scmutil: speed up relativization of paths when it's a no-op

Running commands from the root is commmon, in particular for
automation. Running `hg files > /tmp/a` from the root of
mozilla-central on linux:

before:
real	0m1,510s
user	0m1,387s
sys	0m0,090s

after:
real	0m1,266s
user	0m1,165s
sys	0m0,073s

(there are 280k paths, so this was costing ~1us per path somehow)

Differential Revision: https://phab.mercurial-scm.org/D8585

mercurial/scmutil.py

@@ -1,2209 +1,2212 b''
 # scmutil.py - Mercurial core utility functions
 #
 #  Copyright 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 glob
 import os
 import posixpath
 import re
 import subprocess
 import weakref
 
 from .i18n import _
 from .node import (
     bin,
     hex,
     nullid,
     nullrev,
     short,
     wdirid,
     wdirrev,
 )
 from .pycompat import getattr
 from .thirdparty import attr
 from . import (
     copies as copiesmod,
     encoding,
     error,
     match as matchmod,
     obsolete,
     obsutil,
     pathutil,
     phases,
     policy,
     pycompat,
     revsetlang,
     similar,
     smartset,
     url,
     util,
     vfs,
 )
 
 from .utils import (
     hashutil,
     procutil,
     stringutil,
 )
 
 if pycompat.iswindows:
     from . import scmwindows as scmplatform
 else:
     from . import scmposix as scmplatform
 
 parsers = policy.importmod('parsers')
 rustrevlog = policy.importrust('revlog')
 
 termsize = scmplatform.termsize
 
 
 @attr.s(slots=True, repr=False)
 class status(object):
     '''Struct with a list of files per status.
 
     The 'deleted', 'unknown' and 'ignored' properties are only
     relevant to the working copy.
     '''
 
     modified = attr.ib(default=attr.Factory(list))
     added = attr.ib(default=attr.Factory(list))
     removed = attr.ib(default=attr.Factory(list))
     deleted = attr.ib(default=attr.Factory(list))
     unknown = attr.ib(default=attr.Factory(list))
     ignored = attr.ib(default=attr.Factory(list))
     clean = attr.ib(default=attr.Factory(list))
 
     def __iter__(self):
         yield self.modified
         yield self.added
         yield self.removed
         yield self.deleted
         yield self.unknown
         yield self.ignored
         yield self.clean
 
     def __repr__(self):
         return (
             r'<status modified=%s, added=%s, removed=%s, deleted=%s, '
             r'unknown=%s, ignored=%s, clean=%s>'
         ) % tuple(pycompat.sysstr(stringutil.pprint(v)) for v in self)
 
 
 def itersubrepos(ctx1, ctx2):
     """find subrepos in ctx1 or ctx2"""
     # Create a (subpath, ctx) mapping where we prefer subpaths from
     # ctx1. The subpaths from ctx2 are important when the .hgsub file
     # has been modified (in ctx2) but not yet committed (in ctx1).
     subpaths = dict.fromkeys(ctx2.substate, ctx2)
     subpaths.update(dict.fromkeys(ctx1.substate, ctx1))
 
     missing = set()
 
     for subpath in ctx2.substate:
         if subpath not in ctx1.substate:
             del subpaths[subpath]
             missing.add(subpath)
 
     for subpath, ctx in sorted(pycompat.iteritems(subpaths)):
         yield subpath, ctx.sub(subpath)
 
     # Yield an empty subrepo based on ctx1 for anything only in ctx2.  That way,
     # status and diff will have an accurate result when it does
     # 'sub.{status|diff}(rev2)'.  Otherwise, the ctx2 subrepo is compared
     # against itself.
     for subpath in missing:
         yield subpath, ctx2.nullsub(subpath, ctx1)
 
 
 def nochangesfound(ui, repo, excluded=None):
     '''Report no changes for push/pull, excluded is None or a list of
     nodes excluded from the push/pull.
     '''
     secretlist = []
     if excluded:
         for n in excluded:
             ctx = repo[n]
             if ctx.phase() >= phases.secret and not ctx.extinct():
                 secretlist.append(n)
 
     if secretlist:
         ui.status(
             _(b"no changes found (ignored %d secret changesets)\n")
             % len(secretlist)
         )
     else:
         ui.status(_(b"no changes found\n"))
 
 
 def callcatch(ui, func):
     """call func() with global exception handling
 
     return func() if no exception happens. otherwise do some error handling
     and return an exit code accordingly. does not handle all exceptions.
     """
     try:
         try:
             return func()
         except:  # re-raises
             ui.traceback()
             raise
     # Global exception handling, alphabetically
     # Mercurial-specific first, followed by built-in and library exceptions
     except error.LockHeld as inst:
         if inst.errno == errno.ETIMEDOUT:
             reason = _(b'timed out waiting for lock held by %r') % (
                 pycompat.bytestr(inst.locker)
             )
         else:
             reason = _(b'lock held by %r') % inst.locker
         ui.error(
             _(b"abort: %s: %s\n")
             % (inst.desc or stringutil.forcebytestr(inst.filename), reason)
         )
         if not inst.locker:
             ui.error(_(b"(lock might be very busy)\n"))
     except error.LockUnavailable as inst:
         ui.error(
             _(b"abort: could not lock %s: %s\n")
             % (
                 inst.desc or stringutil.forcebytestr(inst.filename),
                 encoding.strtolocal(inst.strerror),
             )
         )
     except error.OutOfBandError as inst:
         if inst.args:
             msg = _(b"abort: remote error:\n")
         else:
             msg = _(b"abort: remote error\n")
         ui.error(msg)
         if inst.args:
             ui.error(b''.join(inst.args))
         if inst.hint:
             ui.error(b'(%s)\n' % inst.hint)
     except error.RepoError as inst:
         ui.error(_(b"abort: %s!\n") % inst)
         if inst.hint:
             ui.error(_(b"(%s)\n") % inst.hint)
     except error.ResponseError as inst:
         ui.error(_(b"abort: %s") % inst.args[0])
         msg = inst.args[1]
         if isinstance(msg, type(u'')):
             msg = pycompat.sysbytes(msg)
         if not isinstance(msg, bytes):
             ui.error(b" %r\n" % (msg,))
         elif not msg:
             ui.error(_(b" empty string\n"))
         else:
             ui.error(b"\n%r\n" % pycompat.bytestr(stringutil.ellipsis(msg)))
     except error.CensoredNodeError as inst:
         ui.error(_(b"abort: file censored %s!\n") % inst)
     except error.StorageError as inst:
         ui.error(_(b"abort: %s!\n") % inst)
         if inst.hint:
             ui.error(_(b"(%s)\n") % inst.hint)
     except error.InterventionRequired as inst:
         ui.error(b"%s\n" % inst)
         if inst.hint:
             ui.error(_(b"(%s)\n") % inst.hint)
         return 1
     except error.WdirUnsupported:
         ui.error(_(b"abort: working directory revision cannot be specified\n"))
     except error.Abort as inst:
         ui.error(_(b"abort: %s\n") % inst)
         if inst.hint:
             ui.error(_(b"(%s)\n") % inst.hint)
     except ImportError as inst:
         ui.error(_(b"abort: %s!\n") % stringutil.forcebytestr(inst))
         m = stringutil.forcebytestr(inst).split()[-1]
         if m in b"mpatch bdiff".split():
             ui.error(_(b"(did you forget to compile extensions?)\n"))
         elif m in b"zlib".split():
             ui.error(_(b"(is your Python install correct?)\n"))
     except (IOError, OSError) as inst:
         if util.safehasattr(inst, b"code"):  # HTTPError
             ui.error(_(b"abort: %s\n") % stringutil.forcebytestr(inst))
         elif util.safehasattr(inst, b"reason"):  # URLError or SSLError
             try:  # usually it is in the form (errno, strerror)
                 reason = inst.reason.args[1]
             except (AttributeError, IndexError):
                 # it might be anything, for example a string
                 reason = inst.reason
             if isinstance(reason, pycompat.unicode):
                 # SSLError of Python 2.7.9 contains a unicode
                 reason = encoding.unitolocal(reason)
             ui.error(_(b"abort: error: %s\n") % stringutil.forcebytestr(reason))
         elif (
             util.safehasattr(inst, b"args")
             and inst.args
             and inst.args[0] == errno.EPIPE
         ):
             pass
         elif getattr(inst, "strerror", None):  # common IOError or OSError
             if getattr(inst, "filename", None) is not None:
                 ui.error(
                     _(b"abort: %s: '%s'\n")
                     % (
                         encoding.strtolocal(inst.strerror),
                         stringutil.forcebytestr(inst.filename),
                     )
                 )
             else:
                 ui.error(_(b"abort: %s\n") % encoding.strtolocal(inst.strerror))
         else:  # suspicious IOError
             raise
     except MemoryError:
         ui.error(_(b"abort: out of memory\n"))
     except SystemExit as inst:
         # Commands shouldn't sys.exit directly, but give a return code.
         # Just in case catch this and and pass exit code to caller.
         return inst.code
 
