hgext/fetch.py

localrepo.commit: grab locks before getting the list of files to commit

Somebody may change the dirstate after we've determined the parents of
the working dir and run repo.status, but before we called wlock().

This should also fix issue997, where backout would change a file without
changing its size and then call repo.commit without passing the list of
files. If this happened in less than one second, we wouldn't detect any
file changes - the in-memory dirstate still has the cached stat data for
that file. Grabbing the wlock early causes the dirstate to be
invalidated and we end up reading the dirstate file again, which has
that file marked for lookup (size == -1).

A better fix would be for backout to give repo.commit the exact list of
files, but that'll require some changes to the revert operation.

A significant user-visible change is that the precommit hook is always
run with both locks grabbed - previously, hg commit would run it before
grabbing any locks, but hg import would run it after grabbing locks.

# fetch.py - pull and merge remote changes
#
# Copyright 2006 Vadim Gelfer <[e-mail]>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.

from mercurial.i18n import _
from mercurial.node import nullid, short
from mercurial import commands, cmdutil, hg, util

def fetch(ui, repo, source='default', **opts):
    '''Pull changes from a remote repository, merge new changes if needed.

    This finds all changes from the repository at the specified path
    or URL and adds them to the local repository.

    If the pulled changes add a new head, the head is automatically
    merged, and the result of the merge is committed.  Otherwise, the
    working directory is updated to include the new changes.

    When a merge occurs, the newly pulled changes are assumed to be
    "authoritative".  The head of the new changes is used as the first
    parent, with local changes as the second.  To switch the merge
    order, use --switch-parent.

    See 'hg help dates' for a list of formats valid for -d/--date.
    '''

    def postincoming(other, modheads):
        if modheads == 0:
            return 0
        if modheads == 1:
            return hg.clean(repo, repo.changelog.tip())
        newheads = repo.heads(parent)
        newchildren = [n for n in repo.heads(parent) if n != parent]
        newparent = parent
        if newchildren:
            newparent = newchildren[0]
            hg.clean(repo, newparent)
        newheads = [n for n in repo.heads() if n != newparent]
        if len(newheads) > 1:
            ui.status(_('not merging with %d other new heads '
                        '(use "hg heads" and "hg merge" to merge them)') %
                      (len(newheads) - 1))
            return
        err = False
        if newheads:
            # By default, we consider the repository we're pulling
            # *from* as authoritative, so we merge our changes into
            # theirs.
            if opts['switch_parent']:
                firstparent, secondparent = newparent, newheads[0]
            else:
                firstparent, secondparent = newheads[0], newparent
                ui.status(_('updating to %d:%s\n') %
                          (repo.changelog.rev(firstparent),
                           short(firstparent)))
            hg.clean(repo, firstparent)
            ui.status(_('merging with %d:%s\n') %
                      (repo.changelog.rev(secondparent), short(secondparent)))
            err = hg.merge(repo, secondparent, remind=False)
        if not err:
            mod, add, rem = repo.status()[:3]
            message = (cmdutil.logmessage(opts) or
                       (_('Automated merge with %s') %
                        util.removeauth(other.url())))
            force_editor = opts.get('force_editor') or opts.get('edit')
            n = repo.commit(mod + add + rem, message,
                            opts['user'], opts['date'],
                            force_editor=force_editor)
            ui.status(_('new changeset %d:%s merges remote changes '
                        'with local\n') % (repo.changelog.rev(n),
                                           short(n)))

    def pull():
        cmdutil.setremoteconfig(ui, opts)

        other = hg.repository(ui, ui.expandpath(source))
        ui.status(_('pulling from %s\n') %
                  util.hidepassword(ui.expandpath(source)))
        revs = None
        if opts['rev']:
            if not other.local():
                raise util.Abort(_("fetch -r doesn't work for remote "
                                   "repositories yet"))
            else:
                revs = [other.lookup(rev) for rev in opts['rev']]
        modheads = repo.pull(other, heads=revs)
        return postincoming(other, modheads)

    date = opts.get('date')
    if date:
        opts['date'] = util.parsedate(date)

    parent, p2 = repo.dirstate.parents()
    if parent != repo.changelog.tip():
        raise util.Abort(_('working dir not at tip '
                           '(use "hg update" to check out tip)'))
    if p2 != nullid:
        raise util.Abort(_('outstanding uncommitted merge'))
    wlock = lock = None
    try:
        wlock = repo.wlock()
        lock = repo.lock()
        mod, add, rem, del_ = repo.status()[:4]
        if mod or add or rem:
            raise util.Abort(_('outstanding uncommitted changes'))
        if del_:
            raise util.Abort(_('working directory is missing some files'))
        if len(repo.heads()) > 1:
            raise util.Abort(_('multiple heads in this repository '
                               '(use "hg heads" and "hg merge" to merge)'))
        return pull()
    finally:
        del lock, wlock

cmdtable = {
    'fetch':
        (fetch,
        [('r', 'rev', [], _('a specific revision you would like to pull')),
         ('e', 'edit', None, _('edit commit message')),
         ('', 'force-editor', None, _('edit commit message (DEPRECATED)')),
         ('', 'switch-parent', None, _('switch parents when merging')),
        ] + commands.commitopts + commands.commitopts2 + commands.remoteopts,
        _('hg fetch [SOURCE]')),
}