view hgext/split.py @ 43271:99394e6c5d12

rust-dirstate-status: add first Rust implementation of `dirstate.status` Note: This patch also added the rayon crate as a Cargo dependency. It will help us immensely in making Rust code parallel and easy to maintain. It is a stable, well-known, and supported crate maintained by people on the Rust team. The current `dirstate.status` method has grown over the years through bug reports and new features to the point where it got too big and too complex. This series does not yet improve the logic, but adds a Rust fast-path to speed up certain cases. Tested on mozilla-try-2019-02-18 with zstd compression: - `hg diff` on an empty working copy: - c: 1.64(+-)0.04s - rust+c before this change: 2.84(+-)0.1s - rust+c: 849(+-)40ms - `hg commit` when creating a file: - c: 5.960s - rust+c before this change: 5.828s - rust+c: 4.668s - `hg commit` when updating a file: - c: 4.866s - rust+c before this change: 4.371s - rust+c: 3.855s - `hg status -mard` - c: 1.82(+-)0.04s - rust+c before this change: 2.64(+-)0.1s - rust+c: 896(+-)30ms The numbers are clear: the current Rust `dirstatemap` implementation is super slow, its performance needs to be addressed. This will be done in a future series, immediately after this one, with the goal of getting Rust to be at least to the speed of the Python + C implementation in all cases before the 5.2 freeze. At worse, we gate dirstatemap to only be used in those cases. Cases where the fast-path is not executed: - for commands that need ignore support (`status`, for example) - if subrepos are found (should not be hard to add, but winter is coming) - any other matcher than an `alwaysmatcher`, like patterns, etc. - with extensions like `sparse` and `fsmonitor` The next step after this is to rethink the logic to be closer to Jane Street's Valentin Gatien-Baron's Rust fast-path which does a lot less work when possible. Differential Revision: https://phab.mercurial-scm.org/D7058
author Raphaël Gomès <rgomes@octobus.net>
date Fri, 11 Oct 2019 13:39:57 +0200
parents 8ff1ecfadcd1
children 705738def50c
line wrap: on
line source

# split.py - split a changeset into smaller ones
#
# Copyright 2015 Laurent Charignon <lcharignon@fb.com>
# Copyright 2017 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""command to split a changeset into smaller ones (EXPERIMENTAL)"""

from __future__ import absolute_import

from mercurial.i18n import _

from mercurial.node import (
    nullid,
    short,
)

from mercurial import (
    bookmarks,
    cmdutil,
    commands,
    error,
    hg,
    obsolete,
    phases,
    pycompat,
    registrar,
    revsetlang,
    scmutil,
)

# allow people to use split without explicitly enabling rebase extension
from . import rebase

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'


@command(
    b'split',
    [
        (b'r', b'rev', b'', _(b"revision to split"), _(b'REV')),
        (b'', b'rebase', True, _(b'rebase descendants after split')),
    ]
    + cmdutil.commitopts2,
    _(b'hg split [--no-rebase] [[-r] REV]'),
    helpcategory=command.CATEGORY_CHANGE_MANAGEMENT,
    helpbasic=True,
)
def split(ui, repo, *revs, **opts):
    """split a changeset into smaller ones

    Repeatedly prompt changes and commit message for new changesets until there
    is nothing left in the original changeset.

    If --rev was not given, split the working directory parent.

    By default, rebase connected non-obsoleted descendants onto the new
    changeset. Use --no-rebase to avoid the rebase.
    """
    opts = pycompat.byteskwargs(opts)
    revlist = []
    if opts.get(b'rev'):
        revlist.append(opts.get(b'rev'))
    revlist.extend(revs)
    with repo.wlock(), repo.lock(), repo.transaction(b'split') as tr:
        revs = scmutil.revrange(repo, revlist or [b'.'])
        if len(revs) > 1:
            raise error.Abort(_(b'cannot split multiple revisions'))

        rev = revs.first()
        ctx = repo[rev]
        if rev is None or ctx.node() == nullid:
            ui.status(_(b'nothing to split\n'))
            return 1
        if ctx.node() is None:
            raise error.Abort(_(b'cannot split working directory'))