     return -1
 
 
 def checknewlabel(repo, lbl, kind):
     # Do not use the "kind" parameter in ui output.
     # It makes strings difficult to translate.
     if lbl in [b'tip', b'.', b'null']:
         raise error.Abort(_(b"the name '%s' is reserved") % lbl)
     for c in (b':', b'\0', b'\n', b'\r'):
         if c in lbl:
             raise error.Abort(
                 _(b"%r cannot be used in a name") % pycompat.bytestr(c)
             )
     try:
         int(lbl)
         raise error.Abort(_(b"cannot use an integer as a name"))
     except ValueError:
         pass
     if lbl.strip() != lbl:
         raise error.Abort(_(b"leading or trailing whitespace in name %r") % lbl)
 
 
 def checkfilename(f):
     '''Check that the filename f is an acceptable filename for a tracked file'''
     if b'\r' in f or b'\n' in f:
         raise error.Abort(
             _(b"'\\n' and '\\r' disallowed in filenames: %r")
             % pycompat.bytestr(f)
         )
 
 
 def checkportable(ui, f):
     '''Check if filename f is portable and warn or abort depending on config'''
     checkfilename(f)
     abort, warn = checkportabilityalert(ui)
     if abort or warn:
         msg = util.checkwinfilename(f)
         if msg:
             msg = b"%s: %s" % (msg, procutil.shellquote(f))
             if abort:
                 raise error.Abort(msg)
             ui.warn(_(b"warning: %s\n") % msg)
 
 
 def checkportabilityalert(ui):
     '''check if the user's config requests nothing, a warning, or abort for
     non-portable filenames'''
     val = ui.config(b'ui', b'portablefilenames')
     lval = val.lower()
     bval = stringutil.parsebool(val)
     abort = pycompat.iswindows or lval == b'abort'
     warn = bval or lval == b'warn'
     if bval is None and not (warn or abort or lval == b'ignore'):
         raise error.ConfigError(
             _(b"ui.portablefilenames value is invalid ('%s')") % val
         )
     return abort, warn
 
 
 class casecollisionauditor(object):
     def __init__(self, ui, abort, dirstate):
         self._ui = ui
         self._abort = abort
         allfiles = b'\0'.join(dirstate)
         self._loweredfiles = set(encoding.lower(allfiles).split(b'\0'))
         self._dirstate = dirstate
         # The purpose of _newfiles is so that we don't complain about
         # case collisions if someone were to call this object with the
         # same filename twice.
         self._newfiles = set()
 
     def __call__(self, f):
         if f in self._newfiles:
             return
         fl = encoding.lower(f)
         if fl in self._loweredfiles and f not in self._dirstate:
             msg = _(b'possible case-folding collision for %s') % f
             if self._abort:
                 raise error.Abort(msg)
             self._ui.warn(_(b"warning: %s\n") % msg)
         self._loweredfiles.add(fl)
         self._newfiles.add(f)
 
 
 def filteredhash(repo, maxrev):
     """build hash of filtered revisions in the current repoview.
 
     Multiple caches perform up-to-date validation by checking that the
     tiprev and tipnode stored in the cache file match the current repository.
     However, this is not sufficient for validating repoviews because the set
     of revisions in the view may change without the repository tiprev and
     tipnode changing.
 
     This function hashes all the revs filtered from the view and returns
     that SHA-1 digest.
     """
     cl = repo.changelog
     if not cl.filteredrevs:
         return None
     key = None
     revs = sorted(r for r in cl.filteredrevs if r <= maxrev)
     if revs:
         s = hashutil.sha1()
         for rev in revs:
             s.update(b'%d;' % rev)
         key = s.digest()
     return key
 
 
 def walkrepos(path, followsym=False, seen_dirs=None, recurse=False):
     '''yield every hg repository under path, always recursively.
     The recurse flag will only control recursion into repo working dirs'''
 
     def errhandler(err):
         if err.filename == path:
             raise err
 
     samestat = getattr(os.path, 'samestat', None)
     if followsym and samestat is not None:
 
         def adddir(dirlst, dirname):
             dirstat = os.stat(dirname)
             match = any(samestat(dirstat, lstdirstat) for lstdirstat in dirlst)
             if not match:
                 dirlst.append(dirstat)
             return not match
 
     else:
         followsym = False
 
     if (seen_dirs is None) and followsym:
         seen_dirs = []
         adddir(seen_dirs, path)
     for root, dirs, files in os.walk(path, topdown=True, onerror=errhandler):
         dirs.sort()
         if b'.hg' in dirs:
             yield root  # found a repository
             qroot = os.path.join(root, b'.hg', b'patches')
             if os.path.isdir(os.path.join(qroot, b'.hg')):
                 yield qroot  # we have a patch queue repo here
             if recurse:
                 # avoid recursing inside the .hg directory
                 dirs.remove(b'.hg')
             else:
                 dirs[:] = []  # don't descend further
         elif followsym:
             newdirs = []
             for d in dirs:
                 fname = os.path.join(root, d)
                 if adddir(seen_dirs, fname):
                     if os.path.islink(fname):
                         for hgname in walkrepos(fname, True, seen_dirs):
                             yield hgname
                     else:
                         newdirs.append(d)
             dirs[:] = newdirs
 
 
 def binnode(ctx):
     """Return binary node id for a given basectx"""
     node = ctx.node()
     if node is None:
         return wdirid
     return node
 
 
 def intrev(ctx):
     """Return integer for a given basectx that can be used in comparison or
     arithmetic operation"""
     rev = ctx.rev()
     if rev is None:
         return wdirrev
     return rev
 
 
 def formatchangeid(ctx):
     """Format changectx as '{rev}:{node|formatnode}', which is the default
     template provided by logcmdutil.changesettemplater"""
     repo = ctx.repo()
     return formatrevnode(repo.ui, intrev(ctx), binnode(ctx))
 
 
 def formatrevnode(ui, rev, node):
     """Format given revision and node depending on the current verbosity"""
     if ui.debugflag:
         hexfunc = hex
     else:
         hexfunc = short
     return b'%d:%s' % (rev, hexfunc(node))
 
 
 def resolvehexnodeidprefix(repo, prefix):
     if prefix.startswith(b'x'):
         prefix = prefix[1:]
     try:
         # Uses unfiltered repo because it's faster when prefix is ambiguous/
         # This matches the shortesthexnodeidprefix() function below.
         node = repo.unfiltered().changelog._partialmatch(prefix)
     except error.AmbiguousPrefixLookupError:
         revset = repo.ui.config(
             b'experimental', b'revisions.disambiguatewithin'
         )
         if revset:
             # Clear config to avoid infinite recursion
             configoverrides = {
                 (b'experimental', b'revisions.disambiguatewithin'): None
             }
             with repo.ui.configoverride(configoverrides):
                 revs = repo.anyrevs([revset], user=True)
                 matches = []
                 for rev in revs:
                     node = repo.changelog.node(rev)
                     if hex(node).startswith(prefix):
                         matches.append(node)
                 if len(matches) == 1:
                     return matches[0]
         raise
     if node is None:
         return
     repo.changelog.rev(node)  # make sure node isn't filtered
     return node
 
 
 def mayberevnum(repo, prefix):
     """Checks if the given prefix may be mistaken for a revision number"""
     try:
         i = int(prefix)
         # if we are a pure int, then starting with zero will not be
         # confused as a rev; or, obviously, if the int is larger
         # than the value of the tip rev. We still need to disambiguate if
         # prefix == '0', since that *is* a valid revnum.
         if (prefix != b'0' and prefix[0:1] == b'0') or i >= len(repo):
             return False
         return True
     except ValueError:
         return False
 
 
 def shortesthexnodeidprefix(repo, node, minlength=1, cache=None):
     """Find the shortest unambiguous prefix that matches hexnode.
 
