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weliem / bluez_inc

A C library for Bluez (BLE) that hides all DBus communication. It doesn't get easier than this. This library can also be used in C++.
MIT License
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Issue with scanning after turning bluetooth of and then back on #46

Closed bojennett closed 3 months ago

bojennett commented 3 months ago

I have an app that acts as central. When it starts up, it checks the bluetooth state, and if it's off, turns it on and then once on, starts scanning. I have scanning running continuously. For example, a device may get connected, but the scanner is still running such that if the device disconnects, it can be found again and reconnect. As all this happens, I see as I'm starting scanning that I am getting the 'starting' and 'started' states from AdapterDiscoveryStateChangeCallback as expected.

if while this app is running, I go through another method to turn bluetooth off, I get the AdapterPoweredStateChangeCallback as expected with the state off. I try to use this to turn scanning off, but since the adapter is not powered, this calls fails (not surprising).

If I then go into this external method of toggling bluetooth, and I toggle it back on, I get the AdapterPoweredStateChangeCallback as expected saying the state is ON, and then I try to start scanning again.

However, it never seems to actually start scanning again. I don't get any of the AdapterDiscoveryStateChangeCallback anymore. I tried turning scanning off once I see the power state to on, and then turning scanning on, but it doesn't seem to work. It's as if I cannot scan anymore.

bojennett commented 3 months ago

The way I did this - I have one terminal running my app, and then in the other terminal I do bluetoothctl power off to then see my app say "hey power is off", and then I wait a few seconds and in this other terminal do bluetoothctl power on to turn it back on, and I see that the power did come back on in my app, and I call the scanner, binc_adapter_set_discovery_filter and binc_adapter_start_discovery, but nothing seems to happen.

weliem commented 3 months ago

I think this is a bug in my library. I need to reset some internal state when bluetooth is switched off...

Will pick this up

weliem commented 3 months ago

fixed by ec31ca6650d8f378b2161dbb09a0d8d20cfb2105