With the help of Event Dispatcher, rescan is now converted into an event and is accorded the lowest priority and so it gets a chance only after all the dust settles, meaning after all the higher priority events are processed. rescan.lua registers a hook for a rescan event, which runs at the lowest priority and raises a select-target event for that particular source stream node(for example the pw-play/pw-cat client node). This is a hook registered against the select-target event and it will be the first hook to run for this event.