lock: add internal config to not replace signal handlers while locking

signal.signal() is blocked in some WSGI environments, and a horrible warning
is sent to the server log. So we need a way to disable it, and I think
abusing ui.config is the simplest workaround.

mercurial/configitems.py

@@ -1,1344 +1,1347 b''
 # configitems.py - centralized declaration of configuration option
 #
 #  Copyright 2017 Pierre-Yves David <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import
 
 import functools
 import re
 
 from . import (
     encoding,
     error,
 )
 
 def loadconfigtable(ui, extname, configtable):
     """update config item known to the ui with the extension ones"""
     for section, items in sorted(configtable.items()):
         knownitems = ui._knownconfig.setdefault(section, itemregister())
         knownkeys = set(knownitems)
         newkeys = set(items)
         for key in sorted(knownkeys & newkeys):
             msg = "extension '%s' overwrite config item '%s.%s'"
             msg %= (extname, section, key)
             ui.develwarn(msg, config='warn-config')
 
         knownitems.update(items)
 
 class configitem(object):
     """represent a known config item
 
     :section: the official config section where to find this item,
        :name: the official name within the section,
     :default: default value for this item,
     :alias: optional list of tuples as alternatives,
     :generic: this is a generic definition, match name using regular expression.
     """
 
     def __init__(self, section, name, default=None, alias=(),
                  generic=False, priority=0):
         self.section = section
         self.name = name
         self.default = default
         self.alias = list(alias)
         self.generic = generic
         self.priority = priority
         self._re = None
         if generic:
             self._re = re.compile(self.name)
 
 class itemregister(dict):
     """A specialized dictionary that can handle wild-card selection"""
 
     def __init__(self):
         super(itemregister, self).__init__()
         self._generics = set()
 
     def update(self, other):
         super(itemregister, self).update(other)
         self._generics.update(other._generics)
 
     def __setitem__(self, key, item):
         super(itemregister, self).__setitem__(key, item)
         if item.generic:
             self._generics.add(item)
 
     def get(self, key):
         baseitem = super(itemregister, self).get(key)
         if baseitem is not None and not baseitem.generic:
             return baseitem
 
         # search for a matching generic item
         generics = sorted(self._generics, key=(lambda x: (x.priority, x.name)))
         for item in generics:
             # we use 'match' instead of 'search' to make the matching simpler
             # for people unfamiliar with regular expression. Having the match
             # rooted to the start of the string will produce less surprising
             # result for user writing simple regex for sub-attribute.
             #
             # For example using "color\..*" match produces an unsurprising
             # result, while using search could suddenly match apparently
             # unrelated configuration that happens to contains "color."
             # anywhere. This is a tradeoff where we favor requiring ".*" on
             # some match to avoid the need to prefix most pattern with "^".
             # The "^" seems more error prone.
             if item._re.match(key):
                 return item
 
         return None
 
 coreitems = {}
 
 def _register(configtable, *args, **kwargs):
     item = configitem(*args, **kwargs)
     section = configtable.setdefault(item.section, itemregister())
     if item.name in section:
         msg = "duplicated config item registration for '%s.%s'"
         raise error.ProgrammingError(msg % (item.section, item.name))
     section[item.name] = item
 
 # special value for case where the default is derived from other values
 dynamicdefault = object()
 
 # Registering actual config items
 
 def getitemregister(configtable):
     f = functools.partial(_register, configtable)
     # export pseudo enum as configitem.*
     f.dynamicdefault = dynamicdefault
     return f
 
 coreconfigitem = getitemregister(coreitems)
 
 coreconfigitem('alias', '.*',
     default=dynamicdefault,
     generic=True,
 )
 coreconfigitem('annotate', 'nodates',
     default=False,
 )
 coreconfigitem('annotate', 'showfunc',
     default=False,
 )
 coreconfigitem('annotate', 'unified',
     default=None,
 )
 coreconfigitem('annotate', 'git',
     default=False,
 )
 coreconfigitem('annotate', 'ignorews',
     default=False,
 )
 coreconfigitem('annotate', 'ignorewsamount',
     default=False,
 )
 coreconfigitem('annotate', 'ignoreblanklines',
     default=False,
 )
 coreconfigitem('annotate', 'ignorewseol',
     default=False,
 )
 coreconfigitem('annotate', 'nobinary',
     default=False,
 )
 coreconfigitem('annotate', 'noprefix',
     default=False,
 )
 coreconfigitem('auth', 'cookiefile',
     default=None,
 )
 # bookmarks.pushing: internal hack for discovery
 coreconfigitem('bookmarks', 'pushing',
     default=list,
 )
 # bundle.mainreporoot: internal hack for bundlerepo
 coreconfigitem('bundle', 'mainreporoot',
     default='',
 )
 # bundle.reorder: experimental config
 coreconfigitem('bundle', 'reorder',
     default='auto',
 )
 coreconfigitem('censor', 'policy',
     default='abort',
 )
 coreconfigitem('chgserver', 'idletimeout',
     default=3600,
 )
 coreconfigitem('chgserver', 'skiphash',
     default=False,
 )
 coreconfigitem('cmdserver', 'log',
     default=None,
 )
 coreconfigitem('color', '.*',
     default=None,
     generic=True,
 )
 coreconfigitem('color', 'mode',
     default='auto',
 )
 coreconfigitem('color', 'pagermode',
     default=dynamicdefault,
 )
 coreconfigitem('commands', 'show.aliasprefix',
     default=list,
 )
 coreconfigitem('commands', 'status.relative',
     default=False,
 )
 coreconfigitem('commands', 'status.skipstates',
     default=[],
 )
 coreconfigitem('commands', 'status.verbose',
     default=False,
 )
 coreconfigitem('commands', 'update.check',
     default=None,
     # Deprecated, remove after 4.4 release
     alias=[('experimental', 'updatecheck')]
 )
 coreconfigitem('commands', 'update.requiredest',
     default=False,
 )
 coreconfigitem('committemplate', '.*',
     default=None,
     generic=True,
 )
 coreconfigitem('convert', 'cvsps.cache',
     default=True,
 )
 coreconfigitem('convert', 'cvsps.fuzz',
     default=60,
 )
 coreconfigitem('convert', 'cvsps.logencoding',
     default=None,
 )
 coreconfigitem('convert', 'cvsps.mergefrom',
     default=None,
 )
 coreconfigitem('convert', 'cvsps.mergeto',
     default=None,
 )
 coreconfigitem('convert', 'git.committeractions',
     default=lambda: ['messagedifferent'],
 )
 coreconfigitem('convert', 'git.extrakeys',
     default=list,
 )
 coreconfigitem('convert', 'git.findcopiesharder',
     default=False,
 )
 coreconfigitem('convert', 'git.remoteprefix',
     default='remote',
 )
 coreconfigitem('convert', 'git.renamelimit',
     default=400,
 )
 coreconfigitem('convert', 'git.saverev',
     default=True,
 )
 coreconfigitem('convert', 'git.similarity',
     default=50,
 )
 coreconfigitem('convert', 'git.skipsubmodules',
     default=False,
 )
 coreconfigitem('convert', 'hg.clonebranches',
     default=False,
 )
 coreconfigitem('convert', 'hg.ignoreerrors',
     default=False,
 )
 coreconfigitem('convert', 'hg.revs',
     default=None,
 )
 coreconfigitem('convert', 'hg.saverev',
     default=False,
 )
 coreconfigitem('convert', 'hg.sourcename',
     default=None,
 )
 coreconfigitem('convert', 'hg.startrev',
     default=None,
 )
 coreconfigitem('convert', 'hg.tagsbranch',
     default='default',
 )
 coreconfigitem('convert', 'hg.usebranchnames',
     default=True,
 )
 coreconfigitem('convert', 'ignoreancestorcheck',
     default=False,
 )
 coreconfigitem('convert', 'localtimezone',
     default=False,
 )
 coreconfigitem('convert', 'p4.encoding',
     default=dynamicdefault,
 )
 coreconfigitem('convert', 'p4.startrev',
     default=0,
 )
 coreconfigitem('convert', 'skiptags',
     default=False,
 )
 coreconfigitem('convert', 'svn.debugsvnlog',
     default=True,
 )
 coreconfigitem('convert', 'svn.trunk',
     default=None,
 )
 coreconfigitem('convert', 'svn.tags',
     default=None,
 )
 coreconfigitem('convert', 'svn.branches',
     default=None,
 )
 coreconfigitem('convert', 'svn.startrev',
     default=0,
 )
 coreconfigitem('debug', 'dirstate.delaywrite',
     default=0,
 )
 coreconfigitem('defaults', '.*',
     default=None,
     generic=True,
 )
 coreconfigitem('devel', 'all-warnings',
     default=False,
 )
 coreconfigitem('devel', 'bundle2.debug',
     default=False,
 )
 coreconfigitem('devel', 'cache-vfs',
     default=None,
 )
 coreconfigitem('devel', 'check-locks',
     default=False,
 )
 coreconfigitem('devel', 'check-relroot',
     default=False,
 )
 coreconfigitem('devel', 'default-date',
     default=None,
 )
 coreconfigitem('devel', 'deprec-warn',
     default=False,
 )
 coreconfigitem('devel', 'disableloaddefaultcerts',
     default=False,
 )
 coreconfigitem('devel', 'warn-empty-changegroup',
     default=False,
 )
 coreconfigitem('devel', 'legacy.exchange',
     default=list,
 )
 coreconfigitem('devel', 'servercafile',
     default='',
 )
 coreconfigitem('devel', 'serverexactprotocol',
     default='',
 )
 coreconfigitem('devel', 'serverrequirecert',
     default=False,
 )
 coreconfigitem('devel', 'strip-obsmarkers',
     default=True,
 )
 coreconfigitem('devel', 'warn-config',
     default=None,
 )
 coreconfigitem('devel', 'warn-config-default',
     default=None,
 )
 coreconfigitem('devel', 'user.obsmarker',
     default=None,
 )
 coreconfigitem('devel', 'warn-config-unknown',
     default=None,
 )
 coreconfigitem('devel', 'debug.peer-request',
     default=False,
 )
 coreconfigitem('diff', 'nodates',
     default=False,
 )
 coreconfigitem('diff', 'showfunc',
     default=False,
 )
 coreconfigitem('diff', 'unified',
     default=None,
 )
 coreconfigitem('diff', 'git',
     default=False,
 )
 coreconfigitem('diff', 'ignorews',
     default=False,
 )
 coreconfigitem('diff', 'ignorewsamount',
     default=False,
 )
 coreconfigitem('diff', 'ignoreblanklines',
     default=False,
 )
 coreconfigitem('diff', 'ignorewseol',
     default=False,
 )
 coreconfigitem('diff', 'nobinary',
     default=False,
 )
 coreconfigitem('diff', 'noprefix',
     default=False,
 )
 coreconfigitem('email', 'bcc',
     default=None,
 )
 coreconfigitem('email', 'cc',
     default=None,
 )
 coreconfigitem('email', 'charsets',
     default=list,
 )
 coreconfigitem('email', 'from',
     default=None,
 )
 coreconfigitem('email', 'method',
     default='smtp',
 )
 coreconfigitem('email', 'reply-to',
     default=None,
 )
 coreconfigitem('email', 'to',
     default=None,
 )
 coreconfigitem('experimental', 'archivemetatemplate',
     default=dynamicdefault,
 )
 coreconfigitem('experimental', 'bundle-phases',
     default=False,
 )
 coreconfigitem('experimental', 'bundle2-advertise',
     default=True,
 )
 coreconfigitem('experimental', 'bundle2-output-capture',
     default=False,
 )
 coreconfigitem('experimental', 'bundle2.pushback',
     default=False,
 )
 coreconfigitem('experimental', 'bundle2.stream',
     default=False,
 )
 coreconfigitem('experimental', 'bundle2lazylocking',
     default=False,
 )
 coreconfigitem('experimental', 'bundlecomplevel',
     default=None,
 )
 coreconfigitem('experimental', 'bundlecomplevel.bzip2',
     default=None,
 )
 coreconfigitem('experimental', 'bundlecomplevel.gzip',
     default=None,
 )
 coreconfigitem('experimental', 'bundlecomplevel.none',
     default=None,
 )
 coreconfigitem('experimental', 'bundlecomplevel.zstd',
     default=None,
 )
 coreconfigitem('experimental', 'changegroup3',
     default=False,
 )
 coreconfigitem('experimental', 'clientcompressionengines',
     default=list,
 )
 coreconfigitem('experimental', 'copytrace',
     default='on',
 )
 coreconfigitem('experimental', 'copytrace.movecandidateslimit',
     default=100,
 )
 coreconfigitem('experimental', 'copytrace.sourcecommitlimit',
     default=100,
 )
 coreconfigitem('experimental', 'crecordtest',
     default=None,
 )
 coreconfigitem('experimental', 'directaccess',
     default=False,
 )
 coreconfigitem('experimental', 'directaccess.revnums',
     default=False,
 )
 coreconfigitem('experimental', 'editortmpinhg',
     default=False,
 )
 coreconfigitem('experimental', 'evolution',
     default=list,
 )
 coreconfigitem('experimental', 'evolution.allowdivergence',
     default=False,
     alias=[('experimental', 'allowdivergence')]
 )
 coreconfigitem('experimental', 'evolution.allowunstable',
     default=None,
 )
 coreconfigitem('experimental', 'evolution.createmarkers',
     default=None,
 )
 coreconfigitem('experimental', 'evolution.effect-flags',
     default=True,
     alias=[('experimental', 'effect-flags')]
 )
 coreconfigitem('experimental', 'evolution.exchange',
     default=None,
 )
 coreconfigitem('experimental', 'evolution.bundle-obsmarker',
     default=False,
 )
 coreconfigitem('experimental', 'evolution.report-instabilities',
     default=True,
 )
 coreconfigitem('experimental', 'evolution.track-operation',
     default=True,
 )
 coreconfigitem('experimental', 'worddiff',
     default=False,
 )
 coreconfigitem('experimental', 'maxdeltachainspan',
     default=-1,
 )
 coreconfigitem('experimental', 'mergetempdirprefix',
     default=None,
 )
 coreconfigitem('experimental', 'mmapindexthreshold',
     default=None,
 )
 coreconfigitem('experimental', 'nonnormalparanoidcheck',
     default=False,
 )
 coreconfigitem('experimental', 'exportableenviron',
     default=list,
 )
 coreconfigitem('experimental', 'extendedheader.index',
     default=None,
 )
 coreconfigitem('experimental', 'extendedheader.similarity',
     default=False,
 )
 coreconfigitem('experimental', 'format.compression',
     default='zlib',
 )
 coreconfigitem('experimental', 'graphshorten',
     default=False,
 )
 coreconfigitem('experimental', 'graphstyle.parent',
     default=dynamicdefault,
 )
 coreconfigitem('experimental', 'graphstyle.missing',
     default=dynamicdefault,
 )
 coreconfigitem('experimental', 'graphstyle.grandparent',
     default=dynamicdefault,
 )
 coreconfigitem('experimental', 'hook-track-tags',
     default=False,
 )
 coreconfigitem('experimental', 'httppeer.advertise-v2',
     default=False,
 )
 coreconfigitem('experimental', 'httppostargs',
     default=False,
 )
 coreconfigitem('experimental', 'mergedriver',
     default=None,
 )
 coreconfigitem('experimental', 'obsmarkers-exchange-debug',
     default=False,
 )
 coreconfigitem('experimental', 'remotenames',
     default=False,
 )
 coreconfigitem('experimental', 'revlogv2',
     default=None,
 )
 coreconfigitem('experimental', 'single-head-per-branch',
     default=False,
 )
 coreconfigitem('experimental', 'sshserver.support-v2',
     default=False,
 )
 coreconfigitem('experimental', 'spacemovesdown',
     default=False,
 )
 coreconfigitem('experimental', 'sparse-read',
     default=False,
 )
 coreconfigitem('experimental', 'sparse-read.density-threshold',
     default=0.25,
 )
 coreconfigitem('experimental', 'sparse-read.min-gap-size',
     default='256K',
 )
 coreconfigitem('experimental', 'treemanifest',
     default=False,
 )
 coreconfigitem('experimental', 'update.atomic-file',
     default=False,
 )
 coreconfigitem('experimental', 'sshpeer.advertise-v2',
     default=False,
 )
 coreconfigitem('experimental', 'web.apiserver',
     default=False,
 )
 coreconfigitem('experimental', 'web.api.http-v2',
     default=False,
 )
 coreconfigitem('experimental', 'web.api.debugreflect',
     default=False,
 )
 coreconfigitem('experimental', 'xdiff',
     default=False,
 )
 coreconfigitem('extensions', '.*',
     default=None,
     generic=True,
 )
 coreconfigitem('extdata', '.*',
     default=None,
     generic=True,
 )
 coreconfigitem('format', 'aggressivemergedeltas',
     default=False,
 )
 coreconfigitem('format', 'chunkcachesize',
     default=None,
 )
 coreconfigitem('format', 'dotencode',
     default=True,
 )
 coreconfigitem('format', 'generaldelta',
     default=False,
 )
 coreconfigitem('format', 'manifestcachesize',
     default=None,
 )
 coreconfigitem('format', 'maxchainlen',
     default=None,
 )
 coreconfigitem('format', 'obsstore-version',
     default=None,
 )
 coreconfigitem('format', 'usefncache',
     default=True,
 )
 coreconfigitem('format', 'usegeneraldelta',
     default=True,
 )
 coreconfigitem('format', 'usestore',
     default=True,
 )
 coreconfigitem('fsmonitor', 'warn_when_unused',
     default=True,
 )
 coreconfigitem('fsmonitor', 'warn_update_file_count',
     default=50000,
 )
 coreconfigitem('hooks', '.*',
     default=dynamicdefault,
     generic=True,
 )
 coreconfigitem('hgweb-paths', '.*',
     default=list,
     generic=True,
 )
 coreconfigitem('hostfingerprints', '.*',
     default=list,
     generic=True,
 )
 coreconfigitem('hostsecurity', 'ciphers',
     default=None,
 )
 coreconfigitem('hostsecurity', 'disabletls10warning',
     default=False,
 )
 coreconfigitem('hostsecurity', 'minimumprotocol',
     default=dynamicdefault,
 )
 coreconfigitem('hostsecurity', '.*:minimumprotocol$',
     default=dynamicdefault,
     generic=True,
 )
 coreconfigitem('hostsecurity', '.*:ciphers$',
     default=dynamicdefault,
     generic=True,
 )
 coreconfigitem('hostsecurity', '.*:fingerprints$',
     default=list,
     generic=True,
 )
 coreconfigitem('hostsecurity', '.*:verifycertsfile$',
     default=None,
     generic=True,
 )
 
