lock: block signal interrupt while making a lock file
On Windows where symlink isn't supported, util.makelock() could leave an empty
file if interrupted immediately after os.open(). This empty lock never dies
as it has no process id recorded.
ld = os.open(pathname, os.O_CREAT | os.O_WRONLY | os.O_EXCL)
# an interrupt may occur here
os.write(ld, info)
os.close(ld)
This was a long-standing bug of TortoiseHg which runs a command-server and
kills it by CTRL_C_EVENT, reported by random Windows users.
https://bitbucket.org/tortoisehg/thg/issues/4873/#comment-
43591129
At first, I tried to fix makelock() to clean up a stale lock file, which
turned out to be hard because any instructions may be interrupted by a
signal.
ld = None
try:
# CALL_FUNCTION # os.open(...)
# an interrupt may occur here
# STORE_FAST # ld = ...
ld = os.open(pathname, os.O_CREAT | os.O_WRONLY | os.O_EXCL)
os.write(ld, info)
...
return True
except:
if ld:
...
os.unlink(pathname)
return False
So I decided to block signals by temporarily replacing the signal handlers
so makelcok() and held = 1 will never be interrupted.
Many thanks to Fernando Najera for investigating the issue.
# 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 = '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, **pycompat.strkwargs(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, destctx):
rebase.rebase(ui, repo, rev=[revsetlang.formatspec('%ld', src)],
dest=revsetlang.formatspec('%d', destctx.rev()))