perf(shell/zsh.rs): avoid hook-env execution on Enter without command

[powerman]

Some zsh configuration are intentionally optimized to work really fast and it's important to keep it feels this way. And while mise hook-env is really fast (0.008 sec on my system) and slowdown isn't noticeable when running any command (even builtin one like echo or true) it still result in noticeable slowdown when just pressing Enter without any command.

At a glance proposed optimization shouldn't break any functionality, and it fixes mentioned above noticeable slowdown.

[powerman]

This fixes two issues:

• One is related to this PR: first command in a new zsh won't get right env because of this PR's optimization.
• Another issue is not related to this PR and fixes zsh -i -c '...' - current mise implementation won't provide right env to the command executed inside child zsh.

[jdx]

I can't remember why but there is a reason I chose not to run hook-env automatically

[powerman]

I can't remember why but there is a reason I chose not to run hook-env automatically

Sometimes only way to recall it is to change a code and wait until something breaks.

I'm not sure is missing env in a zsh -i -c '...' considered a real issue. This is probably a real "corner" case and might not worth supporting: without -i it won't load Mise anyway, but -i with -c makes not much sense and in my experience it used mostly for testing zsh performance - how fast it loads user configs in interactive mode.

Still, your doc example in https://mise.jdx.dev/dev-tools/shims.html#zshrc-bashrc-files ask user to run it manually after activation - which has exactly same effect as my change to run it automatically but require extra manual change in user's config. Also, same 2-command example is repeated in https://mise.jdx.dev/troubleshooting.html#mise-isn-t-working-when-calling-from-tmux-or-another-shell-initialization-script.

So, I'm not joking here: if you can't remember why you chose not to run hook-env automatically then in current situation I think it makes sense to start running it automatically - this way it either will work and let you simplify UX and clean up docs, or breaks and this time you'll add a comment somewhere describing why it's bad idea to run it automatically on activation.

[powerman]

Maybe this was the reason: #204 (comment)?

[powerman]

If that dotenv conflict is still actual, then you probably need to mention needs to manually add second line with hook-env in shell rc files at https://mise.jdx.dev/getting-started.html#_2-activate-mise (and maybe with a note about direnv and what to do between these two lines to avoid conflict with dotenv.

[powerman]

Also, if mise activate zsh will now output code which runs mise hook-env, then this doc should be updated: https://mise.jdx.dev/dev-tools/shims.html#zshrc-bashrc-files

[joshbode]

It could be my particular setup, but I'm finding that the chpwd and precmd hooks are both executing whenever I change directory (in that order), so I've replaced the _mise_hook in my .zshrc as follows to ensure they're mutually exclusive:

source <(mise activate zsh)

function _mise_hook {
  source <(mise hook-env -s zsh)
  ZLAST_COMMANDS=""  # prevent precmd hook also triggering
}
ZLAST_COMMANDS="_"  # ensure the precmd hook executes initially

[powerman]

ZLAST_COMMANDS="_"  # ensure the precmd hook executes initially

I think it's better to do eval "$(mise hook-env -s zsh)" instead here (after mise activate) - this way is mentioned in the docs, it doesn't mangle ZLAST_COMMANDS and it doesn't makes any assumptions about current hook optimizations.

  ZLAST_COMMANDS=""  # prevent precmd hook also triggering

This may breaks other things which use ZLAST_COMMANDS. So, it's more safe to use own flag instead:

+typeset -g mise_skip_hook_cmd
 _mise_hook() {
   eval "$(mise hook-env -s zsh)";
+  mise_skip_hook_cmd=1
 }
 _mise_hook_cmd() {
-  if [[ -n "$ZLAST_COMMANDS" ]]; then
+  if [[ -n "$ZLAST_COMMANDS" && -z "$mise_skip_hook_cmd" ]]; then
     _mise_hook;
   fi
+  mise_skip_hook_cmd=
 }

If you like to avoid this extra complexity then this one will works too in most (but not all) cases:

-  if [[ -n "$ZLAST_COMMANDS" ]]; then
+  if [[ -n "$ZLAST_COMMANDS" && "$ZLAST_COMMANDS" != "cd" ]]; then

[joshbode]

Good point, @powerman

I ended up with this solution, which seems to work well for me, and doesn't rely on ZLAST_COMMANDS (I don't always use cd to change dirs, sometimes just directly typing the directory name as I have the AUTO_CD option enabled):

_last_mise_hook_trigger=""

function _mise_hook_chpwd {
  _mise_hook
  _last_mise_hook_trigger="chpwd"
}
chpwd_functions[1]=_mise_hook_chpwd

function _mise_hook_precmd {
  if [[ ${_last_mise_hook_trigger} == "precmd" ]]; then
    _mise_hook
  fi
  _last_mise_hook_trigger="precmd"
}
precmd_functions[1]=_mise_hook_precmd