socket.io does not alert adapter when it is shutting down

[bytenik]

You want to:

• report a bug
• request a feature

Current behaviour

socket.io does not notify its adapter that it is shutting down (closing). As a result, there is no opportunity to stop long-running processes within the socket or disconnect from whatever scale-out solution is being used.

Expected behaviour

socket.io should call a method on the adapter to indicate shutdown. It need not wait for a callback, because if shutdown fails, what are you going to do -- not shut down? The in-memory adapter can simply make this function a no-op. While I haven't reviewed the Redis adapter in enough depth to see if there is utility to this function in that adapter, I would imagine that it would be good to detach from Redis to return system resources.

Other information (e.g. stacktraces, related issues, suggestions how to fix)

This is particularly critical for the adapter I am developing that works with AWS SQS/SNS -- https://github.com/thinkalpha/socket.io-sqs