Setup

Installation is straight-forward: just add the gem to your Gemfile:

gem "all_futures", "~> 2.0"

All Futures relies on Redis via the kredis gem. Make sure that you have a Redis server running and that you have followed the Kredis installation instructions to set up your config/redis/shared.yml.

Thankfully, Rails 7 now ships with Kredis installed, which means you should be able to use All Futures going forward. Note that Kredis requires Ruby 2.7 or above.

Redis Cache Eviction Policy

All Futures is designed to create Redis keys on an as-needed basis. No attempt is made to clear keys, as there is an expectation that you will set an eviction policy which will remove old keys to make room for new ones.

The allkeys-lru or volatile-lru policy is likely your best bet for an All Futures configuration, depending on whether you use the expire option.

Configuring Redis

If possible, consider two Redis instances for your application; one with a noeviction policy for Sidekiq and other queues that you want to complain loudly if they are filling up, and one allkeys-lru` for Rails caching and All Futures.

This will allow maximum flexibility and takes advantage of the automatic cache expiration to ensure that your Redis instance will always remain available with a minimum of oversight required, even under load.

Hiredis

hiredis-rb is billed as a wrapper around the high-performance native Redis library. For a long time, it seemed like a no-brainer to use it because who doesn't love "fast"?

However, for reasons that are not entirely clear, at the time of this writing, the hiredis gem still doesn't appear to support SSL connections. This is problematic in many deployment environments, and the delay has caused many Rails developers to question whether they really need the added complexity, given Redis is usually the fastest part of a request anyhow.