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# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License. You may obtain a copy of
# the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations under
# the License.
import abc
from oslo_log import log as logging
from oslo_utils import importutils
from os_brick import exception
from os_brick.i18n import _
LOG = logging.getLogger(__name__)
CACHE_ENGINE_TO_CACHE_CLASS_MAP = {
"opencas": 'os_brick.caches.opencas.OpenCASEngine',
}
class CacheEngineBase(object, metaclass=abc.ABCMeta):
def __init__(self, **kwargs):
self._root_helper = kwargs.get('root_helper')
@abc.abstractmethod
def is_engine_ready(self, **kwargs):
return
@abc.abstractmethod
def attach_volume(self, **kwargs):
return
@abc.abstractmethod
def detach_volume(self, **kwargs):
return
class CacheManager():
"""Cache manager for volumes.
This CacheManager uses cache engines to do volume cache.
"""
def __init__(self, root_helper, connection_info,
*args, **kwargs):
data = connection_info['data']
if not data.get('device_path'):
volume_id = data.get('volume_id') or connection_info.get('serial')
raise exception.VolumeLocalCacheNotSupported(
volume_id=volume_id,
volume_type=connection_info.get('driver_volume_type'))
self.ori_device_path = data.get('device_path')
if not data.get('cacheable'):
self.cacheable = False
return
self.cacheable = True
self.root_helper = root_helper
self.engine_name = kwargs.get('cache_name')
self.args = args
self.kwargs = kwargs
self.kwargs["root_helper"] = root_helper
self.kwargs["dev_path"] = data.get('device_path')
self.engine = self._get_engine(self.engine_name, **self.kwargs)
def _get_engine(self, engine_name, **kwargs):
eng_cls_path = CACHE_ENGINE_TO_CACHE_CLASS_MAP.get(engine_name)
if eng_cls_path:
engine_cls = importutils.import_class(eng_cls_path)
eng = engine_cls(**kwargs)
if eng.is_engine_ready():
return eng
raise exception.Invalid(_("No valid cache engine"))
def attach_volume(self):
"""setup the cache when attaching volume."""
if not self.cacheable:
return self.ori_device_path
LOG.debug("volume before cached: %s", self.kwargs.get('dev_path'))
emulated_disk = self.engine.attach_volume(**self.kwargs)
LOG.debug("volume after cached: %s", emulated_disk)
return emulated_disk
def detach_volume(self):
"""Release the cache on detaching volume."""
if not self.cacheable:
return self.ori_device_path
LOG.debug("volume before detach: %s", self.kwargs.get('dev_path'))
ori_disk = self.engine.detach_volume(**self.kwargs)
LOG.debug("volume after detach: %s", ori_disk)
return ori_disk
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