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Diffstat (limited to 'glance/store/base.py')
| -rw-r--r-- | glance/store/base.py | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/glance/store/base.py b/glance/store/base.py new file mode 100644 index 0000000..f0f89cb --- /dev/null +++ b/glance/store/base.py @@ -0,0 +1,167 @@ +# 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__) + + +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): + + CHUNKSIZE = 16 * units.Mi # 16M + + 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) + + def configure(self): + """ + Configure the Store to use the stored configuration options + Any store that needs special configuration should implement + this method. + """ + pass + + 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 `exception.BadStoreConfiguration`. + """ + pass + + 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 + + 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 + + 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 + + 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 + + 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 + + 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 |