Checks the cache file to see if there is a new enough file list cache, and
    returns the match (if found, along with booleans used by the fileserver
    backend to determine if the cache needs to be refreshed/written).

def write_file_list_cache(opts, data, list_cache, w_lock):
    '''
    Checks the cache file to see if there is a new enough file list cache, and
    returns the match (if found, along with booleans used by the fileserver
    backend to determine if the cache needs to be refreshed/written).
    '''
    serial = salt.payload.Serial(opts)
    with salt.utils.files.fopen(list_cache, 'w+b') as fp_:
        fp_.write(serial.dumps(data))
        _unlock_cache(w_lock)
        log.trace('Lockfile %s removed', w_lock)