semi-advanced question re timers

im writing an extension that manages a set of persistent resources. to be resource friendly, i want to do garbage collection on resources that have been idle for a configurable period of time. id really prefer not to use cron & such, since the extension should be just plun-n-play. in the course of investigation i came across the timeout code in zend_execute_api.c, and im wondering if its safe to use a similar method in my extension to harvest stale resources. l0t3k