view mercurial/commit.py @ 46582:b0a3ca02d17a

copies-rust: implement PartialEqual manually Now that we know that each (dest, rev) pair has at most a unique CopySource, we can simplify comparison a lot. This "simple" step buy a good share of the previous slowdown back in some case: Repo Case Source-Rev Dest-Rev # of revisions old time new time Difference Factor time per rev --------------------------------------------------------------------------------------------------------------------------------------------------------------- mozilla-try x00000_revs_x00000_added_x000_copies 9b2a99adc05e 8e29777b48e6 : 382065 revs, 43.304637 s, 34.443661 s, -8.860976 s, × 0.7954, 90 µs/rev Full benchmark: Repo Case Source-Rev Dest-Rev # of revisions old time new time Difference Factor time per rev --------------------------------------------------------------------------------------------------------------------------------------------------------------- mercurial x_revs_x_added_0_copies ad6b123de1c7 39cfcef4f463 : 1 revs, 0.000043 s, 0.000043 s, +0.000000 s, × 1.0000, 43 µs/rev mercurial x_revs_x_added_x_copies 2b1c78674230 0c1d10351869 : 6 revs, 0.000114 s, 0.000117 s, +0.000003 s, × 1.0263, 19 µs/rev mercurial x000_revs_x000_added_x_copies 81f8ff2a9bf2 dd3267698d84 : 1032 revs, 0.004937 s, 0.004892 s, -0.000045 s, × 0.9909, 4 µs/rev pypy x_revs_x_added_0_copies aed021ee8ae8 099ed31b181b : 9 revs, 0.000339 s, 0.000196 s, -0.000143 s, × 0.5782, 21 µs/rev pypy x_revs_x000_added_0_copies 4aa4e1f8e19a 359343b9ac0e : 1 revs, 0.000049 s, 0.000050 s, +0.000001 s, × 1.0204, 50 µs/rev pypy x_revs_x_added_x_copies ac52eb7bbbb0 72e022663155 : 7 revs, 0.000202 s, 0.000117 s, -0.000085 s, × 0.5792, 16 µs/rev pypy x_revs_x00_added_x_copies c3b14617fbd7 ace7255d9a26 : 1 revs, 0.000409 s, 0.6f1f4a s, -0.000087 s, × 0.7873, 322 µs/rev pypy x_revs_x000_added_x000_copies df6f7a526b60 a83dc6a2d56f : 6 revs, 0.011984 s, 0.011949 s, -0.000035 s, × 0.9971, 1991 µs/rev pypy x000_revs_xx00_added_0_copies 89a76aede314 2f22446ff07e : 4785 revs, 0.050820 s, 0.050802 s, -0.000018 s, × 0.9996, 10 µs/rev pypy x000_revs_x000_added_x_copies 8a3b5bfd266e 2c68e87c3efe : 6780 revs, 0.087953 s, 0.088090 s, +0.000137 s, × 1.0016, 12 µs/rev pypy x000_revs_x000_added_x000_copies 89a76aede314 7b3dda341c84 : 5441 revs, 0.062902 s, 0.062079 s, -0.000823 s, × 0.9869, 11 µs/rev pypy x0000_revs_x_added_0_copies d1defd0dc478 c9cb1334cc78 : 43645 revs, 0.679234 s, 0.635337 s, -0.043897 s, × 0.9354, 14 µs/rev pypy x0000_revs_xx000_added_0_copies bf2c629d0071 4ffed77c095c : 2 revs, 0.013095 s, 0.013262 s, +0.000167 s, × 1.0128, 6631 µs/rev pypy x0000_revs_xx000_added_x000_copies 08ea3258278e d9fa043f30c0 : 11316 revs, 0.120910 s, 0.120085 s, -0.000825 s, × 0.9932, 10 µs/rev netbeans x_revs_x_added_0_copies fb0955ffcbcd a01e9239f9e7 : 2 revs, 0.000087 s, 0.000085 s, -0.000002 s, × 0.9770, 42 µs/rev netbeans x_revs_x000_added_0_copies 6f360122949f 20eb231cc7d0 : 2 revs, 0.000107 s, 0.000110 s, +0.000003 s, × 1.0280, 