     If "cache" is not None, it must be a dictionary that can be used for
     caching between calls to this method.
     """
     # _partialmatch() of filtered changelog could take O(len(repo)) time,
     # which would be unacceptably slow. so we look for hash collision in
     # unfiltered space, which means some hashes may be slightly longer.
 
     minlength = max(minlength, 1)
 
     def disambiguate(prefix):
         """Disambiguate against revnums."""
         if repo.ui.configbool(b'experimental', b'revisions.prefixhexnode'):
             if mayberevnum(repo, prefix):
                 return b'x' + prefix
             else:
                 return prefix
 
         hexnode = hex(node)
         for length in range(len(prefix), len(hexnode) + 1):
             prefix = hexnode[:length]
             if not mayberevnum(repo, prefix):
                 return prefix
 
     cl = repo.unfiltered().changelog
     revset = repo.ui.config(b'experimental', b'revisions.disambiguatewithin')
     if revset:
         revs = None
         if cache is not None:
             revs = cache.get(b'disambiguationrevset')
         if revs is None:
             revs = repo.anyrevs([revset], user=True)
             if cache is not None:
                 cache[b'disambiguationrevset'] = revs
         if cl.rev(node) in revs:
             hexnode = hex(node)
             nodetree = None
             if cache is not None:
                 nodetree = cache.get(b'disambiguationnodetree')
             if not nodetree:
                 if util.safehasattr(parsers, 'nodetree'):
                     # The CExt is the only implementation to provide a nodetree
                     # class so far.
                     index = cl.index
                     if util.safehasattr(index, 'get_cindex'):
                         # the rust wrapped need to give access to its internal index
                         index = index.get_cindex()
                     nodetree = parsers.nodetree(index, len(revs))
                     for r in revs:
                         nodetree.insert(r)
                     if cache is not None:
                         cache[b'disambiguationnodetree'] = nodetree
             if nodetree is not None:
                 length = max(nodetree.shortest(node), minlength)
                 prefix = hexnode[:length]
                 return disambiguate(prefix)
             for length in range(minlength, len(hexnode) + 1):
                 matches = []
                 prefix = hexnode[:length]
                 for rev in revs:
                     otherhexnode = repo[rev].hex()
                     if prefix == otherhexnode[:length]:
                         matches.append(otherhexnode)
                 if len(matches) == 1:
                     return disambiguate(prefix)
 
     try:
         return disambiguate(cl.shortest(node, minlength))
     except error.LookupError:
         raise error.RepoLookupError()
 
 
 def isrevsymbol(repo, symbol):
     """Checks if a symbol exists in the repo.
 
     See revsymbol() for details. Raises error.AmbiguousPrefixLookupError if the
     symbol is an ambiguous nodeid prefix.
     """
     try:
         revsymbol(repo, symbol)
         return True
     except error.RepoLookupError:
         return False
 
 
 def revsymbol(repo, symbol):
     """Returns a context given a single revision symbol (as string).
 
     This is similar to revsingle(), but accepts only a single revision symbol,
     i.e. things like ".", "tip", "1234", "deadbeef", "my-bookmark" work, but
     not "max(public())".
     """
     if not isinstance(symbol, bytes):
         msg = (
             b"symbol (%s of type %s) was not a string, did you mean "
             b"repo[symbol]?" % (symbol, type(symbol))
         )
         raise error.ProgrammingError(msg)
     try:
         if symbol in (b'.', b'tip', b'null'):
             return repo[symbol]
 
         try:
             r = int(symbol)
             if b'%d' % r != symbol:
                 raise ValueError
             l = len(repo.changelog)
             if r < 0:
                 r += l
             if r < 0 or r >= l and r != wdirrev:
                 raise ValueError
             return repo[r]
         except error.FilteredIndexError:
             raise
         except (ValueError, OverflowError, IndexError):
             pass
 
         if len(symbol) == 40:
             try:
                 node = bin(symbol)
                 rev = repo.changelog.rev(node)
                 return repo[rev]
             except error.FilteredLookupError:
                 raise
             except (TypeError, LookupError):
                 pass
 
         # look up bookmarks through the name interface
         try:
             node = repo.names.singlenode(repo, symbol)
             rev = repo.changelog.rev(node)
             return repo[rev]
         except KeyError:
             pass
 
         node = resolvehexnodeidprefix(repo, symbol)
         if node is not None:
             rev = repo.changelog.rev(node)
             return repo[rev]
 
         raise error.RepoLookupError(_(b"unknown revision '%s'") % symbol)
 
     except error.WdirUnsupported:
         return repo[None]
     except (
         error.FilteredIndexError,
         error.FilteredLookupError,
         error.FilteredRepoLookupError,
     ):
         raise _filterederror(repo, symbol)
 
 
 def _filterederror(repo, changeid):
     """build an exception to be raised about a filtered changeid
 
     This is extracted in a function to help extensions (eg: evolve) to
     experiment with various message variants."""
     if repo.filtername.startswith(b'visible'):
 
         # Check if the changeset is obsolete
         unfilteredrepo = repo.unfiltered()
         ctx = revsymbol(unfilteredrepo, changeid)
 
         # If the changeset is obsolete, enrich the message with the reason
         # that made this changeset not visible
         if ctx.obsolete():
             msg = obsutil._getfilteredreason(repo, changeid, ctx)
         else:
             msg = _(b"hidden revision '%s'") % changeid
 
         hint = _(b'use --hidden to access hidden revisions')
 
         return error.FilteredRepoLookupError(msg, hint=hint)
     msg = _(b"filtered revision '%s' (not in '%s' subset)")
     msg %= (changeid, repo.filtername)
     return error.FilteredRepoLookupError(msg)
 
 
 def revsingle(repo, revspec, default=b'.', localalias=None):
     if not revspec and revspec != 0:
         return repo[default]
 
     l = revrange(repo, [revspec], localalias=localalias)
     if not l:
         raise error.Abort(_(b'empty revision set'))
     return repo[l.last()]
 
 
 def _pairspec(revspec):
     tree = revsetlang.parse(revspec)
     return tree and tree[0] in (
         b'range',
         b'rangepre',
         b'rangepost',
         b'rangeall',
     )
 
 
 def revpair(repo, revs):
     if not revs:
         return repo[b'.'], repo[None]
 
     l = revrange(repo, revs)
 
     if not l:
         raise error.Abort(_(b'empty revision range'))
 
     first = l.first()
     second = l.last()
 
     if (
         first == second
         and len(revs) >= 2
         and not all(revrange(repo, [r]) for r in revs)
     ):
         raise error.Abort(_(b'empty revision on one side of range'))
 
     # if top-level is range expression, the result must always be a pair
     if first == second and len(revs) == 1 and not _pairspec(revs[0]):
         return repo[first], repo[None]
 
     return repo[first], repo[second]
 
 
 def revrange(repo, specs, localalias=None):
     """Execute 1 to many revsets and return the union.
 
     This is the preferred mechanism for executing revsets using user-specified
     config options, such as revset aliases.
 
     The revsets specified by ``specs`` will be executed via a chained ``OR``
     expression. If ``specs`` is empty, an empty result is returned.
 
     ``specs`` can contain integers, in which case they are assumed to be
     revision numbers.
 
     It is assumed the revsets are already formatted. If you have arguments
     that need to be expanded in the revset, call ``revsetlang.formatspec()``
     and pass the result as an element of ``specs``.
 
     Specifying a single revset is allowed.
 
     Returns a ``smartset.abstractsmartset`` which is a list-like interface over
     integer revisions.
     """
     allspecs = []
     for spec in specs:
         if isinstance(spec, int):
             spec = revsetlang.formatspec(b'%d', spec)
         allspecs.append(spec)
     return repo.anyrevs(allspecs, user=True, localalias=localalias)
 
 
 def meaningfulparents(repo, ctx):
     """Return list of meaningful (or all if debug) parentrevs for rev.
 
     For merges (two non-nullrev revisions) both parents are meaningful.
     Otherwise the first parent revision is considered meaningful if it
     is not the preceding revision.
     """
     parents = ctx.parents()
     if len(parents) > 1:
         return parents
     if repo.ui.debugflag:
         return [parents[0], repo[nullrev]]
     if parents[0].rev() >= intrev(ctx) - 1:
         return []
     return parents
 
 
 def getuipathfn(repo, legacyrelativevalue=False, forcerelativevalue=None):
     """Return a function that produced paths for presenting to the user.
 
     The returned function takes a repo-relative path and produces a path
     that can be presented in the UI.
 
     Depending on the value of ui.relative-paths, either a repo-relative or
     cwd-relative path will be produced.
 
     legacyrelativevalue is the value to use if ui.relative-paths=legacy
 
     If forcerelativevalue is not None, then that value will be used regardless
     of what ui.relative-paths is set to.
     """
     if forcerelativevalue is not None:
         relative = forcerelativevalue
     else:
         config = repo.ui.config(b'ui', b'relative-paths')
         if config == b'legacy':
             relative = legacyrelativevalue
         else:
             relative = stringutil.parsebool(config)
             if relative is None:
                 raise error.ConfigError(
                     _(b"ui.relative-paths is not a boolean ('%s')") % config
                 )
 
     if relative:
         cwd = repo.getcwd()
-        pathto = repo.pathto
-        return lambda f: pathto(f, cwd)
-    elif repo.ui.configbool(b'ui', b'slash'):
+        if cwd != b'':
+            # this branch is correct when cwd == b'', ie cwd = repo root,
+            # but it's slower
+            pathto = repo.pathto
+            return lambda f: pathto(f, cwd)
+    if repo.ui.configbool(b'ui', b'slash'):
         return lambda f: f
     else:
         return util.localpath
 
 
 def subdiruipathfn(subpath, uipathfn):
     '''Create a new uipathfn that treats the file as relative to subpath.'''
     return lambda f: uipathfn(posixpath.join(subpath, f))
 
 
 def anypats(pats, opts):
     '''Checks if any patterns, including --include and --exclude were given.
 