 coreconfigitem('http_proxy', 'always',
     default=False,
 )
 coreconfigitem('http_proxy', 'host',
     default=None,
 )
 coreconfigitem('http_proxy', 'no',
     default=list,
 )
 coreconfigitem('http_proxy', 'passwd',
     default=None,
 )
 coreconfigitem('http_proxy', 'user',
     default=None,
 )
 coreconfigitem('logtoprocess', 'commandexception',
     default=None,
 )
 coreconfigitem('logtoprocess', 'commandfinish',
     default=None,
 )
 coreconfigitem('logtoprocess', 'command',
     default=None,
 )
 coreconfigitem('logtoprocess', 'develwarn',
     default=None,
 )
 coreconfigitem('logtoprocess', 'uiblocked',
     default=None,
 )
 coreconfigitem('merge', 'checkunknown',
     default='abort',
 )
 coreconfigitem('merge', 'checkignored',
     default='abort',
 )
 coreconfigitem('experimental', 'merge.checkpathconflicts',
     default=False,
 )
 coreconfigitem('merge', 'followcopies',
     default=True,
 )
 coreconfigitem('merge', 'on-failure',
     default='continue',
 )
 coreconfigitem('merge', 'preferancestor',
         default=lambda: ['*'],
 )
 coreconfigitem('merge-tools', '.*',
     default=None,
     generic=True,
 )
 coreconfigitem('merge-tools', br'.*\.args$',
     default="$local $base $other",
     generic=True,
     priority=-1,
 )
 coreconfigitem('merge-tools', br'.*\.binary$',
     default=False,
     generic=True,
     priority=-1,
 )
 coreconfigitem('merge-tools', br'.*\.check$',
     default=list,
     generic=True,
     priority=-1,
 )
 coreconfigitem('merge-tools', br'.*\.checkchanged$',
     default=False,
     generic=True,
     priority=-1,
 )
 coreconfigitem('merge-tools', br'.*\.executable$',
     default=dynamicdefault,
     generic=True,
     priority=-1,
 )
 coreconfigitem('merge-tools', br'.*\.fixeol$',
     default=False,
     generic=True,
     priority=-1,
 )
 coreconfigitem('merge-tools', br'.*\.gui$',
     default=False,
     generic=True,
     priority=-1,
 )
 coreconfigitem('merge-tools', br'.*\.mergemarkers$',
     default='basic',
     generic=True,
     priority=-1,
 )
 coreconfigitem('merge-tools', br'.*\.mergemarkertemplate$',
     default=dynamicdefault,  # take from ui.mergemarkertemplate
     generic=True,
     priority=-1,
 )
 coreconfigitem('merge-tools', br'.*\.priority$',
     default=0,
     generic=True,
     priority=-1,
 )
 coreconfigitem('merge-tools', br'.*\.premerge$',
     default=dynamicdefault,
     generic=True,
     priority=-1,
 )
 coreconfigitem('merge-tools', br'.*\.symlink$',
     default=False,
     generic=True,
     priority=-1,
 )
 coreconfigitem('pager', 'attend-.*',
     default=dynamicdefault,
     generic=True,
 )
 coreconfigitem('pager', 'ignore',
     default=list,
 )
 coreconfigitem('pager', 'pager',
     default=dynamicdefault,
 )
 coreconfigitem('patch', 'eol',
     default='strict',
 )
 coreconfigitem('patch', 'fuzz',
     default=2,
 )
 coreconfigitem('paths', 'default',
     default=None,
 )
 coreconfigitem('paths', 'default-push',
     default=None,
 )
 coreconfigitem('paths', '.*',
     default=None,
     generic=True,
 )
 coreconfigitem('phases', 'checksubrepos',
     default='follow',
 )
 coreconfigitem('phases', 'new-commit',
     default='draft',
 )
 coreconfigitem('phases', 'publish',
     default=True,
 )
 coreconfigitem('profiling', 'enabled',
     default=False,
 )
 coreconfigitem('profiling', 'format',
     default='text',
 )
 coreconfigitem('profiling', 'freq',
     default=1000,
 )
 coreconfigitem('profiling', 'limit',
     default=30,
 )
 coreconfigitem('profiling', 'nested',
     default=0,
 )
 coreconfigitem('profiling', 'output',
     default=None,
 )
 coreconfigitem('profiling', 'showmax',
     default=0.999,
 )
 coreconfigitem('profiling', 'showmin',
     default=dynamicdefault,
 )
 coreconfigitem('profiling', 'sort',
     default='inlinetime',
 )
 coreconfigitem('profiling', 'statformat',
     default='hotpath',
 )
 coreconfigitem('profiling', 'type',
     default='stat',
 )
 coreconfigitem('progress', 'assume-tty',
     default=False,
 )
 coreconfigitem('progress', 'changedelay',
     default=1,
 )
 coreconfigitem('progress', 'clear-complete',
     default=True,
 )
 coreconfigitem('progress', 'debug',
     default=False,
 )
 coreconfigitem('progress', 'delay',
     default=3,
 )
 coreconfigitem('progress', 'disable',
     default=False,
 )
 coreconfigitem('progress', 'estimateinterval',
     default=60.0,
 )
 coreconfigitem('progress', 'format',
     default=lambda: ['topic', 'bar', 'number', 'estimate'],
 )
 coreconfigitem('progress', 'refresh',
     default=0.1,
 )
 coreconfigitem('progress', 'width',
     default=dynamicdefault,
 )
 coreconfigitem('push', 'pushvars.server',
     default=False,
 )
 coreconfigitem('server', 'bookmarks-pushkey-compat',
     default=True,
 )
 coreconfigitem('server', 'bundle1',
     default=True,
 )
 coreconfigitem('server', 'bundle1gd',
     default=None,
 )
 coreconfigitem('server', 'bundle1.pull',
     default=None,
 )
 coreconfigitem('server', 'bundle1gd.pull',
     default=None,
 )
 coreconfigitem('server', 'bundle1.push',
     default=None,
 )
 coreconfigitem('server', 'bundle1gd.push',
     default=None,
 )
 coreconfigitem('server', 'compressionengines',
     default=list,
 )
 coreconfigitem('server', 'concurrent-push-mode',
     default='strict',
 )
 coreconfigitem('server', 'disablefullbundle',
     default=False,
 )
 coreconfigitem('server', 'streamunbundle',
     default=False,
 )
 coreconfigitem('server', 'pullbundle',
     default=False,
 )
 coreconfigitem('server', 'maxhttpheaderlen',
     default=1024,
 )
 coreconfigitem('server', 'preferuncompressed',
     default=False,
 )
 coreconfigitem('server', 'uncompressed',
     default=True,
 )
 coreconfigitem('server', 'uncompressedallowsecret',
     default=False,
 )
 coreconfigitem('server', 'validate',
     default=False,
 )
 coreconfigitem('server', 'zliblevel',
     default=-1,
 )
 coreconfigitem('server', 'zstdlevel',
     default=3,
 )
 coreconfigitem('share', 'pool',
     default=None,
 )
 coreconfigitem('share', 'poolnaming',
     default='identity',
 )
 coreconfigitem('smtp', 'host',
     default=None,
 )
 coreconfigitem('smtp', 'local_hostname',
     default=None,
 )
 coreconfigitem('smtp', 'password',
     default=None,
 )
 coreconfigitem('smtp', 'port',
     default=dynamicdefault,
 )
 coreconfigitem('smtp', 'tls',
     default='none',
 )
 coreconfigitem('smtp', 'username',
     default=None,
 )
 coreconfigitem('sparse', 'missingwarning',
     default=True,
 )
 coreconfigitem('subrepos', 'allowed',
     default=dynamicdefault,  # to make backporting simpler
 )
 coreconfigitem('subrepos', 'hg:allowed',
     default=dynamicdefault,
 )
 coreconfigitem('subrepos', 'git:allowed',
     default=dynamicdefault,
 )
 coreconfigitem('subrepos', 'svn:allowed',
     default=dynamicdefault,
 )
 coreconfigitem('templates', '.*',
     default=None,
     generic=True,
 )
 coreconfigitem('trusted', 'groups',
     default=list,
 )
 coreconfigitem('trusted', 'users',
     default=list,
 )
 coreconfigitem('ui', '_usedassubrepo',
     default=False,
 )
 coreconfigitem('ui', 'allowemptycommit',
     default=False,
 )
 coreconfigitem('ui', 'archivemeta',
     default=True,
 )
 coreconfigitem('ui', 'askusername',
     default=False,
 )
 coreconfigitem('ui', 'clonebundlefallback',
     default=False,
 )
 coreconfigitem('ui', 'clonebundleprefers',
     default=list,
 )
 coreconfigitem('ui', 'clonebundles',
     default=True,
 )
 coreconfigitem('ui', 'color',
     default='auto',
 )
 coreconfigitem('ui', 'commitsubrepos',
     default=False,
 )
 coreconfigitem('ui', 'debug',
     default=False,
 )
 coreconfigitem('ui', 'debugger',
     default=None,
 )
 coreconfigitem('ui', 'editor',
     default=dynamicdefault,
 )
 coreconfigitem('ui', 'fallbackencoding',
     default=None,
 )
 coreconfigitem('ui', 'forcecwd',
     default=None,
 )
 coreconfigitem('ui', 'forcemerge',
     default=None,
 )
 coreconfigitem('ui', 'formatdebug',
     default=False,
 )
 coreconfigitem('ui', 'formatjson',
     default=False,
 )
 coreconfigitem('ui', 'formatted',
     default=None,
 )
 coreconfigitem('ui', 'graphnodetemplate',
     default=None,
 )
 coreconfigitem('ui', 'interactive',
     default=None,
 )
 coreconfigitem('ui', 'interface',
     default=None,
 )
 coreconfigitem('ui', 'interface.chunkselector',
     default=None,
 )
 coreconfigitem('ui', 'logblockedtimes',
     default=False,
 )
 coreconfigitem('ui', 'logtemplate',
     default=None,
 )
 coreconfigitem('ui', 'merge',
     default=None,
 )
 coreconfigitem('ui', 'mergemarkers',
     default='basic',
 )
 coreconfigitem('ui', 'mergemarkertemplate',
     default=('{node|short} '
             '{ifeq(tags, "tip", "", '
             'ifeq(tags, "", "", "{tags} "))}'
             '{if(bookmarks, "{bookmarks} ")}'
             '{ifeq(branch, "default", "", "{branch} ")}'
             '- {author|user}: {desc|firstline}')
 )
 coreconfigitem('ui', 'nontty',
     default=False,
 )
 coreconfigitem('ui', 'origbackuppath',
     default=None,
 )
 coreconfigitem('ui', 'paginate',
     default=True,
 )
 coreconfigitem('ui', 'patch',
     default=None,
 )
 coreconfigitem('ui', 'portablefilenames',
     default='warn',
 )
 coreconfigitem('ui', 'promptecho',
     default=False,
 )
 coreconfigitem('ui', 'quiet',
     default=False,
 )
 coreconfigitem('ui', 'quietbookmarkmove',
     default=False,
 )
 coreconfigitem('ui', 'remotecmd',
     default='hg',
 )
 coreconfigitem('ui', 'report_untrusted',
     default=True,
 )
 coreconfigitem('ui', 'rollback',
     default=True,
 )
+coreconfigitem('ui', 'signal-safe-lock',
+    default=True,
+)
 coreconfigitem('ui', 'slash',
     default=False,
 )
 coreconfigitem('ui', 'ssh',
     default='ssh',
 )
 coreconfigitem('ui', 'ssherrorhint',
     default=None,
 )
 coreconfigitem('ui', 'statuscopies',
     default=False,
 )
 coreconfigitem('ui', 'strict',
     default=False,
 )
 coreconfigitem('ui', 'style',
     default='',
 )
 coreconfigitem('ui', 'supportcontact',
     default=None,
 )
 coreconfigitem('ui', 'textwidth',
     default=78,
 )
 coreconfigitem('ui', 'timeout',
     default='600',
 )
 coreconfigitem('ui', 'timeout.warn',
     default=0,
 )
 coreconfigitem('ui', 'traceback',
     default=False,
 )
 coreconfigitem('ui', 'tweakdefaults',
     default=False,
 )
 coreconfigitem('ui', 'username',
     alias=[('ui', 'user')]
 )
 coreconfigitem('ui', 'verbose',
     default=False,
 )
 coreconfigitem('verify', 'skipflags',
     default=None,
 )
 coreconfigitem('web', 'allowbz2',
     default=False,
 )
 coreconfigitem('web', 'allowgz',
     default=False,
 )
 coreconfigitem('web', 'allow-pull',
     alias=[('web', 'allowpull')],
     default=True,
 )
 coreconfigitem('web', 'allow-push',
     alias=[('web', 'allow_push')],
     default=list,
 )
 coreconfigitem('web', 'allowzip',
     default=False,
 )
 coreconfigitem('web', 'archivesubrepos',
     default=False,
 )
 coreconfigitem('web', 'cache',
     default=True,
 )
 coreconfigitem('web', 'contact',
     default=None,
 )
 coreconfigitem('web', 'deny_push',
     default=list,
 )
 coreconfigitem('web', 'guessmime',
     default=False,
 )
 coreconfigitem('web', 'hidden',
     default=False,
 )
 coreconfigitem('web', 'labels',
     default=list,
 )
 coreconfigitem('web', 'logoimg',
     default='hglogo.png',
 )
 coreconfigitem('web', 'logourl',
     default='https://mercurial-scm.org/',
 )
 coreconfigitem('web', 'accesslog',
     default='-',
 )
 coreconfigitem('web', 'address',
     default='',
 )
 coreconfigitem('web', 'allow_archive',
     default=list,
 )
 coreconfigitem('web', 'allow_read',
     default=list,
 )
 coreconfigitem('web', 'baseurl',
     default=None,
 )
 coreconfigitem('web', 'cacerts',
     default=None,
 )
 coreconfigitem('web', 'certificate',
     default=None,
 )
 coreconfigitem('web', 'collapse',
     default=False,
 )
 coreconfigitem('web', 'csp',
     default=None,
 )
 coreconfigitem('web', 'deny_read',
     default=list,
 )
 coreconfigitem('web', 'descend',
     default=True,
 )
 coreconfigitem('web', 'description',
     default="",
 )
 coreconfigitem('web', 'encoding',
     default=lambda: encoding.encoding,
 )
 coreconfigitem('web', 'errorlog',
     default='-',
 )
 coreconfigitem('web', 'ipv6',
     default=False,
 )
 coreconfigitem('web', 'maxchanges',
     default=10,
 )
 coreconfigitem('web', 'maxfiles',
     default=10,
 )
 coreconfigitem('web', 'maxshortchanges',
     default=60,
 )
 coreconfigitem('web', 'motd',
     default='',
 )
 coreconfigitem('web', 'name',
     default=dynamicdefault,
 )
 coreconfigitem('web', 'port',
     default=8000,
 )
 coreconfigitem('web', 'prefix',
     default='',
 )
 coreconfigitem('web', 'push_ssl',
     default=True,
 )
 coreconfigitem('web', 'refreshinterval',
     default=20,
 )
 coreconfigitem('web', 'server-header',
     default=None,
 )
 coreconfigitem('web', 'staticurl',
     default=None,
 )
 coreconfigitem('web', 'stripes',
     default=1,
 )
 coreconfigitem('web', 'style',
     default='paper',
 )
 coreconfigitem('web', 'templates',
     default=None,
 )
 coreconfigitem('web', 'view',
     default='served',
 )
 coreconfigitem('worker', 'backgroundclose',
     default=dynamicdefault,
 )
 # Windows defaults to a limit of 512 open files. A buffer of 128
 # should give us enough headway.
 coreconfigitem('worker', 'backgroundclosemaxqueue',
     default=384,
 )
 coreconfigitem('worker', 'backgroundcloseminfilecount',
     default=2048,
 )
 coreconfigitem('worker', 'backgroundclosethreadcount',
     default=4,
 )
 coreconfigitem('worker', 'enabled',
     default=True,
 )
 coreconfigitem('worker', 'numcpus',
     default=None,
 )
 
