eef012d4c4
Instead of magically loading `_` into python built-in globals, import it explicitly where needed. Partially-implements: py3k-support Change-Id: Icfedf9f86ead81bbee038506a91c456907af0d05
117 lines
3.9 KiB
Python
117 lines
3.9 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");
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# you may not use this file except in compliance with the License.
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# You may obtain 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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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# implied.
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#
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from oslo.config import cfg
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from stevedore import driver
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from marconi import common
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from marconi.common import decorators
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from marconi.openstack.common.gettextutils import _
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from marconi.openstack.common import log as logging
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from marconi.queues.storage import base
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LOG = logging.getLogger(__name__)
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_PIPELINE_RESOURCES = ('queue', 'message', 'claim')
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_PIPELINE_CONFIGS = [
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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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'which will always be appended to this '
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'pipeline.').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 _get_storage_pipeline(resource_name, conf):
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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('marconi.queues.storage.stages',
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ns, 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)d 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 common.Pipeline(pipeline)
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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):
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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)
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self._storage = storage
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def is_alive(self):
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return self._storage.is_alive()
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@decorators.lazy_property(write=False)
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def queue_controller(self):
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stages = _get_storage_pipeline('queue', self.conf)
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stages.append(self._storage.queue_controller)
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return stages
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@decorators.lazy_property(write=False)
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def message_controller(self):
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stages = _get_storage_pipeline('message', self.conf)
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stages.append(self._storage.message_controller)
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return stages
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@decorators.lazy_property(write=False)
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def claim_controller(self):
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stages = _get_storage_pipeline('claim', self.conf)
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stages.append(self._storage.claim_controller)
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return stages
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