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# RequestStore [](https://travis-ci.org/steveklabnik/request_store) [](https://codeclimate.com/github/steveklabnik/request_store) Ever needed to use a global variable in Rails? Ugh, that's the worst. If you need global state, you've probably reached for `Thread.current`. Like this: ```ruby def self.foo Thread.current[:foo] ||= 0 end def self.foo=(value) Thread.current[:foo] = value end ``` Ugh! I hate it. But you gotta do what you gotta do... ### The problem Everyone's worrying about concurrency these days. So people are using those fancy threaded web servers, like Thin or Puma. But if you use `Thread.current`, and you use one of those servers, watch out! Values can stick around longer than you'd expect, and this can cause bugs. For example, if we had this in our controller: ```ruby def index Thread.current[:counter] ||= 0 Thread.current[:counter] += 1 render :text => Thread.current[:counter] end ``` If we ran this on MRI with Webrick, you'd get `1` as output, every time. But if you run it with Thin, you get `1`, then `2`, then `3`... ### The solution Add this line to your application's Gemfile: ```ruby gem 'request_store' ``` And change the code to this: ```ruby def index RequestStore.store[:foo] ||= 0 RequestStore.store[:foo] += 1 render :text => RequestStore.store[:foo] end ``` Yep, everywhere you used `Thread.current` just change it to `RequestStore.store`. Now no matter what server you use, you'll get `1` every time: the storage is local to that request. ### Rails 2 compatibility The gem includes a Railtie that will configure everything properly for Rails 3+ apps, but if your app is tied to an older (2.x) version, you will have to manually add the middleware yourself. Typically this should just be a matter of adding: ```ruby config.middleware.use RequestStore::Middleware ``` into your config/environment.rb. ### No Rails? No Problem! A Railtie is added that configures the Middleware for you, but if you're not using Rails, no biggie! Just use the Middleware yourself, however you need. You'll probably have to shove this somewhere: ```ruby use RequestStore::Middleware ``` #### No Rails + Rack::Test In order to have `RequestStore` storage cleared between requests, add it to the `app`: ```ruby # spec_helper.rb def app Rack::Builder.new do use RequestStore::Middleware run MyApp end end ``` ## Semantic Versioning This project conforms to [semver](http://semver.org/). As a result of this policy, you can (and should) specify a dependency on this gem using the [Pessimistic Version Constraint](http://guides.rubygems.org/patterns/) with two digits of precision. For example: ```ruby spec.add_dependency 'request_store', '~> 1.0' ``` This means your project is compatible with request_store 1.0 up until 2.0. You can also set a higher minimum version: ```ruby spec.add_dependency 'request_store', '~> 1.1' ``` ## Contributing 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 Don't forget to run the tests with `rake`.