Geist

Geist is a Git-backed key-value store written in Ruby.

require 'geist'

g = Geist.new '~/some/storage/path'
g.set :foo, 'bar'
g.set :baz, 123
g.set :name => 'geist', :platform => 'ruby'

g.keys                 #=> ["foo", "name", "platform"]
g.get :foo             #=> "bar"
g.get :baz             #=> 123
g.get :name, :platform #=> ["geist", "ruby"]

g.delete :baz
g.get :baz             #=> nil

To be honest, the introduction was an outright fabrication. Geist is just a Ruby API to misuse Git as a simple key-value store. Git itself is a pretty good key-value store used to preserve blob (file), tree (directory), commit and tag objects. A key-value store used to store versioned file histories in general.

Geist instead uses some low-level Git commands to store arbitrary Ruby objects in a Git repository. The Ruby objects to store as values will be marshalled into Git blob objects. These objects are referenced with lightweight Git tags named by the given key.

Git will not double store duplicate values. Instead, the different key tags will refer the same Git object.

As Geist uses Git tags as keys, only objects with a working #to_s method can be used as keys. Additionally, based on Git's ref naming rules, Geist rejects keys that can't be used as Git tag names, e.g. containing non-printable characters or backslashes.

Geist was an idea for the Codebrawl contest "Key/value stores" and made it to a honorable 6th place out of 18 contestants with a final score of 3.6.

This code is free software; you can redistribute it and/or modify it under the terms of the new BSD License. A copy of this license can be found in the LICENSE file.

• Sebastian Staudt – koraktor(at)gmail.com