 # Rebase related configuration moved to core because other extension are doing
 # strange things. For example, shelve import the extensions to reuse some bit
 # without formally loading it.
 coreconfigitem('commands', 'rebase.requiredest',
             default=False,
 )
 coreconfigitem('experimental', 'rebaseskipobsolete',
     default=True,
 )
 coreconfigitem('rebase', 'singletransaction',
     default=False,
 )
 coreconfigitem('rebase', 'experimental.inmemory',
     default=False,
 )

mercurial/localrepo.py

@@ -1,2378 +1,2381 b''
 # localrepo.py - read/write repository class for mercurial
 #
 # Copyright 2005-2007 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import
 
 import errno
 import hashlib
 import os
 import random
 import sys
 import time
 import weakref
 
 from .i18n import _
 from .node import (
     hex,
     nullid,
     short,
 )
 from . import (
     bookmarks,
     branchmap,
     bundle2,
     changegroup,
     changelog,
     color,
     context,
     dirstate,
     dirstateguard,
     discovery,
     encoding,
     error,
     exchange,
     extensions,
     filelog,
     hook,
     lock as lockmod,
     manifest,
     match as matchmod,
     merge as mergemod,
     mergeutil,
     namespaces,
     narrowspec,
     obsolete,
     pathutil,
     phases,
     pushkey,
     pycompat,
     repository,
     repoview,
     revset,
     revsetlang,
     scmutil,
     sparse,
     store,
     subrepoutil,
     tags as tagsmod,
     transaction,
     txnutil,
     util,
     vfs as vfsmod,
 )
 from .utils import (
     interfaceutil,
     procutil,
     stringutil,
 )
 
 release = lockmod.release
 urlerr = util.urlerr
 urlreq = util.urlreq
 
 # set of (path, vfs-location) tuples. vfs-location is:
 # - 'plain for vfs relative paths
 # - '' for svfs relative paths
 _cachedfiles = set()
 
 class _basefilecache(scmutil.filecache):
     """All filecache usage on repo are done for logic that should be unfiltered
     """
     def __get__(self, repo, type=None):
         if repo is None:
             return self
         return super(_basefilecache, self).__get__(repo.unfiltered(), type)
     def __set__(self, repo, value):
         return super(_basefilecache, self).__set__(repo.unfiltered(), value)
     def __delete__(self, repo):
         return super(_basefilecache, self).__delete__(repo.unfiltered())
 
 class repofilecache(_basefilecache):
     """filecache for files in .hg but outside of .hg/store"""
     def __init__(self, *paths):
         super(repofilecache, self).__init__(*paths)
         for path in paths:
             _cachedfiles.add((path, 'plain'))
 
     def join(self, obj, fname):
         return obj.vfs.join(fname)
 
 class storecache(_basefilecache):
     """filecache for files in the store"""
     def __init__(self, *paths):
         super(storecache, self).__init__(*paths)
         for path in paths:
             _cachedfiles.add((path, ''))
 
     def join(self, obj, fname):
         return obj.sjoin(fname)
 
 def isfilecached(repo, name):
     """check if a repo has already cached "name" filecache-ed property
 
     This returns (cachedobj-or-None, iscached) tuple.
     """
     cacheentry = repo.unfiltered()._filecache.get(name, None)
     if not cacheentry:
         return None, False
     return cacheentry.obj, True
 
 class unfilteredpropertycache(util.propertycache):
     """propertycache that apply to unfiltered repo only"""
 
     def __get__(self, repo, type=None):
         unfi = repo.unfiltered()
         if unfi is repo:
             return super(unfilteredpropertycache, self).__get__(unfi)
         return getattr(unfi, self.name)
 
 class filteredpropertycache(util.propertycache):
     """propertycache that must take filtering in account"""
 
     def cachevalue(self, obj, value):
         object.__setattr__(obj, self.name, value)
 
 
 def hasunfilteredcache(repo, name):
     """check if a repo has an unfilteredpropertycache value for <name>"""
     return name in vars(repo.unfiltered())
 
 def unfilteredmethod(orig):
     """decorate method that always need to be run on unfiltered version"""
     def wrapper(repo, *args, **kwargs):
         return orig(repo.unfiltered(), *args, **kwargs)
     return wrapper
 
 moderncaps = {'lookup', 'branchmap', 'pushkey', 'known', 'getbundle',
               'unbundle'}
 legacycaps = moderncaps.union({'changegroupsubset'})
 
 @interfaceutil.implementer(repository.ipeercommandexecutor)
 class localcommandexecutor(object):
     def __init__(self, peer):
         self._peer = peer
         self._sent = False
         self._closed = False
 
     def __enter__(self):
         return self
 
     def __exit__(self, exctype, excvalue, exctb):
         self.close()
 
     def callcommand(self, command, args):
         if self._sent:
             raise error.ProgrammingError('callcommand() cannot be used after '
                                          'sendcommands()')
 
         if self._closed:
             raise error.ProgrammingError('callcommand() cannot be used after '
                                          'close()')
 
         # We don't need to support anything fancy. Just call the named
         # method on the peer and return a resolved future.
         fn = getattr(self._peer, pycompat.sysstr(command))
 
         f = pycompat.futures.Future()
 
         try:
             result = fn(**pycompat.strkwargs(args))
         except Exception:
             pycompat.future_set_exception_info(f, sys.exc_info()[1:])
         else:
             f.set_result(result)
 
         return f
 
     def sendcommands(self):
         self._sent = True
 
     def close(self):
         self._closed = True
 
 @interfaceutil.implementer(repository.ipeercommands)
 class localpeer(repository.peer):
     '''peer for a local repo; reflects only the most recent API'''
 
     def __init__(self, repo, caps=None):
         super(localpeer, self).__init__()
 
         if caps is None:
             caps = moderncaps.copy()
         self._repo = repo.filtered('served')
         self.ui = repo.ui
         self._caps = repo._restrictcapabilities(caps)
 
     # Begin of _basepeer interface.
 
     def url(self):
         return self._repo.url()
 
     def local(self):
         return self._repo
 
     def peer(self):
         return self
 
     def canpush(self):
         return True
 
     def close(self):
         self._repo.close()
 
     # End of _basepeer interface.
 
     # Begin of _basewirecommands interface.
 
     def branchmap(self):
         return self._repo.branchmap()
 
     def capabilities(self):
         return self._caps
 
     def clonebundles(self):
         return self._repo.tryread('clonebundles.manifest')
 
     def debugwireargs(self, one, two, three=None, four=None, five=None):
         """Used to test argument passing over the wire"""
         return "%s %s %s %s %s" % (one, two, pycompat.bytestr(three),
                                    pycompat.bytestr(four),
                                    pycompat.bytestr(five))
 
     def getbundle(self, source, heads=None, common=None, bundlecaps=None,
                   **kwargs):
         chunks = exchange.getbundlechunks(self._repo, source, heads=heads,
                                           common=common, bundlecaps=bundlecaps,
                                           **kwargs)[1]
         cb = util.chunkbuffer(chunks)
 
         if exchange.bundle2requested(bundlecaps):
             # When requesting a bundle2, getbundle returns a stream to make the
             # wire level function happier. We need to build a proper object
             # from it in local peer.
             return bundle2.getunbundler(self.ui, cb)
         else:
             return changegroup.getunbundler('01', cb, None)
 
     def heads(self):
         return self._repo.heads()
 
     def known(self, nodes):
         return self._repo.known(nodes)
 
     def listkeys(self, namespace):
         return self._repo.listkeys(namespace)
 
     def lookup(self, key):
         return self._repo.lookup(key)
 
     def pushkey(self, namespace, key, old, new):
         return self._repo.pushkey(namespace, key, old, new)
 
     def stream_out(self):
         raise error.Abort(_('cannot perform stream clone against local '
                             'peer'))
 
     def unbundle(self, bundle, heads, url):
         """apply a bundle on a repo
 
         This function handles the repo locking itself."""
         try:
             try:
                 bundle = exchange.readbundle(self.ui, bundle, None)
                 ret = exchange.unbundle(self._repo, bundle, heads, 'push', url)
                 if util.safehasattr(ret, 'getchunks'):
                     # This is a bundle20 object, turn it into an unbundler.
                     # This little dance should be dropped eventually when the
                     # API is finally improved.
                     stream = util.chunkbuffer(ret.getchunks())
                     ret = bundle2.getunbundler(self.ui, stream)
                 return ret
             except Exception as exc:
                 # If the exception contains output salvaged from a bundle2
                 # reply, we need to make sure it is printed before continuing
                 # to fail. So we build a bundle2 with such output and consume
                 # it directly.
                 #
                 # This is not very elegant but allows a "simple" solution for
                 # issue4594
                 output = getattr(exc, '_bundle2salvagedoutput', ())
                 if output:
                     bundler = bundle2.bundle20(self._repo.ui)
                     for out in output:
                         bundler.addpart(out)
                     stream = util.chunkbuffer(bundler.getchunks())
                     b = bundle2.getunbundler(self.ui, stream)
                     bundle2.processbundle(self._repo, b)
                 raise
         except error.PushRaced as exc:
             raise error.ResponseError(_('push failed:'),
                                       stringutil.forcebytestr(exc))
 
     # End of _basewirecommands interface.
 
     # Begin of peer interface.
 
     def commandexecutor(self):
         return localcommandexecutor(self)
 
     # End of peer interface.
 
 @interfaceutil.implementer(repository.ipeerlegacycommands)
 class locallegacypeer(localpeer):
     '''peer extension which implements legacy methods too; used for tests with
     restricted capabilities'''
 
     def __init__(self, repo):
         super(locallegacypeer, self).__init__(repo, caps=legacycaps)
 
     # Begin of baselegacywirecommands interface.
 
     def between(self, pairs):
         return self._repo.between(pairs)
 
     def branches(self, nodes):
         return self._repo.branches(nodes)
 
     def changegroup(self, nodes, source):
         outgoing = discovery.outgoing(self._repo, missingroots=nodes,
                                       missingheads=self._repo.heads())
         return changegroup.makechangegroup(self._repo, outgoing, '01', source)
 
     def changegroupsubset(self, bases, heads, source):
         outgoing = discovery.outgoing(self._repo, missingroots=bases,
                                       missingheads=heads)
         return changegroup.makechangegroup(self._repo, outgoing, '01', source)
 
     # End of baselegacywirecommands interface.
 
 # Increment the sub-version when the revlog v2 format changes to lock out old
 # clients.
 REVLOGV2_REQUIREMENT = 'exp-revlogv2.0'
 
 # Functions receiving (ui, features) that extensions can register to impact
 # the ability to load repositories with custom requirements. Only
 # functions defined in loaded extensions are called.
 #
 # The function receives a set of requirement strings that the repository
 # is capable of opening. Functions will typically add elements to the
 # set to reflect that the extension knows how to handle that requirements.
 featuresetupfuncs = set()
 
 @interfaceutil.implementer(repository.completelocalrepository)
 class localrepository(object):
 
     # obsolete experimental requirements:
     #  - manifestv2: An experimental new manifest format that allowed
     #    for stem compression of long paths. Experiment ended up not
     #    being successful (repository sizes went up due to worse delta
     #    chains), and the code was deleted in 4.6.
     supportedformats = {
         'revlogv1',
         'generaldelta',
         'treemanifest',
         REVLOGV2_REQUIREMENT,
     }
     _basesupported = supportedformats | {
         'store',
         'fncache',
         'shared',
         'relshared',
         'dotencode',
         'exp-sparse',
     }
     openerreqs = {
         'revlogv1',
         'generaldelta',
         'treemanifest',
     }
 
