+
+ // A set of devices (potentially empty) that should be kept open even
+ // if they're not used in any bus. This allows the delay analyzer to
+ // make sure a given ALSA device is opened to tap into its data, even if
+ // there is no bus using it. (Non-ALSA devices are allowed to be here,
+ // but won't do anything.)
+ std::set<DeviceSpec> extra_devices;