Synnefo

# Copyright 2011 GRNET S.A. All rights reserved.

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"""

The Plankton attributes are the following:

  - checksum: the 'hash' meta

  - container_format: stored as a user meta

  - created_at: the 'modified' meta of the first version

  - deleted_at: the timestamp of the last version

  - disk_format: stored as a user meta

  - id: the 'uuid' meta

  - is_public: True if there is a * entry for the read permission

  - location: generated based on the file's path

  - name: stored as a user meta

  - owner: the file's account

  - properties: stored as user meta prefixed with PROPERTY_PREFIX

  - size: the 'bytes' meta

  - status: stored as a system meta

  - store: is always 'pithos'

  - updated_at: the 'modified' meta

"""

import json

import warnings

from operator import itemgetter

from time import gmtime, strftime, time

from django.conf import settings

from pithos.backends import connect_backend

from pithos.backends.base import NotAllowedError

PLANKTON_DOMAIN = 'plankton'

PLANKTON_PREFIX = 'plankton:'

PROPERTY_PREFIX = 'property:'

PLANKTON_META = ('container_format', 'disk_format', 'name', 'properties',

                 'status')

def get_location(account, container, object):

    assert '/' not in account, "Invalid account"

    assert '/' not in container, "Invalid container"

    return 'pithos://%s/%s/%s' % (account, container, object)

def split_location(location):

    """Returns (accout, container, object) from a location string"""

    t = location.split('/', 4)

    assert len(t) == 5, "Invalid location"

    return t[2:5]

class BackendException(Exception):

    pass

class ImageBackend(object):

    """A wrapper arround the pithos backend to simplify image handling."""

    def __init__(self, user):

        self.user = user

        original_filters = warnings.filters

        warnings.simplefilter('ignore')         # Suppress SQLAlchemy warnings

        db_connection = settings.BACKEND_DB_CONNECTION

        block_path = settings.BACKEND_BLOCK_PATH

        self.backend = connect_backend(db_connection=db_connection,

                                       block_path=block_path)

        warnings.filters = original_filters     # Restore warnings

    def _get_image(self, location):

        def format_timestamp(t):

            return strftime('%Y-%m-%d %H:%M:%S', gmtime(t))

        account, container, object = split_location(location)

        try:

            versions = self.backend.list_versions(self.user, account,

                    container, object)

        except NameError:

            return None

        image = {}

        meta = self._get_meta(location)

        if meta:

            image['deleted_at'] = ''

        else:

            # Object was deleted, use the latest version

            version, timestamp = versions[-1]

            meta = self._get_meta(location, version)

            image['deleted_at'] = format_timestamp(timestamp)

        if PLANKTON_PREFIX + 'name' not in meta:

            return None     # Not a Plankton image

        permissions = self._get_permissions(location)

        image['checksum'] = meta['hash']

        image['created_at'] = format_timestamp(versions[0][1])

        image['id'] = meta['uuid']

        image['is_public'] = '*' in permissions.get('read', [])

        image['location'] = location

        image['owner'] = account

        image['size'] = meta['bytes']

        image['store'] = 'pithos'

        image['updated_at'] = format_timestamp(meta['modified'])

        image['properties'] = {}

        for key, val in meta.items():

            if not key.startswith(PLANKTON_PREFIX):

                continue

            key = key[len(PLANKTON_PREFIX):]

            if key == 'properties':

                val = json.loads(val)

            if key in PLANKTON_META:

                image[key] = val

        return image

    def _get_meta(self, location, version=None):

        account, container, object = split_location(location)

        try:

            return self.backend.get_object_meta(self.user, account, container,

                    object, PLANKTON_DOMAIN, version)

        except NameError:

            return None

    def _get_permissions(self, location):

        account, container, object = split_location(location)

        action, path, permissions = self.backend.get_object_permissions(

                self.user, account, container, object)

        return permissions

    def _store(self, f, size=None):

