evalcache

zsh plugin to cache the output of a binary initialization command, intended to help lower shell startup time.

What it does

There are lots of shell wrapper tools that follow the pattern of asking you to eval a specific init command in your shell startup, for example, rbenv asks:

eval "$(hub alias -s)"

While this is very convenient, the reality is there is a small amount of overhead associated with shelling out to this, and the output is almost always actually static in all of the tools I know. So why bear this cost every time you open a new tab in your shell?

Instead, after you load this plugin, you can replace that same command with:

_evalcache hub alias -s

The first time this runs, it will cache the output of the command to a file, which will be sourced in the future instead when it exists.

If you update a tool and expect for some reason that it's initialization might have changed, you can simply clear the cache and it will be regenerated.

It also gracefully degrades to a no-op if the tool is no longer installed.

Benchmarks

Some informal benchmarks from my MacBook on my .zshrc:

command	without	first run	subsequent runs	savings
rbenv init	~65ms	~65ms	~8ms	88%
hub alias	~30ms	~30ms	~6ms	80%
scmpuff init	~24ms	~25ms	~10ms	58%

The difference isn't huge, but can be handy in shaving down shell startup time, especially if you use a bunch of these tools. Every millisecond counts!

Options

$ZSH_EVALCACHE_DIR: cache files storage, default $HOME/.zsh-evalcache.
$ZSH_EVALCACHE_DISABLE: set to true if you wish to bypass evalcache.

There is a convenience function to clear the cache called _evalcache_clear.

Installation

Antigen

Add antigen bundle mroth/evalcache to your .zshrc with your other bundle commands.

Antigen will handle cloning the plugin for you automatically the next time you start zsh. You can also add the plugin to a running zsh with antigen bundle mroth/evalcache for testing before adding it to your .zshrc.

Fig

Fig adds apps, shortcuts, and autocomplete to your existing terminal.

Install evalcache in just one click.

Oh-My-Zsh

Clone this repository into $ZSH_CUSTOM/plugins (by default ~/.oh-my-zsh/custom/plugins)

git clone https://github.com/mroth/evalcache ${ZSH_CUSTOM:-~/.oh-my-zsh/custom}/plugins/evalcache

Edit ~/.zshrc to add evalcache to your plugin list,
```
- plugins=(...)
+ plugins=(... evalcache)
```

Zgen

Add zgen load mroth/evalcache to your .zshrc file in the same function you're doing your other zgen load calls in. Zgen will handle automatically cloning the plugin for you the next time you do a zgen save.