Add retry logic for Wi-Fi LAN advertising to avoid issues on iOS 14.8.1

[edgarclerigo]

I'm currently using the latest version of the Nearby SPM.

The exact same code runs ok, and I'm able to startAdvertising on iOS 16.6 but on iOS 14.8.1 it fails to start.

These are the logs that I have

[lvl=2] service_controller_router.cc:85() ServiceControllerRouter going up.
[lvl=2] client_proxy.cc:60() ClientProxy ctor event_logger=0x0
[lvl=2] analytics_recorder.cc:101() Start AnalyticsRecorder ctor event_logger_=0x0
[lvl=2] endpoint_manager.cc:377() EndpointManager received request to add registration of frame processor 0x12c0256b0 for frame type PAYLOAD_TRANSFER, self=0x12c025638
[lvl=2] endpoint_manager.cc:377() EndpointManager received request to add registration of frame processor 0x12c0257b8 for frame type BANDWIDTH_UPGRADE_NEGOTIATION, self=0x12c025638
[lvl=2] offline_service_controller.cc:41() Client -2222247868050356217 requested advertising to start.
[lvl=2] base_pcp_handler.cc:179() StartAdvertising with supported mediums: { WIFI_LAN }
[lvl=2] p2p_cluster_pcp_handler.cc:2055() P2pClusterPcpHandler::StartWifiLanAdvertising: service=myserviceid: start
[lvl=2] base_pcp_handler.cc:432() Waiting for future to complete: StartAdvertising(myserviceid)
[lvl=2] wifi_lan.cc:242() Failed to start accepting WifiLan connections for service_id=myserviceid
[lvl=2] p2p_cluster_pcp_handler.cc:2064() In StartWifiLanAdvertising(6970686f6e652038), client=-2222247868050356217 failed to start listening for incoming WifiLan connections to service_id=myserviceid
[lvl=3] p2p_cluster_pcp_handler.cc:174() Failed StartAdvertising(6970686f6e652038) for client=-2222247868050356217
[lvl=2] client_proxy.cc:932() ClientProxy [ExitHighVisibilityMode]: client=-2222247868050356217
[lvl=2] base_pcp_handler.cc:439() Future:[StartAdvertising(myserviceid)] completed with status:12

[edgarclerigo]

@bourdakos1 forgot to tell that the startDiscovery is working as expected

[bourdakos1]

It looks like it failed to start listening for incoming connections, but the system didn't return any an explicit errors. My best guess is that the listener transitioned to the nw_listener_state_waiting which isn't a fatal error, but will end in a fatal nearby error, since we don't attempt retries: https://developer.apple.com/documentation/network/nw_listener_state_t/nw_listener_state_waiting?language=objc

However, I don't have an iOS 14.8.1 device to verify. Do you mind trying to add some logs here:

nearby/internal/platform/implementation/apple/Mediums/WiFiLAN/GNCWiFiLANServerSocket.m

Line 207 in 5589166

return NO;

to see what state the listener is in?

I can also push an update with more logs if thats easier, but that might take some time to get reviewed/submitted

[edgarclerigo]

It looks like your guessing is correct,

[bourdakos1]

Thanks for verifying! I need to look into how to properly handle this case

[edgarclerigo]

I made this workaround

private func startAdvertise(nearbyMessage: NearbyMessage, retryCount: Int) {
        print("[NearbyManager] Retrying startAdvertise: \(retryCount)")

        guard
            let nearbyMessageData = nearbyMessage.dataValue,
            retryCount > 0
        else {
            return
        }

        advertiser.startAdvertising(
            using: nearbyMessageData,
            completionHandler: { error in
                guard let error = error else {
                    print("[NearbyManager] Success on startAdvertising")
                    return
                }

                print("[NearbyManager] Failed to advertise: \(error.localizedDescription)")

                let timer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: false) { [weak self] timer in
                    self?.startAdvertise(nearbyMessage: nearbyMessage, retryCount: retryCount-1)
                }
                timer.fire()
            }
        )
    }

Eventually it will work:

[NearbyManager] Retrying startAdvertise: 10
[NearbyManager] Failed to advertise: The operation couldn’t be completed. (com.google.nearby.connections.error error 11.)
[NearbyManager] Retrying startAdvertise: 9
[NearbyManager] Failed to advertise: The operation couldn’t be completed. (com.google.nearby.connections.error error 11.)
[NearbyManager] Retrying startAdvertise: 8
[NearbyManager] Success on startAdvertising

[bourdakos1]

Awesome! So it is just a matter of retrying. I'll update this issue to reflect the need for adding internal retry logic for Wi-Fi LAN

[edgarclerigo]

Thanks for answering so fast! I will keep subscribed on this issue so we can update the lib on our end :)