        # rewriteutil.precheck is not very useful here because:
        # 1. null check is done above and it's more friendly to return 1
        #    instead of abort
        # 2. mergestate check is done below by cmdutil.bailifchanged
        # 3. unstable check is more complex here because of --rebase
        #
        # So only "public" check is useful and it's checked directly here.
        if ctx.phase() == phases.public:
            raise error.Abort(
                _(b'cannot split public changeset'),
                hint=_(b"see 'hg help phases' for details"),
            )

        descendants = list(repo.revs(b'(%d::) - (%d)', rev, rev))
        alloworphaned = obsolete.isenabled(repo, obsolete.allowunstableopt)
        if opts.get(b'rebase'):
            # Skip obsoleted descendants and their descendants so the rebase
            # won't cause conflicts for sure.
            torebase = list(
                repo.revs(
                    b'%ld - (%ld & obsolete())::', descendants, descendants
                )
            )
            if not alloworphaned and len(torebase) != len(descendants):
                raise error.Abort(
                    _(b'split would leave orphaned changesets behind')
                )
        else:
            if not alloworphaned and descendants:
                raise error.Abort(
                    _(b'cannot split changeset with children without rebase')
                )
            torebase = ()

        if len(ctx.parents()) > 1:
            raise error.Abort(_(b'cannot split a merge changeset'))

        cmdutil.bailifchanged(repo)

        # Deactivate bookmark temporarily so it won't get moved unintentionally
        bname = repo._activebookmark
        if bname and repo._bookmarks[bname] != ctx.node():
            bookmarks.deactivate(repo)

        wnode = repo[b'.'].node()
        top = None
        try:
            top = dosplit(ui, repo, tr, ctx, opts)
        finally:
            # top is None: split failed, need update --clean recovery.
            # wnode == ctx.node(): wnode split, no need to update.
            if top is None or wnode != ctx.node():
                hg.clean(repo, wnode, show_stats=False)
            if bname:
                bookmarks.activate(repo, bname)
        if torebase and top:
            dorebase(ui, repo, torebase, top)


def dosplit(ui, repo, tr, ctx, opts):
    committed = []  # [ctx]

    # Set working parent to ctx.p1(), and keep working copy as ctx's content
    if ctx.node() != repo.dirstate.p1():
        hg.clean(repo, ctx.node(), show_stats=False)
    with repo.dirstate.parentchange():
        scmutil.movedirstate(repo, ctx.p1())

    # Any modified, added, removed, deleted result means split is incomplete
    incomplete = lambda repo: any(repo.status()[:4])

    # Main split loop
    while incomplete(repo):
        if committed:
            header = _(
                b'HG: Splitting %s. So far it has been split into:\n'
            ) % short(ctx.node())
            for c in committed:
                firstline = c.description().split(b'\n', 1)[0]
                header += _(b'HG: - %s: %s\n') % (short(c.node()), firstline)
            header += _(
                b'HG: Write commit message for the next split changeset.\n'
            )
        else:
            header = _(
                b'HG: Splitting %s. Write commit message for the '
                b'first split changeset.\n'
            ) % short(ctx.node())
        opts.update(
            {
                b'edit': True,
                b'interactive': True,
                b'message': header + ctx.description(),
            }
        )
        commands.commit(ui, repo, **pycompat.strkwargs(opts))
        newctx = repo[b'.']
        committed.append(newctx)

    if not committed:
        raise error.Abort(_(b'cannot split an empty revision'))

    scmutil.cleanupnodes(
        repo,
        {ctx.node(): [c.node() for c in committed]},
        operation=b'split',
        fixphase=True,
    )

    return committed[-1]


def dorebase(ui, repo, src, destctx):
    rebase.rebase(
        ui,
        repo,
        rev=[revsetlang.formatspec(b'%ld', src)],
        dest=revsetlang.formatspec(b'%d', destctx.rev()),
    )