     # list of prefix for file which can be written without 'wlock'
     # Extensions should extend this list when needed
     _wlockfreeprefix = {
         # We migh consider requiring 'wlock' for the next
         # two, but pretty much all the existing code assume
         # wlock is not needed so we keep them excluded for
         # now.
         'hgrc',
         'requires',
         # XXX cache is a complicatged business someone
         # should investigate this in depth at some point
         'cache/',
         # XXX shouldn't be dirstate covered by the wlock?
         'dirstate',
         # XXX bisect was still a bit too messy at the time
         # this changeset was introduced. Someone should fix
         # the remainig bit and drop this line
         'bisect.state',
     }
 
     def __init__(self, baseui, path, create=False, intents=None):
         self.requirements = set()
         self.filtername = None
         # wvfs: rooted at the repository root, used to access the working copy
         self.wvfs = vfsmod.vfs(path, expandpath=True, realpath=True)
         # vfs: rooted at .hg, used to access repo files outside of .hg/store
         self.vfs = None
         # svfs: usually rooted at .hg/store, used to access repository history
         # If this is a shared repository, this vfs may point to another
         # repository's .hg/store directory.
         self.svfs = None
         self.root = self.wvfs.base
         self.path = self.wvfs.join(".hg")
         self.origroot = path
         # This is only used by context.workingctx.match in order to
         # detect files in subrepos.
         self.auditor = pathutil.pathauditor(
             self.root, callback=self._checknested)
         # This is only used by context.basectx.match in order to detect
         # files in subrepos.
         self.nofsauditor = pathutil.pathauditor(
             self.root, callback=self._checknested, realfs=False, cached=True)
         self.baseui = baseui
         self.ui = baseui.copy()
         self.ui.copy = baseui.copy # prevent copying repo configuration
         self.vfs = vfsmod.vfs(self.path, cacheaudited=True)
         if (self.ui.configbool('devel', 'all-warnings') or
             self.ui.configbool('devel', 'check-locks')):
             self.vfs.audit = self._getvfsward(self.vfs.audit)
         # A list of callback to shape the phase if no data were found.
         # Callback are in the form: func(repo, roots) --> processed root.
         # This list it to be filled by extension during repo setup
         self._phasedefaults = []
         try:
             self.ui.readconfig(self.vfs.join("hgrc"), self.root)
             self._loadextensions()
         except IOError:
             pass
 
         if featuresetupfuncs:
             self.supported = set(self._basesupported) # use private copy
             extmods = set(m.__name__ for n, m
                           in extensions.extensions(self.ui))
             for setupfunc in featuresetupfuncs:
                 if setupfunc.__module__ in extmods:
                     setupfunc(self.ui, self.supported)
         else:
             self.supported = self._basesupported
         color.setup(self.ui)
 
         # Add compression engines.
         for name in util.compengines:
             engine = util.compengines[name]
             if engine.revlogheader():
                 self.supported.add('exp-compression-%s' % name)
 
         if not self.vfs.isdir():
             if create:
                 self.requirements = newreporequirements(self)
 
                 if not self.wvfs.exists():
                     self.wvfs.makedirs()
                 self.vfs.makedir(notindexed=True)
 
                 if 'store' in self.requirements:
                     self.vfs.mkdir("store")
 
                     # create an invalid changelog
                     self.vfs.append(
                         "00changelog.i",
                         '\0\0\0\2' # represents revlogv2
                         ' dummy changelog to prevent using the old repo layout'
                     )
             else:
                 raise error.RepoError(_("repository %s not found") % path)
         elif create:
             raise error.RepoError(_("repository %s already exists") % path)
         else:
             try:
                 self.requirements = scmutil.readrequires(
                         self.vfs, self.supported)
             except IOError as inst:
                 if inst.errno != errno.ENOENT:
                     raise
 
         cachepath = self.vfs.join('cache')
         self.sharedpath = self.path
         try:
             sharedpath = self.vfs.read("sharedpath").rstrip('\n')
             if 'relshared' in self.requirements:
                 sharedpath = self.vfs.join(sharedpath)
             vfs = vfsmod.vfs(sharedpath, realpath=True)
             cachepath = vfs.join('cache')
             s = vfs.base
             if not vfs.exists():
                 raise error.RepoError(
                     _('.hg/sharedpath points to nonexistent directory %s') % s)
             self.sharedpath = s
         except IOError as inst:
             if inst.errno != errno.ENOENT:
                 raise
 
         if 'exp-sparse' in self.requirements and not sparse.enabled:
             raise error.RepoError(_('repository is using sparse feature but '
                                     'sparse is not enabled; enable the '
                                     '"sparse" extensions to access'))
 
         self.store = store.store(
             self.requirements, self.sharedpath,
             lambda base: vfsmod.vfs(base, cacheaudited=True))
         self.spath = self.store.path
         self.svfs = self.store.vfs
         self.sjoin = self.store.join
         self.vfs.createmode = self.store.createmode
         self.cachevfs = vfsmod.vfs(cachepath, cacheaudited=True)
         self.cachevfs.createmode = self.store.createmode
         if (self.ui.configbool('devel', 'all-warnings') or
             self.ui.configbool('devel', 'check-locks')):
             if util.safehasattr(self.svfs, 'vfs'): # this is filtervfs
                 self.svfs.vfs.audit = self._getsvfsward(self.svfs.vfs.audit)
             else: # standard vfs
                 self.svfs.audit = self._getsvfsward(self.svfs.audit)
         self._applyopenerreqs()
         if create:
             self._writerequirements()
 
         self._dirstatevalidatewarned = False
 
         self._branchcaches = {}
         self._revbranchcache = None
         self._filterpats = {}
         self._datafilters = {}
         self._transref = self._lockref = self._wlockref = None
 
         # A cache for various files under .hg/ that tracks file changes,
         # (used by the filecache decorator)
         #
         # Maps a property name to its util.filecacheentry
         self._filecache = {}
 
         # hold sets of revision to be filtered
         # should be cleared when something might have changed the filter value:
         # - new changesets,
         # - phase change,
         # - new obsolescence marker,
         # - working directory parent change,
         # - bookmark changes
         self.filteredrevcache = {}
 
         # post-dirstate-status hooks
         self._postdsstatus = []
 
         # generic mapping between names and nodes
         self.names = namespaces.namespaces()
 
         # Key to signature value.
         self._sparsesignaturecache = {}
         # Signature to cached matcher instance.
         self._sparsematchercache = {}
 
     def _getvfsward(self, origfunc):
         """build a ward for self.vfs"""
         rref = weakref.ref(self)
         def checkvfs(path, mode=None):
             ret = origfunc(path, mode=mode)
             repo = rref()
             if (repo is None
                 or not util.safehasattr(repo, '_wlockref')
                 or not util.safehasattr(repo, '_lockref')):
                 return
             if mode in (None, 'r', 'rb'):
                 return
             if path.startswith(repo.path):
                 # truncate name relative to the repository (.hg)
                 path = path[len(repo.path) + 1:]
             if path.startswith('cache/'):
                 msg = 'accessing cache with vfs instead of cachevfs: "%s"'
                 repo.ui.develwarn(msg % path, stacklevel=2, config="cache-vfs")
             if path.startswith('journal.'):
                 # journal is covered by 'lock'
                 if repo._currentlock(repo._lockref) is None:
                     repo.ui.develwarn('write with no lock: "%s"' % path,
                                       stacklevel=2, config='check-locks')
             elif repo._currentlock(repo._wlockref) is None:
                 # rest of vfs files are covered by 'wlock'
                 #
                 # exclude special files
                 for prefix in self._wlockfreeprefix:
                     if path.startswith(prefix):
                         return
                 repo.ui.develwarn('write with no wlock: "%s"' % path,
                                   stacklevel=2, config='check-locks')
             return ret
         return checkvfs
 
     def _getsvfsward(self, origfunc):
         """build a ward for self.svfs"""
         rref = weakref.ref(self)
         def checksvfs(path, mode=None):
             ret = origfunc(path, mode=mode)
             repo = rref()
             if repo is None or not util.safehasattr(repo, '_lockref'):
                 return
             if mode in (None, 'r', 'rb'):
                 return
             if path.startswith(repo.sharedpath):
                 # truncate name relative to the repository (.hg)
                 path = path[len(repo.sharedpath) + 1:]
             if repo._currentlock(repo._lockref) is None:
                 repo.ui.develwarn('write with no lock: "%s"' % path,
                                   stacklevel=3)
             return ret
         return checksvfs
 
     def close(self):
         self._writecaches()
 
     def _loadextensions(self):
         extensions.loadall(self.ui)
 
     def _writecaches(self):
         if self._revbranchcache:
             self._revbranchcache.write()
 
     def _restrictcapabilities(self, caps):
         if self.ui.configbool('experimental', 'bundle2-advertise'):
             caps = set(caps)
             capsblob = bundle2.encodecaps(bundle2.getrepocaps(self,
                                                               role='client'))
             caps.add('bundle2=' + urlreq.quote(capsblob))
         return caps
 
     def _applyopenerreqs(self):
         self.svfs.options = dict((r, 1) for r in self.requirements
                                            if r in self.openerreqs)
         # experimental config: format.chunkcachesize
         chunkcachesize = self.ui.configint('format', 'chunkcachesize')
         if chunkcachesize is not None:
             self.svfs.options['chunkcachesize'] = chunkcachesize
         # experimental config: format.maxchainlen
         maxchainlen = self.ui.configint('format', 'maxchainlen')
         if maxchainlen is not None:
             self.svfs.options['maxchainlen'] = maxchainlen
         # experimental config: format.manifestcachesize
         manifestcachesize = self.ui.configint('format', 'manifestcachesize')
         if manifestcachesize is not None:
             self.svfs.options['manifestcachesize'] = manifestcachesize
         # experimental config: format.aggressivemergedeltas
         aggressivemergedeltas = self.ui.configbool('format',
                                                    'aggressivemergedeltas')
         self.svfs.options['aggressivemergedeltas'] = aggressivemergedeltas
         self.svfs.options['lazydeltabase'] = not scmutil.gddeltaconfig(self.ui)
         chainspan = self.ui.configbytes('experimental', 'maxdeltachainspan')
         if 0 <= chainspan:
             self.svfs.options['maxdeltachainspan'] = chainspan
         mmapindexthreshold = self.ui.configbytes('experimental',
                                                  'mmapindexthreshold')
         if mmapindexthreshold is not None:
             self.svfs.options['mmapindexthreshold'] = mmapindexthreshold
         withsparseread = self.ui.configbool('experimental', 'sparse-read')
         srdensitythres = float(self.ui.config('experimental',
                                               'sparse-read.density-threshold'))
         srmingapsize = self.ui.configbytes('experimental',
                                            'sparse-read.min-gap-size')
         self.svfs.options['with-sparse-read'] = withsparseread
         self.svfs.options['sparse-read-density-threshold'] = srdensitythres
         self.svfs.options['sparse-read-min-gap-size'] = srmingapsize
 
         for r in self.requirements:
             if r.startswith('exp-compression-'):
                 self.svfs.options['compengine'] = r[len('exp-compression-'):]
 
         # TODO move "revlogv2" to openerreqs once finalized.
         if REVLOGV2_REQUIREMENT in self.requirements:
             self.svfs.options['revlogv2'] = True
 
     def _writerequirements(self):
         scmutil.writerequires(self.vfs, self.requirements)
 
     def _checknested(self, path):
         """Determine if path is a legal nested repository."""
         if not path.startswith(self.root):
             return False
         subpath = path[len(self.root) + 1:]
         normsubpath = util.pconvert(subpath)
 
         # XXX: Checking against the current working copy is wrong in
         # the sense that it can reject things like
         #
         #   $ hg cat -r 10 sub/x.txt
         #
         # if sub/ is no longer a subrepository in the working copy
         # parent revision.
         #
         # However, it can of course also allow things that would have
         # been rejected before, such as the above cat command if sub/
         # is a subrepository now, but was a normal directory before.
         # The old path auditor would have rejected by mistake since it
         # panics when it sees sub/.hg/.
         #
         # All in all, checking against the working copy seems sensible
         # since we want to prevent access to nested repositories on
         # the filesystem *now*.
         ctx = self[None]
         parts = util.splitpath(subpath)
         while parts:
             prefix = '/'.join(parts)
             if prefix in ctx.substate:
                 if prefix == normsubpath:
                     return True
                 else:
                     sub = ctx.sub(prefix)
                     return sub.checknested(subpath[len(prefix) + 1:])
             else:
                 parts.pop()
         return False
 
     def peer(self):
         return localpeer(self) # not cached to avoid reference cycle
 
     def unfiltered(self):
         """Return unfiltered version of the repository
 
         Intended to be overwritten by filtered repo."""
         return self
 
     def filtered(self, name, visibilityexceptions=None):
         """Return a filtered version of a repository"""
         cls = repoview.newtype(self.unfiltered().__class__)
         return cls(self, name, visibilityexceptions)
 
     @repofilecache('bookmarks', 'bookmarks.current')
     def _bookmarks(self):
         return bookmarks.bmstore(self)
 
     @property
     def _activebookmark(self):
         return self._bookmarks.active
 
     # _phasesets depend on changelog. what we need is to call
     # _phasecache.invalidate() if '00changelog.i' was changed, but it
     # can't be easily expressed in filecache mechanism.
     @storecache('phaseroots', '00changelog.i')
     def _phasecache(self):
         return phases.phasecache(self, self._phasedefaults)
 
     @storecache('obsstore')
     def obsstore(self):
         return obsolete.makestore(self.ui, self)
 
     @storecache('00changelog.i')
     def changelog(self):
         return changelog.changelog(self.svfs,
                                    trypending=txnutil.mayhavepending(self.root))
 
     def _constructmanifest(self):
         # This is a temporary function while we migrate from manifest to
         # manifestlog. It allows bundlerepo and unionrepo to intercept the
         # manifest creation.
         return manifest.manifestrevlog(self.svfs)
 
     @storecache('00manifest.i')
     def manifestlog(self):
         return manifest.manifestlog(self.svfs, self)
 
     @repofilecache('dirstate')
     def dirstate(self):
         sparsematchfn = lambda: sparse.matcher(self)
 
         return dirstate.dirstate(self.vfs, self.ui, self.root,
                                  self._dirstatevalidate, sparsematchfn)
 
     def _dirstatevalidate(self, node):
         try:
             self.changelog.rev(node)
             return node
         except error.LookupError:
             if not self._dirstatevalidatewarned:
                 self._dirstatevalidatewarned = True
                 self.ui.warn(_("warning: ignoring unknown"
                                " working parent %s!\n") % short(node))
             return nullid
 
     @repofilecache(narrowspec.FILENAME)
     def narrowpats(self):
         """matcher patterns for this repository's narrowspec
 
         A tuple of (includes, excludes).
         """
         source = self
         if self.shared():
             from . import hg
             source = hg.sharedreposource(self)
         return narrowspec.load(source)
 
     @repofilecache(narrowspec.FILENAME)
     def _narrowmatch(self):
         if changegroup.NARROW_REQUIREMENT not in self.requirements:
             return matchmod.always(self.root, '')
         include, exclude = self.narrowpats
         return narrowspec.match(self.root, include=include, exclude=exclude)
 
     # TODO(martinvonz): make this property-like instead?
     def narrowmatch(self):
         return self._narrowmatch
 
     def setnarrowpats(self, newincludes, newexcludes):
         target = self
         if self.shared():
             from . import hg
             target = hg.sharedreposource(self)
         narrowspec.save(target, newincludes, newexcludes)
         self.invalidate(clearfilecache=True)
 
     def __getitem__(self, changeid):
         if changeid is None:
             return context.workingctx(self)
         if isinstance(changeid, context.basectx):
             return changeid
         if isinstance(changeid, slice):
             # wdirrev isn't contiguous so the slice shouldn't include it
             return [context.changectx(self, i)
                     for i in xrange(*changeid.indices(len(self)))
                     if i not in self.changelog.filteredrevs]
         try:
             return context.changectx(self, changeid)
         except error.WdirUnsupported:
             return context.workingctx(self)
 
     def __contains__(self, changeid):
         """True if the given changeid exists
 
         error.LookupError is raised if an ambiguous node specified.
         """
         try:
             self[changeid]
             return True
         except error.RepoLookupError:
             return False
 
     def __nonzero__(self):
         return True
 
     __bool__ = __nonzero__
 
     def __len__(self):
         # no need to pay the cost of repoview.changelog
         unfi = self.unfiltered()
         return len(unfi.changelog)
 
     def __iter__(self):
         return iter(self.changelog)
 
     def revs(self, expr, *args):
         '''Find revisions matching a revset.
 
         The revset is specified as a string ``expr`` that may contain
         %-formatting to escape certain types. See ``revsetlang.formatspec``.
 
         Revset aliases from the configuration are not expanded. To expand
         user aliases, consider calling ``scmutil.revrange()`` or
         ``repo.anyrevs([expr], user=True)``.
 
