hgext/commitextras.py

atomicupdate: add an experimental option to use atomictemp when updating

In some cases Mercurial truncating files when updating causes problems. It can
happens when processes are currently reading the file or with big file or on
NFS mounts.

We add an experimental option to use the atomictemp option of vfs.__call__ in
order to avoid the problem.

The localrepository.wwrite seems to assume the files are created without the
`x` flag; with atomictempfile, the new file might inherit the `x` flag from
the destination. We force remove it afterward. This code could be refactored
and the flag processing could be moved inside vfs.

This patch should be tested with
`--extra-config-opt experimental.update.atomic-file=True`
as we disabled the option by default.

Differential Revision: https://phab.mercurial-scm.org/D1882

# commitextras.py
#
# Copyright 2013 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.

'''adds a new flag extras to commit (ADVANCED)'''

from __future__ import absolute_import

import re

from mercurial.i18n import _
from mercurial import (
    commands,
    error,
    extensions,
    registrar,
)

cmdtable = {}
command = registrar.command(cmdtable)
testedwith = 'ships-with-hg-core'

usedinternally = {
    'amend_source',
    'branch',
    'close',
    'histedit_source',
    'topic',
    'rebase_source',
    'intermediate-source',
    '__touch-noise__',
    'source',
    'transplant_source',
}

def extsetup(ui):
    entry = extensions.wrapcommand(commands.table, 'commit', _commit)
    options = entry[1]
    options.append(('', 'extra', [],
        _('set a changeset\'s extra values'), _("KEY=VALUE")))

def _commit(orig, ui, repo, *pats, **opts):
    origcommit = repo.commit
    try:
        def _wrappedcommit(*innerpats, **inneropts):
            extras = opts.get(r'extra')
            if extras:
                for raw in extras:
                    if '=' not in raw:
                        msg = _("unable to parse '%s', should follow "
                                "KEY=VALUE format")
                        raise error.Abort(msg % raw)
                    k, v = raw.split('=', 1)
                    if not k:
                        msg = _("unable to parse '%s', keys can't be empty")
                        raise error.Abort(msg % raw)
                    if re.search('[^\w-]', k):
                        msg = _("keys can only contain ascii letters, digits,"
                                " '_' and '-'")
                        raise error.Abort(msg)
                    if k in usedinternally:
                        msg = _("key '%s' is used internally, can't be set "
                                "manually")
                        raise error.Abort(msg % k)
                    inneropts[r'extra'][k] = v
            return origcommit(*innerpats, **inneropts)

        # This __dict__ logic is needed because the normal
        # extension.wrapfunction doesn't seem to work.
        repo.__dict__['commit'] = _wrappedcommit
        return orig(ui, repo, *pats, **opts)
    finally:
        del repo.__dict__['commit']