55 µs/rev netbeans x_revs_x_added_x_copies 1ada3faf6fb6 5a39d12eecf4 : 3 revs, 0.000186 s, 0.000177 s, -0.000009 s, × 0.9516, 59 µs/rev netbeans x_revs_x00_added_x_copies 35be93ba1e2c 9eec5e90c05f : 9 revs, 0.000754 s, 0.000743 s, -0.000011 s, × 0.9854, 82 µs/rev netbeans x000_revs_xx00_added_0_copies eac3045b4fdd 51d4ae7f1290 : 1421 revs, 0.010443 s, 0.010168 s, -0.000275 s, × 0.9737, 7 µs/rev netbeans x000_revs_x000_added_x_copies e2063d266acd 6081d72689dc : 1533 revs, 0.015697 s, 0.015946 s, +0.000249 s, × 1.0159, 10 µs/rev netbeans x000_revs_x000_added_x000_copies ff453e9fee32 411350406ec2 : 5750 revs, 0.063528 s, 0.062712 s, -0.000816 s, × 0.9872, 10 µs/rev netbeans x0000_revs_xx000_added_x000_copies 588c2d1ced70 1aad62e59ddd : 66949 revs, 0.545515 s, 0.523832 s, -0.021683 s, × 0.9603, 7 µs/rev mozilla-central x_revs_x_added_0_copies 3697f962bb7b 7015fcdd43a2 : 2 revs, 0.000089 s, 0.000090 s, +0.000001 s, × 1.0112, 45 µs/rev mozilla-central x_revs_x000_added_0_copies dd390860c6c9 40d0c5bed75d : 8 revs, 0.000265 s, 0.000264 s, -0.000001 s, × 0.9962, 33 µs/rev mozilla-central x_revs_x_added_x_copies 8d198483ae3b 14207ffc2b2f : 9 revs, 0.000381 s, 0.000187 s, -0.000194 s, × 0.4908, 20 µs/rev mozilla-central x_revs_x00_added_x_copies 98cbc58cc6bc 446a150332c3 : 7 revs, 0.000672 s, 0.000665 s, -0.000007 s, × 0.9896, 95 µs/rev mozilla-central x_revs_x000_added_x000_copies 3c684b4b8f68 0a5e72d1b479 : 3 revs, 0.003497 s, 0.003556 s, +0.000059 s, × 1.0169, 1185 µs/rev mozilla-central x_revs_x0000_added_x0000_copies effb563bb7e5 c07a39dc4e80 : 6 revs, 0.073204 s, 0.071345 s, -0.001859 s, × 0.9746, 11890 µs/rev mozilla-central x000_revs_xx00_added_0_copies 6100d773079a 04a55431795e : 1593 revs, 0.006482 s, 0.006551 s, +0.000069 s, × 1.0106, 4 µs/rev mozilla-central x000_revs_x000_added_x_copies 9f17a6fc04f9 2d37b966abed : 41 revs, 0.005066 s, 0.005078 s, +0.000012 s, × 1.0024, 123 µs/rev mozilla-central x000_revs_x000_added_x000_copies 7c97034feb78 4407bd0c6330 : 7839 revs, 0.065707 s, 0.065823 s, +0.000116 s, × 1.0018, 8 µs/rev mozilla-central x0000_revs_xx000_added_0_copies 9eec5917337d 67118cc6dcad : 615 revs, 0.026800 s, 0.027050 s, +0.000250 s, × 1.0093, 43 µs/rev mozilla-central x0000_revs_xx000_added_x000_copies f78c615a656c 96a38b690156 : 30263 revs, 0.203856 s, 0.202443 s, -0.001413 s, × 0.9931, 6 µs/rev mozilla-central x00000_revs_x0000_added_x0000_copies 6832ae71433c 4c222a1d9a00 : 153721 revs, 1.293394 s, 1.261583 s, -0.031811 s, × 0.9754, 8 µs/rev mozilla-central x00000_revs_x00000_added_x000_copies 76caed42cf7c 1daa622bbe42 : 204976 revs, 1.698239 s, 1.643869 s, -0.054370 s, × 0.9680, 8 µs/rev mozilla-try x_revs_x_added_0_copies aaf6dde0deb8 9790f499805a : 2 revs, 0.000875 s, 0.000868 s, -0.000007 s, × 0.9920, 434 µs/rev mozilla-try x_revs_x000_added_0_copies d8d0222927b4 5bb8ce8c7450 : 2 revs, 0.000891 s, 0.000887 s, -0.000004 s, × 0.9955, 443 µs/rev mozilla-try x_revs_x_added_x_copies 092fcca11bdb 936255a0384a : 4 revs, 0.000292 s, 0.000168 