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