         Returns a revset.abstractsmartset, which is a list-like interface
         that contains integer revisions.
         '''
         expr = revsetlang.formatspec(expr, *args)
         m = revset.match(None, expr)
         return m(self)
 
     def set(self, expr, *args):
         '''Find revisions matching a revset and emit changectx instances.
 
         This is a convenience wrapper around ``revs()`` that iterates the
         result and is a generator of changectx instances.
 
         Revset aliases from the configuration are not expanded. To expand
         user aliases, consider calling ``scmutil.revrange()``.
         '''
         for r in self.revs(expr, *args):
             yield self[r]
 
     def anyrevs(self, specs, user=False, localalias=None):
         '''Find revisions matching one of the given revsets.
 
         Revset aliases from the configuration are not expanded by default. To
         expand user aliases, specify ``user=True``. To provide some local
         definitions overriding user aliases, set ``localalias`` to
         ``{name: definitionstring}``.
         '''
         if user:
             m = revset.matchany(self.ui, specs,
                                 lookup=revset.lookupfn(self),
                                 localalias=localalias)
         else:
             m = revset.matchany(None, specs, localalias=localalias)
         return m(self)
 
     def url(self):
         return 'file:' + self.root
 
     def hook(self, name, throw=False, **args):
         """Call a hook, passing this repo instance.
 
         This a convenience method to aid invoking hooks. Extensions likely
         won't call this unless they have registered a custom hook or are
         replacing code that is expected to call a hook.
         """
         return hook.hook(self.ui, self, name, throw, **args)
 
     @filteredpropertycache
     def _tagscache(self):
         '''Returns a tagscache object that contains various tags related
         caches.'''
 
         # This simplifies its cache management by having one decorated
         # function (this one) and the rest simply fetch things from it.
         class tagscache(object):
             def __init__(self):
                 # These two define the set of tags for this repository. tags
                 # maps tag name to node; tagtypes maps tag name to 'global' or
                 # 'local'. (Global tags are defined by .hgtags across all
                 # heads, and local tags are defined in .hg/localtags.)
                 # They constitute the in-memory cache of tags.
                 self.tags = self.tagtypes = None
 
                 self.nodetagscache = self.tagslist = None
 
         cache = tagscache()
         cache.tags, cache.tagtypes = self._findtags()
 
         return cache
 
     def tags(self):
         '''return a mapping of tag to node'''
         t = {}
         if self.changelog.filteredrevs:
             tags, tt = self._findtags()
         else:
             tags = self._tagscache.tags
         for k, v in tags.iteritems():
             try:
                 # ignore tags to unknown nodes
                 self.changelog.rev(v)
                 t[k] = v
             except (error.LookupError, ValueError):
                 pass
         return t
 
     def _findtags(self):
         '''Do the hard work of finding tags.  Return a pair of dicts
         (tags, tagtypes) where tags maps tag name to node, and tagtypes
         maps tag name to a string like \'global\' or \'local\'.
         Subclasses or extensions are free to add their own tags, but
         should be aware that the returned dicts will be retained for the
         duration of the localrepo object.'''
 
         # XXX what tagtype should subclasses/extensions use?  Currently
         # mq and bookmarks add tags, but do not set the tagtype at all.
         # Should each extension invent its own tag type?  Should there
         # be one tagtype for all such "virtual" tags?  Or is the status
         # quo fine?
 
 
         # map tag name to (node, hist)
         alltags = tagsmod.findglobaltags(self.ui, self)
         # map tag name to tag type
         tagtypes = dict((tag, 'global') for tag in alltags)
 
         tagsmod.readlocaltags(self.ui, self, alltags, tagtypes)
 
         # Build the return dicts.  Have to re-encode tag names because
         # the tags module always uses UTF-8 (in order not to lose info
         # writing to the cache), but the rest of Mercurial wants them in
         # local encoding.
         tags = {}
         for (name, (node, hist)) in alltags.iteritems():
             if node != nullid:
                 tags[encoding.tolocal(name)] = node
         tags['tip'] = self.changelog.tip()
         tagtypes = dict([(encoding.tolocal(name), value)
                          for (name, value) in tagtypes.iteritems()])
         return (tags, tagtypes)
 
     def tagtype(self, tagname):
         '''
         return the type of the given tag. result can be:
 
         'local'  : a local tag
         'global' : a global tag
         None     : tag does not exist
         '''
 
         return self._tagscache.tagtypes.get(tagname)
 
     def tagslist(self):
         '''return a list of tags ordered by revision'''
         if not self._tagscache.tagslist:
             l = []
             for t, n in self.tags().iteritems():
                 l.append((self.changelog.rev(n), t, n))
             self._tagscache.tagslist = [(t, n) for r, t, n in sorted(l)]
 
         return self._tagscache.tagslist
 
     def nodetags(self, node):
         '''return the tags associated with a node'''
         if not self._tagscache.nodetagscache:
             nodetagscache = {}
             for t, n in self._tagscache.tags.iteritems():
                 nodetagscache.setdefault(n, []).append(t)
             for tags in nodetagscache.itervalues():
                 tags.sort()
             self._tagscache.nodetagscache = nodetagscache
         return self._tagscache.nodetagscache.get(node, [])
 
     def nodebookmarks(self, node):
         """return the list of bookmarks pointing to the specified node"""
         marks = []
         for bookmark, n in self._bookmarks.iteritems():
             if n == node:
                 marks.append(bookmark)
         return sorted(marks)
 
     def branchmap(self):
         '''returns a dictionary {branch: [branchheads]} with branchheads
         ordered by increasing revision number'''
         branchmap.updatecache(self)
         return self._branchcaches[self.filtername]
 
     @unfilteredmethod
     def revbranchcache(self):
         if not self._revbranchcache:
             self._revbranchcache = branchmap.revbranchcache(self.unfiltered())
         return self._revbranchcache
 
     def branchtip(self, branch, ignoremissing=False):
         '''return the tip node for a given branch
 
         If ignoremissing is True, then this method will not raise an error.
         This is helpful for callers that only expect None for a missing branch
         (e.g. namespace).
 
         '''
         try:
             return self.branchmap().branchtip(branch)
         except KeyError:
             if not ignoremissing:
                 raise error.RepoLookupError(_("unknown branch '%s'") % branch)
             else:
                 pass
 
     def lookup(self, key):
         return scmutil.revsymbol(self, key).node()
 
     def lookupbranch(self, key):
         if key in self.branchmap():
             return key
 
         return scmutil.revsymbol(self, key).branch()
 
     def known(self, nodes):
         cl = self.changelog
         nm = cl.nodemap
         filtered = cl.filteredrevs
         result = []
         for n in nodes:
             r = nm.get(n)
             resp = not (r is None or r in filtered)
             result.append(resp)
         return result
 
     def local(self):
         return self
 
     def publishing(self):
         # it's safe (and desirable) to trust the publish flag unconditionally
         # so that we don't finalize changes shared between users via ssh or nfs
         return self.ui.configbool('phases', 'publish', untrusted=True)
 
     def cancopy(self):
         # so statichttprepo's override of local() works
         if not self.local():
             return False
         if not self.publishing():
             return True
         # if publishing we can't copy if there is filtered content
         return not self.filtered('visible').changelog.filteredrevs
 
     def shared(self):
         '''the type of shared repository (None if not shared)'''
         if self.sharedpath != self.path:
             return 'store'
         return None
 
     def wjoin(self, f, *insidef):
         return self.vfs.reljoin(self.root, f, *insidef)
 
     def file(self, f):
         if f[0] == '/':
             f = f[1:]
         return filelog.filelog(self.svfs, f)
 
     def setparents(self, p1, p2=nullid):
         with self.dirstate.parentchange():
             copies = self.dirstate.setparents(p1, p2)
             pctx = self[p1]
             if copies:
                 # Adjust copy records, the dirstate cannot do it, it
                 # requires access to parents manifests. Preserve them
                 # only for entries added to first parent.
                 for f in copies:
                     if f not in pctx and copies[f] in pctx:
                         self.dirstate.copy(copies[f], f)
             if p2 == nullid:
                 for f, s in sorted(self.dirstate.copies().items()):
                     if f not in pctx and s not in pctx:
                         self.dirstate.copy(None, f)
 
     def filectx(self, path, changeid=None, fileid=None, changectx=None):
         """changeid can be a changeset revision, node, or tag.
            fileid can be a file revision or node."""
         return context.filectx(self, path, changeid, fileid,
                                changectx=changectx)
 
     def getcwd(self):
         return self.dirstate.getcwd()
 
     def pathto(self, f, cwd=None):
         return self.dirstate.pathto(f, cwd)
 
     def _loadfilter(self, filter):
         if filter not in self._filterpats:
             l = []
             for pat, cmd in self.ui.configitems(filter):
                 if cmd == '!':
                     continue
                 mf = matchmod.match(self.root, '', [pat])
                 fn = None
                 params = cmd
                 for name, filterfn in self._datafilters.iteritems():
                     if cmd.startswith(name):
                         fn = filterfn
                         params = cmd[len(name):].lstrip()
                         break
                 if not fn:
                     fn = lambda s, c, **kwargs: procutil.filter(s, c)
                 # Wrap old filters not supporting keyword arguments
                 if not pycompat.getargspec(fn)[2]:
                     oldfn = fn
                     fn = lambda s, c, **kwargs: oldfn(s, c)
                 l.append((mf, fn, params))
             self._filterpats[filter] = l
         return self._filterpats[filter]
 
     def _filter(self, filterpats, filename, data):
         for mf, fn, cmd in filterpats:
             if mf(filename):
                 self.ui.debug("filtering %s through %s\n" % (filename, cmd))
                 data = fn(data, cmd, ui=self.ui, repo=self, filename=filename)
                 break
 
         return data
 
     @unfilteredpropertycache
     def _encodefilterpats(self):
         return self._loadfilter('encode')
 
     @unfilteredpropertycache
     def _decodefilterpats(self):
         return self._loadfilter('decode')
 
     def adddatafilter(self, name, filter):
         self._datafilters[name] = filter
 
     def wread(self, filename):
         if self.wvfs.islink(filename):
             data = self.wvfs.readlink(filename)
         else:
             data = self.wvfs.read(filename)
         return self._filter(self._encodefilterpats, filename, data)
 
     def wwrite(self, filename, data, flags, backgroundclose=False, **kwargs):
         """write ``data`` into ``filename`` in the working directory
 
         This returns length of written (maybe decoded) data.
         """
         data = self._filter(self._decodefilterpats, filename, data)
         if 'l' in flags:
             self.wvfs.symlink(data, filename)
         else:
             self.wvfs.write(filename, data, backgroundclose=backgroundclose,
                             **kwargs)
             if 'x' in flags:
                 self.wvfs.setflags(filename, False, True)
             else:
                 self.wvfs.setflags(filename, False, False)
         return len(data)
 
     def wwritedata(self, filename, data):
         return self._filter(self._decodefilterpats, filename, data)
 
     def currenttransaction(self):
         """return the current transaction or None if non exists"""
         if self._transref:
             tr = self._transref()
         else:
             tr = None
 
         if tr and tr.running():
             return tr
         return None
 
     def transaction(self, desc, report=None):
         if (self.ui.configbool('devel', 'all-warnings')
                 or self.ui.configbool('devel', 'check-locks')):
             if self._currentlock(self._lockref) is None:
                 raise error.ProgrammingError('transaction requires locking')
         tr = self.currenttransaction()
         if tr is not None:
             return tr.nest(name=desc)
 
         # abort here if the journal already exists
         if self.svfs.exists("journal"):
             raise error.RepoError(
                 _("abandoned transaction found"),
                 hint=_("run 'hg recover' to clean up transaction"))
 
         idbase = "%.40f#%f" % (random.random(), time.time())
         ha = hex(hashlib.sha1(idbase).digest())
         txnid = 'TXN:' + ha
         self.hook('pretxnopen', throw=True, txnname=desc, txnid=txnid)
 
         self._writejournal(desc)
         renames = [(vfs, x, undoname(x)) for vfs, x in self._journalfiles()]
         if report:
             rp = report
         else:
             rp = self.ui.warn
         vfsmap = {'plain': self.vfs} # root of .hg/
         # we must avoid cyclic reference between repo and transaction.
         reporef = weakref.ref(self)
         # Code to track tag movement
         #
         # Since tags are all handled as file content, it is actually quite hard
         # to track these movement from a code perspective. So we fallback to a
         # tracking at the repository level. One could envision to track changes
         # to the '.hgtags' file through changegroup apply but that fails to
         # cope with case where transaction expose new heads without changegroup
         # being involved (eg: phase movement).
         #
         # For now, We gate the feature behind a flag since this likely comes
         # with performance impacts. The current code run more often than needed
         # and do not use caches as much as it could.  The current focus is on
         # the behavior of the feature so we disable it by default. The flag
         # will be removed when we are happy with the performance impact.
         #
         # Once this feature is no longer experimental move the following
         # documentation to the appropriate help section:
         #
         # The ``HG_TAG_MOVED`` variable will be set if the transaction touched
         # tags (new or changed or deleted tags). In addition the details of
         # these changes are made available in a file at:
         #     ``REPOROOT/.hg/changes/tags.changes``.
         # Make sure you check for HG_TAG_MOVED before reading that file as it
         # might exist from a previous transaction even if no tag were touched
         # in this one. Changes are recorded in a line base format::
         #
         #     <action> <hex-node> <tag-name>\n
         #
         # Actions are defined as follow:
         #   "-R": tag is removed,
         #   "+A": tag is added,
         #   "-M": tag is moved (old value),
         #   "+M": tag is moved (new value),
         tracktags = lambda x: None
         # experimental config: experimental.hook-track-tags
         shouldtracktags = self.ui.configbool('experimental', 'hook-track-tags')
         if desc != 'strip' and shouldtracktags:
             oldheads = self.changelog.headrevs()
             def tracktags(tr2):
                 repo = reporef()
                 oldfnodes = tagsmod.fnoderevs(repo.ui, repo, oldheads)
                 newheads = repo.changelog.headrevs()
                 newfnodes = tagsmod.fnoderevs(repo.ui, repo, newheads)
                 # notes: we compare lists here.
                 # As we do it only once buiding set would not be cheaper
                 changes = tagsmod.difftags(repo.ui, repo, oldfnodes, newfnodes)
                 if changes:
                     tr2.hookargs['tag_moved'] = '1'
                     with repo.vfs('changes/tags.changes', 'w',
                                   atomictemp=True) as changesfile:
                         # note: we do not register the file to the transaction
                         # because we needs it to still exist on the transaction
                         # is close (for txnclose hooks)
                         tagsmod.writediff(changesfile, changes)
         def validate(tr2):
             """will run pre-closing hooks"""
             # XXX the transaction API is a bit lacking here so we take a hacky
             # path for now
             #
             # We cannot add this as a "pending" hooks since the 'tr.hookargs'
             # dict is copied before these run. In addition we needs the data
             # available to in memory hooks too.
             #
             # Moreover, we also need to make sure this runs before txnclose
             # hooks and there is no "pending" mechanism that would execute
             # logic only if hooks are about to run.
             #
             # Fixing this limitation of the transaction is also needed to track
             # other families of changes (bookmarks, phases, obsolescence).
             #
             # This will have to be fixed before we remove the experimental
             # gating.
             tracktags(tr2)
             repo = reporef()
             if repo.ui.configbool('experimental', 'single-head-per-branch'):
                 scmutil.enforcesinglehead(repo, tr2, desc)
             if hook.hashook(repo.ui, 'pretxnclose-bookmark'):
                 for name, (old, new) in sorted(tr.changes['bookmarks'].items()):
                     args = tr.hookargs.copy()
                     args.update(bookmarks.preparehookargs(name, old, new))
                     repo.hook('pretxnclose-bookmark', throw=True,
                               txnname=desc,
                               **pycompat.strkwargs(args))
             if hook.hashook(repo.ui, 'pretxnclose-phase'):
                 cl = repo.unfiltered().changelog
                 for rev, (old, new) in tr.changes['phases'].items():
                     args = tr.hookargs.copy()
                     node = hex(cl.node(rev))
                     args.update(phases.preparehookargs(node, old, new))
                     repo.hook('pretxnclose-phase', throw=True, txnname=desc,
                               **pycompat.strkwargs(args))
 
