RedisLockingCache

Warning: This gem is alpha quality and not intended for production use. Code of this nature is fraught with race conditions and edge cases, and this gem was quickly constructed as an example.

WIP Redis caching gem that attempts to mitigate cache stampede by only permitting a single concurrent cache request to refresh the cache at a time. While the cache is refreshing, the stale value will be served. If cache refresh raises an error, the stale value will be served.

This gem is inspired by some helpful behavior in Nginx’s HTTP proxy module: proxy_cache_lock and proxy_cache_use_stale.

Installation

Add this line to your application’s Gemfile:

gem 'redis_locking_cache'

And then execute:

$ bundle

Or install it yourself as:

$ gem install redis_locking_cache

Usage

require 'redis_locking_cache'
cache = RedisLockingCache.new(Redis.new)
expensive_value = cache.fetch('expensive_key', expires_in: 300) do
  compute_expensive_value
end

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake test 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/dpirotte/redis_locking_cache. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

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

Code of Conduct

Everyone interacting in the RedisLockingCache project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.