Deferred Request

A simple plugin to defer an http request until you can actually process it. This is good in situtations where work performed is not needed immidiately (think status callbacks from services like Twilio or Stripe). This pattern can help prevent you from getting DDoS'd by services you might interact with.

Installation

Add this line to your application's Gemfile:

gem "deferred_request"

And then execute:

$ bundle

Or install it yourself as:

$ gem install deferred_request

Migrations

Copy the Deferred Request migrations to your app:

bin/rails deferred_request:install:migrations

Then, run the migrations:

bin/rails db:migrate

Usage

Controllers

In your controllers you can use the library like so. Make sure you add a method with a _deferred suffix so that it can be processed later

# app/controllers/twilio.rb

# ... (snipped for brevity)
def status_callback
  # We can go ahead and give a :ok response (fast and snappy)
  head :ok

  # Then queue the request to run later
  deferred_request = DeferredRequest::DeferredRequest.perform_later_from_request!(request)
end

# Your deferred request method will be called later (via a job)
# deferred_request will be of type DeferredRequest::DeferredRequest
def status_callback_deferred(deferred_request)
  # do some actual processing
  if deferred_request.params["SmsStatus"] == "delivered"
    # mark message as delivered
  end

  # return a status and it will be saved to the database
  true
end
# ...

Class Methods

• DeferredRequest::DeferredRequest.from_request(request) - returns a DeferredRequest::DeferredRequest object (unsaved). Returns the DeferredRequest::DeferredRequest instance.
• DeferredRequest::DeferredRequest.perform_later_from_request!(request) - creates a deferred request (saved) and enqueues job to process the request. Returns the DeferredRequest::DeferredRequest instance.

Instance Methods

• deferred_request.perform_later - Enqueues a job to perform! the deferred request later. Returns the job id.
• deferred_request.perform! - Calls the #{controller}_deferred(deferred_request) method to be processed. Returns the deferred_request instance or raises an exception.

Configuration

• DeferredRequest.model_parent_class - Set the parent class
• DeferredRequest.deferred_request_instance_class - Set the instance class that is created (in-case you sub-class)
• DeferredRequest.job_queue - Set the job queue for the deferred request job

# config/initializers/deferred_request.rb
DeferredRequest.model_parent_class = "MyParentClass"
DeferredRequest.job_queue = "low"

🙏 Contributing

If you have an issue you'd like to submit, please do so using the issue tracker in GitHub. In order for us to help you in the best way possible, please be as detailed as you can.

If you'd like to open a PR please make sure the following things pass:

bin/rails db:test:prepare
bin/rails test
bundle exec standardrb

📝 License

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