d090087df2
Commit 3c584084 introduce a routine where the return value of a function is assigned to a local variable named 'meh' and then immediately returned. This is a poor programming style and an even poorer variable name choice. Change-Id: I4da66c99689a999a30f83390dfe3c79db646e431
311 lines
14 KiB
Python
311 lines
14 KiB
Python
# Copyright (c) 2015 OpenStack Foundation. 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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from oslo_config import cfg
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from oslo_db import api as oslo_db_api
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from oslo_db import exception as oslo_db_exception
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from oslo_log import log
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from oslo_utils import excutils
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from sqlalchemy import event
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from sqlalchemy import exc as sql_exc
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from neutron._i18n import _LE, _LW
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from neutron.db import api as db_api
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from neutron.db.quota import api as quota_api
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LOG = log.getLogger(__name__)
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def _count_resource(context, plugin, collection_name, tenant_id):
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count_getter_name = "get_%s_count" % collection_name
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# Some plugins support a count method for particular resources,
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# using a DB's optimized counting features. We try to use that one
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# if present. Otherwise just use regular getter to retrieve all objects
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# and count in python, allowing older plugins to still be supported
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try:
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obj_count_getter = getattr(plugin, count_getter_name)
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return obj_count_getter(context, filters={'tenant_id': [tenant_id]})
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except (NotImplementedError, AttributeError):
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obj_getter = getattr(plugin, "get_%s" % collection_name)
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obj_list = obj_getter(context, filters={'tenant_id': [tenant_id]})
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return len(obj_list) if obj_list else 0
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class BaseResource(object):
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"""Describe a single resource for quota checking."""
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def __init__(self, name, flag, plural_name=None):
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"""Initializes a resource.
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:param name: The name of the resource, i.e., "instances".
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:param flag: The name of the flag or configuration option
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:param plural_name: Plural form of the resource name. If not
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specified, it is generated automatically by
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appending an 's' to the resource name, unless
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it ends with a 'y'. In that case the last
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letter is removed, and 'ies' is appended.
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Dashes are always converted to underscores.
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"""
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self.name = name
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# If a plural name is not supplied, default to adding an 's' to
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# the resource name, unless the resource name ends in 'y', in which
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# case remove the 'y' and add 'ies'. Even if the code should not fiddle
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# too much with English grammar, this is a rather common and easy to
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# implement rule.
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if plural_name:
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self.plural_name = plural_name
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elif self.name[-1] == 'y':
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self.plural_name = "%sies" % self.name[:-1]
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else:
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self.plural_name = "%ss" % self.name
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# always convert dashes to underscores
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self.plural_name = self.plural_name.replace('-', '_')
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self.flag = flag
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@property
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def default(self):
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"""Return the default value of the quota."""
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# Any negative value will be interpreted as an infinite quota,
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# and stored as -1 for compatibility with current behaviour
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value = getattr(cfg.CONF.QUOTAS,
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self.flag,
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cfg.CONF.QUOTAS.default_quota)
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return max(value, -1)
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@property
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def dirty(self):
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"""Return the current state of the Resource instance.
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:returns: True if the resource count is out of sync with actual date,
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False if it is in sync, and None if the resource instance
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does not track usage.
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"""
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class CountableResource(BaseResource):
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"""Describe a resource where the counts are determined by a function."""
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def __init__(self, name, count, flag=None, plural_name=None):
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"""Initializes a CountableResource.
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Countable resources are those resources which directly
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correspond to objects in the database, i.e., network, subnet,
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etc.,. A CountableResource must be constructed with a counting
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function, which will be called to determine the current counts
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of the resource.
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The counting function will be passed the context, along with
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the extra positional and keyword arguments that are passed to
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Quota.count(). It should return an integer specifying the
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count.
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:param name: The name of the resource, i.e., "instances".
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:param count: A callable which returns the count of the
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resource. The arguments passed are as described
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above.
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:param flag: The name of the flag or configuration option
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which specifies the default value of the quota
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for this resource.
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:param plural_name: Plural form of the resource name. If not
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specified, it is generated automatically by
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appending an 's' to the resource name, unless
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it ends with a 'y'. In that case the last
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letter is removed, and 'ies' is appended.
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Dashes are always converted to underscores.
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"""
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super(CountableResource, self).__init__(
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name, flag=flag, plural_name=plural_name)
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self._count_func = count
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def count(self, context, plugin, tenant_id, **kwargs):
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return self._count_func(context, plugin, self.plural_name, tenant_id)
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class TrackedResource(BaseResource):
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"""Resource which keeps track of its usage data."""
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def __init__(self, name, model_class, flag, plural_name=None):
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"""Initializes an instance for a given resource.
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TrackedResource are directly mapped to data model classes.
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Resource usage is tracked in the database, and the model class to
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which this resource refers is monitored to ensure always "fresh"
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usage data are employed when performing quota checks.
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This class operates under the assumption that the model class
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describing the resource has a tenant identifier attribute.
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:param name: The name of the resource, i.e., "networks".
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:param model_class: The sqlalchemy model class of the resource for
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which this instance is being created
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:param flag: The name of the flag or configuration option
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which specifies the default value of the quota
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for this resource.
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:param plural_name: Plural form of the resource name. If not
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specified, it is generated automatically by
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appending an 's' to the resource name, unless
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it ends with a 'y'. In that case the last
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letter is removed, and 'ies' is appended.
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Dashes are always converted to underscores.
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"""
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super(TrackedResource, self).__init__(
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name, flag=flag, plural_name=plural_name)
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# Register events for addition/removal of records in the model class
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# As tenant_id is immutable for all Neutron objects there is no need
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# to register a listener for update events
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self._model_class = model_class
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self._dirty_tenants = set()
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self._out_of_sync_tenants = set()
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@property
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def dirty(self):
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return self._dirty_tenants
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def mark_dirty(self, context):
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if not self._dirty_tenants:
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return
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with db_api.autonested_transaction(context.session):
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# It is not necessary to protect this operation with a lock.
