comparison mercurial/ancestor.py @ 39473:b6db2e80a9ce

ancestors: actually iterate over ancestors in topological order (issue5979)

This code previously used a dequeue logic, the first ancestors seen were the
first ancestors to be emitted. In branching/merging situations, it can result
in ancestors being yielded before their descendants, breaking the object
contract.

We got affected by this issue while working on the copy tracing code. At about
the same time, Axel Hecht <[e-mail]> reported the issue and provided
the test case used in this changeset. Thanks Axel.

Running `hg perfancestors` does not show a significant difference between the
old and the new version.

39472:4e4fae1dda5c

# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import collections
import heapq

from .node import nullrev
from . import (
    pycompat,

    def __iter__(self):
        """Generate the ancestors of _initrevs in reverse topological order.

        If inclusive is False, yield a sequence of revision numbers starting
        with the parents of each revision in revs, i.e., each revision is *not*
        considered an ancestor of itself.  Results are in breadth-first order:
        parents of each rev in revs, then parents of those, etc.

        If inclusive is True, yield all the revs first (ignoring stoprev),
        then yield all the ancestors of revs as when inclusive is False.
        If an element in revs is an ancestor of a different rev it is not
        yielded again."""
        seen = set()
        revs = self._initrevs
        if self._inclusive:
            for rev in revs:
                yield rev
            seen.update(revs)

        parentrevs = self._parentrevs
        stoprev = self._stoprev
        visit = collections.deque(revs)

        see = seen.add
        schedule = visit.append

        while visit:
            for parent in parentrevs(visit.popleft()):
                if parent >= stoprev and parent not in seen:
                    schedule(parent)
                    see(parent)
                    yield parent

    def __contains__(self, target):
        """Test whether target is an ancestor of self._initrevs."""
        # Trying to do both __iter__ and __contains__ using the same visit
        # heap and seen set is complex enough that it slows down both. Keep

39473:b6db2e80a9ce

# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import heapq

from .node import nullrev
from . import (
    pycompat,

    def __iter__(self):
        """Generate the ancestors of _initrevs in reverse topological order.

        If inclusive is False, yield a sequence of revision numbers starting
        with the parents of each revision in revs, i.e., each revision is
        *not* considered an ancestor of itself. Results are emitted in reverse
        revision number order. That order is also topological: a child is
        always emitted before its parent.

        If inclusive is True, yield all the revs first (ignoring stoprev),
        then yield all the ancestors of revs as when inclusive is False. If an
        element in revs is an ancestor of a different rev it is not yielded
        again."""
        seen = set()
        revs = self._initrevs
        if self._inclusive:
            for rev in revs:
                yield rev
            seen.update(revs)

        parentrevs = self._parentrevs
        stoprev = self._stoprev
        visit = []
        heapq.heapify(visit)
        schedule = heapq.heappush
        nextitem = heapq.heappop
        see = seen.add
        see(nullrev)

        for r in revs:
            for parent in parentrevs(r):
                if parent not in seen:
                    schedule(visit, -parent)
                    see(parent)

        while visit:
            current = -nextitem(visit)
            if current >= stoprev:
                yield current
                for parent in parentrevs(current):
                    if parent not in seen:
                        schedule(visit, -parent)
                        see(parent)

    def __contains__(self, target):
        """Test whether target is an ancestor of self._initrevs."""
        # Trying to do both __iter__ and __contains__ using the same visit
        # heap and seen set is complex enough that it slows down both. Keep