SoOneShotSensor(3) on Linux
The text 2ab285d4767f, as Debian 8 (Jessie) shipped it.
The SoOneShotSensor class is a sensor which will trigger once. Since SoOneShotSensor is a subclass of SoDelayQueueSensor, it will trigger as soon as either the run-time system is idle, or if it is continually busy it will trigger within a fixed amount of time (this is by default 1/12th of a second, see SoSensorManager::setDelaySensorTimeout()).