python类Timeout()的实例源码

def _power_off_instance(self, context, instance, clean_shutdown=True):
        """Power off an instance on this host."""
        timeout, retry_interval = self._get_power_off_values(context,
                                        instance, clean_shutdown)
        self.driver.power_off(instance, timeout, retry_interval)

def _running_deleted_instances(self, context):
        """Returns a list of instances nova thinks is deleted,
        but the hypervisor thinks is still running.
        """
        timeout = CONF.running_deleted_instance_timeout
        filters = {'deleted': True,
                   'soft_deleted': False,
                   'host': self.host}
        instances = self._get_instances_on_driver(context, filters)
        return [i for i in instances if self._deleted_old_enough(i, timeout)]

def wait_for_instance_event(self, instance, event_names, deadline=300,
                                error_callback=None):
        """Plan to wait for some events, run some code, then wait.

        This context manager will first create plans to wait for the
        provided event_names, yield, and then wait for all the scheduled
        events to complete.

        Note that this uses an eventlet.timeout.Timeout to bound the
        operation, so callers should be prepared to catch that
        failure and handle that situation appropriately.

        If the event is not received by the specified timeout deadline,
        eventlet.timeout.Timeout is raised.

        If the event is received but did not have a 'completed'
        status, a NovaException is raised.  If an error_callback is
        provided, instead of raising an exception as detailed above
        for the failure case, the callback will be called with the
        event_name and instance, and can return True to continue
        waiting for the rest of the events, False to stop processing,
        or raise an exception which will bubble up to the waiter.

        :param instance: The instance for which an event is expected
        :param event_names: A list of event names. Each element can be a
                            string event name or tuple of strings to
                            indicate (name, tag).
        :param deadline: Maximum number of seconds we should wait for all
                         of the specified events to arrive.
        :param error_callback: A function to be called if an event arrives

        """

        if error_callback is None:
            error_callback = self._default_error_callback
        events = {}
        for event_name in event_names:
            if isinstance(event_name, tuple):
                name, tag = event_name
                event_name = objects.InstanceExternalEvent.make_key(
                    name, tag)
            try:
                events[event_name] = (
                    self._compute.instance_events.prepare_for_instance_event(
                        instance, event_name))
            except exception.NovaException:
                error_callback(event_name, instance)
                # NOTE(danms): Don't wait for any of the events. They
                # should all be canceled and fired immediately below,
                # but don't stick around if not.
                deadline = 0
        yield
        with eventlet.timeout.Timeout(deadline):
            for event_name, event in events.items():
                actual_event = event.wait()
                if actual_event.status == 'completed':
                    continue
                decision = error_callback(event_name, instance)
                if decision is False:
                    break