     Some commands (e.g. addremove) use this condition for deciding whether to
     print absolute or relative paths.
     '''
     return bool(pats or opts.get(b'include') or opts.get(b'exclude'))
 
 
 def expandpats(pats):
     '''Expand bare globs when running on windows.
     On posix we assume it already has already been done by sh.'''
     if not util.expandglobs:
         return list(pats)
     ret = []
     for kindpat in pats:
         kind, pat = matchmod._patsplit(kindpat, None)
         if kind is None:
             try:
                 globbed = glob.glob(pat)
             except re.error:
                 globbed = [pat]
             if globbed:
                 ret.extend(globbed)
                 continue
         ret.append(kindpat)
     return ret
 
 
 def matchandpats(
     ctx, pats=(), opts=None, globbed=False, default=b'relpath', badfn=None
 ):
     '''Return a matcher and the patterns that were used.
     The matcher will warn about bad matches, unless an alternate badfn callback
     is provided.'''
     if opts is None:
         opts = {}
     if not globbed and default == b'relpath':
         pats = expandpats(pats or [])
 
     uipathfn = getuipathfn(ctx.repo(), legacyrelativevalue=True)
 
     def bad(f, msg):
         ctx.repo().ui.warn(b"%s: %s\n" % (uipathfn(f), msg))
 
     if badfn is None:
         badfn = bad
 
     m = ctx.match(
         pats,
         opts.get(b'include'),
         opts.get(b'exclude'),
         default,
         listsubrepos=opts.get(b'subrepos'),
         badfn=badfn,
     )
 
     if m.always():
         pats = []
     return m, pats
 
 
 def match(
     ctx, pats=(), opts=None, globbed=False, default=b'relpath', badfn=None
 ):
     '''Return a matcher that will warn about bad matches.'''
     return matchandpats(ctx, pats, opts, globbed, default, badfn=badfn)[0]
 
 
 def matchall(repo):
     '''Return a matcher that will efficiently match everything.'''
     return matchmod.always()
 
 
 def matchfiles(repo, files, badfn=None):
     '''Return a matcher that will efficiently match exactly these files.'''
     return matchmod.exact(files, badfn=badfn)
 
 
 def parsefollowlinespattern(repo, rev, pat, msg):
     """Return a file name from `pat` pattern suitable for usage in followlines
     logic.
     """
     if not matchmod.patkind(pat):
         return pathutil.canonpath(repo.root, repo.getcwd(), pat)
     else:
         ctx = repo[rev]
         m = matchmod.match(repo.root, repo.getcwd(), [pat], ctx=ctx)
         files = [f for f in ctx if m(f)]
         if len(files) != 1:
             raise error.ParseError(msg)
         return files[0]
 
 
 def getorigvfs(ui, repo):
     """return a vfs suitable to save 'orig' file
 
     return None if no special directory is configured"""
     origbackuppath = ui.config(b'ui', b'origbackuppath')
     if not origbackuppath:
         return None
     return vfs.vfs(repo.wvfs.join(origbackuppath))
 
 
 def backuppath(ui, repo, filepath):
     '''customize where working copy backup files (.orig files) are created
 
     Fetch user defined path from config file: [ui] origbackuppath = <path>
     Fall back to default (filepath with .orig suffix) if not specified
 
     filepath is repo-relative
 
     Returns an absolute path
     '''
     origvfs = getorigvfs(ui, repo)
     if origvfs is None:
         return repo.wjoin(filepath + b".orig")
 
     origbackupdir = origvfs.dirname(filepath)
     if not origvfs.isdir(origbackupdir) or origvfs.islink(origbackupdir):
         ui.note(_(b'creating directory: %s\n') % origvfs.join(origbackupdir))
 
         # Remove any files that conflict with the backup file's path
         for f in reversed(list(pathutil.finddirs(filepath))):
             if origvfs.isfileorlink(f):
                 ui.note(_(b'removing conflicting file: %s\n') % origvfs.join(f))
                 origvfs.unlink(f)
                 break
 
         origvfs.makedirs(origbackupdir)
 
     if origvfs.isdir(filepath) and not origvfs.islink(filepath):
         ui.note(
             _(b'removing conflicting directory: %s\n') % origvfs.join(filepath)
         )
         origvfs.rmtree(filepath, forcibly=True)
 
     return origvfs.join(filepath)
 
 
 class _containsnode(object):
     """proxy __contains__(node) to container.__contains__ which accepts revs"""
 
     def __init__(self, repo, revcontainer):
         self._torev = repo.changelog.rev
         self._revcontains = revcontainer.__contains__
 
     def __contains__(self, node):
         return self._revcontains(self._torev(node))
 
 
 def cleanupnodes(
     repo,
     replacements,
     operation,
     moves=None,
     metadata=None,
     fixphase=False,
     targetphase=None,
     backup=True,
 ):
     """do common cleanups when old nodes are replaced by new nodes
 
     That includes writing obsmarkers or stripping nodes, and moving bookmarks.
     (we might also want to move working directory parent in the future)
 
     By default, bookmark moves are calculated automatically from 'replacements',
     but 'moves' can be used to override that. Also, 'moves' may include
     additional bookmark moves that should not have associated obsmarkers.
 
     replacements is {oldnode: [newnode]} or a iterable of nodes if they do not
     have replacements. operation is a string, like "rebase".
 
     metadata is dictionary containing metadata to be stored in obsmarker if
     obsolescence is enabled.
     """
     assert fixphase or targetphase is None
     if not replacements and not moves:
         return
 
     # translate mapping's other forms
     if not util.safehasattr(replacements, b'items'):
         replacements = {(n,): () for n in replacements}
     else:
         # upgrading non tuple "source" to tuple ones for BC
         repls = {}
         for key, value in replacements.items():
             if not isinstance(key, tuple):
                 key = (key,)
             repls[key] = value
         replacements = repls
 
     # Unfiltered repo is needed since nodes in replacements might be hidden.
     unfi = repo.unfiltered()
 
     # Calculate bookmark movements
     if moves is None:
         moves = {}
         for oldnodes, newnodes in replacements.items():
             for oldnode in oldnodes:
                 if oldnode in moves:
                     continue
                 if len(newnodes) > 1:
                     # usually a split, take the one with biggest rev number
                     newnode = next(unfi.set(b'max(%ln)', newnodes)).node()
                 elif len(newnodes) == 0:
                     # move bookmark backwards
                     allreplaced = []
                     for rep in replacements:
                         allreplaced.extend(rep)
                     roots = list(
                         unfi.set(b'max((::%n) - %ln)', oldnode, allreplaced)
                     )
                     if roots:
                         newnode = roots[0].node()
                     else:
                         newnode = nullid
                 else:
                     newnode = newnodes[0]
                 moves[oldnode] = newnode
 
     allnewnodes = [n for ns in replacements.values() for n in ns]
     toretract = {}
     toadvance = {}
     if fixphase:
         precursors = {}
         for oldnodes, newnodes in replacements.items():
             for oldnode in oldnodes:
                 for newnode in newnodes:
                     precursors.setdefault(newnode, []).append(oldnode)
 
         allnewnodes.sort(key=lambda n: unfi[n].rev())
         newphases = {}
 
         def phase(ctx):
             return newphases.get(ctx.node(), ctx.phase())
 
         for newnode in allnewnodes:
             ctx = unfi[newnode]
             parentphase = max(phase(p) for p in ctx.parents())
             if targetphase is None:
                 oldphase = max(
                     unfi[oldnode].phase() for oldnode in precursors[newnode]
                 )
                 newphase = max(oldphase, parentphase)
             else:
                 newphase = max(targetphase, parentphase)
             newphases[newnode] = newphase
             if newphase > ctx.phase():
                 toretract.setdefault(newphase, []).append(newnode)
             elif newphase < ctx.phase():
                 toadvance.setdefault(newphase, []).append(newnode)
 
     with repo.transaction(b'cleanup') as tr:
         # Move bookmarks
         bmarks = repo._bookmarks
         bmarkchanges = []
         for oldnode, newnode in moves.items():
             oldbmarks = repo.nodebookmarks(oldnode)
             if not oldbmarks:
                 continue
             from . import bookmarks  # avoid import cycle
 
