driver.py 文件源码

def __init__(self):
        try:
            self.host_manager = driver.DriverManager(
                    "nova.scheduler.host_manager",
                    CONF.scheduler_host_manager,
                    invoke_on_load=True).driver
        # TODO(Yingxin): Change to catch stevedore.exceptions.NoMatches
        # after stevedore v1.9.0
        except RuntimeError:
            # NOTE(Yingxin): Loading full class path is deprecated and
            # should be removed in the N release.
            try:
                self.host_manager = importutils.import_object(
                    CONF.scheduler_host_manager)
                LOG.warning(_LW("DEPRECATED: scheduler_host_manager uses "
                                "classloader to load %(path)s. This legacy "
                                "loading style will be removed in the "
                                "N release."),
                            {'path': CONF.scheduler_host_manager})
            except (ImportError, ValueError):
                raise RuntimeError(
                        _("Cannot load host manager from configuration "
                          "scheduler_host_manager = %(conf)s."),
                        {'conf': CONF.scheduler_host_manager})
        self.servicegroup_api = servicegroup.API()