s, -0.000124 s, × 0.5753, 42 µs/rev mozilla-try x_revs_x00_added_x_copies b53d2fadbdb5 017afae788ec : 2 revs, 0.003939 s, 0.001160 s, -0.002779 s, × 0.2945, 580 µs/rev mozilla-try x_revs_x000_added_x000_copies 20408ad61ce5 6f0ee96e21ad : 1 revs, 0.033027 s, 0.033016 s, -0.000011 s, × 0.9997, 33016 µs/rev mozilla-try x_revs_x0000_added_x0000_copies effb563bb7e5 c07a39dc4e80 : 6 revs, 0.073703 s, 0.073312 s, -0.39ae31 s, × 0.9947, 12218 µs/rev mozilla-try x000_revs_xx00_added_0_copies 6100d773079a 04a55431795e : 1593 revs, 0.006469 s, 0.006485 s, +0.000016 s, × 1.0025, 4 µs/rev mozilla-try x000_revs_x000_added_x_copies 9f17a6fc04f9 2d37b966abed : 41 revs, 0.005278 s, 0.005494 s, +0.000216 s, × 1.0409, 134 µs/rev mozilla-try x000_revs_x000_added_x000_copies 1346fd0130e4 4c65cbdabc1f : 6657 revs, 0.064995 s, 0.064879 s, -0.000116 s, × 0.9982, 9 µs/rev mozilla-try x0000_revs_x_added_0_copies 63519bfd42ee a36a2a865d92 : 40314 revs, 0.301041 s, 0.301469 s, +0.000428 s, × 1.0014, 7 µs/rev mozilla-try x0000_revs_x_added_x_copies 9fe69ff0762d bcabf2a78927 : 38690 revs, 0.285575 s, 0.297113 s, +0.011538 s, × 1.0404, 7 µs/rev mozilla-try x0000_revs_xx000_added_x_copies 156f6e2674f2 4d0f2c178e66 : 8598 revs, 0.085597 s, 0.085890 s, +0.000293 s, × 1.0034, 9 µs/rev mozilla-try x0000_revs_xx000_added_0_copies 9eec5917337d 67118cc6dcad : 615 revs, 0.027118 s, 0.027718 s, +0.000600 s, × 1.0221, 45 µs/rev mozilla-try x0000_revs_xx000_added_x000_copies 89294cd501d9 7ccb2fc7ccb5 : 97052 revs, 2.119204 s, 2.048949 s, -0.070255 s, × 0.9668, 21 µs/rev mozilla-try x0000_revs_x0000_added_x0000_copies e928c65095ed e951f4ad123a : 52031 revs, 0.701479 s, 0.685924 s, -0.015555 s, × 0.9778, 13 µs/rev mozilla-try x00000_revs_x_added_0_copies 6a320851d377 1ebb79acd503 : 363753 revs, 4.482399 s, 4.482891 s, +0.000492 s, × 1.0001, 12 µs/rev mozilla-try x00000_revs_x00000_added_0_copies dc8a3ca7010e d16fde900c9c : 34414 revs, 0.574082 s, 0.577633 s, +0.003551 s, × 1.0062, 16 µs/rev mozilla-try x00000_revs_x_added_x_copies 5173c4b6f97c 95d83ee7242d : 362229 revs, 4.480366 s, 4.397816 s, -0.082550 s, × 0.9816, 12 µs/rev mozilla-try x00000_revs_x000_added_x_copies 9126823d0e9c ca82787bb23c : 359344 revs, 4.369070 s, 4.370538 s, +0.001468 s, × 1.0003, 12 µs/rev mozilla-try x00000_revs_x0000_added_x0000_copies 8d3fafa80d4b eb884023b810 : 192665 revs, 1.592506 s, 1.570439 s, -0.022067 s, × 0.9861, 8 µs/rev mozilla-try x00000_revs_x00000_added_x0000_copies 1b661134e2ca 1ae03d022d6d : 228985 revs, 87.824489 s, 88.388512 s, +0.564023 s, × 1.0064, 386 µs/rev mozilla-try x00000_revs_x00000_added_x000_copies 9b2a99adc05e 8e29777b48e6 : 382065 revs, 43.304637 s, 34.443661 s, -8.860976 s, × 0.7954, 90 µs/rev private : 459513 revs, 33.853687 s, 27.370148 s, -6.483539 s, × 0.8085, 59 µs/rev Differential Revision: https://phab.mercurial-scm.org/D9653
author Pierre-Yves David <pierre-yves.david@octobus.net>
date Wed, 16 Dec 2020 11:11:05 +0100
parents 0903d6b9b1df
children e2f7b2695ba1
line wrap: on
line source

