def update():
    try:
        salt.fileserver.reap_fileserver_cache_dir(
            os.path.join(__opts__['cachedir'], 'minionfs/hash'),
            find_file)
    except os.error:
        # Hash file won't exist if no files have yet been served up
        pass
When we are asked to update (regular interval) lets reap the cache
dataset/ETHPy150Open saltstack/salt/salt/fileserver/minionfs.py/update