adapter functions don't get callback argument or opportunity to return a promise, so there's no way to do long-running processes such as join to room

[bytenik]

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• [] report a bug
• request a feature

Current behaviour

socket.io calls functions on the adapter, and then immediately invokes its own internal callback function with an argument of null.

Expected behaviour

socket.io should pass a callback function to adapter functions and then use that to trigger callback to the rest of the socket.io stack.

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
Specifically, actions like addAll can't be properly handled in time; e.g. if you addAll a socket to room xxx and then immediately .to(xxx).emit(...), your message doesn't necessarily end up back at that socket.