# commit.py - fonction to perform commit
#
# 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 errno

from .i18n import _
from .node import (
    hex,
    nullid,
    nullrev,
)

from . import (
    context,
    mergestate,
    metadata,
    phases,
    scmutil,
    subrepoutil,
)


def _write_copy_meta(repo):
    """return a (changelog, filelog) boolean tuple

    changelog: copy related information should be stored in the changeset
    filelof:   copy related information should be written in the file revision
    """
    if repo.filecopiesmode == b'changeset-sidedata':
        writechangesetcopy = True
        writefilecopymeta = True
    else:
        writecopiesto = repo.ui.config(b'experimental', b'copies.write-to')
        writefilecopymeta = writecopiesto != b'changeset-only'
        writechangesetcopy = writecopiesto in (
            b'changeset-only',
            b'compatibility',
        )
    return writechangesetcopy, writefilecopymeta


def commitctx(repo, ctx, error=False, origctx=None):
    """Add a new revision to the target repository.
    Revision information is passed via the context argument.

    ctx.files() should list all files involved in this commit, i.e.
    modified/added/removed files. On merge, it may be wider than the
    ctx.files() to be committed, since any file nodes derived directly
    from p1 or p2 are excluded from the committed ctx.files().

    origctx is for convert to work around the problem that bug
    fixes to the files list in changesets change hashes. For
    convert to be the identity, it can pass an origctx and this
    function will use the same files list when it makes sense to
    do so.
    """
    repo = repo.unfiltered()

    p1, p2 = ctx.p1(), ctx.p2()
    user = ctx.user()

    with repo.lock(), repo.transaction(b"commit") as tr:
        mn, files = _prepare_files(tr, ctx, error=error, origctx=origctx)

        extra = ctx.extra().copy()

        if extra is not None:
            for name in (
                b'p1copies',
                b'p2copies',
                b'filesadded',
                b'filesremoved',
            ):
                extra.pop(name, None)
        if repo.changelog._copiesstorage == b'extra':
            extra = _extra_with_copies(repo, extra, files)

        # save the tip to check whether we actually committed anything
        oldtip = repo.changelog.tiprev()

        # update changelog
        repo.ui.note(_(b"committing changelog\n"))
        repo.changelog.delayupdate(tr)
        n = repo.changelog.add(
            mn,
            files,
            ctx.description(),
            tr,
            p1.node(),
            p2.node(),
            user,
            ctx.date(),
            extra,
        )
        rev = repo[n].rev()
        if oldtip != repo.changelog.tiprev():
            repo.register_changeset(rev, repo.changelog.changelogrevision(rev))

        xp1, xp2 = p1.hex(), p2 and p2.hex() or b''
        repo.hook(
            b'pretxncommit',
            throw=True,
            node=hex(n),
            parent1=xp1,
            parent2=xp2,
        )
        # set the new commit is proper phase
        targetphase = subrepoutil.newcommitphase(repo.ui, ctx)

