revlog: abort on attempt to write null revision
My repo got corrupted yesterday by something that ended up writing the
null revision to the revlog (nullid hash, not nullrev index, of
course). We use many extensions internally (narrowhg, remotefilelog,
evolve, internal extensions) and treemanifests are on. The null
revision was written to the changelog, the root manifest log, and one
subdirectory manifest log. I have no idea exactly why the null
revision was written, but it seems cheap enough to check that we
should fail instead of corrupting the repo.
Differential Revision: https://phab.mercurial-scm.org/D522
# automv.py
#
# Copyright 2013-2016 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.
"""check for unrecorded moves at commit time (EXPERIMENTAL)
This extension checks at commit/amend time if any of the committed files
comes from an unrecorded mv.
The threshold at which a file is considered a move can be set with the
``automv.similarity`` config option. This option takes a percentage between 0
(disabled) and 100 (files must be identical), the default is 95.
"""
# Using 95 as a default similarity is based on an analysis of the mercurial
# repositories of the cpython, mozilla-central & mercurial repositories, as
# well as 2 very large facebook repositories. At 95 50% of all potential
# missed moves would be caught, as well as correspond with 87% of all
# explicitly marked moves. Together, 80% of moved files are 95% similar or
# more.
#
# See http://markmail.org/thread/5pxnljesvufvom57 for context.
from __future__ import absolute_import
from mercurial.i18n import _
from mercurial import (
commands,
copies,
error,
extensions,
registrar,
scmutil,
similar
)
configtable = {}
configitem = registrar.configitem(configtable)
configitem('automv', 'similarity',
default=95,
)
def extsetup(ui):
entry = extensions.wrapcommand(
commands.table, 'commit', mvcheck)
entry[1].append(
('', 'no-automv', None,
_('disable automatic file move detection')))
def mvcheck(orig, ui, repo, *pats, **opts):
"""Hook to check for moves at commit time"""
renames = None
disabled = opts.pop('no_automv', False)
if not disabled:
threshold = ui.configint('automv', 'similarity')
if not 0 <= threshold <= 100:
raise error.Abort(_('automv.similarity must be between 0 and 100'))
if threshold > 0:
match = scmutil.match(repo[None], pats, opts)
added, removed = _interestingfiles(repo, match)
renames = _findrenames(repo, match, added, removed,
threshold / 100.0)
with repo.wlock():
if renames is not None:
scmutil._markchanges(repo, (), (), renames)
return orig(ui, repo, *pats, **opts)
def _interestingfiles(repo, matcher):
"""Find what files were added or removed in this commit.
Returns a tuple of two lists: (added, removed). Only files not *already*
marked as moved are included in the added list.
"""
stat = repo.status(match=matcher)
added = stat[1]
removed = stat[2]
copy = copies._forwardcopies(repo['.'], repo[None], matcher)
# remove the copy files for which we already have copy info
added = [f for f in added if f not in copy]
return added, removed
def _findrenames(repo, matcher, added, removed, similarity):
"""Find what files in added are really moved files.
Any file named in removed that is at least similarity% similar to a file
in added is seen as a rename.
"""
renames = {}
if similarity > 0:
for src, dst, score in similar.findrenames(
repo, added, removed, similarity):
if repo.ui.verbose:
repo.ui.status(
_('detected move of %s as %s (%d%% similar)\n') % (
matcher.rel(src), matcher.rel(dst), score * 100))
renames[dst] = src
if renames:
repo.ui.status(_('detected move of %d files\n') % len(renames))
return renames