             repo.hook('pretxnclose', throw=True,
                       txnname=desc, **pycompat.strkwargs(tr.hookargs))
         def releasefn(tr, success):
             repo = reporef()
             if success:
                 # this should be explicitly invoked here, because
                 # in-memory changes aren't written out at closing
                 # transaction, if tr.addfilegenerator (via
                 # dirstate.write or so) isn't invoked while
                 # transaction running
                 repo.dirstate.write(None)
             else:
                 # discard all changes (including ones already written
                 # out) in this transaction
                 repo.dirstate.restorebackup(None, 'journal.dirstate')
 
                 repo.invalidate(clearfilecache=True)
 
         tr = transaction.transaction(rp, self.svfs, vfsmap,
                                      "journal",
                                      "undo",
                                      aftertrans(renames),
                                      self.store.createmode,
                                      validator=validate,
                                      releasefn=releasefn,
                                      checkambigfiles=_cachedfiles,
                                      name=desc)
         tr.changes['revs'] = xrange(0, 0)
         tr.changes['obsmarkers'] = set()
         tr.changes['phases'] = {}
         tr.changes['bookmarks'] = {}
 
         tr.hookargs['txnid'] = txnid
         # note: writing the fncache only during finalize mean that the file is
         # outdated when running hooks. As fncache is used for streaming clone,
         # this is not expected to break anything that happen during the hooks.
         tr.addfinalize('flush-fncache', self.store.write)
         def txnclosehook(tr2):
             """To be run if transaction is successful, will schedule a hook run
             """
             # Don't reference tr2 in hook() so we don't hold a reference.
             # This reduces memory consumption when there are multiple
             # transactions per lock. This can likely go away if issue5045
             # fixes the function accumulation.
             hookargs = tr2.hookargs
 
             def hookfunc():
                 repo = reporef()
                 if hook.hashook(repo.ui, 'txnclose-bookmark'):
                     bmchanges = sorted(tr.changes['bookmarks'].items())
                     for name, (old, new) in bmchanges:
                         args = tr.hookargs.copy()
                         args.update(bookmarks.preparehookargs(name, old, new))
                         repo.hook('txnclose-bookmark', throw=False,
                                   txnname=desc, **pycompat.strkwargs(args))
 
                 if hook.hashook(repo.ui, 'txnclose-phase'):
                     cl = repo.unfiltered().changelog
                     phasemv = sorted(tr.changes['phases'].items())
                     for rev, (old, new) in phasemv:
                         args = tr.hookargs.copy()
                         node = hex(cl.node(rev))
                         args.update(phases.preparehookargs(node, old, new))
                         repo.hook('txnclose-phase', throw=False, txnname=desc,
                                   **pycompat.strkwargs(args))
 
                 repo.hook('txnclose', throw=False, txnname=desc,
                           **pycompat.strkwargs(hookargs))
             reporef()._afterlock(hookfunc)
         tr.addfinalize('txnclose-hook', txnclosehook)
         # Include a leading "-" to make it happen before the transaction summary
         # reports registered via scmutil.registersummarycallback() whose names
         # are 00-txnreport etc. That way, the caches will be warm when the
         # callbacks run.
         tr.addpostclose('-warm-cache', self._buildcacheupdater(tr))
         def txnaborthook(tr2):
             """To be run if transaction is aborted
             """
             reporef().hook('txnabort', throw=False, txnname=desc,
                            **pycompat.strkwargs(tr2.hookargs))
         tr.addabort('txnabort-hook', txnaborthook)
         # avoid eager cache invalidation. in-memory data should be identical
         # to stored data if transaction has no error.
         tr.addpostclose('refresh-filecachestats', self._refreshfilecachestats)
         self._transref = weakref.ref(tr)
         scmutil.registersummarycallback(self, tr, desc)
         return tr
 
     def _journalfiles(self):
         return ((self.svfs, 'journal'),
                 (self.vfs, 'journal.dirstate'),
                 (self.vfs, 'journal.branch'),
                 (self.vfs, 'journal.desc'),
                 (self.vfs, 'journal.bookmarks'),
                 (self.svfs, 'journal.phaseroots'))
 
     def undofiles(self):
         return [(vfs, undoname(x)) for vfs, x in self._journalfiles()]
 
     @unfilteredmethod
     def _writejournal(self, desc):
         self.dirstate.savebackup(None, 'journal.dirstate')
         self.vfs.write("journal.branch",
                           encoding.fromlocal(self.dirstate.branch()))
         self.vfs.write("journal.desc",
                           "%d\n%s\n" % (len(self), desc))
         self.vfs.write("journal.bookmarks",
                           self.vfs.tryread("bookmarks"))
         self.svfs.write("journal.phaseroots",
                            self.svfs.tryread("phaseroots"))
 
     def recover(self):
         with self.lock():
             if self.svfs.exists("journal"):
                 self.ui.status(_("rolling back interrupted transaction\n"))
                 vfsmap = {'': self.svfs,
                           'plain': self.vfs,}
                 transaction.rollback(self.svfs, vfsmap, "journal",
                                      self.ui.warn,
                                      checkambigfiles=_cachedfiles)
                 self.invalidate()
                 return True
             else:
                 self.ui.warn(_("no interrupted transaction available\n"))
                 return False
 
     def rollback(self, dryrun=False, force=False):
         wlock = lock = dsguard = None
         try:
             wlock = self.wlock()
             lock = self.lock()
             if self.svfs.exists("undo"):
                 dsguard = dirstateguard.dirstateguard(self, 'rollback')
 
                 return self._rollback(dryrun, force, dsguard)
             else:
                 self.ui.warn(_("no rollback information available\n"))
                 return 1
         finally:
             release(dsguard, lock, wlock)
 
     @unfilteredmethod # Until we get smarter cache management
     def _rollback(self, dryrun, force, dsguard):
         ui = self.ui
         try:
             args = self.vfs.read('undo.desc').splitlines()
             (oldlen, desc, detail) = (int(args[0]), args[1], None)
             if len(args) >= 3:
                 detail = args[2]
             oldtip = oldlen - 1
 
             if detail and ui.verbose:
                 msg = (_('repository tip rolled back to revision %d'
                          ' (undo %s: %s)\n')
                        % (oldtip, desc, detail))
             else:
                 msg = (_('repository tip rolled back to revision %d'
                          ' (undo %s)\n')
                        % (oldtip, desc))
         except IOError:
             msg = _('rolling back unknown transaction\n')
             desc = None
 
         if not force and self['.'] != self['tip'] and desc == 'commit':
             raise error.Abort(
                 _('rollback of last commit while not checked out '
                   'may lose data'), hint=_('use -f to force'))
 
         ui.status(msg)
         if dryrun:
             return 0
 
         parents = self.dirstate.parents()
         self.destroying()
         vfsmap = {'plain': self.vfs, '': self.svfs}
         transaction.rollback(self.svfs, vfsmap, 'undo', ui.warn,
                              checkambigfiles=_cachedfiles)
         if self.vfs.exists('undo.bookmarks'):
             self.vfs.rename('undo.bookmarks', 'bookmarks', checkambig=True)
         if self.svfs.exists('undo.phaseroots'):
             self.svfs.rename('undo.phaseroots', 'phaseroots', checkambig=True)
         self.invalidate()
 
         parentgone = (parents[0] not in self.changelog.nodemap or
                       parents[1] not in self.changelog.nodemap)
         if parentgone:
             # prevent dirstateguard from overwriting already restored one
             dsguard.close()
 
             self.dirstate.restorebackup(None, 'undo.dirstate')
             try:
                 branch = self.vfs.read('undo.branch')
                 self.dirstate.setbranch(encoding.tolocal(branch))
             except IOError:
                 ui.warn(_('named branch could not be reset: '
                           'current branch is still \'%s\'\n')
                         % self.dirstate.branch())
 
             parents = tuple([p.rev() for p in self[None].parents()])
             if len(parents) > 1:
                 ui.status(_('working directory now based on '
                             'revisions %d and %d\n') % parents)
             else:
                 ui.status(_('working directory now based on '
                             'revision %d\n') % parents)
             mergemod.mergestate.clean(self, self['.'].node())
 
         # TODO: if we know which new heads may result from this rollback, pass
         # them to destroy(), which will prevent the branchhead cache from being
         # invalidated.
         self.destroyed()
         return 0
 
     def _buildcacheupdater(self, newtransaction):
         """called during transaction to build the callback updating cache
 
         Lives on the repository to help extension who might want to augment
         this logic. For this purpose, the created transaction is passed to the
         method.
         """
         # we must avoid cyclic reference between repo and transaction.
         reporef = weakref.ref(self)
         def updater(tr):
             repo = reporef()
             repo.updatecaches(tr)
         return updater
 
     @unfilteredmethod
     def updatecaches(self, tr=None, full=False):
         """warm appropriate caches
 
         If this function is called after a transaction closed. The transaction
         will be available in the 'tr' argument. This can be used to selectively
         update caches relevant to the changes in that transaction.
 
         If 'full' is set, make sure all caches the function knows about have
         up-to-date data. Even the ones usually loaded more lazily.
         """
         if tr is not None and tr.hookargs.get('source') == 'strip':
             # During strip, many caches are invalid but
             # later call to `destroyed` will refresh them.
             return
 
         if tr is None or tr.changes['revs']:
             # updating the unfiltered branchmap should refresh all the others,
             self.ui.debug('updating the branch cache\n')
             branchmap.updatecache(self.filtered('served'))
 
         if full:
             rbc = self.revbranchcache()
             for r in self.changelog:
                 rbc.branchinfo(r)
             rbc.write()
 
     def invalidatecaches(self):
 
         if '_tagscache' in vars(self):
             # can't use delattr on proxy
             del self.__dict__['_tagscache']
 
         self.unfiltered()._branchcaches.clear()
         self.invalidatevolatilesets()
         self._sparsesignaturecache.clear()
 
     def invalidatevolatilesets(self):
         self.filteredrevcache.clear()
         obsolete.clearobscaches(self)
 
     def invalidatedirstate(self):
         '''Invalidates the dirstate, causing the next call to dirstate
         to check if it was modified since the last time it was read,
         rereading it if it has.
 
         This is different to dirstate.invalidate() that it doesn't always
         rereads the dirstate. Use dirstate.invalidate() if you want to
         explicitly read the dirstate again (i.e. restoring it to a previous
         known good state).'''
         if hasunfilteredcache(self, 'dirstate'):
             for k in self.dirstate._filecache:
                 try:
                     delattr(self.dirstate, k)
                 except AttributeError:
                     pass
             delattr(self.unfiltered(), 'dirstate')
 
     def invalidate(self, clearfilecache=False):
         '''Invalidates both store and non-store parts other than dirstate
 
         If a transaction is running, invalidation of store is omitted,
         because discarding in-memory changes might cause inconsistency
         (e.g. incomplete fncache causes unintentional failure, but
         redundant one doesn't).
         '''
         unfiltered = self.unfiltered() # all file caches are stored unfiltered
         for k in list(self._filecache.keys()):
             # dirstate is invalidated separately in invalidatedirstate()
             if k == 'dirstate':
                 continue
             if (k == 'changelog' and
                 self.currenttransaction() and
                 self.changelog._delayed):
                 # The changelog object may store unwritten revisions. We don't
                 # want to lose them.
                 # TODO: Solve the problem instead of working around it.
                 continue
 
             if clearfilecache:
                 del self._filecache[k]
             try:
                 delattr(unfiltered, k)
             except AttributeError:
                 pass
         self.invalidatecaches()
         if not self.currenttransaction():
             # TODO: Changing contents of store outside transaction
             # causes inconsistency. We should make in-memory store
             # changes detectable, and abort if changed.
             self.store.invalidatecaches()
 
     def invalidateall(self):
         '''Fully invalidates both store and non-store parts, causing the
         subsequent operation to reread any outside changes.'''
         # extension should hook this to invalidate its caches
         self.invalidate()
         self.invalidatedirstate()
 
     @unfilteredmethod
     def _refreshfilecachestats(self, tr):
         """Reload stats of cached files so that they are flagged as valid"""
         for k, ce in self._filecache.items():
             k = pycompat.sysstr(k)
             if k == r'dirstate' or k not in self.__dict__:
                 continue
             ce.refresh()
 
     def _lock(self, vfs, lockname, wait, releasefn, acquirefn, desc,
               inheritchecker=None, parentenvvar=None):
         parentlock = None
         # the contents of parentenvvar are used by the underlying lock to
         # determine whether it can be inherited
         if parentenvvar is not None:
             parentlock = encoding.environ.get(parentenvvar)
 
         timeout = 0
         warntimeout = 0
         if wait:
             timeout = self.ui.configint("ui", "timeout")
             warntimeout = self.ui.configint("ui", "timeout.warn")
+        # internal config: ui.signal-safe-lock
+        signalsafe = self.ui.configbool('ui', 'signal-safe-lock')
 
         l = lockmod.trylock(self.ui, vfs, lockname, timeout, warntimeout,
                             releasefn=releasefn,
                             acquirefn=acquirefn, desc=desc,
                             inheritchecker=inheritchecker,
-                            parentlock=parentlock)
+                            parentlock=parentlock,
+                            signalsafe=signalsafe)
         return l
 
     def _afterlock(self, callback):
         """add a callback to be run when the repository is fully unlocked
 
         The callback will be executed when the outermost lock is released
         (with wlock being higher level than 'lock')."""
         for ref in (self._wlockref, self._lockref):
             l = ref and ref()
             if l and l.held:
                 l.postrelease.append(callback)
                 break
         else: # no lock have been found.
             callback()
 
     def lock(self, wait=True):
         '''Lock the repository store (.hg/store) and return a weak reference
         to the lock. Use this before modifying the store (e.g. committing or
         stripping). If you are opening a transaction, get a lock as well.)
 
         If both 'lock' and 'wlock' must be acquired, ensure you always acquires
         'wlock' first to avoid a dead-lock hazard.'''
         l = self._currentlock(self._lockref)
         if l is not None:
             l.lock()
             return l
 
         l = self._lock(self.svfs, "lock", wait, None,
                        self.invalidate, _('repository %s') % self.origroot)
         self._lockref = weakref.ref(l)
         return l
 
     def _wlockchecktransaction(self):
         if self.currenttransaction() is not None:
             raise error.LockInheritanceContractViolation(
                 'wlock cannot be inherited in the middle of a transaction')
 
     def wlock(self, wait=True):
         '''Lock the non-store parts of the repository (everything under
         .hg except .hg/store) and return a weak reference to the lock.
 
         Use this before modifying files in .hg.
 
