Re-subscribe to the scaling channel when the underlying connection is lost

[ashiquzzaman33]

In scaling mode, when the subscribingClient connection is lost while the app is running, the main app continues to operate without any errors or logs. However, it loses the ability to listen for events on the scaling channel.

According to the clue/reactphp-redis:

When using the createLazyClient() method, the unsubscribe and punsubscribe events will be invoked automatically when the underlying connection is lost. This gives you control over re-subscribing to the channels and patterns as appropriate.

So, we need to re-subscribe to the channel when the unsubscribe event is detected.

[taylorotwell]

Drafting until @joedixon can review.

[joedixon]

Hey @ashiquzzaman33 - did you manage to check if your implementation behaves as expected? According to the createLazyClient section of the docs, you would actually need to create a whole new connection.

Additionally, if the underlying database connection drops, it will automatically send the appropriate unsubscribe and punsubscribe events for all currently active channel and pattern subscriptions. This allows you to react to these events and restore your subscriptions by creating a new underlying connection repeating the above commands again.

[ashiquzzaman33]

Hello @joedixon, thank you for your comment.

Yes, I’ve tested it, and the implementation behaves as expected. The documentation seems a bit misleading.
Re-subscribing should be sufficient unless we explicitly call $this->subscribingClient->close().

It will automatically create a new client if current connection is lost.