OpenStack Block Storage (Cinder)
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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_config import cfg
from oslo_utils import importutils
from cinder import exception
from cinder.i18n import _
CONF = cfg.CONF
# NOTE(ZhengMa): The order of the option is improtant, accelerators
# are looked by this list order
# Be careful to edit it
_ACCEL_PATH_PREFERENCE_ORDER_LIST = [
'cinder.image.accelerators.qat.AccelQAT',
'cinder.image.accelerators.gzip.AccelGZIP',
]
class AccelBase(object, metaclass=abc.ABCMeta):
def __init__(self):
return
@abc.abstractmethod
def is_accel_exist(self):
return
@abc.abstractmethod
def compress_img(self, run_as_root):
return
@abc.abstractmethod
def decompress_img(self, run_as_root):
return
class ImageAccel(object):
def __init__(self, src, dest):
self.src = src
self.dest = dest
self.compression_format = CONF.compression_format
if(self.compression_format == 'gzip'):
self._accel_engine_path = _ACCEL_PATH_PREFERENCE_ORDER_LIST
else:
self._accel_engine_path = None
self.engine = self._get_engine()
def _get_engine(self, *args, **kwargs):
if self._accel_engine_path:
for accel in self._accel_engine_path:
engine_cls = importutils.import_class(accel)
eng = engine_cls(*args, **kwargs)
if eng.is_accel_exist():
return eng
ex_msg = _("No valid accelerator")
raise exception.CinderException(ex_msg)
def is_engine_ready(self):
if not self.engine:
return False
if not self.engine.is_accel_exist():
return False
return True
def compress_img(self, run_as_root):
if not self.is_engine_ready():
return
self.engine.compress_img(self.src,
self.dest,
run_as_root)
def decompress_img(self, run_as_root):
if not self.is_engine_ready():
return
self.engine.decompress_img(self.src,
self.dest,
run_as_root)
def is_gzip_compressed(image_file):
# The first two bytes of a gzip file are: 1f 8b
GZIP_MAGIC_BYTES = b'\x1f\x8b'
with open(image_file, 'rb') as f:
return f.read(2) == GZIP_MAGIC_BYTES