comparison hgext/rebase.py @ 35058:a68c3420be41

rebase: exclude descendants of obsoletes w/o a successor in dest (issue5300)

.. feature::

   Let 'hg rebase' avoid content-divergence by skipping obsolete
   changesets (and their descendants) when they are present in the rebase
   set along with one of their successors but none of their successors is
   in destination.

In the following example, when trying to rebase 3:: onto 2, the rebase
will abort with "this rebase will cause divergence from: 4":

    o  7 f
    |
    | o  6 e
    | |
    | o  5 d'
    | |
    x |  4 d (rewritten as 5)
    |/
    o  3 c
    |
    | o  2 x
    | |
    o |  1 b
    |/
    o  0 a

By excluding obsolete changesets without a successor in destination (4
in the example above) and their descendants, we make rebase work in this
case, thus giving:

    o  11 e
    |
    o  10 d'
    |
    o  9 c
    |
    o  8 b
    |
    | o  7 f
    | |
    | | x  6 e (rewritten using rebase as 11)
    | | |
    | | x  5 d' (rewritten using rebase as 10)
    | | |
    | x |  4 d
    | |/
    | x  3 c (rewritten using rebase as 9)
    | |
    o |  2 x
    | |
    | x  1 b (rewritten using rebase as 8)
    |/
    o  0 a

where branch 4:: is left behind while branch 5:: is rebased as expected.

The rationale is that users may not be interested in rebasing orphan
changesets when specifying a rebase set that include them but would
still want "stable" ones to be rebased. Currently, the user is suggested
to allow divergence (but probably does not want it) or they must specify
a rebase set excluding problematic changesets (which might be a bit
cumbersome). The approach proposed here corresponds to "Option 2" in
https://www.mercurial-scm.org/wiki/CEDRebase.


We extend _computeobsoletenotrebased() so that it also return a set of
obsolete changesets in rebase set without a successor in destination but
with at least one successor in rebase set. This
'obsoletewithoutsuccessorindestination' is then stored as an attribute
of rebaseruntime and used in _performrebasesubset() to:

* filter out descendants of these changesets from the revisions to
  rebase;
* issue a message about these revisions being skipped.

This only occurs if 'evolution.allowdivergence' option is off and
'rebaseskipobsolete' is on.

35057:0564e7c7f4cd

        self.keepbranchesf = opts.get('keepbranches', False)
        # keepopen is not meant for use on the command line, but by
        # other extensions
        self.keepopen = opts.get('keepopen', False)
        self.obsoletenotrebased = {}

    @property
    def repo(self):
        if self.prepared:
            return self._repo.unfiltered()

        """
        self.obsoletenotrebased = {}
        if not self.ui.configbool('experimental', 'rebaseskipobsolete'):
            return
        obsoleteset = set(obsoleterevs)
        self.obsoletenotrebased = _computeobsoletenotrebased(self.repo,
                                    obsoleteset, destmap)
        skippedset = set(self.obsoletenotrebased)
        _checkobsrebase(self.repo, self.ui, obsoleteset, skippedset)

    def _prepareabortorcontinue(self, isabort):
        try:
            self.restorestatus()

        ui.note(_('rebase merging completed\n'))

    def _performrebasesubset(self, tr, subset, pos, total):
        repo, ui, opts = self.repo, self.ui, self.opts
        sortedrevs = repo.revs('sort(%ld, -topo)', subset)
        for rev in sortedrevs:
            dest = self.destmap[rev]
            ctx = repo[rev]
            desc = _ctxdesc(ctx)
            if self.state[rev] == rev:
                ui.status(_('already rebased %s\n') % desc)
            elif rev in self.obsoletenotrebased:
                succ = self.obsoletenotrebased[rev]
                if succ is None:
                    msg = _('note: not rebasing %s, it has no '
                            'successor\n') % desc

def _filterobsoleterevs(repo, revs):
    """returns a set of the obsolete revisions in revs"""
    return set(r for r in revs if repo[r].obsolete())

def _computeobsoletenotrebased(repo, rebaseobsrevs, destmap):
    """return a mapping obsolete => successor for all obsolete nodes to be
    rebased that have a successors in the destination

    obsolete => None entries in the mapping indicate nodes with no successor"""
    obsoletenotrebased = {}

    assert repo.filtername is None
    cl = repo.changelog
    nodemap = cl.nodemap
    for srcrev in rebaseobsrevs:

                if succnode == srcnode or succnode not in nodemap:
                    continue
                if cl.isancestor(succnode, destnode):
                    obsoletenotrebased[srcrev] = nodemap[succnode]
                    break

    return obsoletenotrebased

def summaryhook(ui, repo):
    if not repo.vfs.exists('rebasestate'):
        return
    try:

