Yeller

Simple in-process pub sub notifier for ruby. Everything runs inside the process with no queue. All the listeners get notified about events in real time with no repeats.

Add this line to your application's Gemfile:

gem 'yeller'

And then execute:

$ bundle

Or install it yourself as:

$ gem install yeller

There's 2 actions, as you would expect:

To broadcast a message, just specify the message and the keys (they will be joined into one; this is for complex keys, so that you don't have to build them yourself)

class MyLoudClass
  def yell!
    Yeller.broadcast "HELLO, EVERYONE!", "my", "many", "keys"
  end
end

and it will publish "HELLO, EVERYONE!" to everyone who is subscribed to any of those keys.

The keys can be a string, symbol, array, or hash. The Boradcaster will normalize them. This means that the key [:a, :b, :c] is the same as the key [:c, :a, :b]

NOTE: strings will strip out non-symbolizable characters, so "a@example.com" and "a/example.com" will be the same key: "a_example_com"

The subscribers define what they listen to and how to respond.

class MyListenerClass
  include Yeller::Subscribable

  # the subscribable module provides this method
  subscribe with: :react, to: ["keys", "my"]
  
  # or, if you have just the one key
  subscribe with: :react, to: "key"

  # you can also subscribe to an arbitrary regexp key
  subscribe with: :react, to: "key.*"

  # if you want to force your subscriber to block until it is done
  subscribe with: :react, to: "key", async: false

  def self.react( message )
    puts "received #{message}"
  end
end

which will print "received HELLO, EVERYONE!" when MyLoudClass.yell! is called.

You can also subscribe on the instance level with

Yeller.subscribe( MyListenerClass.new, with: :instance_level_react, to: ["key", "other key"] )

NOTE: the subscribers will run your code in a new thread. If you want your subscriber to block for the duration of its execution, you can add async: false to your subscribe call. This is highly inadvisable, as the subscibers fire in order and you will block the entire process.

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.

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

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