152 lines
5.3 KiB
Python
152 lines
5.3 KiB
Python
# -*- coding: utf-8 -*-
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright (C) 2012 Yahoo! Inc. 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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# -*- coding: utf-8 -*-
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright (C) 2012 Yahoo! Inc. 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 oslo.config import cfg
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"""Define APIs for the logbook providers."""
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from nova.openstack.common import importutils
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from nova.openstack.common import log as logging
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LOG = logging.getLogger(__name__)
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logprovider_driver_opt = cfg.StrOpt('logbook_provider_driver',
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default='memory',
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help='The driver for that satisfies the '
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'remote lock providing service ( '
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'valid options are: db, memory, zk)')
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CONF = cfg.CONF
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CONF.register_opts([logprovider_driver_opt])
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class API(object):
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_driver = None
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_driver_name_class_mapping = {
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# Note these drivers can be used for persistant logging.
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'zk': 'nova.logbook.drivers.zk.ZooKeeperProviderDriver',
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'db': 'nova.logbook.drivers.db.DBProviderDriver',
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# This driver is pretty much only useful for testing.
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'memory': 'nova.logbook.drivers.memory.MemoryProviderDriver',
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}
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def __new__(cls, *args, **kwargs):
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'''Create an instance of the logbook provider API.
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args and kwargs are passed down to the logbook provider driver when it
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gets created.
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'''
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if not cls._driver:
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LOG.debug(_('Logbook provider driver defined as an instance of %s'),
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str(CONF.logbook_provider_driver))
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driver_name = CONF.logbook_provider_driver
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try:
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driver_class = cls._driver_name_class_mapping[driver_name]
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except KeyError:
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raise TypeError(_("Unknown logbook provider driver name: %s")
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% driver_name)
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cls._driver = importutils.import_object(driver_class,
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*args, **kwargs)
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utils.check_isinstance(cls._driver, LogBookProviderDriver)
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return super(API, cls).__new__(cls)
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class RecordNotFound(Exception):
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pass
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class LogBook(object):
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"""Base class for what a logbook (distributed or local or in-between)
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should provide"""
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__metaclass__ = abc.ABCMeta
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def __init__(self, resource_uri):
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self.uri = resource_uri
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@abc.abstractmethod
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def add_record(self, name, metadata=None):
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"""Atomically adds a new entry to the given logbook with the supplied
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metadata (if any)."""
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raise NotImplementedError()
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@abc.abstractmethod
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def fetch_record(self, name):
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"""Fetchs a record with the given name and returns any metadata about
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said record."""
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raise NotImplementedError()
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@abc.abstractmethod
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def __contains__(self, name):
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"""Determines if any entry with the given name exists in this
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logbook."""
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raise NotImplementedError()
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@abc.abstractmethod
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def mark(self, name, metadata, merge_functor=None):
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"""Marks the given logbook entry (which must exist) with the given
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metadata, if said entry already exists then the provided merge functor
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or a default function, will be activated to merge the existing metadata
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with the supplied metadata."""
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raise NotImplementedError()
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@abc.abstractmethod
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def __iter__(self):
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"""Iterates over all names and metadata and provides back both of these
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via a (name, metadata) tuple. The order will be in the same order that
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they were added."""
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raise NotImplementedError()
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class LogBookProvider(object):
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"""Base class for logbook provider drivers."""
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__metaclass__ = abc.ABCMeta
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@abc.abstractmethod
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def provide(self, resource_uri):
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"""Returns a new (if not existent) logbook object or used logbook
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object (if already existent) which can be used to determine the actions
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performed on a given resource uri"""
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raise NotImplementedError()
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def close(self):
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"""Allows the log provider to free any resources that it has."""
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pass
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