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# ubuntuone.u1sync.metadata
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# u1sync metadata routines
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# Author: Tim Cole <tim.cole@canonical.com>
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# Copyright 2009 Canonical Ltd.
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# This program is free software: you can redistribute it and/or modify it
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# under the terms of the GNU General Public License version 3, as published
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# by the Free Software Foundation.
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranties of
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# MERCHANTABILITY, SATISFACTORY QUALITY, or FITNESS FOR A PARTICULAR
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# PURPOSE. See the GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License along
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# with this program. If not, see <http://www.gnu.org/licenses/>.
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"""Routines for loading/storing u1sync mirror metadata."""
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from __future__ import with_statement
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import cPickle as pickle
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from errno import ENOENT
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from contextlib import contextmanager
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from ubuntuone.storageprotocol.dircontent_pb2 import DIRECTORY
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from ubuntuone.u1sync.merge import MergeNode
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from ubuntuone.u1sync.utils import safe_unlink
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class Metadata(object):
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"""Object representing mirror metadata."""
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def __init__(self, local_tree=None, remote_tree=None, share_uuid=None,
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root_uuid=None, path=None):
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"""Populate fields."""
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self.local_tree = local_tree
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self.remote_tree = remote_tree
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self.share_uuid = share_uuid
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self.root_uuid = root_uuid
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def read(metadata_dir):
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"""Read metadata for a mirror rooted at directory."""
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index_file = os.path.join(metadata_dir, "local-index")
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share_uuid_file = os.path.join(metadata_dir, "share-uuid")
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root_uuid_file = os.path.join(metadata_dir, "root-uuid")
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path_file = os.path.join(metadata_dir, "path")
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index = read_pickle_file(index_file, {})
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share_uuid = read_uuid_file(share_uuid_file)
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root_uuid = read_uuid_file(root_uuid_file)
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path = read_string_file(path_file, '/')
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local_tree = index.get("tree", None)
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remote_tree = index.get("remote_tree", None)
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if local_tree is None:
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local_tree = MergeNode(node_type=DIRECTORY, children={})
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if remote_tree is None:
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remote_tree = MergeNode(node_type=DIRECTORY, children={})
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return Metadata(local_tree=local_tree, remote_tree=remote_tree,
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share_uuid=share_uuid, root_uuid=root_uuid,
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def write(metadata_dir, info):
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"""Writes all metadata for the mirror rooted at directory."""
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share_uuid_file = os.path.join(metadata_dir, "share-uuid")
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root_uuid_file = os.path.join(metadata_dir, "root-uuid")
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index_file = os.path.join(metadata_dir, "local-index")
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path_file = os.path.join(metadata_dir, "path")
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if info.share_uuid is not None:
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write_uuid_file(share_uuid_file, info.share_uuid)
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safe_unlink(share_uuid_file)
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if info.root_uuid is not None:
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write_uuid_file(root_uuid_file, info.root_uuid)
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safe_unlink(root_uuid_file)
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write_string_file(path_file, info.path)
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write_pickle_file(index_file, {"tree": info.local_tree,
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"remote_tree": info.remote_tree})
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def write_pickle_file(filename, value):
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"""Writes a pickled python object to a file."""
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with atomic_update_file(filename) as stream:
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pickle.dump(value, stream, 2)
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def write_string_file(filename, value):
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"""Writes a string to a file with an added line feed, or
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deletes the file if value is None.
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with atomic_update_file(filename) as stream:
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safe_unlink(filename)
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def write_uuid_file(filename, value):
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"""Writes a UUID to a file."""
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write_string_file(filename, str(value))
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def read_pickle_file(filename, default_value=None):
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"""Reads a pickled python object from a file."""
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with open(filename, "rb") as stream:
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return pickle.load(stream)
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if e.errno != ENOENT:
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def read_string_file(filename, default_value=None):
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"""Reads a string from a file, discarding the final character."""
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with open(filename, "r") as stream:
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return stream.read()[:-1]
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if e.errno != ENOENT:
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def read_uuid_file(filename, default_value=None):
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"""Reads a UUID from a file."""
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with open(filename, "r") as stream:
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return uuid.UUID(stream.read()[:-1])
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if e.errno != ENOENT:
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def atomic_update_file(filename):
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"""Returns a context manager for atomically updating a file."""
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temp_filename = "%s.%s" % (filename, uuid.uuid4())
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with open(temp_filename, "w") as stream:
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os.rename(temp_filename, filename)
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safe_unlink(temp_filename)
added
removed
ubuntuone/u1sync/metadata.py
