comparison mercurial/localrepo.py @ 39606:c5e6c1ba1c79

hg: don't reuse repo instance after unshare()

Unsharing a repository is a pretty invasive procedure and fundamentally
changes the behavior of the repository.

Currently, hg.unshare() calls into localrepository.__init__ to
re-initialize the repository instance. This is a bit hacky. And
future commits that refactor how localrepository instances are
constructed will make this difficult to support.

This commit changes unshare() so it constructs a new repo instance
once the unshare I/O has completed. It then poisons the old repo
instance so any further use will result in error.

Surprisingly, nothing in core appears to access a repo instance
after it has been unshared!

.. api::

   ``hg.unshare()`` now poisons the repo instance so it can't be used.

   It also returns a new repo instance suitable for interacting with
   the unshared repository.

Differential Revision: https://phab.mercurial-scm.org/D4557

39605:23f2299e9e53

        hgvfs.append(b'00changelog.i',
                     b'\0\0\0\2 dummy changelog to prevent using the old repo '
                     b'layout')

    scmutil.writerequires(hgvfs, requirements)

39606:c5e6c1ba1c79

        hgvfs.append(b'00changelog.i',
                     b'\0\0\0\2 dummy changelog to prevent using the old repo '
                     b'layout')

    scmutil.writerequires(hgvfs, requirements)

def poisonrepository(repo):
    """Poison a repository instance so it can no longer be used."""
    # Perform any cleanup on the instance.
    repo.close()

    # Our strategy is to replace the type of the object with one that
    # has all attribute lookups result in error.
    #
    # But we have to allow the close() method because some constructors
    # of repos call close() on repo references.
    class poisonedrepository(object):
        def __getattribute__(self, item):
            if item == r'close':
                return object.__getattribute__(self, item)

            raise error.ProgrammingError('repo instances should not be used '
                                         'after unshare')

        def close(self):
            pass

    # We may have a repoview, which intercepts __setattr__. So be sure
    # we operate at the lowest level possible.
    object.__setattr__(repo, r'__class__', poisonedrepository)