Function sync

vdirsyncer/sync/__init__.py:90–158

Synchronizes two storages. :param storage_a: The first storage :type storage_a: :class:`vdirsyncer.storage.base.Storage` :param storage_b: The second storage :type storage_b: :class:`vdirsyncer.storage.base.Storage` :param status: {ident: (href_a, etag_a, href_b, etag_b)}

(storage_a, storage_b, status, conflict_resolution=None,
         force_delete=False, error_callback=None, partial_sync='revert')

def sync(storage_a, storage_b, status, conflict_resolution=None,
         force_delete=False, error_callback=None, partial_sync='revert'):
    '''Synchronizes two storages.

    :param storage_a: The first storage
    :type storage_a: :class:`vdirsyncer.storage.base.Storage`
    :param storage_b: The second storage
    :type storage_b: :class:`vdirsyncer.storage.base.Storage`
    :param status: {ident: (href_a, etag_a, href_b, etag_b)}
        metadata about the two storages for detection of changes. Will be
        modified by the function and should be passed to it at the next sync.
        If this is the first sync, an empty dictionary should be provided.
    :param conflict_resolution: A function that, given two conflicting item
        versions A and B, returns a new item with conflicts resolved. The UID
        must be the same. The strings `"a wins"` and `"b wins"` are also
        accepted to mean that side's version will always be taken. If none
        is provided, the sync function will raise :py:exc:`SyncConflict`.
    :param force_delete: When one storage got completely emptied between two
        syncs, :py:exc:`StorageEmpty` is raised for
        safety. Setting this parameter to ``True`` disables this safety
        measure.
    :param error_callback: Instead of raising errors when executing actions,
        call the given function with an `Exception` as the only argument.
    :param partial_sync: What to do when doing sync actions on read-only
        storages.

        - ``error``: Raise an error.
        - ``ignore``: Those actions are simply skipped.
        - ``revert`` (default): Revert changes on other side.
    '''
    if storage_a.read_only and storage_b.read_only:
        raise BothReadOnly()

    if conflict_resolution == 'a wins':
        conflict_resolution = lambda a, b: a
    elif conflict_resolution == 'b wins':
        conflict_resolution = lambda a, b: b

    status_nonempty = bool(next(status.iter_old(), None))

    with status.transaction():
        a_info = _StorageInfo(storage_a, SubStatus(status, 'a'))
        b_info = _StorageInfo(storage_b, SubStatus(status, 'b'))

        a_nonempty = a_info.prepare_new_status()
        b_nonempty = b_info.prepare_new_status()

        if status_nonempty and not force_delete:
            if a_nonempty and not b_nonempty:
                raise StorageEmpty(empty_storage=storage_b)
            elif not a_nonempty and b_nonempty:
                raise StorageEmpty(empty_storage=storage_a)

        actions = list(_get_actions(a_info, b_info))

        with storage_a.at_once(), storage_b.at_once():
            for action in actions:
                try: