Once

Executes a block of code only once within a specified timeframe. Uses Redis to ensure uniqueness.

Add this line to your application's Gemfile:

gem 'once'

And then execute:

$ bundle

Or install it yourself as:

$ gem install once

First, connect to redis:

Once.redis = Redis.new(...)

If you don't specify the redis connection, we will assume the presence of a $redis global

Now, use Once to wrap a call that you want done uniquely

Once.do(name: "sending_email", params: { email: "foo@bar.com" }, within: 1.hour) do
  # executes once
end

The combination of the name and params makes the check unique. So typically it would be the command you're executing, plus the params to that command

This does not implement an atomic lock, nor does it take into account distributed locks across a cluster. This is more of a simple "probably guarantee uniqueness" implementation used to guard against things happening multiple times within minutes/hours/days, not milliseconds.

See: redlock for an example of distributed locking.

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request