             repo.ui.debug(
                 b'moving bookmarks %r from %s to %s\n'
                 % (
                     pycompat.rapply(pycompat.maybebytestr, oldbmarks),
                     hex(oldnode),
                     hex(newnode),
                 )
             )
             # Delete divergent bookmarks being parents of related newnodes
             deleterevs = repo.revs(
                 b'parents(roots(%ln & (::%n))) - parents(%n)',
                 allnewnodes,
                 newnode,
                 oldnode,
             )
             deletenodes = _containsnode(repo, deleterevs)
             for name in oldbmarks:
                 bmarkchanges.append((name, newnode))
                 for b in bookmarks.divergent2delete(repo, deletenodes, name):
                     bmarkchanges.append((b, None))
 
         if bmarkchanges:
             bmarks.applychanges(repo, tr, bmarkchanges)
 
         for phase, nodes in toretract.items():
             phases.retractboundary(repo, tr, phase, nodes)
         for phase, nodes in toadvance.items():
             phases.advanceboundary(repo, tr, phase, nodes)
 
         mayusearchived = repo.ui.config(b'experimental', b'cleanup-as-archived')
         # Obsolete or strip nodes
         if obsolete.isenabled(repo, obsolete.createmarkersopt):
             # If a node is already obsoleted, and we want to obsolete it
             # without a successor, skip that obssolete request since it's
             # unnecessary. That's the "if s or not isobs(n)" check below.
             # Also sort the node in topology order, that might be useful for
             # some obsstore logic.
             # NOTE: the sorting might belong to createmarkers.
             torev = unfi.changelog.rev
             sortfunc = lambda ns: torev(ns[0][0])
             rels = []
             for ns, s in sorted(replacements.items(), key=sortfunc):
                 rel = (tuple(unfi[n] for n in ns), tuple(unfi[m] for m in s))
                 rels.append(rel)
             if rels:
                 obsolete.createmarkers(
                     repo, rels, operation=operation, metadata=metadata
                 )
         elif phases.supportinternal(repo) and mayusearchived:
             # this assume we do not have "unstable" nodes above the cleaned ones
             allreplaced = set()
             for ns in replacements.keys():
                 allreplaced.update(ns)
             if backup:
                 from . import repair  # avoid import cycle
 
                 node = min(allreplaced, key=repo.changelog.rev)
                 repair.backupbundle(
                     repo, allreplaced, allreplaced, node, operation
                 )
             phases.retractboundary(repo, tr, phases.archived, allreplaced)
         else:
             from . import repair  # avoid import cycle
 
             tostrip = list(n for ns in replacements for n in ns)
             if tostrip:
                 repair.delayedstrip(
                     repo.ui, repo, tostrip, operation, backup=backup
                 )
 
 
 def addremove(repo, matcher, prefix, uipathfn, opts=None):
     if opts is None:
         opts = {}
     m = matcher
     dry_run = opts.get(b'dry_run')
     try:
         similarity = float(opts.get(b'similarity') or 0)
     except ValueError:
         raise error.Abort(_(b'similarity must be a number'))
     if similarity < 0 or similarity > 100:
         raise error.Abort(_(b'similarity must be between 0 and 100'))
     similarity /= 100.0
 
     ret = 0
 
     wctx = repo[None]
     for subpath in sorted(wctx.substate):
         submatch = matchmod.subdirmatcher(subpath, m)
         if opts.get(b'subrepos') or m.exact(subpath) or any(submatch.files()):
             sub = wctx.sub(subpath)
             subprefix = repo.wvfs.reljoin(prefix, subpath)
             subuipathfn = subdiruipathfn(subpath, uipathfn)
             try:
                 if sub.addremove(submatch, subprefix, subuipathfn, opts):
                     ret = 1
             except error.LookupError:
                 repo.ui.status(
                     _(b"skipping missing subrepository: %s\n")
                     % uipathfn(subpath)
                 )
 
     rejected = []
 
     def badfn(f, msg):
         if f in m.files():
             m.bad(f, msg)
         rejected.append(f)
 
     badmatch = matchmod.badmatch(m, badfn)
     added, unknown, deleted, removed, forgotten = _interestingfiles(
         repo, badmatch
     )
 
     unknownset = set(unknown + forgotten)
     toprint = unknownset.copy()
     toprint.update(deleted)
     for abs in sorted(toprint):
         if repo.ui.verbose or not m.exact(abs):
             if abs in unknownset:
                 status = _(b'adding %s\n') % uipathfn(abs)
                 label = b'ui.addremove.added'
             else:
                 status = _(b'removing %s\n') % uipathfn(abs)
                 label = b'ui.addremove.removed'
             repo.ui.status(status, label=label)
 
     renames = _findrenames(
         repo, m, added + unknown, removed + deleted, similarity, uipathfn
     )
 
     if not dry_run:
         _markchanges(repo, unknown + forgotten, deleted, renames)
 
     for f in rejected:
         if f in m.files():
             return 1
     return ret
 
 
 def marktouched(repo, files, similarity=0.0):
     '''Assert that files have somehow been operated upon. files are relative to
     the repo root.'''
     m = matchfiles(repo, files, badfn=lambda x, y: rejected.append(x))
     rejected = []
 
     added, unknown, deleted, removed, forgotten = _interestingfiles(repo, m)
 
     if repo.ui.verbose:
         unknownset = set(unknown + forgotten)
         toprint = unknownset.copy()
         toprint.update(deleted)
         for abs in sorted(toprint):
             if abs in unknownset:
                 status = _(b'adding %s\n') % abs
             else:
                 status = _(b'removing %s\n') % abs
             repo.ui.status(status)
 
     # TODO: We should probably have the caller pass in uipathfn and apply it to
     # the messages above too. legacyrelativevalue=True is consistent with how
     # it used to work.
     uipathfn = getuipathfn(repo, legacyrelativevalue=True)
     renames = _findrenames(
         repo, m, added + unknown, removed + deleted, similarity, uipathfn
     )
 
     _markchanges(repo, unknown + forgotten, deleted, renames)
 
     for f in rejected:
         if f in m.files():
             return 1
     return 0
 
 
 def _interestingfiles(repo, matcher):
     '''Walk dirstate with matcher, looking for files that addremove would care
     about.
 
     This is different from dirstate.status because it doesn't care about
     whether files are modified or clean.'''
     added, unknown, deleted, removed, forgotten = [], [], [], [], []
     audit_path = pathutil.pathauditor(repo.root, cached=True)
 
     ctx = repo[None]
     dirstate = repo.dirstate
     matcher = repo.narrowmatch(matcher, includeexact=True)
     walkresults = dirstate.walk(
         matcher,
         subrepos=sorted(ctx.substate),
         unknown=True,
         ignored=False,
         full=False,
     )
     for abs, st in pycompat.iteritems(walkresults):
         dstate = dirstate[abs]
         if dstate == b'?' and audit_path.check(abs):
             unknown.append(abs)
         elif dstate != b'r' and not st:
             deleted.append(abs)
         elif dstate == b'r' and st:
             forgotten.append(abs)
         # for finding renames
         elif dstate == b'r' and not st:
             removed.append(abs)
         elif dstate == b'a':
             added.append(abs)
 
     return added, unknown, deleted, removed, forgotten
 
 
 def _findrenames(repo, matcher, added, removed, similarity, uipathfn):
     '''Find renames from removed files to added ones.'''
     renames = {}
     if similarity > 0:
         for old, new, score in similar.findrenames(
             repo, added, removed, similarity
         ):
             if (
                 repo.ui.verbose
                 or not matcher.exact(old)
                 or not matcher.exact(new)
             ):
                 repo.ui.status(
                     _(
                         b'recording removal of %s as rename to %s '
                         b'(%d%% similar)\n'
                     )
                     % (uipathfn(old), uipathfn(new), score * 100)
                 )
             renames[new] = old
     return renames
 
 
 def _markchanges(repo, unknown, deleted, renames):
     '''Marks the files in unknown as added, the files in deleted as removed,
     and the files in renames as copied.'''
     wctx = repo[None]
     with repo.wlock():
         wctx.forget(deleted)
         wctx.add(unknown)
         for new, old in pycompat.iteritems(renames):
             wctx.copy(old, new)
 
 
 def getrenamedfn(repo, endrev=None):
     if copiesmod.usechangesetcentricalgo(repo):
 
         def getrenamed(fn, rev):
             ctx = repo[rev]
             p1copies = ctx.p1copies()
             if fn in p1copies:
                 return p1copies[fn]
             p2copies = ctx.p2copies()
             if fn in p2copies:
                 return p2copies[fn]
             return None
 
         return getrenamed
 
     rcache = {}
     if endrev is None:
         endrev = len(repo)
 
     def getrenamed(fn, rev):
         '''looks up all renames for a file (up to endrev) the first
         time the file is given. It indexes on the changerev and only
         parses the manifest if linkrev != changerev.
         Returns rename info for fn at changerev rev.'''
         if fn not in rcache:
             rcache[fn] = {}
             fl = repo.file(fn)
             for i in fl:
                 lr = fl.linkrev(i)
                 renamed = fl.renamed(fl.node(i))
                 rcache[fn][lr] = renamed and renamed[0]
                 if lr >= endrev:
                     break
         if rev in rcache[fn]:
             return rcache[fn][rev]
 
