nova/nova/filters.py
Sylvain Bauza aeae7040c7 Prepare filters for using RequestSpec object
Now that the FilterScheduler is using a RequestSpec object,
we need to change the filters for backporting the object
into the legacy dicts before changing each of them.

Release Notes will be updated to mention that custom filters
need to be modified to either use a RequestSpec object or
primitive them into a dict.

Partially-Implements: blueprint request-spec-object-mitaka

UpgradeImpact - see the reno file attached.

Change-Id: I14f18c4507498b1d24a9318fafc97193861ca0b6
2015-11-16 22:41:02 +01:00

132 lines
5.5 KiB
Python

# Copyright (c) 2011-2012 OpenStack Foundation
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
Filter support
"""
from oslo_log import log as logging
from nova.i18n import _LI
from nova import loadables
LOG = logging.getLogger(__name__)
class BaseFilter(object):
"""Base class for all filter classes."""
def _filter_one(self, obj, spec_obj):
"""Return True if it passes the filter, False otherwise.
Override this in a subclass.
"""
return True
def filter_all(self, filter_obj_list, spec_obj):
"""Yield objects that pass the filter.
Can be overridden in a subclass, if you need to base filtering
decisions on all objects. Otherwise, one can just override
_filter_one() to filter a single object.
"""
for obj in filter_obj_list:
if self._filter_one(obj, spec_obj):
yield obj
# Set to true in a subclass if a filter only needs to be run once
# for each request rather than for each instance
run_filter_once_per_request = False
def run_filter_for_index(self, index):
"""Return True if the filter needs to be run for the "index-th"
instance in a request. Only need to override this if a filter
needs anything other than "first only" or "all" behaviour.
"""
if self.run_filter_once_per_request and index > 0:
return False
else:
return True
class BaseFilterHandler(loadables.BaseLoader):
"""Base class to handle loading filter classes.
This class should be subclassed where one needs to use filters.
"""
def get_filtered_objects(self, filters, objs, spec_obj, index=0):
list_objs = list(objs)
LOG.debug("Starting with %d host(s)", len(list_objs))
# Track the hosts as they are removed. The 'full_filter_results' list
# contains the host/nodename info for every host that passes each
# filter, while the 'part_filter_results' list just tracks the number
# removed by each filter, unless the filter returns zero hosts, in
# which case it records the host/nodename for the last batch that was
# removed. Since the full_filter_results can be very large, it is only
# recorded if the LOG level is set to debug.
part_filter_results = []
full_filter_results = []
log_msg = "%(cls_name)s: (start: %(start)s, end: %(end)s)"
for filter_ in filters:
if filter_.run_filter_for_index(index):
cls_name = filter_.__class__.__name__
start_count = len(list_objs)
objs = filter_.filter_all(list_objs, spec_obj)
if objs is None:
LOG.debug("Filter %s says to stop filtering", cls_name)
return
list_objs = list(objs)
end_count = len(list_objs)
part_filter_results.append(log_msg % {"cls_name": cls_name,
"start": start_count, "end": end_count})
if list_objs:
remaining = [(getattr(obj, "host", obj),
getattr(obj, "nodename", ""))
for obj in list_objs]
full_filter_results.append((cls_name, remaining))
else:
LOG.info(_LI("Filter %s returned 0 hosts"), cls_name)
full_filter_results.append((cls_name, None))
break
LOG.debug("Filter %(cls_name)s returned "
"%(obj_len)d host(s)",
{'cls_name': cls_name, 'obj_len': len(list_objs)})
if not list_objs:
# Log the filtration history
# NOTE(sbauza): Since the Cells scheduler still provides a legacy
# dictionary for filter_props, and since we agreed on not modifying
# the Cells scheduler to support that because of Cells v2, we
# prefer to define a compatible way to address both types
if isinstance(spec_obj, dict):
rspec = spec_obj.get("request_spec", {})
inst_props = rspec.get("instance_properties", {})
inst_uuid = inst_props.get("uuid", "")
else:
inst_uuid = spec_obj.instance_uuid
msg_dict = {"inst_uuid": inst_uuid,
"str_results": str(full_filter_results),
}
full_msg = ("Filtering removed all hosts for the request with "
"instance ID "
"'%(inst_uuid)s'. Filter results: %(str_results)s"
) % msg_dict
msg_dict["str_results"] = str(part_filter_results)
part_msg = _LI("Filtering removed all hosts for the request with "
"instance ID "
"'%(inst_uuid)s'. Filter results: %(str_results)s"
) % msg_dict
LOG.debug(full_msg)
LOG.info(part_msg)
return list_objs