         If both 'lock' and 'wlock' must be acquired, ensure you always acquires
         'wlock' first to avoid a dead-lock hazard.'''
         l = self._wlockref and self._wlockref()
         if l is not None and l.held:
             l.lock()
             return l
 
         # We do not need to check for non-waiting lock acquisition.  Such
         # acquisition would not cause dead-lock as they would just fail.
         if wait and (self.ui.configbool('devel', 'all-warnings')
                      or self.ui.configbool('devel', 'check-locks')):
             if self._currentlock(self._lockref) is not None:
                 self.ui.develwarn('"wlock" acquired after "lock"')
 
         def unlock():
             if self.dirstate.pendingparentchange():
                 self.dirstate.invalidate()
             else:
                 self.dirstate.write(None)
 
             self._filecache['dirstate'].refresh()
 
         l = self._lock(self.vfs, "wlock", wait, unlock,
                        self.invalidatedirstate, _('working directory of %s') %
                        self.origroot,
                        inheritchecker=self._wlockchecktransaction,
                        parentenvvar='HG_WLOCK_LOCKER')
         self._wlockref = weakref.ref(l)
         return l
 
     def _currentlock(self, lockref):
         """Returns the lock if it's held, or None if it's not."""
         if lockref is None:
             return None
         l = lockref()
         if l is None or not l.held:
             return None
         return l
 
     def currentwlock(self):
         """Returns the wlock if it's held, or None if it's not."""
         return self._currentlock(self._wlockref)
 
     def _filecommit(self, fctx, manifest1, manifest2, linkrev, tr, changelist):
         """
         commit an individual file as part of a larger transaction
         """
 
         fname = fctx.path()
         fparent1 = manifest1.get(fname, nullid)
         fparent2 = manifest2.get(fname, nullid)
         if isinstance(fctx, context.filectx):
             node = fctx.filenode()
             if node in [fparent1, fparent2]:
                 self.ui.debug('reusing %s filelog entry\n' % fname)
                 if manifest1.flags(fname) != fctx.flags():
                     changelist.append(fname)
                 return node
 
         flog = self.file(fname)
         meta = {}
         copy = fctx.renamed()
         if copy and copy[0] != fname:
             # Mark the new revision of this file as a copy of another
             # file.  This copy data will effectively act as a parent
             # of this new revision.  If this is a merge, the first
             # parent will be the nullid (meaning "look up the copy data")
             # and the second one will be the other parent.  For example:
             #
             # 0 --- 1 --- 3   rev1 changes file foo
             #   \       /     rev2 renames foo to bar and changes it
             #    \- 2 -/      rev3 should have bar with all changes and
             #                      should record that bar descends from
             #                      bar in rev2 and foo in rev1
             #
             # this allows this merge to succeed:
             #
             # 0 --- 1 --- 3   rev4 reverts the content change from rev2
             #   \       /     merging rev3 and rev4 should use bar@rev2
             #    \- 2 --- 4        as the merge base
             #
 
             cfname = copy[0]
             crev = manifest1.get(cfname)
             newfparent = fparent2
 
             if manifest2: # branch merge
                 if fparent2 == nullid or crev is None: # copied on remote side
                     if cfname in manifest2:
                         crev = manifest2[cfname]
                         newfparent = fparent1
 
             # Here, we used to search backwards through history to try to find
             # where the file copy came from if the source of a copy was not in
             # the parent directory. However, this doesn't actually make sense to
             # do (what does a copy from something not in your working copy even
             # mean?) and it causes bugs (eg, issue4476). Instead, we will warn
             # the user that copy information was dropped, so if they didn't
             # expect this outcome it can be fixed, but this is the correct
             # behavior in this circumstance.
 
             if crev:
                 self.ui.debug(" %s: copy %s:%s\n" % (fname, cfname, hex(crev)))
                 meta["copy"] = cfname
                 meta["copyrev"] = hex(crev)
                 fparent1, fparent2 = nullid, newfparent
             else:
                 self.ui.warn(_("warning: can't find ancestor for '%s' "
                                "copied from '%s'!\n") % (fname, cfname))
 
         elif fparent1 == nullid:
             fparent1, fparent2 = fparent2, nullid
         elif fparent2 != nullid:
             # is one parent an ancestor of the other?
             fparentancestors = flog.commonancestorsheads(fparent1, fparent2)
             if fparent1 in fparentancestors:
                 fparent1, fparent2 = fparent2, nullid
             elif fparent2 in fparentancestors:
                 fparent2 = nullid
 
         # is the file changed?
         text = fctx.data()
         if fparent2 != nullid or flog.cmp(fparent1, text) or meta:
             changelist.append(fname)
             return flog.add(text, meta, tr, linkrev, fparent1, fparent2)
         # are just the flags changed during merge?
         elif fname in manifest1 and manifest1.flags(fname) != fctx.flags():
             changelist.append(fname)
 
         return fparent1
 
     def checkcommitpatterns(self, wctx, vdirs, match, status, fail):
         """check for commit arguments that aren't committable"""
         if match.isexact() or match.prefix():
             matched = set(status.modified + status.added + status.removed)
 
             for f in match.files():
                 f = self.dirstate.normalize(f)
                 if f == '.' or f in matched or f in wctx.substate:
                     continue
                 if f in status.deleted:
                     fail(f, _('file not found!'))
                 if f in vdirs: # visited directory
                     d = f + '/'
                     for mf in matched:
                         if mf.startswith(d):
                             break
                     else:
                         fail(f, _("no match under directory!"))
                 elif f not in self.dirstate:
                     fail(f, _("file not tracked!"))
 
     @unfilteredmethod
     def commit(self, text="", user=None, date=None, match=None, force=False,
                editor=False, extra=None):
         """Add a new revision to current repository.
 
         Revision information is gathered from the working directory,
         match can be used to filter the committed files. If editor is
         supplied, it is called to get a commit message.
         """
         if extra is None:
             extra = {}
 
         def fail(f, msg):
             raise error.Abort('%s: %s' % (f, msg))
 
         if not match:
             match = matchmod.always(self.root, '')
 
         if not force:
             vdirs = []
             match.explicitdir = vdirs.append
             match.bad = fail
 
         wlock = lock = tr = None
         try:
             wlock = self.wlock()
             lock = self.lock() # for recent changelog (see issue4368)
 
             wctx = self[None]
             merge = len(wctx.parents()) > 1
 
             if not force and merge and not match.always():
                 raise error.Abort(_('cannot partially commit a merge '
                                    '(do not specify files or patterns)'))
 
             status = self.status(match=match, clean=force)
             if force:
                 status.modified.extend(status.clean) # mq may commit clean files
 
             # check subrepos
             subs, commitsubs, newstate = subrepoutil.precommit(
                 self.ui, wctx, status, match, force=force)
 
             # make sure all explicit patterns are matched
             if not force:
                 self.checkcommitpatterns(wctx, vdirs, match, status, fail)
 
             cctx = context.workingcommitctx(self, status,
                                             text, user, date, extra)
 
             # internal config: ui.allowemptycommit
             allowemptycommit = (wctx.branch() != wctx.p1().branch()
                                 or extra.get('close') or merge or cctx.files()
                                 or self.ui.configbool('ui', 'allowemptycommit'))
             if not allowemptycommit:
                 return None
 
             if merge and cctx.deleted():
                 raise error.Abort(_("cannot commit merge with missing files"))
 
             ms = mergemod.mergestate.read(self)
             mergeutil.checkunresolved(ms)
 
             if editor:
                 cctx._text = editor(self, cctx, subs)
             edited = (text != cctx._text)
 
             # Save commit message in case this transaction gets rolled back
             # (e.g. by a pretxncommit hook).  Leave the content alone on
             # the assumption that the user will use the same editor again.
             msgfn = self.savecommitmessage(cctx._text)
 
             # commit subs and write new state
             if subs:
                 for s in sorted(commitsubs):
                     sub = wctx.sub(s)
                     self.ui.status(_('committing subrepository %s\n') %
                                    subrepoutil.subrelpath(sub))
                     sr = sub.commit(cctx._text, user, date)
                     newstate[s] = (newstate[s][0], sr)
                 subrepoutil.writestate(self, newstate)
 
             p1, p2 = self.dirstate.parents()
             hookp1, hookp2 = hex(p1), (p2 != nullid and hex(p2) or '')
             try:
                 self.hook("precommit", throw=True, parent1=hookp1,
                           parent2=hookp2)
                 tr = self.transaction('commit')
                 ret = self.commitctx(cctx, True)
             except: # re-raises
                 if edited:
                     self.ui.write(
                         _('note: commit message saved in %s\n') % msgfn)
                 raise
             # update bookmarks, dirstate and mergestate
             bookmarks.update(self, [p1, p2], ret)
             cctx.markcommitted(ret)
             ms.reset()
             tr.close()
 
         finally:
             lockmod.release(tr, lock, wlock)
 
         def commithook(node=hex(ret), parent1=hookp1, parent2=hookp2):
             # hack for command that use a temporary commit (eg: histedit)
             # temporary commit got stripped before hook release
             if self.changelog.hasnode(ret):
                 self.hook("commit", node=node, parent1=parent1,
                           parent2=parent2)
         self._afterlock(commithook)
         return ret
 
     @unfilteredmethod
     def commitctx(self, ctx, error=False):
         """Add a new revision to current repository.
         Revision information is passed via the context argument.
         """
 
         tr = None
         p1, p2 = ctx.p1(), ctx.p2()
         user = ctx.user()
 
         lock = self.lock()
         try:
             tr = self.transaction("commit")
             trp = weakref.proxy(tr)
 
             if ctx.manifestnode():
                 # reuse an existing manifest revision
                 mn = ctx.manifestnode()
                 files = ctx.files()
             elif ctx.files():
                 m1ctx = p1.manifestctx()
                 m2ctx = p2.manifestctx()
                 mctx = m1ctx.copy()
 
                 m = mctx.read()
                 m1 = m1ctx.read()
                 m2 = m2ctx.read()
 
                 # check in files
                 added = []
                 changed = []
                 removed = list(ctx.removed())
                 linkrev = len(self)
                 self.ui.note(_("committing files:\n"))
                 for f in sorted(ctx.modified() + ctx.added()):
                     self.ui.note(f + "\n")
                     try:
                         fctx = ctx[f]
                         if fctx is None:
                             removed.append(f)
                         else:
                             added.append(f)
                             m[f] = self._filecommit(fctx, m1, m2, linkrev,
                                                     trp, changed)
                             m.setflag(f, fctx.flags())
                     except OSError as inst:
                         self.ui.warn(_("trouble committing %s!\n") % f)
                         raise
                     except IOError as inst:
                         errcode = getattr(inst, 'errno', errno.ENOENT)
                         if error or errcode and errcode != errno.ENOENT:
                             self.ui.warn(_("trouble committing %s!\n") % f)
                         raise
 
                 # update manifest
                 self.ui.note(_("committing manifest\n"))
                 removed = [f for f in sorted(removed) if f in m1 or f in m2]
                 drop = [f for f in removed if f in m]
                 for f in drop:
                     del m[f]
                 mn = mctx.write(trp, linkrev,
                                 p1.manifestnode(), p2.manifestnode(),
                                 added, drop)
                 files = changed + removed
             else:
                 mn = p1.manifestnode()
                 files = []
 
             # update changelog
             self.ui.note(_("committing changelog\n"))
             self.changelog.delayupdate(tr)
             n = self.changelog.add(mn, files, ctx.description(),
                                    trp, p1.node(), p2.node(),
                                    user, ctx.date(), ctx.extra().copy())
             xp1, xp2 = p1.hex(), p2 and p2.hex() or ''
             self.hook('pretxncommit', throw=True, node=hex(n), parent1=xp1,
                       parent2=xp2)
             # set the new commit is proper phase
             targetphase = subrepoutil.newcommitphase(self.ui, ctx)
             if targetphase:
                 # retract boundary do not alter parent changeset.
                 # if a parent have higher the resulting phase will
                 # be compliant anyway
                 #
                 # if minimal phase was 0 we don't need to retract anything
                 phases.registernew(self, tr, targetphase, [n])
             tr.close()
             return n
         finally:
             if tr:
                 tr.release()
             lock.release()
 
     @unfilteredmethod
     def destroying(self):
         '''Inform the repository that nodes are about to be destroyed.
         Intended for use by strip and rollback, so there's a common
         place for anything that has to be done before destroying history.
 
         This is mostly useful for saving state that is in memory and waiting
         to be flushed when the current lock is released. Because a call to
         destroyed is imminent, the repo will be invalidated causing those
         changes to stay in memory (waiting for the next unlock), or vanish
         completely.
         '''
         # When using the same lock to commit and strip, the phasecache is left
         # dirty after committing. Then when we strip, the repo is invalidated,
         # causing those changes to disappear.
         if '_phasecache' in vars(self):
             self._phasecache.write()
 
     @unfilteredmethod
     def destroyed(self):
         '''Inform the repository that nodes have been destroyed.
         Intended for use by strip and rollback, so there's a common
         place for anything that has to be done after destroying history.
         '''
         # When one tries to:
         # 1) destroy nodes thus calling this method (e.g. strip)
         # 2) use phasecache somewhere (e.g. commit)
         #
         # then 2) will fail because the phasecache contains nodes that were
         # removed. We can either remove phasecache from the filecache,
         # causing it to reload next time it is accessed, or simply filter
         # the removed nodes now and write the updated cache.
         self._phasecache.filterunknown(self)
         self._phasecache.write()
 
         # refresh all repository caches
         self.updatecaches()
 
         # Ensure the persistent tag cache is updated.  Doing it now
         # means that the tag cache only has to worry about destroyed
         # heads immediately after a strip/rollback.  That in turn
         # guarantees that "cachetip == currenttip" (comparing both rev
         # and node) always means no nodes have been added or destroyed.
 
         # XXX this is suboptimal when qrefresh'ing: we strip the current
         # head, refresh the tag cache, then immediately add a new head.
         # But I think doing it this way is necessary for the "instant
         # tag cache retrieval" case to work.
         self.invalidate()
 
     def status(self, node1='.', node2=None, match=None,
                ignored=False, clean=False, unknown=False,
                listsubrepos=False):
         '''a convenience method that calls node1.status(node2)'''
         return self[node1].status(node2, match, ignored, clean, unknown,
                                   listsubrepos)
 
     def addpostdsstatus(self, ps):
         """Add a callback to run within the wlock, at the point at which status
         fixups happen.
 
         On status completion, callback(wctx, status) will be called with the
         wlock held, unless the dirstate has changed from underneath or the wlock
         couldn't be grabbed.
 
         Callbacks should not capture and use a cached copy of the dirstate --
         it might change in the meanwhile. Instead, they should access the
         dirstate via wctx.repo().dirstate.
 
