261 lines
10 KiB
Python
261 lines
10 KiB
Python
# Copyright (c) 2011 OpenStack, LLC.
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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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The FilterScheduler is for creating instances locally.
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You can customize this scheduler by specifying your own Host Filters and
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Weighing Functions.
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"""
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import operator
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from nova import exception
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from nova import flags
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from nova import log as logging
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from nova.notifier import api as notifier
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from nova.openstack.common import importutils
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from nova.scheduler import driver
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from nova.scheduler import least_cost
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from nova.scheduler import scheduler_options
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FLAGS = flags.FLAGS
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LOG = logging.getLogger(__name__)
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class FilterScheduler(driver.Scheduler):
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"""Scheduler that can be used for filtering and weighing."""
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def __init__(self, *args, **kwargs):
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super(FilterScheduler, self).__init__(*args, **kwargs)
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self.cost_function_cache = {}
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self.options = scheduler_options.SchedulerOptions()
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def schedule(self, context, topic, method, *args, **kwargs):
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"""The schedule() contract requires we return the one
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best-suited host for this request.
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NOTE: We're only focused on compute instances right now,
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so this method will always raise NoValidHost()."""
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msg = _("No host selection for %s defined.") % topic
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raise exception.NoValidHost(reason=msg)
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def schedule_run_instance(self, context, request_spec, *args, **kwargs):
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"""This method is called from nova.compute.api to provision
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an instance. We first create a build plan (a list of WeightedHosts)
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and then provision.
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Returns a list of the instances created.
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"""
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elevated = context.elevated()
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num_instances = request_spec.get('num_instances', 1)
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LOG.debug(_("Attempting to build %(num_instances)d instance(s)") %
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locals())
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payload = dict(request_spec=request_spec)
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notifier.notify(context, notifier.publisher_id("scheduler"),
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'scheduler.run_instance.start', notifier.INFO, payload)
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weighted_hosts = self._schedule(context, "compute", request_spec,
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*args, **kwargs)
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if not weighted_hosts:
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raise exception.NoValidHost(reason="")
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# NOTE(comstud): Make sure we do not pass this through. It
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# contains an instance of RpcContext that cannot be serialized.
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kwargs.pop('filter_properties', None)
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instances = []
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for num in xrange(num_instances):
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if not weighted_hosts:
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break
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weighted_host = weighted_hosts.pop(0)
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request_spec['instance_properties']['launch_index'] = num
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instance = self._provision_resource(elevated, weighted_host,
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request_spec, kwargs)
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if instance:
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instances.append(instance)
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notifier.notify(context, notifier.publisher_id("scheduler"),
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'scheduler.run_instance.end', notifier.INFO, payload)
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return instances
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def schedule_prep_resize(self, context, request_spec, *args, **kwargs):
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"""Select a target for resize.
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Selects a target host for the instance, post-resize, and casts
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the prep_resize operation to it.
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"""
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hosts = self._schedule(context, 'compute', request_spec,
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*args, **kwargs)
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if not hosts:
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raise exception.NoValidHost(reason="")
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host = hosts.pop(0)
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# NOTE(comstud): Make sure we do not pass this through. It
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# contains an instance of RpcContext that cannot be serialized.
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kwargs.pop('filter_properties', None)
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# Forward off to the host
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driver.cast_to_compute_host(context, host.host_state.host,
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'prep_resize', **kwargs)
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def _provision_resource(self, context, weighted_host, request_spec,
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kwargs):
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"""Create the requested resource in this Zone."""
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instance = self.create_instance_db_entry(context, request_spec)
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payload = dict(request_spec=request_spec,
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weighted_host=weighted_host.to_dict(),
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instance_id=instance['uuid'])
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notifier.notify(context, notifier.publisher_id("scheduler"),
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'scheduler.run_instance.scheduled', notifier.INFO,
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payload)
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driver.cast_to_compute_host(context, weighted_host.host_state.host,
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'run_instance', instance_uuid=instance['uuid'], **kwargs)
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inst = driver.encode_instance(instance, local=True)
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# So if another instance is created, create_instance_db_entry will
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# actually create a new entry, instead of assume it's been created
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# already
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del request_spec['instance_properties']['uuid']
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return inst
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def _get_configuration_options(self):
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"""Fetch options dictionary. Broken out for testing."""
