'Creates all necessary directories under the base cache directory'

def set_paths(self):

    self.base_dir = CONF.image_cache_dir
    if (self.base_dir is None):
        msg = (_('Failed    to    read    %s    from    config') % 'image_cache_dir')
        LOG.error(msg)
        driver = self.__class__.__module__
        raise exception.BadDriverConfiguration(driver_name=driver, reason=msg)
    self.incomplete_dir = os.path.join(self.base_dir, 'incomplete')
    self.invalid_dir = os.path.join(self.base_dir, 'invalid')
    self.queue_dir = os.path.join(self.base_dir, 'queue')
    dirs = [self.incomplete_dir, self.invalid_dir, self.queue_dir]
    for path in dirs:
        utils.safe_mkdirs(path)
