view hgext/split.py @ 35506:fa865878a849

lfs: show a friendly message when pushing lfs to a server without lfs enabled

Upfront disclaimer: I don't know anything about the wire protocol, and this was
pretty much cargo-culted from largefiles, and then clonebundles, since it seems
more modern.  I was surprised that exchange.push() will ensure all of the proper
requirements when exchanging between two local repos, but doesn't care when one
is remote.

All this new capability marker does is inform the client that the extension is
enabled remotely.  It may or may not contain commits with external blobs.

Open issues:

  - largefiles uses 'largefiles=serve' for its capability.  Someday I hope to
    be able to push lfs blobs to an `hg serve` instance.  That will probably
    require a distinct capability.  Should it change to '=serve' then?  Or just
    add an 'lfs-serve' capability then?

  - The flip side of this is more complicated.  It looks like largefiles adds an
    'lheads' command for the client to signal to the server that the extension
    is loaded.  That is then converted to 'heads' and sent through the normal
    wire protocol plumbing.  A client using the 'heads' command directly is
    kicked out with a message indicating that the largefiles extension must be
    loaded.  We could do similar with 'lfsheads', but then a repo with both
    largefiles and lfs blobs can't be pushed over the wire.  Hopefully somebody
    with more wire protocol experience can think of something else.  I see
    'x-hgarg-1' on some commands in the tests, but not on heads, and didn't dig
    any further.

# split.py - split a changeset into smaller ones
#
# Copyright 2015 Laurent Charignon <[e-mail]>
# 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,
    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 = 'ships-with-hg-core'

@command('^split',
    [('r', 'rev', '', _("revision to split"), _('REV')),
     ('', 'rebase', True, _('rebase descendants after split')),
    ] + cmdutil.commitopts2,
    _('hg split [--no-rebase] [[-r] REV]'))
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.
    """
    revlist = []
    if opts.get('rev'):
        revlist.append(opts.get('rev'))
    revlist.extend(revs)
    with repo.wlock(), repo.lock(), repo.transaction('split') as tr:
        revs = scmutil.revrange(repo, revlist or ['.'])
        if len(revs) > 1:
            raise error.Abort(_('cannot split multiple revisions'))

        rev = revs.first()
        ctx = repo[rev]
        if rev is None or ctx.node() == nullid:
            ui.status(_('nothing to split\n'))
            return 1
        if ctx.node() is None:
            raise error.Abort(_('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(_('cannot split public changeset'),
                              hint=_("see 'hg help phases' for details"))

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

        if len(ctx.parents()) > 1:
            raise error.Abort(_('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['.'].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
    # NOTE: if we can have "update without touching working copy" API, the
    # revert step could be cheaper.
    hg.clean(repo, ctx.p1().node(), show_stats=False)
    parents = repo.changelog.parents(ctx.node())
    ui.pushbuffer()
    cmdutil.revert(ui, repo, ctx, parents)
    ui.popbuffer() # discard "reverting ..." messages

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

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

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

    return committed[-1]

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