Gorilla Websocket - Read error: repeated read on failed websocket connection

Question

Using the gorilla websocket api for go, how do i know if a client is still connected?

What Im trying with now is:

func Listen(ws *websocket.Conn) {
    connTimeout := 3
    timeLastSent := time.Now().Second()

    for ((timeLastSent + connTimeout) % 60) != time.Now().Second() {

        msg := Message{}
        err := ws.ReadJSON(&msg)

        if err == websocket.ErrCloseSent {
            break
        } else if err != nil {
            continue
        }

        //Message recived
        EventMessage <- msg

        timeLastSent = time.Now().Second()
    }
  //Connection timed out.
    return
}

But this results in the error repeated read on failed websocket connection.

Ive been looking into using ws.SetReadDeadline(t), but Ive no idea of either how to use it nor if its even the thing Im looking for.

How should i go about this?

Answer 1

When the websocket connection fails with an error other than websocket.ErrCloseSent, the program spins in a tight loop until the timeout.

To help applications detect this programming error, the websocket package panics when read is called 1000 times on a failed connection (view code here).

To fix the problem, break out of the loop on all errors:

    err := ws.ReadJSON(&msg)
    if err != nil {
        // optional: log the error
        break
    }

Use the connection's read deadline to handle timeouts.