        # prevent unmarking changesets as public on recommit
        waspublic = oldtip == repo.changelog.tiprev() and not repo[rev].phase()

        if targetphase and not waspublic:
            # retract boundary do not alter parent changeset.
            # if a parent have higher the resulting phase will
            # be compliant anyway
            #
            # if minimal phase was 0 we don't need to retract anything
            phases.registernew(repo, tr, targetphase, [rev])
        return n


def _prepare_files(tr, ctx, error=False, origctx=None):
    repo = ctx.repo()
    p1 = ctx.p1()

    writechangesetcopy, writefilecopymeta = _write_copy_meta(repo)
    files = metadata.ChangingFiles()
    ms = mergestate.mergestate.read(repo)
    salvaged = _get_salvaged(repo, ms, ctx)
    for s in salvaged:
        files.mark_salvaged(s)

    if ctx.manifestnode():
        # reuse an existing manifest revision
        repo.ui.debug(b'reusing known manifest\n')
        mn = ctx.manifestnode()
        files.update_touched(ctx.files())
        if writechangesetcopy:
            files.update_added(ctx.filesadded())
            files.update_removed(ctx.filesremoved())
    elif not ctx.files():
        repo.ui.debug(b'reusing manifest from p1 (no file change)\n')
        mn = p1.manifestnode()
    else:
        mn = _process_files(tr, ctx, ms, files, error=error)

    if origctx and origctx.manifestnode() == mn:
        origfiles = origctx.files()
        assert files.touched.issubset(origfiles)
        files.update_touched(origfiles)

    if writechangesetcopy:
        files.update_copies_from_p1(ctx.p1copies())
        files.update_copies_from_p2(ctx.p2copies())

    return mn, files


def _get_salvaged(repo, ms, ctx):
    """returns a list of salvaged files

    returns empty list if config option which process salvaged files are
    not enabled"""
    salvaged = []
    copy_sd = repo.filecopiesmode == b'changeset-sidedata'
    if copy_sd and len(ctx.parents()) > 1:
        if ms.active():
            for fname in sorted(ms.allextras().keys()):
                might_removed = ms.extras(fname).get(b'merge-removal-candidate')
                if might_removed == b'yes':
                    if fname in ctx:
                        salvaged.append(fname)
    return salvaged


def _process_files(tr, ctx, ms, files, error=False):
    repo = ctx.repo()
    p1 = ctx.p1()
    p2 = ctx.p2()

    writechangesetcopy, writefilecopymeta = _write_copy_meta(repo)

    m1ctx = p1.manifestctx()
    m2ctx = p2.manifestctx()
    mctx = m1ctx.copy()

    m = mctx.read()
    m1 = m1ctx.read()
    m2 = m2ctx.read()

    # check in files
    added = []
    removed = list(ctx.removed())
    linkrev = len(repo)
    repo.ui.note(_(b"committing files:\n"))
    uipathfn = scmutil.getuipathfn(repo)
    for f in sorted(ctx.modified() + ctx.added()):
        repo.ui.note(uipathfn(f) + b"\n")
        try:
            fctx = ctx[f]
            if fctx is None:
                removed.append(f)
            else:
                added.append(f)
                m[f], is_touched = _filecommit(
                    repo, fctx, m1, m2, linkrev, tr, writefilecopymeta, ms
                )
                if is_touched:
                    if is_touched == 'added':
                        files.mark_added(f)
                    elif is_touched == 'merged':
                        files.mark_merged(f)
                    else:
                        files.mark_touched(f)
                m.setflag(f, fctx.flags())
        except OSError:
            repo.ui.warn(_(b"trouble committing %s!\n") % uipathfn(f))
            raise
        except IOError as inst:
            errcode = getattr(inst, 'errno', errno.ENOENT)
            if error or errcode and errcode != errno.ENOENT:
                repo.ui.warn(_(b"trouble committing %s!\n") % uipathfn(f))
            raise

