134 lines
4.8 KiB
Python
134 lines
4.8 KiB
Python
# Copyright (c) 2013 Hewlett-Packard Development Company, L.P.
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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 stevedore
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from nova.i18n import _LW
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from nova.openstack.common import log as logging
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LOG = logging.getLogger(__name__)
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RESOURCE_NAMESPACE = 'nova.compute.resources'
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class ResourceHandler(object):
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def _log_missing_plugins(self, names):
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for name in names:
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if name not in self._mgr.names():
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LOG.warning(_LW('Compute resource plugin %s was not loaded'),
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name)
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def __init__(self, names, propagate_map_exceptions=False):
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"""Initialise the resource handler by loading the plugins.
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The ResourceHandler uses stevedore to load the resource plugins.
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The handler can handle and report exceptions raised in the plugins
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depending on the value of the propagate_map_exceptions parameter.
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It is useful in testing to propagate exceptions so they are exposed
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as part of the test. If exceptions are not propagated they are
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logged at error level.
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Any named plugins that are not located are logged.
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:param names: the list of plugins to load by name
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:param propagate_map_exceptions: True indicates exceptions in the
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plugins should be raised, False indicates they should be handled and
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logged.
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"""
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self._mgr = stevedore.NamedExtensionManager(
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namespace=RESOURCE_NAMESPACE,
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names=names,
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propagate_map_exceptions=propagate_map_exceptions,
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invoke_on_load=True)
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self._log_missing_plugins(names)
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def reset_resources(self, resources, driver):
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"""Reset the resources to their initial state.
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Each plugin is called to reset its state. The resources data provided
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is initial state gathered from the hypervisor. The driver is also
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provided in case the plugin needs to obtain additional information
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from the driver, for example, the memory calculation obtains
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the memory overhead from the driver.
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:param resources: the resources reported by the hypervisor
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:param driver: the driver for the hypervisor
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:returns: None
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"""
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if self._mgr.extensions:
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self._mgr.map_method('reset', resources, driver)
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def test_resources(self, usage, limits):
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"""Test the ability to support the given instance.
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Each resource plugin is called to determine if it's resource is able
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to support the additional requirements of a new instance. The
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plugins either return None to indicate they have sufficient resource
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available or a human readable string to indicate why they can not.
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:param usage: the additional resource usage
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:param limits: limits used for the calculation
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:returns: a list or return values from the plugins
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"""
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if not self._mgr.extensions:
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return []
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reasons = self._mgr.map_method('test', usage, limits)
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return reasons
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def update_from_instance(self, usage, sign=1):
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"""Update the resource information to reflect the allocation for
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an instance with the given resource usage.
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:param usage: the resource usage of the instance
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:param sign: has value 1 or -1. 1 indicates the instance is being
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added to the current usage, -1 indicates the instance is being removed.
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:returns: None
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"""
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if not self._mgr.extensions:
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return
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if sign == 1:
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self._mgr.map_method('add_instance', usage)
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else:
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self._mgr.map_method('remove_instance', usage)
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def write_resources(self, resources):
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"""Write the resource data to populate the resources.
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Each resource plugin is called to write its resource data to
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resources.
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:param resources: the compute node resources
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:returns: None
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"""
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if self._mgr.extensions:
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self._mgr.map_method('write', resources)
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def report_free_resources(self):
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"""Each resource plugin is called to log free resource information.
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:returns: None
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"""
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if not self._mgr.extensions:
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return
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self._mgr.map_method('report_free')
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