cmdHash=$(echo -n "${data}" | md5sum | cut -d' ' -f1)
+  fi
+
+  local cacheFile="$ZSH_EVALCACHE_DIR/init-${name##*/}-${cmdHash}.sh"
+
+  if [ "$ZSH_EVALCACHE_DISABLE" = "true" ]; then
+    eval ${(q)@}
+  elif [ -s "$cacheFile" ]; then
+    source "$cacheFile"
+  else
+    if type "${name}" > /dev/null; then
+      echo "evalcache: ${name} initialization not cached, caching output of: $*" >&2
+      mkdir -p "$ZSH_EVALCACHE_DIR"
+      eval ${(q)@} > "$cacheFile"
+      source "$cacheFile"
+    else
+      echo "evalcache: ERROR: ${name} is not installed or in PATH" >&2
+    fi
+  fi
+}
+
+function _evalcache_clear () {
+  rm -i "$ZSH_EVALCACHE_DIR"/init-*.sh
+}
diff --git a/zsh/functions/_hub b/zsh/functions/_hub
deleted file mode 100644
index c7b2bb2..0000000
--- a/zsh/functions/_hub
+++ /dev/null
@@ -1,160 +0,0 @@
-#compdef hub
-
-# Zsh will source this file when attempting to autoload the "_hub" function,
-# typically on the first attempt to complete the hub command.  We define two new
-# setup helper routines (one for the zsh-distributed version, one for the
-# git-distributed, bash-based version).  Then we redefine the "_hub" function to
-# call "_git" after some other interception.
-#
-# This is pretty fragile, if you think about it.  Any number of implementation
-# changes in the "_git" scripts could cause problems down the road.  It would be
-# better if the stock git completions were just a bit more permissive about how
-# it allowed third-party commands to be added.
-
-(( $+functions[__hub_setup_zsh_fns] )) ||
-__hub_setup_zsh_fns () {
-  (( $+functions[_git-alias] )) ||
-  _git-alias () {
-    _arguments \
-      '-s[output shell script suitable for eval]' \
-      '1::shell:(zsh bash csh)'
-  }
-
-  (( $+functions[_git-browse] )) ||
-  _git-browse () {
-    _arguments \
-      '-u[output the URL]' \
-      '2::subpage:(wiki commits issues)'
-  }
-
-  (( $+functions[_git-compare] )) ||
-  _git-compare () {
-    _arguments \
-      '-u[output the URL]' \
-      ':[start...]end range:'
-  }
-
-  (( $+functions[_git-create] )) ||
-  _git-create () {
-    _arguments \
-      '::name (REPOSITORY or ORGANIZATION/REPOSITORY):' \
-      '-p[make repository private]' \
-      '-d[description]:description' \
-      '-h[home page]:repository home page URL:_urls'
-  }
-
-  (( $+functions[_git-fork] )) ||
-  _git-fork () {
-    _arguments \
-      '--no-remote[do not add a remote for the new fork]'
-  }
-
-  (( $+functions[_git-pull-request] )) ||
-  _git-pull-request () {
-    _arguments \
-      '-f[force (skip check for local commits)]' \
-      '-b[base]:base ("branch", "owner\:branch", "owner/repo\:branch"):' \
-      '-h[head]:head ("branch", "owner\:branch", "owner/repo\:branch"):' \
-      - set1 \
-        '-m[message]' \
-        '-F[file]' \
-      - set2 \
-        '-i[issue]:issue number:' \
-      - set3 \
-        '::issue-url:_urls'
-  }
-
-  # stash the "real" command for later
-  functions[_hub_orig_git_commands]=$functions[_git_commands]
-
-  # Replace it with our own wrapper.
-  declare -f _git_commands >& /dev/null && unfunction _git_commands
-  _git_commands () {
-    local ret=1
-    # call the original routine
-    _call_function ret _hub_orig_git_commands
-
-    # Effectively "append" our hub commands to the behavior of the original
-    # _git_commands function.  Using this wrapper function approach ensures
-    # that we only offer the user the hub subcommands when the user is
-    # actually trying to complete subcommands.
-    hub_commands=(
-      alias:'show shell instructions for wrapping git'
-      pull-request:'open a pull request on GitHub'
-      fork:'fork origin repo on GitHub'
-      create:'create new repo on GitHub for the current project'
-      browse:'browse the project on GitHub'
-      compare:'open GitHub compare view'
-      ci-status:'lookup commit in GitHub Status API'
-    )
-    _describe -t hub-commands 'hub command' hub_commands && ret=0
-
-    return ret
-  }
-}
-
-(( $+functions[__hub_setup_bash_fns] )) ||
-__hub_setup_bash_fns () {
-  # TODO more bash-style fns needed here to complete subcommand args.  They take
-  # the form "_git_CMD" where "CMD" is something like "pull-request".
-
-  # Duplicate and rename the 'list_all_commands' function
-  eval "$(declare -f __git_list_all_commands | \
-        sed 's/__git_list_all_commands/__git_list_all_commands_without_hub/')"
-
-  # Wrap the 'list_all_commands' function with extra hub commands
-  __git_list_all_commands() {
-    cat <<-EOF
-alias
-pull-request
-fork
-create
-browse
-compare
-ci-status
-EOF
-    __git_list_all_commands_without_hub
-  }
-
-  # Ensure cached commands are cleared
-  __git_all_commands=""
-}
-
-# redefine _hub to a much smaller function in the steady state
-_hub () {
-  # only attempt to intercept the normal "_git" helper functions once
-  (( $+__hub_func_replacement_done )) ||
-    () {
-      # At this stage in the shell's execution the "_git" function has not yet
-      # been autoloaded, so the "_git_commands" or "__git_list_all_commands"
-      # functions will not be defined.  Call it now (with a bogus no-op service
-      # to prevent premature completion) so that we can wrap them.
-      if declare -f _git >& /dev/null ; then
-        _hub_noop () { __hub_zsh_provided=1 }       # zsh-provided will call this one
-        __hub_noop_main () { __hub_git_provided=1 } # git-provided will call this one
-        local service=hub_noop
-        _git
-        unfunction _hub_noop
-        unfunction __hub_noop_main
-        service=git
-      fi
-
-      if (( $__hub_zsh_provided )) ; then
-        __hub_setup_zsh_fns
-      elif (( $__hub_git_provided )) ; then
-        __hub_setup_bash_fns
-      fi
-
-      __hub_func_replacement_done=1
-    }
-
-  # Now perform the actual completion, allowing the "_git" function to call our
-  # replacement "_git_commands" function as needed.  Both versions expect
-  # service=git or they will call nonexistent routines or end up in an infinite
-  # loop.
-  service=git
-  declare -f _git >& /dev/null && _git
-}
-
-# make sure we actually attempt to complete on the first "tab" from the user
-_hub
\ No newline at end of file
diff --git a/zshrc b/zshrc
index 76bd604..c9d2971 100755
--- a/zshrc
+++ b/zshrc
@@ -13,6 +13,13 @@ function is_interactive() { [ -t 1 ] }
 
