Add support for graphql-transport-ws with duplex ping-pong

[zdraganov]

Extending this PR, included also the duplex ping-pong functionality.

How to use:

srv.AddTransport(transport.Websocket{
    PingPongInterval: 5 * time.Second,
    # Other options ...
})

Example Apollo client usage:

let activeSocket: unknown = null;
let timedOut: unknown = null;

const wsLink = new WebSocketLink({
  url: REACT_APP_GRAPHQL_WS_ENDPOINT as string,
  keepAlive: 10_000, // ping server every 10 seconds
  on: {
    ping: (received) => {
      if (!received) {
        timedOut = setTimeout(() => {
          if (activeSocket && activeSocket.readyState === WebSocket.OPEN) {
            activeSocket.close(4408, 'Request Timeout');
          }
        }, 5_000); // wait 5 seconds for the pong and then close the connection
      }
    },
    pong: (received) => {
      if (received) {
        clearTimeout(timedOut);
      }
    },
  },
});

[jaredly]

@zdraganov did you make any substantive changes to #1507, or did you just extend it? It might be nice to merge the other first so I can review the extension in isolation.

[zdraganov]

@jaredly I've just extended it. This one uses the feature of graphql-transport-ws protocol to have two-way keep-alive.
Feel free to merge the #1507 and then I will create a new one pointing the master branch.

[StevenACoffman]

@zdraganov I rebased and squash merged #1507. If you could rebase yours (and add that comment mentioned in #1507 ) I would appreciate it very much. Thanks!

[zdraganov]

Rebased with the master branch.

[coveralls]

Coverage increased (+0.09%) to 70.408% when pulling 09f97c8 on Seven-of-Di:feature/IN-1281 into ae92c83 on 99designs:master.

[jaredly]

code looks good! Could you add a test or two to websocket_test.go?

[StevenACoffman]

So when I run this:

go generate ./... && cd example/ && go generate ./...
git status

I get this:

deleted:    ../plugin/resolvergen/testdata/singlefile/out/resolver.go

And as a result, I then when I run this:

go test -race ./... && cd example && go test -race ./... && cd ..

I get a lot of failures which I assume are related. Sorry if I missed that when Jared and I reviewed it earlier (although maybe it's a new problem). Can you please take a look a this so we can get this merged? Thanks!

[zdraganov]

Fixed the test, but the generation problem doesn't happens on my side - BigSlur M1
Can you check again?

[StevenACoffman]

Huh, well it didn't happen when I refreshed everything and tried it again, so maybe I was on some other branch and they merged weird.

Thanks!

[jaredly]

(It would also be nice to have a test that is "client/server shuts down if pong isn't received within time limit")