178 lines
6.4 KiB
Python
178 lines
6.4 KiB
Python
# Copyright (c) 2013 Rackspace, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may not
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# use this file except in compliance with the License. You may obtain a copy
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# 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 under
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# the License.
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from oslo_config import cfg
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from oslo_log import log as logging
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from osprofiler import profiler
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from stevedore import driver
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from stevedore import extension
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from zaqar import common
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from zaqar.common import decorators
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from zaqar.i18n import _
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from zaqar.storage import base
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LOG = logging.getLogger(__name__)
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_PIPELINE_RESOURCES = ('queue', 'message', 'claim', 'subscription')
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_PIPELINE_CONFIGS = tuple((
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cfg.ListOpt(resource + '_pipeline', default=[],
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help=_('Pipeline to use for processing {0} operations. '
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'This pipeline will be consumed before calling '
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'the storage driver\'s controller methods.')
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.format(resource))
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for resource in _PIPELINE_RESOURCES
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))
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_PIPELINE_GROUP = 'storage'
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def _config_options():
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return [(_PIPELINE_GROUP, _PIPELINE_CONFIGS)]
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def _get_storage_pipeline(resource_name, conf, *args, **kwargs):
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"""Constructs and returns a storage resource pipeline.
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This is a helper function for any service supporting
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pipelines for the storage layer. The function returns
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a pipeline based on the `{resource_name}_pipeline`
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config option.
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Stages in the pipeline implement controller methods
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that they want to hook. A stage can halt the
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pipeline immediate by returning a value that is
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not None; otherwise, processing will continue
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to the next stage, ending with the actual storage
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controller.
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:param conf: Configuration instance.
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:type conf: `cfg.ConfigOpts`
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:returns: A pipeline to use.
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:rtype: `Pipeline`
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"""
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conf.register_opts(_PIPELINE_CONFIGS,
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group=_PIPELINE_GROUP)
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storage_conf = conf[_PIPELINE_GROUP]
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pipeline = []
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for ns in storage_conf[resource_name + '_pipeline']:
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try:
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mgr = driver.DriverManager('zaqar.storage.stages',
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ns,
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invoke_args=args,
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invoke_kwds=kwargs,
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invoke_on_load=True)
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pipeline.append(mgr.driver)
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except RuntimeError as exc:
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LOG.warning(_(u'Stage %(stage)s could not be imported: %(ex)s'),
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{'stage': ns, 'ex': str(exc)})
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continue
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return pipeline
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def _get_builtin_entry_points(resource_name, storage, control_driver, conf):
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# Load builtin stages
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builtin_entry_points = []
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# NOTE(flaper87): The namespace will look like:
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# `zaqar.storage.$STORAGE.driver.stages`. For now,
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# the builtin stages are bound to a single store and
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# are not applied to every store.
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namespace = '%s.%s.stages' % (storage.__module__, resource_name)
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extensions = extension.ExtensionManager(namespace,
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invoke_on_load=True,
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invoke_args=[storage,
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control_driver])
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if len(extensions.extensions) == 0:
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return []
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for ext in extensions.extensions:
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builtin_entry_points.append(ext.obj)
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if conf.profiler.enabled and conf.profiler.trace_message_store:
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return (profiler.trace_cls("stages_controller")
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(builtin_entry_points))
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return builtin_entry_points
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class DataDriver(base.DataDriverBase):
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"""Meta-driver for injecting pipelines in front of controllers.
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:param conf: Configuration from which to load pipeline settings
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:param storage: Storage driver that will service requests as the
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last step in the pipeline
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"""
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def __init__(self, conf, storage, control_driver):
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# NOTE(kgriffs): Pass None for cache since it won't ever
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# be referenced.
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super(DataDriver, self).__init__(conf, None, control_driver)
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self._storage = storage
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@property
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def capabilities(self):
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return self._storage.capabilities()
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def close(self):
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self._storage.close()
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def is_alive(self):
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return self._storage.is_alive()
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def _health(self):
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return self._storage._health()
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@decorators.lazy_property(write=False)
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def queue_controller(self):
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stages = _get_builtin_entry_points('queue', self._storage,
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self.control_driver, self.conf)
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stages.extend(_get_storage_pipeline('queue', self.conf))
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stages.append(self._storage.queue_controller)
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return common.Pipeline(stages)
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@decorators.lazy_property(write=False)
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def message_controller(self):
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stages = _get_builtin_entry_points('message', self._storage,
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self.control_driver, self.conf)
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kwargs = {'subscription_controller':
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self._storage.subscription_controller,
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'max_notifier_workers':
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self.conf.notification.max_notifier_workers,
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'require_confirmation':
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self.conf.notification.require_confirmation}
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stages.extend(_get_storage_pipeline('message', self.conf, **kwargs))
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stages.append(self._storage.message_controller)
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return common.Pipeline(stages)
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@decorators.lazy_property(write=False)
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def claim_controller(self):
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stages = _get_builtin_entry_points('claim', self._storage,
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self.control_driver, self.conf)
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stages.extend(_get_storage_pipeline('claim', self.conf))
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stages.append(self._storage.claim_controller)
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return common.Pipeline(stages)
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@decorators.lazy_property(write=False)
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def subscription_controller(self):
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stages = _get_builtin_entry_points('subscription', self._storage,
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self.control_driver, self.conf)
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stages.extend(_get_storage_pipeline('subscription', self.conf))
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stages.append(self._storage.subscription_controller)
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return common.Pipeline(stages)
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