Go Gorilla Websockets ~ On ping/pong fail (user disconnct) call function?

Question

I'm writing a chat program with Golang and Gorilla's Websocket toolkit.

I'm wondering if there is a way to run a function whenever a user disconnects or a ping/pong message fails. I need this to remove them from variables and such. Is there any easy way to do this?

Ress

Answer 1

The application should close the connection and cleanup variables and such when the read methods (NextReader, ReadMessage) return an error.

Use ping/pong to detect disconnects. The chat example shows how to do this.

• Send pings on a regular interval.
• Set read deadline to a time less than next expected pong.
• Reset the read deadline when a pong is received.

If a pong goes missing, the read methods will return with the read past deadline error.

Fructidor

In the chat example, the frontend side seems to have nothing about ping-pong. Is it handled only on the backend side? – Lanham

@anil The front end automatically responds to PING with a PONG. No code is required. – Quagga

Would re-setting read dead line after every read alone work? – Burnish

@Burnish Setting the read deadline before each read works if the application has a known upper bound for when the next message should be received at that upper bound is acceptable for detecting disconnects. – Quagga