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# -*- coding: utf-8 -*-
# interfaces.py
# Copyright (C) 2017 LEAP
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
from zope.interface import Interface
class IBlobsBackend(Interface):
"""
An interface for a backend that can store blobs.
Classes that implement this interface are supposed to be used by
``BlobsResource``, which is a ``twisted.web.resource.Resource`` that serves
the Blobs API. Because of that, their methods receive instances of
``twisted.web.server.Request`` and should use them to serve the Blobs API.
"""
def read_blob(user, blob_id, request, namespace=''):
"""
Read a blob from the backend storage and write it as a response to a
request.
:param user: The id of the user who owns the blob.
:type user: str
:param blob_id: The id of the blob.
:type blob_id: str
:param request: A representation of all of the information about the
request that is being made.
:type request: twisted.web.server.Request
:param namespace: An optional namespace for the blob.
:type namespace: str
:return: Either ``server.NOT_DONE_YET`` to indicate an asynchronous
operation or a ``bytes`` instance to write as the response to the
request. If ``NOT_DONE_YET`` is returned, at some point later (for
example, in a Deferred callback) call ``request.write(b"data")`` to
write data to the request, and ``request.finish()`` to send the
data to the browser.
"""
def write_blob(user, blob_id, request, namespace=''):
"""
Write a blob to the backend storage after reading it from a request.
:param user: The id of the user who owns the blob.
:type user: str
:param blob_id: The id of the blob.
:type blob_id: str
:param request: A representation of all of the information about the
request that is being made.
:type request: twisted.web.server.Request
:param namespace: An optional namespace for the blob.
:type namespace: str
:return: A deferred that fires when the blob has been written to the
backend storage.
"""
def delete_blob(user, blob_id, namespace=''):
"""
Delete a blob from the backend storage.
:param user: The id of the user who owns the blob.
:type user: str
:param blob_id: The id of the blob.
:type blob_id: str
:param namespace: An optional namespace for the blob.
:type namespace: str
"""
def get_blob_size(user, blob_id, namespace=''):
"""
Get the size of a blob.
:param user: The id of the user who owns the blob.
:type user: str
:param blob_id: The id of the blob.
:type blob_id: str
:param namespace: An optional namespace for the blob.
:type namespace: str
:return: The size of the blob.
:rtype: int
"""
def count(user, namespace=''):
"""
Count the total number of blobs.
:param user: The id of the user who owns the blob.
:type user: str
:param namespace: Restrict the count to a certain namespace.
:type namespace: str
:return: The number of blobs in the backend storage, possibly
restricted to a certain namespace.
:rtype: int
"""
def list_blobs(user, namespace='', order_by=None, deleted=False,
filter_flag=None):
"""
List the blobs stored in the backend.
The resulting list can be ordered by date, filtered by namespace or
flag, and include deleted items or not.
:param user: The id of the user who owns the blob.
:type user: str
:param namespace: Restrict the count to a certain namespace.
:type namespace: str
:param order_by: 'date' (equivalent to '+date') or '-date', to sort
ascending or descending by date, respectivelly.
:type order_by: str
:param deleted: Whether to include deleted items in the result.
:type deleted: bool
:param filter_flag: If given, only results flagged with that flag will
be returned.
:type filter_flag: str
:return: A list of blob ids, optionally ordered and/or restricted by
namespace.
:rtype: list of str
"""
def get_total_storage(user):
"""
Get the size used by a given user as the sum of all the blobs stored
under all that user's namespaces.
:param user: The id of a user.
:type user: str
:return: The size in units of 1024 bytes.
:rtype: int
"""
def get_tag(user, blob_id, namespace=''):
"""
Get the tag of a blob.
:param blob_id: The id of the blob.
:type blob_id: str
:param namespace: An optional namespace for the blob.
:type namespace: str
:return: The tag of the blob.
:rtype: str
"""
def get_flags(user, blob_id, namespace=''):
"""
Get the flags for a blob.
:param user: The id of the user who owns the blob.
:type user: str
:param blob_id: The id of the blob.
:type blob_id: str
:param namespace: An optional namespace for the blob.
:type namespace: str
:return: a list of flags.
:rtype: list of str
"""
def set_flags(user, blob_id, request, namespace=''):
"""
Set flags for a blob.
The flags are expected to be send in the body of the request, as a JSON
list of strings.
:param user: The id of the user who owns the blob.
:type user: str
:param blob_id: The id of the blob.
:type blob_id: str
:param request: A representation of all of the information about the
request that is being made.
:type request: twisted.web.server.Request
:param namespace: An optional namespace for the blob.
:type namespace: str
:return: A string describing an error or ``None`` in case of success.
:rtype: str
"""
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