78 lines
2.8 KiB
Python
78 lines
2.8 KiB
Python
# Copyright (c) 2015 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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import abc
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from operator import attrgetter
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import random
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import six
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@six.add_metaclass(abc.ABCMeta)
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class BaseScheduler(object):
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"""The base scheduler (agnostic to resource type).
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Child classes of BaseScheduler must define the
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self.resource_filter to filter agents of
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particular type.
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"""
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resource_filter = None
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@abc.abstractmethod
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def select(self, plugin, context, resource_hostable_agents,
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resource_hosted_agents, num_agents_needed):
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"""Return a subset of agents based on the specific scheduling logic."""
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def schedule(self, plugin, context, resource):
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"""Select and bind agents to a given resource."""
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if not self.resource_filter:
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return
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# filter the agents that can host the resource
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filtered_agents_dict = self.resource_filter.filter_agents(
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plugin, context, resource)
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num_agents = filtered_agents_dict['n_agents']
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hostable_agents = filtered_agents_dict['hostable_agents']
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hosted_agents = filtered_agents_dict['hosted_agents']
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chosen_agents = self.select(plugin, context, hostable_agents,
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hosted_agents, num_agents)
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# bind the resource to the agents
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self.resource_filter.bind(context, chosen_agents, resource['id'])
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return chosen_agents
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class BaseChanceScheduler(BaseScheduler):
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"""Choose agents randomly."""
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def __init__(self, resource_filter):
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self.resource_filter = resource_filter
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def select(self, plugin, context, resource_hostable_agents,
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resource_hosted_agents, num_agents_needed):
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chosen_agents = random.sample(resource_hostable_agents,
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num_agents_needed)
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return chosen_agents
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class BaseWeightScheduler(BaseScheduler):
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"""Choose agents based on load."""
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def __init__(self, resource_filter):
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self.resource_filter = resource_filter
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def select(self, plugin, context, resource_hostable_agents,
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resource_hosted_agents, num_agents_needed):
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chosen_agents = sorted(resource_hostable_agents,
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key=attrgetter('load'))[0:num_agents_needed]
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return chosen_agents
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