Redlocker

Acquire and keep distributed locks alive using redis

There are already quite some ruby libraries available which use redis for the purpose of distributed locking, but they require you to specify the time time-to-live of your locks. Contrary, Redlocker allows you to easily acquire and keep distributed locks alive using redis. An acquired lock gets automatically renewed every second from a thread, i.e. its 5 second expiry value gets renewed in redis every second, and it gets released as soon as the given block finishes.

Installation

Add this line to your application's Gemfile:

gem 'redlocker'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install redlocker

Usage

Using Redlocker could not be easier:

RedlockerClient = Redlocker::Client.new(redis: Redis.new)

RedlockerClient.with_lock('some_lock', timeout: 5) do
  # lock acquired
end

If the lock can not be acquired within the specified timeout, a Redlocker::TimeoutError is raised.

When the block finishes or raises, the acquired lock gets freed.

You can optionally pass a delay when acquiring a lock, which specifies the time to wait between subsequent calls which check in redis whether or not the lock is free. Default is 0.25 seconds:

RedlockerClient.with_lock("some lock", timeout: 5, delay: 1) do
  # lock acquired
end

If you are using a shared redis, you can pass a namespace, which will be used for prefixing redis keys in addition to the default redlocker: namespace.

RedlockerClient = Redlocker::Client.new(redis: Redis.new, namespace: "my-namespace")

That's it.

Reference docs

Please find the reference docs at http://www.rubydoc.info/github/mrkamel/redlocker

Development

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

Contributing

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

License

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