         # If linkrev != rev (i.e. rev not found in rcache) fallback to
         # filectx logic.
         try:
             return repo[rev][fn].copysource()
         except error.LookupError:
             return None
 
     return getrenamed
 
 
 def getcopiesfn(repo, endrev=None):
     if copiesmod.usechangesetcentricalgo(repo):
 
         def copiesfn(ctx):
             if ctx.p2copies():
                 allcopies = ctx.p1copies().copy()
                 # There should be no overlap
                 allcopies.update(ctx.p2copies())
                 return sorted(allcopies.items())
             else:
                 return sorted(ctx.p1copies().items())
 
     else:
         getrenamed = getrenamedfn(repo, endrev)
 
         def copiesfn(ctx):
             copies = []
             for fn in ctx.files():
                 rename = getrenamed(fn, ctx.rev())
                 if rename:
                     copies.append((fn, rename))
             return copies
 
     return copiesfn
 
 
 def dirstatecopy(ui, repo, wctx, src, dst, dryrun=False, cwd=None):
     """Update the dirstate to reflect the intent of copying src to dst. For
     different reasons it might not end with dst being marked as copied from src.
     """
     origsrc = repo.dirstate.copied(src) or src
     if dst == origsrc:  # copying back a copy?
         if repo.dirstate[dst] not in b'mn' and not dryrun:
             repo.dirstate.normallookup(dst)
     else:
         if repo.dirstate[origsrc] == b'a' and origsrc == src:
             if not ui.quiet:
                 ui.warn(
                     _(
                         b"%s has not been committed yet, so no copy "
                         b"data will be stored for %s.\n"
                     )
                     % (repo.pathto(origsrc, cwd), repo.pathto(dst, cwd))
                 )
             if repo.dirstate[dst] in b'?r' and not dryrun:
                 wctx.add([dst])
         elif not dryrun:
             wctx.copy(origsrc, dst)
 
 
 def movedirstate(repo, newctx, match=None):
     """Move the dirstate to newctx and adjust it as necessary.
 
     A matcher can be provided as an optimization. It is probably a bug to pass
     a matcher that doesn't match all the differences between the parent of the
     working copy and newctx.
     """
     oldctx = repo[b'.']
     ds = repo.dirstate
     copies = dict(ds.copies())
     ds.setparents(newctx.node(), nullid)
     s = newctx.status(oldctx, match=match)
     for f in s.modified:
         if ds[f] == b'r':
             # modified + removed -> removed
             continue
         ds.normallookup(f)
 
     for f in s.added:
         if ds[f] == b'r':
             # added + removed -> unknown
             ds.drop(f)
         elif ds[f] != b'a':
             ds.add(f)
 
     for f in s.removed:
         if ds[f] == b'a':
             # removed + added -> normal
             ds.normallookup(f)
         elif ds[f] != b'r':
             ds.remove(f)
 
     # Merge old parent and old working dir copies
     oldcopies = copiesmod.pathcopies(newctx, oldctx, match)
     oldcopies.update(copies)
     copies = {
         dst: oldcopies.get(src, src)
         for dst, src in pycompat.iteritems(oldcopies)
     }
     # Adjust the dirstate copies
     for dst, src in pycompat.iteritems(copies):
         if src not in newctx or dst in newctx or ds[dst] != b'a':
             src = None
         ds.copy(src, dst)
     repo._quick_access_changeid_invalidate()
 
 
 def writerequires(opener, requirements):
     with opener(b'requires', b'w', atomictemp=True) as fp:
         for r in sorted(requirements):
             fp.write(b"%s\n" % r)
 
 
 class filecachesubentry(object):
     def __init__(self, path, stat):
         self.path = path
         self.cachestat = None
         self._cacheable = None
 
         if stat:
             self.cachestat = filecachesubentry.stat(self.path)
 
             if self.cachestat:
                 self._cacheable = self.cachestat.cacheable()
             else:
                 # None means we don't know yet
                 self._cacheable = None
 
     def refresh(self):
         if self.cacheable():
             self.cachestat = filecachesubentry.stat(self.path)
 
     def cacheable(self):
         if self._cacheable is not None:
             return self._cacheable
 
         # we don't know yet, assume it is for now
         return True
 
     def changed(self):
         # no point in going further if we can't cache it
         if not self.cacheable():
             return True
 
         newstat = filecachesubentry.stat(self.path)
 
         # we may not know if it's cacheable yet, check again now
         if newstat and self._cacheable is None:
             self._cacheable = newstat.cacheable()
 
             # check again
             if not self._cacheable:
                 return True
 
         if self.cachestat != newstat:
             self.cachestat = newstat
             return True
         else:
             return False
 
     @staticmethod
     def stat(path):
         try:
             return util.cachestat(path)
         except OSError as e:
             if e.errno != errno.ENOENT:
                 raise
 
 
 class filecacheentry(object):
     def __init__(self, paths, stat=True):
         self._entries = []
         for path in paths:
             self._entries.append(filecachesubentry(path, stat))
 
     def changed(self):
         '''true if any entry has changed'''
         for entry in self._entries:
             if entry.changed():
                 return True
         return False
 
     def refresh(self):
         for entry in self._entries:
             entry.refresh()
 
 
 class filecache(object):
     """A property like decorator that tracks files under .hg/ for updates.
 
     On first access, the files defined as arguments are stat()ed and the
     results cached. The decorated function is called. The results are stashed
     away in a ``_filecache`` dict on the object whose method is decorated.
 
     On subsequent access, the cached result is used as it is set to the
     instance dictionary.
 
     On external property set/delete operations, the caller must update the
     corresponding _filecache entry appropriately. Use __class__.<attr>.set()
     instead of directly setting <attr>.
 
     When using the property API, the cached data is always used if available.
     No stat() is performed to check if the file has changed.
 
     Others can muck about with the state of the ``_filecache`` dict. e.g. they
     can populate an entry before the property's getter is called. In this case,
     entries in ``_filecache`` will be used during property operations,
     if available. If the underlying file changes, it is up to external callers
     to reflect this by e.g. calling ``delattr(obj, attr)`` to remove the cached
     method result as well as possibly calling ``del obj._filecache[attr]`` to
     remove the ``filecacheentry``.
     """
 
     def __init__(self, *paths):
         self.paths = paths
 
     def join(self, obj, fname):
         """Used to compute the runtime path of a cached file.
 
         Users should subclass filecache and provide their own version of this
         function to call the appropriate join function on 'obj' (an instance
         of the class that its member function was decorated).
         """
         raise NotImplementedError
 
     def __call__(self, func):
         self.func = func
         self.sname = func.__name__
         self.name = pycompat.sysbytes(self.sname)
         return self
 
     def __get__(self, obj, type=None):
         # if accessed on the class, return the descriptor itself.
         if obj is None:
             return self
 
         assert self.sname not in obj.__dict__
 
         entry = obj._filecache.get(self.name)
 
         if entry:
             if entry.changed():
                 entry.obj = self.func(obj)
         else:
             paths = [self.join(obj, path) for path in self.paths]
 
             # We stat -before- creating the object so our cache doesn't lie if
             # a writer modified between the time we read and stat
             entry = filecacheentry(paths, True)
             entry.obj = self.func(obj)
 
             obj._filecache[self.name] = entry
 
         obj.__dict__[self.sname] = entry.obj
         return entry.obj
 
     # don't implement __set__(), which would make __dict__ lookup as slow as
     # function call.
 
     def set(self, obj, value):
         if self.name not in obj._filecache:
             # we add an entry for the missing value because X in __dict__
             # implies X in _filecache
             paths = [self.join(obj, path) for path in self.paths]
             ce = filecacheentry(paths, False)
             obj._filecache[self.name] = ce
         else:
             ce = obj._filecache[self.name]
 
         ce.obj = value  # update cached copy
         obj.__dict__[self.sname] = value  # update copy returned by obj.x
 
 
 def extdatasource(repo, source):
     """Gather a map of rev -> value dict from the specified source
 
     A source spec is treated as a URL, with a special case shell: type
     for parsing the output from a shell command.
 
     The data is parsed as a series of newline-separated records where
     each record is a revision specifier optionally followed by a space
     and a freeform string value. If the revision is known locally, it
     is converted to a rev, otherwise the record is skipped.
 
