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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"""
from glance.common import exception
from glance.openstack.common import importutils
import glance.openstack.common.log as logging
from glance.openstack.common import strutils
from glance.openstack.common import units
LOG = logging.getLogger(__name__)
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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')
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class Store(object):
CHUNKSIZE = 16 * units.Mi # 16M
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def __init__(self, context=None, location=None):
"""
Initialize the Store
"""
self.store_location_class = None
self.context = context
self.configure()
try:
self.configure_add()
except exception.BadStoreConfiguration as e:
self.add = self.add_disabled
msg = (_(u"Failed to configure store correctly: %s "
"Disabling add method.") % _exception_to_unicode(e))
LOG.warn(msg)
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def configure(self):
"""
Configure the Store to use the stored configuration options
Any store that needs special configuration should implement
this method.
"""
pass
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def get_schemes(self):
"""
Returns a tuple of schemes which this store can handle.
"""
raise NotImplementedError
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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
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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 `exception.BadStoreConfiguration`.
"""
pass
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def get(self, location):
"""
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.exception.NotFound` if image does not exist
"""
raise NotImplementedError
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def get_size(self, location):
"""
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.exception.NotFound` if image does not exist
"""
raise NotImplementedError
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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 exception.StoreAddDisabled
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def add(self, image_id, image_file, image_size):
"""
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.common.exception.Duplicate` if the image already
existed
"""
raise NotImplementedError
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def delete(self, location):
"""
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.exception.NotFound` if image does not exist
"""
raise NotImplementedError
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def set_acls(self, location, public=False, read_tenants=[],
write_tenants=[]):
"""
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