Managing listener lifecycle

[christopher-b]

Hi Folks, I have a class that includes a listener as a rails "class attribute":

module MyModule
  class MyClass
    cattr_accessor(:file_listener)

    def initialize
      initialize_file_listener
    end

    def initialize_file_listener
      self.file_listener&.stop

      self.file_listener = Listen.to(config[:local_path]) do |modified, added, _|
        # ...
      end

      self.file_listener.start
    end
  end
end

I periodically get this exception when calling start:

ArgumentError: Listen::Listener can't change state from 'stopped' to 'processing_events', only to: backend_started

I'm not sure why this is happening. I believe I'm setting the file_listener variable to a new Listener instance, so the state of that instance should be the default state, :initializing.

Unfortunately, there's nothing in my logs to shed light on this (I have set LISTEN_GEM_DEBUGGING=debug).

Is there additional lifecycle management I need to do on the listeners? Is there a better approach to be taking?

Thanks!

[ColinDKelley]

@christopher-b One approach you could use would be to nil out the file listener once you stop it. That's reasonable since it won't be useful after that point. Then you'd need to create a new one when needed.