     Note that both key and value are treated as UTF-8 and converted to
     the local encoding. This allows uniformity between local and
     remote data sources.
     """
 
     spec = repo.ui.config(b"extdata", source)
     if not spec:
         raise error.Abort(_(b"unknown extdata source '%s'") % source)
 
     data = {}
     src = proc = None
     try:
         if spec.startswith(b"shell:"):
             # external commands should be run relative to the repo root
             cmd = spec[6:]
             proc = subprocess.Popen(
                 procutil.tonativestr(cmd),
                 shell=True,
                 bufsize=-1,
                 close_fds=procutil.closefds,
                 stdout=subprocess.PIPE,
                 cwd=procutil.tonativestr(repo.root),
             )
             src = proc.stdout
         else:
             # treat as a URL or file
             src = url.open(repo.ui, spec)
         for l in src:
             if b" " in l:
                 k, v = l.strip().split(b" ", 1)
             else:
                 k, v = l.strip(), b""
 
             k = encoding.tolocal(k)
             try:
                 data[revsingle(repo, k).rev()] = encoding.tolocal(v)
             except (error.LookupError, error.RepoLookupError):
                 pass  # we ignore data for nodes that don't exist locally
     finally:
         if proc:
             try:
                 proc.communicate()
             except ValueError:
                 # This happens if we started iterating src and then
                 # get a parse error on a line. It should be safe to ignore.
                 pass
         if src:
             src.close()
     if proc and proc.returncode != 0:
         raise error.Abort(
             _(b"extdata command '%s' failed: %s")
             % (cmd, procutil.explainexit(proc.returncode))
         )
 
     return data
 
 
 def _locksub(repo, lock, envvar, cmd, environ=None, *args, **kwargs):
     if lock is None:
         raise error.LockInheritanceContractViolation(
             b'lock can only be inherited while held'
         )
     if environ is None:
         environ = {}
     with lock.inherit() as locker:
         environ[envvar] = locker
         return repo.ui.system(cmd, environ=environ, *args, **kwargs)
 
 
 def wlocksub(repo, cmd, *args, **kwargs):
     """run cmd as a subprocess that allows inheriting repo's wlock
 
     This can only be called while the wlock is held. This takes all the
     arguments that ui.system does, and returns the exit code of the
     subprocess."""
     return _locksub(
         repo, repo.currentwlock(), b'HG_WLOCK_LOCKER', cmd, *args, **kwargs
     )
 
 
 class progress(object):
     def __init__(self, ui, updatebar, topic, unit=b"", total=None):
         self.ui = ui
         self.pos = 0
         self.topic = topic
         self.unit = unit
         self.total = total
         self.debug = ui.configbool(b'progress', b'debug')
         self._updatebar = updatebar
 
     def __enter__(self):
         return self
 
     def __exit__(self, exc_type, exc_value, exc_tb):
         self.complete()
 
     def update(self, pos, item=b"", total=None):
         assert pos is not None
         if total:
             self.total = total
         self.pos = pos
         self._updatebar(self.topic, self.pos, item, self.unit, self.total)
         if self.debug:
             self._printdebug(item)
 
     def increment(self, step=1, item=b"", total=None):
         self.update(self.pos + step, item, total)
 
     def complete(self):
         self.pos = None
         self.unit = b""
         self.total = None
         self._updatebar(self.topic, self.pos, b"", self.unit, self.total)
 
     def _printdebug(self, item):
         unit = b''
         if self.unit:
             unit = b' ' + self.unit
         if item:
             item = b' ' + item
 
         if self.total:
             pct = 100.0 * self.pos / self.total
             self.ui.debug(
                 b'%s:%s %d/%d%s (%4.2f%%)\n'
                 % (self.topic, item, self.pos, self.total, unit, pct)
             )
         else:
             self.ui.debug(b'%s:%s %d%s\n' % (self.topic, item, self.pos, unit))
 
 
 def gdinitconfig(ui):
     """helper function to know if a repo should be created as general delta
     """
     # experimental config: format.generaldelta
     return ui.configbool(b'format', b'generaldelta') or ui.configbool(
         b'format', b'usegeneraldelta'
     )
 
 
 def gddeltaconfig(ui):
     """helper function to know if incoming delta should be optimised
     """
     # experimental config: format.generaldelta
     return ui.configbool(b'format', b'generaldelta')
 
 
 class simplekeyvaluefile(object):
     """A simple file with key=value lines
 
     Keys must be alphanumerics and start with a letter, values must not
     contain '\n' characters"""
 
     firstlinekey = b'__firstline'
 
     def __init__(self, vfs, path, keys=None):
         self.vfs = vfs
         self.path = path
 
     def read(self, firstlinenonkeyval=False):
         """Read the contents of a simple key-value file
 
         'firstlinenonkeyval' indicates whether the first line of file should
         be treated as a key-value pair or reuturned fully under the
         __firstline key."""
         lines = self.vfs.readlines(self.path)
         d = {}
         if firstlinenonkeyval:
             if not lines:
                 e = _(b"empty simplekeyvalue file")
                 raise error.CorruptedState(e)
             # we don't want to include '\n' in the __firstline
             d[self.firstlinekey] = lines[0][:-1]
             del lines[0]
 
         try:
             # the 'if line.strip()' part prevents us from failing on empty
             # lines which only contain '\n' therefore are not skipped
             # by 'if line'
             updatedict = dict(
                 line[:-1].split(b'=', 1) for line in lines if line.strip()
             )
             if self.firstlinekey in updatedict:
                 e = _(b"%r can't be used as a key")
                 raise error.CorruptedState(e % self.firstlinekey)
             d.update(updatedict)
         except ValueError as e:
             raise error.CorruptedState(stringutil.forcebytestr(e))
         return d
 
     def write(self, data, firstline=None):
         """Write key=>value mapping to a file
         data is a dict. Keys must be alphanumerical and start with a letter.
         Values must not contain newline characters.
 
         If 'firstline' is not None, it is written to file before
         everything else, as it is, not in a key=value form"""
         lines = []
         if firstline is not None:
             lines.append(b'%s\n' % firstline)
 
         for k, v in data.items():
             if k == self.firstlinekey:
                 e = b"key name '%s' is reserved" % self.firstlinekey
                 raise error.ProgrammingError(e)
             if not k[0:1].isalpha():
                 e = b"keys must start with a letter in a key-value file"
                 raise error.ProgrammingError(e)
             if not k.isalnum():
                 e = b"invalid key name in a simple key-value file"
                 raise error.ProgrammingError(e)
             if b'\n' in v:
                 e = b"invalid value in a simple key-value file"
                 raise error.ProgrammingError(e)
             lines.append(b"%s=%s\n" % (k, v))
         with self.vfs(self.path, mode=b'wb', atomictemp=True) as fp:
             fp.write(b''.join(lines))
 
 
 _reportobsoletedsource = [
     b'debugobsolete',
     b'pull',
     b'push',
     b'serve',
     b'unbundle',
 ]
 
 _reportnewcssource = [
     b'pull',
     b'unbundle',
 ]
 
 
 def prefetchfiles(repo, revs, match):
     """Invokes the registered file prefetch functions, allowing extensions to
     ensure the corresponding files are available locally, before the command
     uses them."""
     if match:
         # The command itself will complain about files that don't exist, so
         # don't duplicate the message.
         match = matchmod.badmatch(match, lambda fn, msg: None)
     else:
         match = matchall(repo)
 
     fileprefetchhooks(repo, revs, match)
 
 
 # a list of (repo, revs, match) prefetch functions
 fileprefetchhooks = util.hooks()
 
 # A marker that tells the evolve extension to suppress its own reporting
 _reportstroubledchangesets = True
 
 
 def registersummarycallback(repo, otr, txnname=b'', as_validator=False):
     """register a callback to issue a summary after the transaction is closed
 
     If as_validator is true, then the callbacks are registered as transaction
     validators instead
     """
 
     def txmatch(sources):
         return any(txnname.startswith(source) for source in sources)
 
     categories = []
 
     def reportsummary(func):
         """decorator for report callbacks."""
         # The repoview life cycle is shorter than the one of the actual
         # underlying repository. So the filtered object can die before the
         # weakref is used leading to troubles. We keep a reference to the
         # unfiltered object and restore the filtering when retrieving the
         # repository through the weakref.
         filtername = repo.filtername
         reporef = weakref.ref(repo.unfiltered())
 
         def wrapped(tr):
             repo = reporef()
             if filtername:
                 assert repo is not None  # help pytype
                 repo = repo.filtered(filtername)
             func(repo, tr)
 
         newcat = b'%02i-txnreport' % len(categories)
         if as_validator:
             otr.addvalidator(newcat, wrapped)
         else:
             otr.addpostclose(newcat, wrapped)
         categories.append(newcat)
         return wrapped
 