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return self.options.get_configuration()
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def populate_filter_properties(self, request_spec, filter_properties):
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"""Stuff things into filter_properties. Can be overriden in a
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subclass to add more data.
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"""
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pass
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def _schedule(self, context, topic, request_spec, *args, **kwargs):
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"""Returns a list of hosts that meet the required specs,
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ordered by their fitness.
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"""
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elevated = context.elevated()
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if topic != "compute":
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msg = _("Scheduler only understands Compute nodes (for now)")
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raise NotImplementedError(msg)
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instance_properties = request_spec['instance_properties']
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instance_type = request_spec.get("instance_type", None)
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cost_functions = self.get_cost_functions()
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config_options = self._get_configuration_options()
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filter_properties = kwargs.get('filter_properties', {})
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filter_properties.update({'context': context,
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'request_spec': request_spec,
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'config_options': config_options,
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'instance_type': instance_type})
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self.populate_filter_properties(request_spec,
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filter_properties)
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# Find our local list of acceptable hosts by repeatedly
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# filtering and weighing our options. Each time we choose a
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# host, we virtually consume resources on it so subsequent
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# selections can adjust accordingly.
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# unfiltered_hosts_dict is {host : ZoneManager.HostInfo()}
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unfiltered_hosts_dict = self.host_manager.get_all_host_states(
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elevated, topic)
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# Note: remember, we are using an iterator here. So only
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# traverse this list once. This can bite you if the hosts
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# are being scanned in a filter or weighing function.
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hosts = unfiltered_hosts_dict.itervalues()
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num_instances = request_spec.get('num_instances', 1)
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selected_hosts = []
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for num in xrange(num_instances):
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# Filter local hosts based on requirements ...
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hosts = self.host_manager.filter_hosts(hosts,
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filter_properties)
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if not hosts:
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# Can't get any more locally.
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break
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LOG.debug(_("Filtered %(hosts)s") % locals())
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# weighted_host = WeightedHost() ... the best
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# host for the job.
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# TODO(comstud): filter_properties will also be used for
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# weighing and I plan fold weighing into the host manager
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# in a future patch. I'll address the naming of this
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# variable at that time.
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weighted_host = least_cost.weighted_sum(cost_functions,
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hosts, filter_properties)
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LOG.debug(_("Weighted %(weighted_host)s") % locals())
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selected_hosts.append(weighted_host)
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# Now consume the resources so the filter/weights
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# will change for the next instance.
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weighted_host.host_state.consume_from_instance(
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instance_properties)
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selected_hosts.sort(key=operator.attrgetter('weight'))
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return selected_hosts[:num_instances]
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def get_cost_functions(self, topic=None):
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"""Returns a list of tuples containing weights and cost functions to
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use for weighing hosts
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"""
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if topic is None:
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# Schedulers only support compute right now.
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topic = "compute"
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if topic in self.cost_function_cache:
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return self.cost_function_cache[topic]
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cost_fns = []
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for cost_fn_str in FLAGS.least_cost_functions:
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if '.' in cost_fn_str:
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short_name = cost_fn_str.split('.')[-1]
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else:
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short_name = cost_fn_str
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cost_fn_str = "%s.%s.%s" % (
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__name__, self.__class__.__name__, short_name)
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if not (short_name.startswith('%s_' % topic) or
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short_name.startswith('noop')):
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continue
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try:
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# NOTE: import_class is somewhat misnamed since
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# the weighing function can be any non-class callable
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# (i.e., no 'self')
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cost_fn = importutils.import_class(cost_fn_str)
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except ImportError:
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raise exception.SchedulerCostFunctionNotFound(
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cost_fn_str=cost_fn_str)
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try:
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flag_name = "%s_weight" % cost_fn.__name__
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weight = getattr(FLAGS, flag_name)
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except AttributeError:
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raise exception.SchedulerWeightFlagNotFound(
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flag_name=flag_name)
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cost_fns.append((weight, cost_fn))
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self.cost_function_cache[topic] = cost_fns
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return cost_fns
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