EventBusBridge does not cleanup if websocket is terminated exceptionally leading to memory leak

[ikstewa]

Version

4.0.3, 4.1.0

Context

When using the SockJSBridge, if a websocket is terminated without a close message the idle timeout timer is never cleaned up. As a result the SOCKET_IDLE events will be dispatched indefinitely.

Do you have a reproducer?

I'm unable to create a reproducer as it requires an unhealthy termination of the socket.
Possibly similar to reproducer here: #1676

When a websocket is terminated exceptionally it calls the close and exception handlers but does not call the end handler. The EventBusBridgeImpl registers the cleanup on the endHandler, but not on the exceptionHandler. (SockJSSocket does not have a closedHandler).
https://github.com/vert-x3/vertx-web/blob/master/vertx-web/src/main/java/io/vertx/ext/web/handler/sockjs/impl/EventBusBridgeImpl.java#L333

Steps to reproduce

1. Connect a websocket through the SockJS bridge.
2. Terminate the socket (so a close is not sent).
3. Observe the idle handler is still called every pingTimeout milliseconds.

[pmlopes]

@ikstewa @vietj it seems we miss an enum value for BridgeEventType.SOCKET_EXCEPTION as a type of event, as SOCKET_CLOSED assumes that the socket was closed properly, right?

[pmlopes]

@ikstewa can you verify if the fixes proposed in the PR's above solve the bug? I think they should but like you said it's hard to automate.

[ikstewa]

Yes. The changes from #1987 will cleanup the resources as we were expecting.

@pmlopes Can we confirm that a SOCKET_EXCEPTION always means the socket is closed? I.e. the terminal state for a socket is either SOCKET_CLOSED or SOCKET_EXCEPTION?

[pmlopes]

Ok we can disambiguate the state by keep using close but we pass "exception" : true in the event body

[ikstewa]

@pmlopes Apologies I didn't notice this earlier. The PR fixed the issue however it is logging an 'error' when this occurs. I don't believe this should be considered an error as we can't always assume a client closes the websocket connection properly.