83 lines
3.1 KiB
Markdown
83 lines
3.1 KiB
Markdown
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# evalcache
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> zsh plugin to cache the output of a binary initialization command, intended
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> to help lower shell startup time.
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## What it does
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There are lots of shell wrapper tools that follow the pattern of asking you to
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eval a specific init command in your shell startup, for example, rbenv asks:
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eval "$(hub alias -s)"
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While this is very convenient, the reality is there is a small amount of
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overhead associated with shelling out to this, and the output is almost always
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actually static in all of the tools I know. So why bear this cost every time
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you open a new tab in your shell?
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Instead, after you load this plugin, you can replace that same command with:
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_evalcache hub alias -s
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The first time this runs, it will cache the output of the command to a file,
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which will be sourced in the future instead when it exists.
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If you update a tool and expect for some reason that it's initialization might
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have changed, you can simply clear the cache and it will be regenerated.
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It also gracefully degrades to a no-op if the tool is no longer installed.
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## Benchmarks
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Some informal benchmarks from my MacBook on my .zshrc:
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| command | without | first run | subsequent runs | savings |
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| ------------ | ------: | --------: | --------------: | ------: |
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| rbenv init | ~65ms | ~65ms | ~8ms | 88% |
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| hub alias | ~30ms | ~30ms | ~6ms | 80% |
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| scmpuff init | ~24ms | ~25ms | ~10ms | 58% |
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The difference isn't huge, but can be handy in shaving down shell startup time,
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especially if you use a bunch of these tools. Every millisecond counts!
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## Options
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- `$ZSH_EVALCACHE_DIR`: cache files storage, default `$HOME/.zsh-evalcache`.
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- `$ZSH_EVALCACHE_DISABLE`: set to `true` if you wish to bypass evalcache.
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There is a convenience function to clear the cache called `_evalcache_clear`.
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## Installation
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### [Antigen](https://github.com/zsh-users/antigen)
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Add `antigen bundle mroth/evalcache` to your `.zshrc` with your other bundle commands.
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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`.
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### [Fig](https://fig.io)
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Fig adds apps, shortcuts, and autocomplete to your existing terminal.
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Install `evalcache` in just one click.
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<a href="https://fig.io/plugins/other/evalcache_mroth" target="_blank"><img src="https://fig.io/badges/install-with-fig.svg" /></a>
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### [Oh-My-Zsh](http://ohmyz.sh/)
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1. Clone this repository into `$ZSH_CUSTOM/plugins` (by default `~/.oh-my-zsh/custom/plugins`)
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```sh
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git clone https://github.com/mroth/evalcache ${ZSH_CUSTOM:-~/.oh-my-zsh/custom}/plugins/evalcache
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```
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2. Edit `~/.zshrc` to add _evalcache_ to your plugin list,
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```diff
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- plugins=(...)
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+ plugins=(... evalcache)
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```
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### [Zgen](https://github.com/tarjoilija/zgen)
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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`.
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