comparison mercurial/copies.py @ 45637:ad6ebb6f0dfe

copies: make two version of the changeset centric algorithm

They are two main ways to run the changeset-centric copy-tracing algorithm. One
fed from data stored in side-data and still in development, and one based on
data stored in extra (with a "compatibility" mode).

The `extra` based is used in production at Google, but still experimental in
code. It is mostly unsuitable for other users because it affects the hash.

The side-data based storage and algorithm have been evolving to store more data, cover more cases
(mostly around merge, that Google do not really care about) and use lower level
storage for efficiency.

All this changes make is increasingly hard to maintain de common code base,
without impacting code complexity and performance. For example, the
compatibility mode requires to keep things at different level than what we
need for side-data.

So, I am duplicating the involved functions. The newly added `_extra` variants
will be kept as today, while I will do some deeper rework of the side data
versions.

Long terms, the side-data version should be more featureful and performant than
the extra based version, so I expect the duplicated `_extra` functions to
eventually get dropped.

Differential Revision: https://phab.mercurial-scm.org/D9114

45636:053c9014fd39

    iterrevs = set(from_head)
    iterrevs &= mrset
    iterrevs.update(roots)
    iterrevs.remove(b.rev())
    revs = sorted(iterrevs)
    return _combine_changeset_copies(
        revs, children, b.rev(), revinfo, match, isancestor
    )


def _combine_changeset_copies(
    revs, children, targetrev, revinfo, match, isancestor
):

                or ismerged(dest)
            ):
                minor[dest] = value


def _forwardcopies(a, b, base=None, match=None):
    """find {dst@b: src@a} copy mapping where a is an ancestor of b"""

    if base is None:
        base = a

45637:ad6ebb6f0dfe

    iterrevs = set(from_head)
    iterrevs &= mrset
    iterrevs.update(roots)
    iterrevs.remove(b.rev())
    revs = sorted(iterrevs)

    if repo.filecopiesmode == b'changeset-sidedata':
        return _combine_changeset_copies(
            revs, children, b.rev(), revinfo, match, isancestor
        )
    else:
        return _combine_changeset_copies_extra(
            revs, children, b.rev(), revinfo, match, isancestor
        )


def _combine_changeset_copies(
    revs, children, targetrev, revinfo, match, isancestor
):

                or ismerged(dest)
            ):
                minor[dest] = value


def _combine_changeset_copies_extra(
    revs, children, targetrev, revinfo, match, isancestor
):
    """version of `_combine_changeset_copies` that works with the Google
    specific "extra" based storage for copy information"""
    all_copies = {}
    alwaysmatch = match.always()
    for r in revs:
        copies = all_copies.pop(r, None)
        if copies is None:
            # this is a root
            copies = {}
        for i, c in enumerate(children[r]):
            p1, p2, p1copies, p2copies, removed, ismerged = revinfo(c)
            if r == p1:
                parent = 1
                childcopies = p1copies
            else:
                assert r == p2
                parent = 2
                childcopies = p2copies
            if not alwaysmatch:
                childcopies = {
                    dst: src for dst, src in childcopies.items() if match(dst)
                }
            newcopies = copies
            if childcopies:
                newcopies = copies.copy()
                for dest, source in pycompat.iteritems(childcopies):
                    prev = copies.get(source)
                    if prev is not None and prev[1] is not None:
                        source = prev[1]
                    newcopies[dest] = (c, source)
                assert newcopies is not copies
            for f in removed:
                if f in newcopies:
                    if newcopies is copies:
                        # copy on write to avoid affecting potential other
                        # branches.  when there are no other branches, this
                        # could be avoided.
                        newcopies = copies.copy()
                    newcopies[f] = (c, None)
            othercopies = all_copies.get(c)
            if othercopies is None:
                all_copies[c] = newcopies
            else:
                # we are the second parent to work on c, we need to merge our
                # work with the other.
                #
                # In case of conflict, parent 1 take precedence over parent 2.
                # This is an arbitrary choice made anew when implementing
                # changeset based copies. It was made without regards with
                # potential filelog related behavior.
                if parent == 1:
                    _merge_copies_dict_extra(
                        othercopies, newcopies, isancestor, ismerged
                    )
                else:
                    _merge_copies_dict_extra(
                        newcopies, othercopies, isancestor, ismerged
                    )
                    all_copies[c] = newcopies

    final_copies = {}
    for dest, (tt, source) in all_copies[targetrev].items():
        if source is not None:
            final_copies[dest] = source
    return final_copies


def _merge_copies_dict_extra(minor, major, isancestor, ismerged):
    """version of `_merge_copies_dict` that works with the Google
    specific "extra" based storage for copy information"""
    for dest, value in major.items():
        other = minor.get(dest)
        if other is None:
            minor[dest] = value
        else:
            new_tt = value[0]
            other_tt = other[0]
            if value[1] == other[1]:
                continue
            # content from "major" wins, unless it is older
            # than the branch point or there is a merge
            if (
                new_tt == other_tt
                or not isancestor(new_tt, other_tt)
                or ismerged(dest)
            ):
                minor[dest] = value


def _forwardcopies(a, b, base=None, match=None):
    """find {dst@b: src@a} copy mapping where a is an ancestor of b"""

    if base is None:
        base = a