 [[ -d "$HOME/config/zsh" ]] && ZDOTDIR="$HOME/config/zsh"
 
+fpath=($fpath $ZDOTDIR/functions $ZDOTDIR/completions)
+typeset -U fpath
+
+# Cache the output of commands that take a long time to run even
+# though they almost always return the same output.
+autoload _evalcache
+
 if [[ -r "$ZDOTDIR/zlocal" ]]; then
     source "$ZDOTDIR/zlocal"
 fi
@@ -22,13 +29,13 @@ fi
 # Do this before setting up PATH so ~/bin and similar still have the highest precedence.
 
 if command_exists rbenv; then
-    eval "$(rbenv init -)"
+    _evalcache rbenv init -
 fi
 if command_exists pyenv; then
-    eval "$(pyenv init -)"
+    _evalcache pyenv init -
 fi
 if command_exists direnv; then
-    eval "$(direnv hook zsh)"
+    _evalcache direnv hook zsh
 fi
 
 ### SSH keys
@@ -58,9 +65,6 @@ typeset -U path
 # remove / from word chars
 export WORDCHARS='*?_-.[]~=&;!#$%^(){}<>'
 
-fpath=($fpath $ZDOTDIR/functions $ZDOTDIR/completions)
-typeset -U fpath
-
 cdpath=(~)
 
 HOSTNAME=`hostname -s`