Question

I have a Ruby on Rails application which need to send HTTP request to a remote server frequently. And I want to keep those (there’re more than one clients) em-http-client globally instead of creating one client every time. But I’m not very clear about WHERE should I store that client array in?
For example, store in the session? Or, ROR has prepared something like a out-of-box singleton pattern?

Answer 1

First of all, ruby itself has singleton pattern ability. Check out the doc.

So you need in-process storage which are persistent between request.

In RubyOnRails you can use following options:

• global variables (bad idea, i don’t know why)
• class variables (bad idea because they are shared through entire inheritance tree)
• instance variable of metaclass
• in-thread storage (Thread.current[:whatever])
• somewhere else where I’ve forgotten

And good idea is initialize it in config/initializers/your_initializer.rb.

I prefer third option.

Here is naive implementation what you’re looking for.

  class EMClient

    class << self
      attr_accessor :pool
    end
    @pool = []

  end