Link subscriber to subscription

[timbuchwaldt]

Otherwise a dying subscription leaves the subscriber alive.

[slashdotdash]

@timbuchwaldt Have you seen a subscription process go down without being restarted by the supervisor?

The subscriptions supervisor is supposed to restart the subscription process when it terminates abnormally. Restarting should reconnect to the event store and continue sending events to the subscriber.

[timbuchwaldt]

Hey.
That is very strange, I am 95% sure we had an issue that went away once we switched to my fork with this change. Sadly I have been way to deep into debugging all sorts of libraries we have been using and my brain garbage collected the details. I'll get back to you once I am able to remember why we had this problem.

[slashdotdash]

If this change improves things then we'll also need to change the restart strategy in the subscriptions supervisor from :transient to :temporary so that it doesn't get restarted on shutdown.

Instead of restarting the subscription, the subscriber process should be supervised (e.g. Commanded event handler) and then can create a new subscription when either subscriber or subscription go down. This is similar to how the Elixir EventStore subscription process works.