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# Indeed when this method is called the request has been processed
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# and therefore all resources created or deleted.
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# dirty_tenants will contain all the tenants for which the
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# resource count is changed. The list might contain also tenants
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# for which resource count was altered in other requests, but this
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# won't be harmful.
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dirty_tenants_snap = self._dirty_tenants.copy()
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for tenant_id in dirty_tenants_snap:
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quota_api.set_quota_usage_dirty(context, self.name, tenant_id)
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LOG.debug(("Persisted dirty status for tenant:%(tenant_id)s "
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"on resource:%(resource)s"),
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{'tenant_id': tenant_id, 'resource': self.name})
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self._out_of_sync_tenants |= dirty_tenants_snap
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self._dirty_tenants -= dirty_tenants_snap
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def _db_event_handler(self, mapper, _conn, target):
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try:
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tenant_id = target['tenant_id']
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except AttributeError:
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with excutils.save_and_reraise_exception():
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LOG.error(_LE("Model class %s does not have a tenant_id "
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"attribute"), target)
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self._dirty_tenants.add(tenant_id)
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# Retry the operation if a duplicate entry exception is raised. This
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# can happen is two or more workers are trying to create a resource of a
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# give kind for the same tenant concurrently. Retrying the operation will
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# ensure that an UPDATE statement is emitted rather than an INSERT one
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@oslo_db_api.wrap_db_retry(
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max_retries=db_api.MAX_RETRIES,
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exception_checker=lambda exc:
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isinstance(exc, (oslo_db_exception.DBDuplicateEntry,
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oslo_db_exception.DBDeadlock)))
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def _set_quota_usage(self, context, tenant_id, in_use):
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return quota_api.set_quota_usage(
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context, self.name, tenant_id, in_use=in_use)
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def _resync(self, context, tenant_id, in_use):
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# Update quota usage
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usage_info = self._set_quota_usage(context, tenant_id, in_use)
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self._dirty_tenants.discard(tenant_id)
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self._out_of_sync_tenants.discard(tenant_id)
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LOG.debug(("Unset dirty status for tenant:%(tenant_id)s on "
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"resource:%(resource)s"),
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{'tenant_id': tenant_id, 'resource': self.name})
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return usage_info
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def resync(self, context, tenant_id):
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if tenant_id not in self._out_of_sync_tenants:
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return
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LOG.debug(("Synchronizing usage tracker for tenant:%(tenant_id)s on "
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"resource:%(resource)s"),
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{'tenant_id': tenant_id, 'resource': self.name})
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in_use = context.session.query(self._model_class).filter_by(
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tenant_id=tenant_id).count()
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# Update quota usage
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return self._resync(context, tenant_id, in_use)
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def count(self, context, _plugin, tenant_id, resync_usage=True):
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"""Return the current usage count for the resource.
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This method will fetch aggregate information for resource usage
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data, unless usage data are marked as "dirty".
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In the latter case resource usage will be calculated counting
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rows for tenant_id in the resource's database model.
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Active reserved amount are instead always calculated by summing
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amounts for matching records in the 'reservations' database model.
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The _plugin and _resource parameters are unused but kept for
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compatibility with the signature of the count method for
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CountableResource instances.
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"""
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# Load current usage data, setting a row-level lock on the DB
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usage_info = quota_api.get_quota_usage_by_resource_and_tenant(
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context, self.name, tenant_id, lock_for_update=True)
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# Always fetch reservations, as they are not tracked by usage counters
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reservations = quota_api.get_reservations_for_resources(
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context, tenant_id, [self.name])
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reserved = reservations.get(self.name, 0)
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# If dirty or missing, calculate actual resource usage querying
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# the database and set/create usage info data
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# NOTE: this routine "trusts" usage counters at service startup. This
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# assumption is generally valid, but if the database is tampered with,
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# or if data migrations do not take care of usage counters, the
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# assumption will not hold anymore
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if (tenant_id in self._dirty_tenants or
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not usage_info or usage_info.dirty):
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LOG.debug(("Usage tracker for resource:%(resource)s and tenant:"
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"%(tenant_id)s is out of sync, need to count used "
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"quota"), {'resource': self.name,
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'tenant_id': tenant_id})
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in_use = context.session.query(self._model_class).filter_by(
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tenant_id=tenant_id).count()
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# Update quota usage, if requested (by default do not do that, as
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# typically one counts before adding a record, and that would mark
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# the usage counter as dirty again)
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if resync_usage:
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usage_info = self._resync(context, tenant_id, in_use)
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else:
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resource = usage_info.resource if usage_info else self.name
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tenant_id = usage_info.tenant_id if usage_info else tenant_id
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dirty = usage_info.dirty if usage_info else True
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usage_info = quota_api.QuotaUsageInfo(
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resource, tenant_id, in_use, dirty)
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LOG.debug(("Quota usage for %(resource)s was recalculated. "
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"Used quota:%(used)d."),
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{'resource': self.name,
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'used': usage_info.used})
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return usage_info.used + reserved
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def register_events(self):
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event.listen(self._model_class, 'after_insert', self._db_event_handler)
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event.listen(self._model_class, 'after_delete', self._db_event_handler)
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def unregister_events(self):
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try:
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event.remove(self._model_class, 'after_insert',
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self._db_event_handler)
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event.remove(self._model_class, 'after_delete',
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self._db_event_handler)
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except sql_exc.InvalidRequestError:
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LOG.warning(_LW("No sqlalchemy event for resource %s found"),
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self.name)
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