    # update manifest
    removed = [f for f in removed if f in m1 or f in m2]
    drop = sorted([f for f in removed if f in m])
    for f in drop:
        del m[f]
    if p2.rev() == nullrev:
        files.update_removed(removed)
    else:
        rf = metadata.get_removal_filter(ctx, (p1, p2, m1, m2))
        for f in removed:
            if not rf(f):
                files.mark_removed(f)

    mn = _commit_manifest(tr, linkrev, ctx, mctx, m, files.touched, added, drop)

    return mn


def _filecommit(
    repo,
    fctx,
    manifest1,
    manifest2,
    linkrev,
    tr,
    includecopymeta,
    ms,
):
    """
    commit an individual file as part of a larger transaction

    input:

        fctx:       a file context with the content we are trying to commit
        manifest1:  manifest of changeset first parent
        manifest2:  manifest of changeset second parent
        linkrev:    revision number of the changeset being created
        tr:         current transation
        includecopymeta: boolean, set to False to skip storing the copy data
                    (only used by the Google specific feature of using
                    changeset extra as copy source of truth).
        ms:         mergestate object

    output: (filenode, touched)

        filenode: the filenode that should be used by this changeset
        touched:  one of: None (mean untouched), 'added' or 'modified'
    """

    fname = fctx.path()
    fparent1 = manifest1.get(fname, nullid)
    fparent2 = manifest2.get(fname, nullid)
    touched = None
    if fparent1 == fparent2 == nullid:
        touched = 'added'

    if isinstance(fctx, context.filectx):
        # This block fast path most comparisons which are usually done. It
        # assumes that bare filectx is used and no merge happened, hence no
        # need to create a new file revision in this case.
        node = fctx.filenode()
        if node in [fparent1, fparent2]:
            repo.ui.debug(b'reusing %s filelog entry\n' % fname)
            if (
                fparent1 != nullid and manifest1.flags(fname) != fctx.flags()
            ) or (
                fparent2 != nullid and manifest2.flags(fname) != fctx.flags()
            ):
                touched = 'modified'
            return node, touched

    flog = repo.file(fname)
    meta = {}
    cfname = fctx.copysource()
    fnode = None

    if cfname and cfname != fname:
        # Mark the new revision of this file as a copy of another
        # file.  This copy data will effectively act as a parent
        # of this new revision.  If this is a merge, the first
        # parent will be the nullid (meaning "look up the copy data")
        # and the second one will be the other parent.  For example:
        #
        # 0 --- 1 --- 3   rev1 changes file foo
        #   \       /     rev2 renames foo to bar and changes it
        #    \- 2 -/      rev3 should have bar with all changes and
        #                      should record that bar descends from
        #                      bar in rev2 and foo in rev1
        #
        # this allows this merge to succeed:
        #
        # 0 --- 1 --- 3   rev4 reverts the content change from rev2
        #   \       /     merging rev3 and rev4 should use bar@rev2
        #    \- 2 --- 4        as the merge base
        #

        cnode = manifest1.get(cfname)
        newfparent = fparent2

        if manifest2:  # branch merge
            if fparent2 == nullid or cnode is None:  # copied on remote side
                if cfname in manifest2:
                    cnode = manifest2[cfname]
                    newfparent = fparent1

        # Here, we used to search backwards through history to try to find
        # where the file copy came from if the source of a copy was not in
        # the parent directory. However, this doesn't actually make sense to
        # do (what does a copy from something not in your working copy even
        # mean?) and it causes bugs (eg, issue4476). Instead, we will warn
        # the user that copy information was dropped, so if they didn't
        # expect this outcome it can be fixed, but this is the correct
        # behavior in this circumstance.

        if cnode:
            repo.ui.debug(b" %s: copy %s:%s\n" % (fname, cfname, hex(cnode)))
            if includecopymeta:
                meta[b"copy"] = cfname
                meta[b"copyrev"] = hex(cnode)
            fparent1, fparent2 = nullid, newfparent
        else:
            repo.ui.warn(
                _(
                    b"warning: can't find ancestor for '%s' "
                    b"copied from '%s'!\n"
                )
                % (fname, cfname)
            )

    elif fparent1 == nullid:
        fparent1, fparent2 = fparent2, nullid
    elif fparent2 != nullid:
        # is one parent an ancestor of the other?
        fparentancestors = flog.commonancestorsheads(fparent1, fparent2)
        if fparent1 in fparentancestors:
            fparent1, fparent2 = fparent2, nullid
        elif fparent2 in fparentancestors:
            fparent2 = nullid
        elif not fparentancestors:
            # TODO: this whole if-else might be simplified much more
            if (
                ms.active()
                and ms.extras(fname).get(b'filenode-source') == b'other'
            ):
                fparent1, fparent2 = fparent2, nullid

