Singleton in scope of a request in rails [closed]

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Closed 5 years ago.

Using singleton mixin from rails I could create a singleton class in the scope of rails app. But I was wondering Is there a way to create it in the scope of a particular request ?

回答1:

Since a request is tied to a thread, you can use Thread local store:

class RequestSingleton
  def self.instance
    Thread.current['request-singleton'] ||= RequestSingleton.new
  end

  def self.clear
    Thread.current['request-singleton'] = nil
  end
end

Usage:

def index
  RequestSingleton.instance.do_some_setup

  # ...

  RequestSingleton.clear
end

...and anywhere else simply use RequestSingleton.instance to access it.

Since it is thread local, there are no synchronization issues.

来源：https://stackoverflow.com/questions/24927928/singleton-in-scope-of-a-request-in-rails