        """Breaks data into blocks and stores them in the backend"""

        bytes = 0

        hashmap = []

        backend = self.backend

        blocksize = backend.block_size

        data = f.read(blocksize)

        while data:

            hash = backend.put_block(data)

            hashmap.append(hash)

            bytes += len(data)

            data = f.read(blocksize)

        if size and size != bytes:

            raise BackendException("Invalid size")

        return hashmap, bytes

    def _update(self, location, size, hashmap, meta, permissions):

        account, container, object = split_location(location)

        self.backend.update_object_hashmap(self.user, account, container,

                object, size, hashmap, PLANKTON_DOMAIN,

                permissions=permissions)

        self._update_meta(location, meta, replace=True)

    def _update_meta(self, location, meta, replace=False):

        account, container, object = split_location(location)

        prefixed = {}

        for key, val in meta.items():

            if key == 'properties':

                val = json.dumps(val)

            if key in PLANKTON_META:

                prefixed[PLANKTON_PREFIX + key] = val

        self.backend.update_object_meta(self.user, account, container, object,

                PLANKTON_DOMAIN, prefixed, replace)

    def _update_permissions(self, location, permissions):

        account, container, object = split_location(location)

        self.backend.update_object_permissions(self.user, account, container,

                object, permissions)

    def add_user(self, image_id, user):

        image = self.get_image(image_id)

        assert image, "Image not found"

        location = image['location']

        permissions = self._get_permissions(location)

        read = set(permissions.get('read', []))

        read.add(user)

        permissions['read'] = list(read)

        self._update_permissions(location, permissions)

    def close(self):

        self.backend.close()

    def get_data(self, location):

        account, container, object = split_location(location)

        size, hashmap = self.backend.get_object_hashmap(self.user, account,

                container, object)

        data = ''.join(self.backend.get_block(hash) for hash in hashmap)

        assert len(data) == size

        return data

    def get_image(self, image_id):

        try:

            account, container, object = self.backend.get_uuid(self.user,

                    image_id)

        except NameError:

            return None

        location = get_location(account, container, object)

        return self._get_image(location)

    def iter_public(self, filters):

        backend = self.backend

        keys = [PLANKTON_PREFIX + 'name']

        for key, val in filters.items():

            if key == 'size_min':

                filter = 'bytes >= %d' % int(val)

            elif key == 'size_max':

                filter = 'bytes <= %d' % int(val)

            else:

                filter = '%s = %s' % (PLANKTON_PREFIX + key, val)

            keys.append(filter)

        for account in backend.list_accounts(None):

            for container in backend.list_containers(None, account,

                                                     shared=True):

                for path, version_id in backend.list_objects(None, account,

                        container, prefix='', delimiter='/',

                        domain=PLANKTON_DOMAIN,

                        keys=keys, shared=True):

                    location = get_location(account, container, path)

                    image = self._get_image(location)

                    if image:

                        yield image

    def iter_shared(self, member):

        """Iterate over image ids shared to this member"""

        backend = self.backend

        # To get the list we connect as member and get the list shared by us

        for container in  backend.list_containers(member, self.user):

            for object, version_id in backend.list_objects(member, self.user,

                    container, prefix='', delimiter='/',

                    domain=PLANKTON_DOMAIN):

                try:

                    location = get_location(self.user, container, object)

                    meta = backend.get_object_meta(member, self.user,

                            container, object, PLANKTON_DOMAIN)

                    if PLANKTON_PREFIX + 'name' in meta:

