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# Copyright 2011 OpenStack Foundation
# Copyright 2012 RedHat Inc.
# All Rights Reserved.
#
# 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.
"""Base class for all storage backends"""
import logging
from oslo.config import cfg
from glance_store import exceptions
from glance_store.i18n import _
from glance_store.openstack.common import importutils
from glance_store.openstack.common import strutils
LOG = logging.getLogger(__name__)
def _exception_to_unicode(exc):
try:
return unicode(exc)
except UnicodeError:
try:
return strutils.safe_decode(str(exc), errors='ignore')
except UnicodeError:
msg = (_("Caught '%(exception)s' exception.") %
{"exception": exc.__class__.__name__})
return strutils.safe_decode(msg, errors='ignore')
class Store(object):
OPTIONS = None
READ_CHUNKSIZE = 16 * (1024 * 1024) # 16M
WRITE_CHUNKSIZE = READ_CHUNKSIZE
def __init__(self, conf):
"""
Initialize the Store
"""
self.conf = conf
self.store_location_class = None
try:
if self.OPTIONS is not None:
# NOTE(flaper87): To be removed in k-2. This should
# give deployers enough time to migrate their systems
# and move configs under the new section.
for opt in self.OPTIONS:
opt.deprecated_opts = [cfg.DeprecatedOpt(opt.name)]
self.conf.register_opts(self.OPTIONS, group='glance_store')
except cfg.DuplicateOptError:
pass
self.configure()
def configure(self):
"""
Configure the Store to use the stored configuration options
Any store that needs special configuration should implement
this method.
"""
try:
self.configure_add()
self.add = getattr(self, '_add', self.add)
except exceptions.BadStoreConfiguration as e:
self._add = self.add
self.add = self.add_disabled
msg = (_(u"Failed to configure store correctly: %s "
"Disabling add method.") % _exception_to_unicode(e))
LOG.warn(msg)
def get_schemes(self):
"""
Returns a tuple of schemes which this store can handle.
"""
raise NotImplementedError
def get_store_location_class(self):
"""
Returns the store location class that is used by this store.
"""
if not self.store_location_class:
class_name = "%s.StoreLocation" % (self.__module__)
LOG.debug("Late loading location class %s", class_name)
self.store_location_class = importutils.import_class(class_name)
return self.store_location_class
def configure_add(self):
"""
This is like `configure` except that it's specifically for
configuring the store to accept objects.
If the store was not able to successfully configure
itself, it should raise `exceptions.BadStoreConfiguration`.
"""
# NOTE(flaper87): This should probably go away
def validate_location(self, location):
"""
Takes a location and validates it for the presence
of any account references
"""
pass
def get(self, location, offset=0, chunk_size=None, context=None):
"""
Takes a `glance_store.location.Location` object that indicates
where to find the image file, and returns a tuple of generator
(for reading the image file) and image_size
:param location `glance_store.location.Location` object, supplied
from glance_store.location.get_location_from_uri()
:raises `glance.exceptions.NotFound` if image does not exist
"""
raise NotImplementedError
def get_size(self, location, context=None):
"""
Takes a `glance_store.location.Location` object that indicates
where to find the image file, and returns the size
:param location `glance_store.location.Location` object, supplied
from glance_store.location.get_location_from_uri()
:raises `glance_store.exceptions.NotFound` if image does not exist
"""
raise NotImplementedError
def add_disabled(self, *args, **kwargs):
"""
Add method that raises an exception because the Store was
not able to be configured properly and therefore the add()
method would error out.
"""
raise exceptions.StoreAddDisabled
def add(self, image_id, image_file, image_size, context=None):
"""
Stores an image file with supplied identifier to the backend
storage system and returns a tuple containing information
about the stored image.
:param image_id: The opaque image identifier
:param image_file: The image data to write, as a file-like object
:param image_size: The size of the image data to write, in bytes
:retval tuple of URL in backing store, bytes written, checksum
and a dictionary with storage system specific information
:raises `glance_store.exceptions.Duplicate` if the image already
existed
"""
raise NotImplementedError
def delete(self, location, context=None):
"""
Takes a `glance_store.location.Location` object that indicates
where to find the image file to delete
:location `glance_store.location.Location` object, supplied
from glance_store.location.get_location_from_uri()
:raises `glance_store.exceptions.NotFound` if image does not exist
"""
raise NotImplementedError
def set_acls(self, location, public=False, read_tenants=[],
write_tenants=[], context=None):
"""
Sets the read and write access control list for an image in the
backend store.
:location `glance_store.location.Location` object, supplied
from glance_store.location.get_location_from_uri()
:public A boolean indicating whether the image should be public.
:read_tenants A list of tenant strings which should be granted
read access for an image.
:write_tenants A list of tenant strings which should be granted
write access for an image.
"""
raise NotImplementedError
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