    force_new_node = False
    # The file might have been deleted by merge code and user explicitly choose
    # to revert the file and keep it. The other case can be where there is
    # change-delete or delete-change conflict and user explicitly choose to keep
    # the file. The goal is to create a new filenode for users explicit choices
    if (
        repo.ui.configbool(b'experimental', b'merge-track-salvaged')
        and ms.active()
        and ms.extras(fname).get(b'merge-removal-candidate') == b'yes'
    ):
        force_new_node = True
    # is the file changed?
    text = fctx.data()
    if fparent2 != nullid or meta or flog.cmp(fparent1, text) or force_new_node:
        if touched is None:  # do not overwrite added
            if fparent2 == nullid:
                touched = 'modified'
            else:
                touched = 'merged'
        fnode = flog.add(text, meta, tr, linkrev, fparent1, fparent2)
    # are just the flags changed during merge?
    elif fname in manifest1 and manifest1.flags(fname) != fctx.flags():
        touched = 'modified'
        fnode = fparent1
    else:
        fnode = fparent1
    return fnode, touched


def _commit_manifest(tr, linkrev, ctx, mctx, manifest, files, added, drop):
    """make a new manifest entry (or reuse a new one)

    given an initialised manifest context and precomputed list of
    - files: files affected by the commit
    - added: new entries in the manifest
    - drop:  entries present in parents but absent of this one

    Create a new manifest revision, reuse existing ones if possible.

    Return the nodeid of the manifest revision.
    """
    repo = ctx.repo()

    md = None

    # all this is cached, so it is find to get them all from the ctx.
    p1 = ctx.p1()
    p2 = ctx.p2()
    m1ctx = p1.manifestctx()

    m1 = m1ctx.read()

    if not files:
        # if no "files" actually changed in terms of the changelog,
        # try hard to detect unmodified manifest entry so that the
        # exact same commit can be reproduced later on convert.
        md = m1.diff(manifest, scmutil.matchfiles(repo, ctx.files()))
    if not files and md:
        repo.ui.debug(
            b'not reusing manifest (no file change in '
            b'changelog, but manifest differs)\n'
        )
    if files or md:
        repo.ui.note(_(b"committing manifest\n"))
        # we're using narrowmatch here since it's already applied at
        # other stages (such as dirstate.walk), so we're already
        # ignoring things outside of narrowspec in most cases. The
        # one case where we might have files outside the narrowspec
        # at this point is merges, and we already error out in the
        # case where the merge has files outside of the narrowspec,
        # so this is safe.
        mn = mctx.write(
            tr,
            linkrev,
            p1.manifestnode(),
            p2.manifestnode(),
            added,
            drop,
            match=repo.narrowmatch(),
        )
    else:
        repo.ui.debug(
            b'reusing manifest from p1 (listed files ' b'actually unchanged)\n'
        )
        mn = p1.manifestnode()

    return mn


def _extra_with_copies(repo, extra, files):
    """encode copy information into a `extra` dictionnary"""
    p1copies = files.copied_from_p1
    p2copies = files.copied_from_p2
    filesadded = files.added
    filesremoved = files.removed
    files = sorted(files.touched)
    if not _write_copy_meta(repo)[1]:
        # If writing only to changeset extras, use None to indicate that
        # no entry should be written. If writing to both, write an empty
        # entry to prevent the reader from falling back to reading
        # filelogs.
        p1copies = p1copies or None
        p2copies = p2copies or None
        filesadded = filesadded or None
        filesremoved = filesremoved or None

    extrasentries = p1copies, p2copies, filesadded, filesremoved
    if extra is None and any(x is not None for x in extrasentries):
        extra = {}
    if p1copies is not None:
        p1copies = metadata.encodecopies(files, p1copies)
        extra[b'p1copies'] = p1copies
    if p2copies is not None:
        p2copies = metadata.encodecopies(files, p2copies)
        extra[b'p2copies'] = p2copies
    if filesadded is not None:
        filesadded = metadata.encodefileindices(files, filesadded)
        extra[b'filesadded'] = filesadded
    if filesremoved is not None:
        filesremoved = metadata.encodefileindices(files, filesremoved)
        extra[b'filesremoved'] = filesremoved
    return extra