fn add_devices_changed_listener()

in src/backend/mod.rs [2524:2586]

• 57 lines of code
• 10 McCabe index (conditional complexity)

    fn add_devices_changed_listener(
        &mut self,
        devtype: DeviceType,
        collection_changed_callback: ffi::cubeb_device_collection_changed_callback,
        user_ptr: *mut c_void,
    ) -> Result<()> {
        assert!(devtype.intersects(DeviceType::INPUT | DeviceType::OUTPUT));
        assert!(collection_changed_callback.is_some());

        let context_ptr = self as *mut AudioUnitContext;
        let mut devices = self.devices.lock().unwrap();

        // Note: second register without unregister first causes 'nope' error.
        // Current implementation requires unregister before register a new cb.
        if devtype.contains(DeviceType::INPUT) && devices.input.changed_callback.is_some()
            || devtype.contains(DeviceType::OUTPUT) && devices.output.changed_callback.is_some()
        {
            return Err(Error::invalid_parameter());
        }

        if devices.input.changed_callback.is_none() && devices.output.changed_callback.is_none() {
            let address = get_property_address(
                Property::HardwareDevices,
                DeviceType::INPUT | DeviceType::OUTPUT,
            );
            let ret = audio_object_add_property_listener(
                kAudioObjectSystemObject,
                &address,
                audiounit_collection_changed_callback,
                context_ptr,
            );
            if ret != NO_ERR {
                cubeb_log!(
                    "Cannot add devices-changed listener for {:?}, Error: {}",
                    devtype,
                    ret
                );
                return Err(Error::error());
            }
        }

        if devtype.contains(DeviceType::INPUT) {
            // Expected empty after unregister.
            assert!(devices.input.is_empty());
            devices.input.set(
                collection_changed_callback,
                user_ptr,
                audiounit_get_devices_of_type(DeviceType::INPUT),
            );
        }

        if devtype.contains(DeviceType::OUTPUT) {
            // Expected empty after unregister.
            assert!(devices.output.is_empty());
            devices.output.set(
                collection_changed_callback,
                user_ptr,
                audiounit_get_devices_of_type(DeviceType::OUTPUT),
            );
        }

        Ok(())
    }