Synnefo

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class BaseBackend(object):

    """Abstract backend class that serves as a reference for actual implementations.

    The purpose of the backend is to provide the necessary functions for handling data

    and metadata. It is responsible for the actual storage and retrieval of information.

    Note that the account level is always valid as it is checked from another subsystem.

    The following variables should be available:

        'hash_algorithm': Suggested is 'sha256'

        'block_size': Suggested is 4MB

    """

    def get_account_meta(self, account):

        """Return a dictionary with the account metadata.

        The keys returned are all user-defined, except:

            'name': The account name

            'count': The number of containers (or 0)

            'bytes': The total data size (or 0)

            'modified': Last modification timestamp

        """

        return {}

    def update_account_meta(self, account, meta, replace=False):

        """Update the metadata associated with the account.

        Parameters:

            'meta': Dictionary with metadata to update

            'replace': Replace instead of update

        """

        return

    def put_container(self, account, name):

        """Create a new container with the given name.

        Raises:

            NameError: Container already exists

        """

        return

    def delete_container(self, account, name):

        """Delete the container with the given name.

        Raises:

            NameError: Container does not exist

            IndexError: Container is not empty

        """

        return

    def get_container_meta(self, account, name):

        """Return a dictionary with the container metadata.

        The keys returned are all user-defined, except:

            'name': The container name

            'count': The number of objects

            'bytes': The total data size

            'created': Creation timestamp

            'modified': Last modification timestamp

        Raises:

            NameError: Container does not exist

        """

        return {}

    def update_container_meta(self, account, name, meta, replace=False):

        """Update the metadata associated with the container.

        Parameters:

            'meta': Dictionary with metadata to update

            'replace': Replace instead of update

        Raises:

            NameError: Container does not exist

        """

        return

    def list_containers(self, account, marker=None, limit=10000):

        """Return a list of containers existing under an account.

        Parameters:

            'marker': Start list from the next item after 'marker'

            'limit': Number of containers to return

        """

        return []

    def list_objects(self, account, container, prefix='', delimiter=None, marker=None, limit=10000, virtual=True, keys=[]):

        """Return a list of objects existing under a container.

        Parameters:

            'prefix': List objects starting with 'prefix'

            'delimiter': Return unique names before 'delimiter' and after 'prefix'

            'marker': Start list from the next item after 'marker'

            'limit': Number of objects to return

            'virtual': If not set, the result will only include names starting\

                       with 'prefix' and ending without a 'delimiter' or with\

                       the first occurance of the 'delimiter' after 'prefix'.\

                       If set, the result will include all names after 'prefix',\

                       up to and including the 'delimiter' if it is found

            'keys': Include objects that have meta with the keys in the list

        Raises:

            NameError: Container does not exist

        """

        return []

    def list_object_meta(self, account, name):

        """Return a list with all the container's object meta keys.

        Raises:

            NameError: Container does not exist

        """

        return []

    def get_object_meta(self, account, container, name):

        """Return a dictionary with the object metadata.

        The keys returned are all user-defined, except:

            'name': The account name

            'bytes': The total data size

            'version': The latest version (zero if not versioned)

            'created': Creation timestamp

            'modified': Last modification timestamp

        Raises:

            NameError: Container/object does not exist

        """

        return {}

    def update_object_meta(self, account, container, name, meta, replace=False):

        """Update the metadata associated with the object.

        Parameters:

            'meta': Dictionary with metadata to update.\

                    Use the 'versioned' key to control versioning

            'replace': Replace instead of update

        Raises:

            NameError: Container/object does not exist

        """

        return

    def get_object_hashmap(self, account, container, name, version=None):

        """Return the object's size and a list with partial hashes.

        Raises:

            NameError: Container/object does not exist

            IndexError: Version does not exist

        """

        return 0, []

    def update_object_hashmap(self, account, container, name, size, hashmap):

        """Create/update an object with the specified size and partial hashes.

        Raises:

            NameError: Container/block does not exist

        """

        return

    def copy_object(self, account, src_container, src_name, dest_container, dest_name, dest_meta={}, replace_meta=False):

        """Copy an object's data and metadata.

        Parameters:

            'dest_meta': Dictionary with metadata to changes from source to destination

            'replace_meta': Replace metadata instead of update

        Raises:

            NameError: Container/object does not exist

        """

        return

    def move_object(self, account, src_container, src_name, dest_container, dest_name, dest_meta={}, replace_meta=False):

        """Move an object's data and metadata.

        Parameters:

            'dest_meta': Dictionary with metadata to changes from source to destination

            'replace_meta': Replace metadata instead of update

        Raises:

            NameError: Container/object does not exist

        """

        return

    def delete_object(self, account, container, name):

        """Delete an object.

        Raises:

            NameError: Container/object does not exist

        """

        return

    def get_block(self, hash):

        """Return a block's data.

        Raises:

            NameError: Block does not exist

        """

        return ''

    def put_block(self, data):

        """Store a block and return the hash."""

        return 0

    def update_block(self, hash, data, offset=0):

        """Update a known block and return the hash.

        Raises:

            IndexError: Offset or data outside block limits

        """

        return 0