How do I use many instances of the same event handler with different state?

Question

I have an OTP application with an event that happens periodically. There are several actors that want to do stuff in response to the event. The stuff each actor does is a function of its own state, but otherwise they're identical.

My problem is with how I go about incorporating this setup into a supervision tree. I have a gen_event manager with each actor being an event handler. This would work well if it weren't for the fact that gen_event supervision is weird. Once my first handler is add_sup_handler'd the rest fail with already_started and my gen_server that's acting as a supervisor for the event handlers dies.

So what should I do here? I'm starting to think I should just write my own event manager that can keep track of all my actors and their state.

Answer 1

gen_event:add_handler/3:

Handler is the name of the callback module Module or a tuple {Module,Id}, where Id is any term. The {Module,Id} representation makes it possible to identify a specific event handler when there are several event handlers using the same callback module.