hgext/closehead.py

branchmap: avoid ancestor computations in absence of non-continous branches

The branchhead computation is one of the more heavy operations for
bigger repositories as it has to scan all changesets and potentially
involves the expensive computation of the ancestor sets. Redo the
computation to handle the common cases directly and use tighter
conditions for when the ancestor scan is necessary. Most importantly,
avoid it completely if the non-continous branches are processed in one
update as seen in the initial computation after a clone.

For the Mercurial repository, it gives a small 2-3% performance boost.
For the NetBSD test repository, it cuts the time in half.

Differential Revision: https://phab.mercurial-scm.org/D9631

# closehead.py - Close arbitrary heads without checking them out first
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

'''close arbitrary heads without checking them out first'''

from __future__ import absolute_import

from mercurial.i18n import _
from mercurial import (
    bookmarks,
    cmdutil,
    context,
    error,
    pycompat,
    registrar,
    scmutil,
)

cmdtable = {}
command = registrar.command(cmdtable)
# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = b'ships-with-hg-core'

commitopts = cmdutil.commitopts
commitopts2 = cmdutil.commitopts2
commitopts3 = [(b'r', b'rev', [], _(b'revision to check'), _(b'REV'))]


@command(
    b'close-head|close-heads',
    commitopts + commitopts2 + commitopts3,
    _(b'[OPTION]... [REV]...'),
    helpcategory=command.CATEGORY_CHANGE_MANAGEMENT,
    inferrepo=True,
)
def close_branch(ui, repo, *revs, **opts):
    """close the given head revisions

    This is equivalent to checking out each revision in a clean tree and running
    ``hg commit --close-branch``, except that it doesn't change the working
    directory.

    The commit message must be specified with -l or -m.
    """

    def docommit(rev):
        cctx = context.memctx(
            repo,
            parents=[rev, None],
            text=message,
            files=[],
            filectxfn=None,
            user=opts.get(b'user'),
            date=opts.get(b'date'),
            extra=extra,
        )
        tr = repo.transaction(b'commit')
        ret = repo.commitctx(cctx, True)
        bookmarks.update(repo, [rev, None], ret)
        cctx.markcommitted(ret)
        tr.close()

    opts = pycompat.byteskwargs(opts)

    revs += tuple(opts.get(b'rev', []))
    revs = scmutil.revrange(repo, revs)

    if not revs:
        raise error.Abort(_(b'no revisions specified'))

    heads = []
    for branch in repo.branchmap():
        heads.extend(repo.branchheads(branch))
    heads = {repo[h].rev() for h in heads}
    for rev in revs:
        if rev not in heads:
            raise error.Abort(_(b'revision is not an open head: %d') % rev)

    message = cmdutil.logmessage(ui, opts)
    if not message:
        raise error.Abort(_(b"no commit message specified with -l or -m"))
    extra = {b'close': b'1'}

    with repo.wlock(), repo.lock():
        for rev in revs:
            r = repo[rev]
            branch = r.branch()
            extra[b'branch'] = branch
            docommit(r)
    return 0