                        yield meta['uuid']

                except NotAllowedError:

                    continue

    def list_public(self, filters, params):

        images = list(self.iter_public(filters))

        key = itemgetter(params.get('sort_key', 'created_at'))

        reverse = params.get('sort_dir', 'desc') == 'desc'

        images.sort(key=key, reverse=reverse)

        return images

    def list_users(self, image_id):

        image = self.get_image(image_id)

        assert image, "Image not found"

        permissions = self._get_permissions(image['location'])

        return [user for user in permissions.get('read', []) if user != '*']

    def put(self, name, f, params):

        assert 'checksum' not in params, "Passing a checksum is not supported"

        assert 'id' not in params, "Passing an ID is not supported"

        assert params.pop('store', 'pithos') == 'pithos', "Invalid store"

        assert params.setdefault('disk_format',

                settings.DEFAULT_DISK_FORMAT) in \

                settings.ALLOWED_DISK_FORMATS, "Invalid disk_format"

        assert params.setdefault('container_format',

                settings.DEFAULT_CONTAINER_FORMAT) in \

                settings.ALLOWED_CONTAINER_FORMATS, "Invalid container_format"

        container = settings.DEFAULT_PLANKTON_CONTAINER

        filename = params.pop('filename', name)

        location = 'pithos://%s/%s/%s' % (self.user, container, filename)

        is_public = params.pop('is_public', False)

        permissions = {'read': ['*']} if is_public else {}

        size = params.pop('size', None)

        hashmap, size = self._store(f, size)

        meta = {}

        meta['properties'] = params.pop('properties', {})

        meta.update(name=name, status='available', **params)

        self._update(location, size, hashmap, meta, permissions)

        return self._get_image(location)

    def register(self, name, location, params):

        assert 'id' not in params, "Passing an ID is not supported"

        assert location.startswith('pithos://'), "Invalid location"

        assert params.pop('store', 'pithos') == 'pithos', "Invalid store"

        assert params.setdefault('disk_format',

                settings.DEFAULT_DISK_FORMAT) in \

                settings.ALLOWED_DISK_FORMATS, "Invalid disk_format"

        assert params.setdefault('container_format',

                settings.DEFAULT_CONTAINER_FORMAT) in \

                settings.ALLOWED_CONTAINER_FORMATS, "Invalid container_format"

        user = self.user

        account, container, object = split_location(location)

        meta = self._get_meta(location)

        assert meta, "File not found"

        size = int(params.pop('size', meta['bytes']))

        if size != meta['bytes']:

            print repr(size)

            print repr(meta['bytes'])

            raise BackendException("Invalid size")

        checksum = params.pop('checksum', meta['hash'])

        if checksum != meta['hash']:

            raise BackendException("Invalid checksum")

        is_public = params.pop('is_public', False)

        permissions = {'read': ['*']} if is_public else {}

        meta = {}

        meta['properties'] = params.pop('properties', {})

        meta.update(name=name, status='available', **params)

        self._update_meta(location, meta)

        self._update_permissions(location, permissions)

        return self._get_image(location)

    def remove_user(self, image_id, user):

        image = self.get_image(image_id)

        assert image, "Image not found"

        location = image['location']

        permissions = self._get_permissions(location)

        try:

            permissions.get('read', []).remove(user)

        except ValueError:

            return      # User did not have access anyway

        self._update_permissions(location, permissions)

    def replace_users(self, image_id, users):

        image = self.get_image(image_id)

        assert image, "Image not found"

        location = image['location']

        permissions = self._get_permissions(location)

        permissions['read'] = users

        if image.get('is_public', False):

            permissions['read'].append('*')

        self._update_permissions(location, permissions)

    def update(self, image_id, params):

        image = self.get_image(image_id)

        assert image, "Image not found"

        location = image['location']

        is_public = params.pop('is_public', None)

        if is_public is not None:

            permissions = self._get_permissions(location)

            read = set(permissions.get('read', []))

            if is_public:

                read.add('*')

            else:

                read.discard('*')

            permissions['read'] = list(read)

            self.backend._update_permissions(location, permissions)

        meta = {}

        meta['properties'] = params.pop('properties', {})

        meta.update(**params)

        self._update_meta(location, meta)

        return self.get_image(image_id)