35058:a68c3420be41

        self.keepbranchesf = opts.get('keepbranches', False)
        # keepopen is not meant for use on the command line, but by
        # other extensions
        self.keepopen = opts.get('keepopen', False)
        self.obsoletenotrebased = {}
        self.obsoletewithoutsuccessorindestination = set()

    @property
    def repo(self):
        if self.prepared:
            return self._repo.unfiltered()

        """
        self.obsoletenotrebased = {}
        if not self.ui.configbool('experimental', 'rebaseskipobsolete'):
            return
        obsoleteset = set(obsoleterevs)
        self.obsoletenotrebased, self.obsoletewithoutsuccessorindestination = \
            _computeobsoletenotrebased(self.repo, obsoleteset, destmap)
        skippedset = set(self.obsoletenotrebased)
        skippedset.update(self.obsoletewithoutsuccessorindestination)
        _checkobsrebase(self.repo, self.ui, obsoleteset, skippedset)

    def _prepareabortorcontinue(self, isabort):
        try:
            self.restorestatus()

        ui.note(_('rebase merging completed\n'))

    def _performrebasesubset(self, tr, subset, pos, total):
        repo, ui, opts = self.repo, self.ui, self.opts
        sortedrevs = repo.revs('sort(%ld, -topo)', subset)
        allowdivergence = self.ui.configbool(
            'experimental', 'evolution.allowdivergence')
        if not allowdivergence:
            sortedrevs -= repo.revs(
                'descendants(%ld) and not %ld',
                self.obsoletewithoutsuccessorindestination,
                self.obsoletewithoutsuccessorindestination,
            )
        for rev in sortedrevs:
            dest = self.destmap[rev]
            ctx = repo[rev]
            desc = _ctxdesc(ctx)
            if self.state[rev] == rev:
                ui.status(_('already rebased %s\n') % desc)
            elif (not allowdivergence
                  and rev in self.obsoletewithoutsuccessorindestination):
                msg = _('note: not rebasing %s and its descendants as '
                        'this would cause divergence\n') % desc
                repo.ui.status(msg)
                self.skipped.add(rev)
            elif rev in self.obsoletenotrebased:
                succ = self.obsoletenotrebased[rev]
                if succ is None:
                    msg = _('note: not rebasing %s, it has no '
                            'successor\n') % desc

def _filterobsoleterevs(repo, revs):
    """returns a set of the obsolete revisions in revs"""
    return set(r for r in revs if repo[r].obsolete())

def _computeobsoletenotrebased(repo, rebaseobsrevs, destmap):
    """Return (obsoletenotrebased, obsoletewithoutsuccessorindestination).

    `obsoletenotrebased` is a mapping mapping obsolete => successor for all
    obsolete nodes to be rebased given in `rebaseobsrevs`.

    `obsoletewithoutsuccessorindestination` is a set with obsolete revisions
    without a successor in destination.
    """
    obsoletenotrebased = {}
    obsoletewithoutsuccessorindestination = set([])

    assert repo.filtername is None
    cl = repo.changelog
    nodemap = cl.nodemap
    for srcrev in rebaseobsrevs:

                if succnode == srcnode or succnode not in nodemap:
                    continue
                if cl.isancestor(succnode, destnode):
                    obsoletenotrebased[srcrev] = nodemap[succnode]
                    break
            else:
                # If 'srcrev' has a successor in rebase set but none in
                # destination (which would be catched above), we shall skip it
                # and its descendants to avoid divergence.
                if any(nodemap[s] in destmap
                       for s in successors if s != srcnode):
                    obsoletewithoutsuccessorindestination.add(srcrev)

    return obsoletenotrebased, obsoletewithoutsuccessorindestination

def summaryhook(ui, repo):
    if not repo.vfs.exists('rebasestate'):
        return
    try: