OpenStack Block Storage (Cinder)
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# 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 cinder.scheduler import base_handler
LOG = logging.getLogger(__name__)
class BaseFilter(object):
"""Base class for all filter classes."""
def _filter_one(self, obj, filter_properties):
"""Return True if it passes the filter, False otherwise.
Override this in a subclass.
"""
return True
def filter_all(self, filter_obj_list, filter_properties):
"""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, filter_properties):
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 n-th instances.
Only need to override this if a filter needs anything other than
"first only" or "all" behaviour.
"""
return not (self.run_filter_once_per_request and index > 0)
class BaseFilterHandler(base_handler.BaseHandler):
"""Base class to handle loading filter classes.
This class should be subclassed where one needs to use filters.
"""
def _log_filtration(self, full_filter_results,
part_filter_results, filter_properties):
# Log the filtration history
rspec = filter_properties.get("request_spec", {})
msg_dict = {"vol_id": rspec.get("volume_id", ""),
"str_results": full_filter_results}
LOG.debug("Filtering removed all hosts for the request with "
"volume ID '%(vol_id)s'. Filter results: %(str_results)s",
msg_dict)
msg_dict["str_results"] = ', '.join(
"%(cls_name)s: (start: %(start)s, end: %(end)s)" % {
"cls_name": value[0], "start": value[1], "end": value[2]}
for value in part_filter_results)
LOG.info("Filtering removed all hosts for the request with "
"volume ID '%(vol_id)s'. Filter results: %(str_results)s",
msg_dict)
def get_filtered_objects(self, filter_classes, objs,
filter_properties, index=0):
"""Get objects after filter
:param filter_classes: filters that will be used to filter the
objects
:param objs: objects that will be filtered
:param filter_properties: client filter properties
:param index: This value needs to be increased in the caller
function of get_filtered_objects when handling
each resource.
"""
list_objs = list(objs)
LOG.debug("Starting with %d host(s)", len(list_objs))
# The 'part_filter_results' list just tracks the number of hosts
# before and after the filter, unless the filter returns zero
# hosts, in which 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 = []
for filter_cls in filter_classes:
cls_name = filter_cls.__name__
start_count = len(list_objs)
filter_class = filter_cls()
if filter_class.run_filter_for_index(index):
objs = filter_class.filter_all(list_objs, filter_properties)
if objs is None:
LOG.info("Filter %s returned 0 hosts", cls_name)
full_filter_results.append((cls_name, None))
list_objs = None
break
list_objs = list(objs)
end_count = len(list_objs)
part_filter_results.append((cls_name, start_count, end_count))
remaining = [getattr(obj, "host", obj)
for obj in list_objs]
full_filter_results.append((cls_name, remaining))
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:
self._log_filtration(full_filter_results,
part_filter_results, filter_properties)
return list_objs