         This list is emptied out after each status run -- extensions should
         make sure it adds to this list each time dirstate.status is called.
         Extensions should also make sure they don't call this for statuses
         that don't involve the dirstate.
         """
 
         # The list is located here for uniqueness reasons -- it is actually
         # managed by the workingctx, but that isn't unique per-repo.
         self._postdsstatus.append(ps)
 
     def postdsstatus(self):
         """Used by workingctx to get the list of post-dirstate-status hooks."""
         return self._postdsstatus
 
     def clearpostdsstatus(self):
         """Used by workingctx to clear post-dirstate-status hooks."""
         del self._postdsstatus[:]
 
     def heads(self, start=None):
         if start is None:
             cl = self.changelog
             headrevs = reversed(cl.headrevs())
             return [cl.node(rev) for rev in headrevs]
 
         heads = self.changelog.heads(start)
         # sort the output in rev descending order
         return sorted(heads, key=self.changelog.rev, reverse=True)
 
     def branchheads(self, branch=None, start=None, closed=False):
         '''return a (possibly filtered) list of heads for the given branch
 
         Heads are returned in topological order, from newest to oldest.
         If branch is None, use the dirstate branch.
         If start is not None, return only heads reachable from start.
         If closed is True, return heads that are marked as closed as well.
         '''
         if branch is None:
             branch = self[None].branch()
         branches = self.branchmap()
         if branch not in branches:
             return []
         # the cache returns heads ordered lowest to highest
         bheads = list(reversed(branches.branchheads(branch, closed=closed)))
         if start is not None:
             # filter out the heads that cannot be reached from startrev
             fbheads = set(self.changelog.nodesbetween([start], bheads)[2])
             bheads = [h for h in bheads if h in fbheads]
         return bheads
 
     def branches(self, nodes):
         if not nodes:
             nodes = [self.changelog.tip()]
         b = []
         for n in nodes:
             t = n
             while True:
                 p = self.changelog.parents(n)
                 if p[1] != nullid or p[0] == nullid:
                     b.append((t, n, p[0], p[1]))
                     break
                 n = p[0]
         return b
 
     def between(self, pairs):
         r = []
 
         for top, bottom in pairs:
             n, l, i = top, [], 0
             f = 1
 
             while n != bottom and n != nullid:
                 p = self.changelog.parents(n)[0]
                 if i == f:
                     l.append(n)
                     f = f * 2
                 n = p
                 i += 1
 
             r.append(l)
 
         return r
 
     def checkpush(self, pushop):
         """Extensions can override this function if additional checks have
         to be performed before pushing, or call it if they override push
         command.
         """
 
     @unfilteredpropertycache
     def prepushoutgoinghooks(self):
         """Return util.hooks consists of a pushop with repo, remote, outgoing
         methods, which are called before pushing changesets.
         """
         return util.hooks()
 
     def pushkey(self, namespace, key, old, new):
         try:
             tr = self.currenttransaction()
             hookargs = {}
             if tr is not None:
                 hookargs.update(tr.hookargs)
             hookargs = pycompat.strkwargs(hookargs)
             hookargs[r'namespace'] = namespace
             hookargs[r'key'] = key
             hookargs[r'old'] = old
             hookargs[r'new'] = new
             self.hook('prepushkey', throw=True, **hookargs)
         except error.HookAbort as exc:
             self.ui.write_err(_("pushkey-abort: %s\n") % exc)
             if exc.hint:
                 self.ui.write_err(_("(%s)\n") % exc.hint)
             return False
         self.ui.debug('pushing key for "%s:%s"\n' % (namespace, key))
         ret = pushkey.push(self, namespace, key, old, new)
         def runhook():
             self.hook('pushkey', namespace=namespace, key=key, old=old, new=new,
                       ret=ret)
         self._afterlock(runhook)
         return ret
 
     def listkeys(self, namespace):
         self.hook('prelistkeys', throw=True, namespace=namespace)
         self.ui.debug('listing keys for "%s"\n' % namespace)
         values = pushkey.list(self, namespace)
         self.hook('listkeys', namespace=namespace, values=values)
         return values
 
     def debugwireargs(self, one, two, three=None, four=None, five=None):
         '''used to test argument passing over the wire'''
         return "%s %s %s %s %s" % (one, two, pycompat.bytestr(three),
                                    pycompat.bytestr(four),
                                    pycompat.bytestr(five))
 
     def savecommitmessage(self, text):
         fp = self.vfs('last-message.txt', 'wb')
         try:
             fp.write(text)
         finally:
             fp.close()
         return self.pathto(fp.name[len(self.root) + 1:])
 
 # used to avoid circular references so destructors work
 def aftertrans(files):
     renamefiles = [tuple(t) for t in files]
     def a():
         for vfs, src, dest in renamefiles:
             # if src and dest refer to a same file, vfs.rename is a no-op,
             # leaving both src and dest on disk. delete dest to make sure
             # the rename couldn't be such a no-op.
             vfs.tryunlink(dest)
             try:
                 vfs.rename(src, dest)
             except OSError: # journal file does not yet exist
                 pass
     return a
 
 def undoname(fn):
     base, name = os.path.split(fn)
     assert name.startswith('journal')
     return os.path.join(base, name.replace('journal', 'undo', 1))
 
 def instance(ui, path, create, intents=None):
     return localrepository(ui, util.urllocalpath(path), create,
                            intents=intents)
 
 def islocal(path):
     return True
 
 def newreporequirements(repo):
     """Determine the set of requirements for a new local repository.
 
     Extensions can wrap this function to specify custom requirements for
     new repositories.
     """
     ui = repo.ui
     requirements = {'revlogv1'}
     if ui.configbool('format', 'usestore'):
         requirements.add('store')
         if ui.configbool('format', 'usefncache'):
             requirements.add('fncache')
             if ui.configbool('format', 'dotencode'):
                 requirements.add('dotencode')
 
     compengine = ui.config('experimental', 'format.compression')
     if compengine not in util.compengines:
         raise error.Abort(_('compression engine %s defined by '
                             'experimental.format.compression not available') %
                           compengine,
                           hint=_('run "hg debuginstall" to list available '
                                  'compression engines'))
 
     # zlib is the historical default and doesn't need an explicit requirement.
     if compengine != 'zlib':
         requirements.add('exp-compression-%s' % compengine)
 
     if scmutil.gdinitconfig(ui):
         requirements.add('generaldelta')
     if ui.configbool('experimental', 'treemanifest'):
         requirements.add('treemanifest')
 
     revlogv2 = ui.config('experimental', 'revlogv2')
     if revlogv2 == 'enable-unstable-format-and-corrupt-my-data':
         requirements.remove('revlogv1')
         # generaldelta is implied by revlogv2.
         requirements.discard('generaldelta')
         requirements.add(REVLOGV2_REQUIREMENT)
 
     return requirements

mercurial/lock.py

@@ -1,392 +1,397 b''
 # lock.py - simple advisory locking scheme for mercurial
 #
 # Copyright 2005, 2006 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import
 
 import contextlib
 import errno
 import os
 import signal
 import socket
 import time
 import warnings
 
 from .i18n import _
 
 from . import (
     encoding,
     error,
     pycompat,
+    util,
 )
 
 from .utils import (
     procutil,
 )
 
 def _getlockprefix():
     """Return a string which is used to differentiate pid namespaces
 
     It's useful to detect "dead" processes and remove stale locks with
     confidence. Typically it's just hostname. On modern linux, we include an
     extra Linux-specific pid namespace identifier.
     """
     result = encoding.strtolocal(socket.gethostname())
     if pycompat.sysplatform.startswith('linux'):
         try:
             result += '/%x' % os.stat('/proc/self/ns/pid').st_ino
         except OSError as ex:
             if ex.errno not in (errno.ENOENT, errno.EACCES, errno.ENOTDIR):
                 raise
     return result
 
 @contextlib.contextmanager
 def _delayedinterrupt():
     """Block signal interrupt while doing something critical
 
     This makes sure that the code block wrapped by this context manager won't
     be interrupted.
 
     For Windows developers: It appears not possible to guard time.sleep()
     from CTRL_C_EVENT, so please don't use time.sleep() to test if this is
     working.
     """
     assertedsigs = []
     blocked = False
     orighandlers = {}
 
     def raiseinterrupt(num):
         if (num == getattr(signal, 'SIGINT', None) or
             num == getattr(signal, 'CTRL_C_EVENT', None)):
             raise KeyboardInterrupt
         else:
             raise error.SignalInterrupt
     def catchterm(num, frame):
         if blocked:
             assertedsigs.append(num)
         else:
             raiseinterrupt(num)
 
     try:
         # save handlers first so they can be restored even if a setup is
         # interrupted between signal.signal() and orighandlers[] =.
         for name in ['CTRL_C_EVENT', 'SIGINT', 'SIGBREAK', 'SIGHUP', 'SIGTERM']:
             num = getattr(signal, name, None)
             if num and num not in orighandlers:
                 orighandlers[num] = signal.getsignal(num)
         try:
             for num in orighandlers:
                 signal.signal(num, catchterm)
         except ValueError:
             pass # in a thread? no luck
 
         blocked = True
         yield
     finally:
         # no simple way to reliably restore all signal handlers because
         # any loops, recursive function calls, except blocks, etc. can be
         # interrupted. so instead, make catchterm() raise interrupt.
         blocked = False
         try:
             for num, handler in orighandlers.items():
                 signal.signal(num, handler)
         except ValueError:
             pass # in a thread?
 
     # re-raise interrupt exception if any, which may be shadowed by a new
     # interrupt occurred while re-raising the first one
     if assertedsigs:
         raiseinterrupt(assertedsigs[0])
 
 def trylock(ui, vfs, lockname, timeout, warntimeout, *args, **kwargs):
     """return an acquired lock or raise an a LockHeld exception
 
     This function is responsible to issue warnings and or debug messages about
     the held lock while trying to acquires it."""
 
     def printwarning(printer, locker):
         """issue the usual "waiting on lock" message through any channel"""
         # show more details for new-style locks
         if ':' in locker:
             host, pid = locker.split(":", 1)
             msg = (_("waiting for lock on %s held by process %r on host %r\n")
                    % (pycompat.bytestr(l.desc), pycompat.bytestr(pid),
                       pycompat.bytestr(host)))
         else:
             msg = (_("waiting for lock on %s held by %r\n")
                    % (l.desc, pycompat.bytestr(locker)))
         printer(msg)
 
     l = lock(vfs, lockname, 0, *args, dolock=False, **kwargs)
 
     debugidx = 0 if (warntimeout and timeout) else -1
     warningidx = 0
     if not timeout:
         warningidx = -1
     elif warntimeout:
         warningidx = warntimeout
 
     delay = 0
     while True:
         try:
             l._trylock()
             break
         except error.LockHeld as inst:
             if delay == debugidx:
                 printwarning(ui.debug, inst.locker)
             if delay == warningidx:
                 printwarning(ui.warn, inst.locker)
             if timeout <= delay:
                 raise error.LockHeld(errno.ETIMEDOUT, inst.filename,
                                      l.desc, inst.locker)
             time.sleep(1)
             delay += 1
 
     l.delay = delay
     if l.delay:
         if 0 <= warningidx <= l.delay:
             ui.warn(_("got lock after %d seconds\n") % l.delay)
         else:
             ui.debug("got lock after %d seconds\n" % l.delay)
     if l.acquirefn:
         l.acquirefn()
     return l
 
 class lock(object):
     '''An advisory lock held by one process to control access to a set
     of files.  Non-cooperating processes or incorrectly written scripts
     can ignore Mercurial's locking scheme and stomp all over the
     repository, so don't do that.
 
     Typically used via localrepository.lock() to lock the repository
     store (.hg/store/) or localrepository.wlock() to lock everything
     else under .hg/.'''
 
     # lock is symlink on platforms that support it, file on others.
 
     # symlink is used because create of directory entry and contents
     # are atomic even over nfs.
 
     # old-style lock: symlink to pid
     # new-style lock: symlink to hostname:pid
 
     _host = None
 
     def __init__(self, vfs, fname, timeout=-1, releasefn=None, acquirefn=None,
                  desc=None, inheritchecker=None, parentlock=None,
-                 dolock=True):
+                 signalsafe=True, dolock=True):
         self.vfs = vfs
         self.f = fname
         self.held = 0
         self.timeout = timeout
         self.releasefn = releasefn
         self.acquirefn = acquirefn
         self.desc = desc
         self._inheritchecker = inheritchecker
         self.parentlock = parentlock
         self._parentheld = False
         self._inherited = False
+        if signalsafe:
+            self._maybedelayedinterrupt = _delayedinterrupt
+        else:
+            self._maybedelayedinterrupt = util.nullcontextmanager
         self.postrelease  = []
         self.pid = self._getpid()
         if dolock:
             self.delay = self.lock()
             if self.acquirefn:
                 self.acquirefn()
 
     def __enter__(self):
         return self
 
     def __exit__(self, exc_type, exc_value, exc_tb):
         self.release()
 
     def __del__(self):
         if self.held:
             warnings.warn("use lock.release instead of del lock",
                     category=DeprecationWarning,
                     stacklevel=2)
 
             # ensure the lock will be removed
             # even if recursive locking did occur
             self.held = 1
 
         self.release()
 
     def _getpid(self):
         # wrapper around procutil.getpid() to make testing easier
         return procutil.getpid()
 
     def lock(self):
         timeout = self.timeout
         while True:
             try:
                 self._trylock()
                 return self.timeout - timeout
             except error.LockHeld as inst:
                 if timeout != 0:
                     time.sleep(1)
                     if timeout > 0:
                         timeout -= 1
                     continue
                 raise error.LockHeld(errno.ETIMEDOUT, inst.filename, self.desc,
                                      inst.locker)
 
     def _trylock(self):
         if self.held:
             self.held += 1
             return
         if lock._host is None:
             lock._host = _getlockprefix()
         lockname = '%s:%d' % (lock._host, self.pid)
         retry = 5
         while not self.held and retry:
             retry -= 1
             try:
-                with _delayedinterrupt():
+                with self._maybedelayedinterrupt():
                     self.vfs.makelock(lockname, self.f)
                     self.held = 1
             except (OSError, IOError) as why:
                 if why.errno == errno.EEXIST:
                     locker = self._readlock()
                     if locker is None:
                         continue
 
                     # special case where a parent process holds the lock -- this
                     # is different from the pid being different because we do
                     # want the unlock and postrelease functions to be called,
                     # but the lockfile to not be removed.
                     if locker == self.parentlock:
                         self._parentheld = True
                         self.held = 1
                         return
                     locker = self._testlock(locker)
                     if locker is not None:
                         raise error.LockHeld(errno.EAGAIN,
                                              self.vfs.join(self.f), self.desc,
                                              locker)
                 else:
                     raise error.LockUnavailable(why.errno, why.strerror,
                                                 why.filename, self.desc)
 
         if not self.held:
             # use empty locker to mean "busy for frequent lock/unlock
             # by many processes"
             raise error.LockHeld(errno.EAGAIN,
                                  self.vfs.join(self.f), self.desc, "")
 
     def _readlock(self):
         """read lock and return its value
 
         Returns None if no lock exists, pid for old-style locks, and host:pid
         for new-style locks.
         """
         try:
             return self.vfs.readlock(self.f)
         except (OSError, IOError) as why:
             if why.errno == errno.ENOENT:
                 return None
             raise
 
     def _testlock(self, locker):
         if locker is None:
             return None
         try:
             host, pid = locker.split(":", 1)
         except ValueError:
             return locker
         if host != lock._host:
             return locker
         try:
             pid = int(pid)
         except ValueError:
             return locker
         if procutil.testpid(pid):
             return locker
         # if locker dead, break lock.  must do this with another lock
         # held, or can race and break valid lock.
         try:
             l = lock(self.vfs, self.f + '.break', timeout=0)
             self.vfs.unlink(self.f)
             l.release()
         except error.LockError:
             return locker
 
     def testlock(self):
         """return id of locker if lock is valid, else None.
 
         If old-style lock, we cannot tell what machine locker is on.
         with new-style lock, if locker is on this machine, we can
         see if locker is alive.  If locker is on this machine but
         not alive, we can safely break lock.
 
         The lock file is only deleted when None is returned.
 
         """
         locker = self._readlock()
         return self._testlock(locker)
 
     @contextlib.contextmanager
     def inherit(self):
         """context for the lock to be inherited by a Mercurial subprocess.
 
         Yields a string that will be recognized by the lock in the subprocess.
         Communicating this string to the subprocess needs to be done separately
         -- typically by an environment variable.
         """
         if not self.held:
             raise error.LockInheritanceContractViolation(
                 'inherit can only be called while lock is held')
         if self._inherited:
             raise error.LockInheritanceContractViolation(
                 'inherit cannot be called while lock is already inherited')
         if self._inheritchecker is not None:
             self._inheritchecker()
         if self.releasefn:
             self.releasefn()
         if self._parentheld:
             lockname = self.parentlock
         else:
             lockname = b'%s:%d' % (lock._host, self.pid)
         self._inherited = True
         try:
             yield lockname
         finally:
             if self.acquirefn:
                 self.acquirefn()
             self._inherited = False
 
     def release(self):
         """release the lock and execute callback function if any
 
         If the lock has been acquired multiple times, the actual release is
         delayed to the last release call."""
         if self.held > 1:
             self.held -= 1
         elif self.held == 1:
             self.held = 0
             if self._getpid() != self.pid:
                 # we forked, and are not the parent
                 return
             try:
                 if self.releasefn:
                     self.releasefn()
             finally:
                 if not self._parentheld:
                     try:
                         self.vfs.unlink(self.f)
                     except OSError:
                         pass
             # The postrelease functions typically assume the lock is not held
             # at all.
             if not self._parentheld:
                 for callback in self.postrelease:
                     callback()
                 # Prevent double usage and help clear cycles.
                 self.postrelease = None
 
 def release(*locks):
     for lock in locks:
         if lock is not None:
             lock.release()