     @reportsummary
     def reportchangegroup(repo, tr):
         cgchangesets = tr.changes.get(b'changegroup-count-changesets', 0)
         cgrevisions = tr.changes.get(b'changegroup-count-revisions', 0)
         cgfiles = tr.changes.get(b'changegroup-count-files', 0)
         cgheads = tr.changes.get(b'changegroup-count-heads', 0)
         if cgchangesets or cgrevisions or cgfiles:
             htext = b""
             if cgheads:
                 htext = _(b" (%+d heads)") % cgheads
             msg = _(b"added %d changesets with %d changes to %d files%s\n")
             if as_validator:
                 msg = _(b"adding %d changesets with %d changes to %d files%s\n")
             assert repo is not None  # help pytype
             repo.ui.status(msg % (cgchangesets, cgrevisions, cgfiles, htext))
 
     if txmatch(_reportobsoletedsource):
 
         @reportsummary
         def reportobsoleted(repo, tr):
             obsoleted = obsutil.getobsoleted(repo, tr)
             newmarkers = len(tr.changes.get(b'obsmarkers', ()))
             if newmarkers:
                 repo.ui.status(_(b'%i new obsolescence markers\n') % newmarkers)
             if obsoleted:
                 msg = _(b'obsoleted %i changesets\n')
                 if as_validator:
                     msg = _(b'obsoleting %i changesets\n')
                 repo.ui.status(msg % len(obsoleted))
 
     if obsolete.isenabled(
         repo, obsolete.createmarkersopt
     ) and repo.ui.configbool(
         b'experimental', b'evolution.report-instabilities'
     ):
         instabilitytypes = [
             (b'orphan', b'orphan'),
             (b'phase-divergent', b'phasedivergent'),
             (b'content-divergent', b'contentdivergent'),
         ]
 
         def getinstabilitycounts(repo):
             filtered = repo.changelog.filteredrevs
             counts = {}
             for instability, revset in instabilitytypes:
                 counts[instability] = len(
                     set(obsolete.getrevs(repo, revset)) - filtered
                 )
             return counts
 
         oldinstabilitycounts = getinstabilitycounts(repo)
 
         @reportsummary
         def reportnewinstabilities(repo, tr):
             newinstabilitycounts = getinstabilitycounts(repo)
             for instability, revset in instabilitytypes:
                 delta = (
                     newinstabilitycounts[instability]
                     - oldinstabilitycounts[instability]
                 )
                 msg = getinstabilitymessage(delta, instability)
                 if msg:
                     repo.ui.warn(msg)
 
     if txmatch(_reportnewcssource):
 
         @reportsummary
         def reportnewcs(repo, tr):
             """Report the range of new revisions pulled/unbundled."""
             origrepolen = tr.changes.get(b'origrepolen', len(repo))
             unfi = repo.unfiltered()
             if origrepolen >= len(unfi):
                 return
 
             # Compute the bounds of new visible revisions' range.
             revs = smartset.spanset(repo, start=origrepolen)
             if revs:
                 minrev, maxrev = repo[revs.min()], repo[revs.max()]
 
                 if minrev == maxrev:
                     revrange = minrev
                 else:
                     revrange = b'%s:%s' % (minrev, maxrev)
                 draft = len(repo.revs(b'%ld and draft()', revs))
                 secret = len(repo.revs(b'%ld and secret()', revs))
                 if not (draft or secret):
                     msg = _(b'new changesets %s\n') % revrange
                 elif draft and secret:
                     msg = _(b'new changesets %s (%d drafts, %d secrets)\n')
                     msg %= (revrange, draft, secret)
                 elif draft:
                     msg = _(b'new changesets %s (%d drafts)\n')
                     msg %= (revrange, draft)
                 elif secret:
                     msg = _(b'new changesets %s (%d secrets)\n')
                     msg %= (revrange, secret)
                 else:
                     errormsg = b'entered unreachable condition'
                     raise error.ProgrammingError(errormsg)
                 repo.ui.status(msg)
 
             # search new changesets directly pulled as obsolete
             duplicates = tr.changes.get(b'revduplicates', ())
             obsadded = unfi.revs(
                 b'(%d: + %ld) and obsolete()', origrepolen, duplicates
             )
             cl = repo.changelog
             extinctadded = [r for r in obsadded if r not in cl]
             if extinctadded:
                 # They are not just obsolete, but obsolete and invisible
                 # we call them "extinct" internally but the terms have not been
                 # exposed to users.
                 msg = b'(%d other changesets obsolete on arrival)\n'
                 repo.ui.status(msg % len(extinctadded))
 
         @reportsummary
         def reportphasechanges(repo, tr):
             """Report statistics of phase changes for changesets pre-existing
             pull/unbundle.
             """
             origrepolen = tr.changes.get(b'origrepolen', len(repo))
             published = []
             for revs, (old, new) in tr.changes.get(b'phases', []):
                 if new != phases.public:
                     continue
                 published.extend(rev for rev in revs if rev < origrepolen)
             if not published:
                 return
             msg = _(b'%d local changesets published\n')
             if as_validator:
                 msg = _(b'%d local changesets will be published\n')
             repo.ui.status(msg % len(published))
 
 
 def getinstabilitymessage(delta, instability):
     """function to return the message to show warning about new instabilities
 
     exists as a separate function so that extension can wrap to show more
     information like how to fix instabilities"""
     if delta > 0:
         return _(b'%i new %s changesets\n') % (delta, instability)
 
 
 def nodesummaries(repo, nodes, maxnumnodes=4):
     if len(nodes) <= maxnumnodes or repo.ui.verbose:
         return b' '.join(short(h) for h in nodes)
     first = b' '.join(short(h) for h in nodes[:maxnumnodes])
     return _(b"%s and %d others") % (first, len(nodes) - maxnumnodes)
 
 
 def enforcesinglehead(repo, tr, desc, accountclosed=False):
     """check that no named branch has multiple heads"""
     if desc in (b'strip', b'repair'):
         # skip the logic during strip
         return
     visible = repo.filtered(b'visible')
     # possible improvement: we could restrict the check to affected branch
     bm = visible.branchmap()
     for name in bm:
         heads = bm.branchheads(name, closed=accountclosed)
         if len(heads) > 1:
             msg = _(b'rejecting multiple heads on branch "%s"')
             msg %= name
             hint = _(b'%d heads: %s')
             hint %= (len(heads), nodesummaries(repo, heads))
             raise error.Abort(msg, hint=hint)
 
 
 def wrapconvertsink(sink):
     """Allow extensions to wrap the sink returned by convcmd.convertsink()
     before it is used, whether or not the convert extension was formally loaded.
     """
     return sink
 
 
 def unhidehashlikerevs(repo, specs, hiddentype):
     """parse the user specs and unhide changesets whose hash or revision number
     is passed.
 
     hiddentype can be: 1) 'warn': warn while unhiding changesets
                        2) 'nowarn': don't warn while unhiding changesets
 
     returns a repo object with the required changesets unhidden
     """
     if not repo.filtername or not repo.ui.configbool(
         b'experimental', b'directaccess'
     ):
         return repo
 
     if repo.filtername not in (b'visible', b'visible-hidden'):
         return repo
 
     symbols = set()
     for spec in specs:
         try:
             tree = revsetlang.parse(spec)
         except error.ParseError:  # will be reported by scmutil.revrange()
             continue
 
         symbols.update(revsetlang.gethashlikesymbols(tree))
 
     if not symbols:
         return repo
 
     revs = _getrevsfromsymbols(repo, symbols)
 
     if not revs:
         return repo
 
     if hiddentype == b'warn':
         unfi = repo.unfiltered()
         revstr = b", ".join([pycompat.bytestr(unfi[l]) for l in revs])
         repo.ui.warn(
             _(
                 b"warning: accessing hidden changesets for write "
                 b"operation: %s\n"
             )
             % revstr
         )
 
     # we have to use new filtername to separate branch/tags cache until we can
     # disbale these cache when revisions are dynamically pinned.
     return repo.filtered(b'visible-hidden', revs)
 
 
 def _getrevsfromsymbols(repo, symbols):
     """parse the list of symbols and returns a set of revision numbers of hidden
     changesets present in symbols"""
     revs = set()
     unfi = repo.unfiltered()
     unficl = unfi.changelog
     cl = repo.changelog
     tiprev = len(unficl)
     allowrevnums = repo.ui.configbool(b'experimental', b'directaccess.revnums')
     for s in symbols:
         try:
             n = int(s)
             if n <= tiprev:
                 if not allowrevnums:
                     continue
                 else:
                     if n not in cl:
                         revs.add(n)
                     continue
         except ValueError:
             pass
 
         try:
             s = resolvehexnodeidprefix(unfi, s)
         except (error.LookupError, error.WdirUnsupported):
             s = None
 
         if s is not None:
             rev = unficl.rev(s)
             if rev not in cl:
                 revs.add(rev)
 
     return revs
 
 
 def bookmarkrevs(repo, mark):
     """
     Select revisions reachable by a given bookmark
     """
     return repo.revs(
         b"ancestors(bookmark(%s)) - "
         b"ancestors(head() and not bookmark(%s)) - "
         b"ancestors(bookmark() and not bookmark(%s))",
         mark,
         mark,
         mark,
     )