BuildCache

A simple cache for files. It is currently used in production to cache the results of frequently run built steps (using a custom build flow).

The cache receives the input files and some metadata. It generates a hash key and checks the cache. If the cache is hit, the files are copied from the cache to the provided location. If we have a cache miss, the provided block is run, and the resulting files are copied to the cache.

Installation

Add this line to your application's Gemfile:

gem 'buildcache'

And then execute:

$ bundle

Or install it yourself as:

$ gem install buildcache

Usage

Block Style

:::ruby
require 'buildcache'
@my_cache = BuildCache::DiskCache.new('/tmp/cache')
@input_files = ['./input.txt']
@metadata = {:cmd => 'parse input'}
@dest_dir = './build'
@my_cache.cache(@input_files, @metadata, @dest_dir) do
  # This is time consuming code where you generate result files.
  # The block is only run on a cache miss
  ...
  # You must return resulting files so they can be cached
  next files
end

Use API

The cache uses 2 keys. The first_key corresponds to directory name in the cache. second_key (optional) is held in a file and is used to resolve hash conflicts on first_key.

The following methods are available:

:::ruby
# Generate first_key
first_key = BuildCache.key_gen(input_files_array, metadata)

:::ruby
# Check for a cache hit
@my_cache.hit?(first_key, second_key)

:::ruby
# Set the cache
@my_cache.set(first_key, second_key, files_array)

:::ruby
# Retrieve from cache. The result is a cache directory where the files are stored
contents_dir = @my_cache.get(first_key, second_key)

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/getvictor/buildcache.

License

The gem is available as open source under the terms of the MIT License.