view hgext/evolve.py @ 1460:44a9dcb3fefc stable 5.2.0

merge with 3.3

# Copyright 2011 Peter Arrenbrecht <[e-mail]>
#                Logilab SA        <[e-mail]>
#                Pierre-Yves David <[e-mail]>
#                Patrick Mezard <[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.

'''extends Mercurial feature related to Changeset Evolution

This extension provides several commands to mutate history and deal with
issues it may raise.

It also:

    - enables the "Changeset Obsolescence" feature of mercurial,
    - alters core commands and extensions that rewrite history to use
      this feature,
    - improves some aspect of the early implementation in Mercurial core
'''

__version__ = '5.2.0'
testedwith = '3.3.3 3.4.1'
buglink = 'http://bz.selenic.com/'


evolutionhelptext = """
Obsolescence markers make it possible to mark changesets that have been
deleted or superset in a new version of the changeset.

Unlike the previous way of handling such changes, by stripping the old
changesets from the repository, obsolescence markers can be propagated
between repositories. This allows for a safe and simple way of exchanging
mutable history and altering it after the fact. Changeset phases are
respected, such that only draft and secret changesets can be altered (see
:hg:`hg phases` for details).

Obsolescence is tracked using "obsolete markers", a piece of metadata
tracking which changesets have been made obsolete, potential successors for
a given changeset, the moment the changeset was marked as obsolete, and the
user who performed the rewriting operation. The markers are stored
separately from standard changeset data can be exchanged without any of the
precursor changesets, preventing unnecessary exchange of obsolescence data.

The complete set of obsolescence markers describes a history of changeset
modifications that is orthogonal to the repository history of file
modifications. This changeset history allows for detection and automatic
resolution of edge cases arising from multiple users rewriting the same part
of history concurrently.

Current feature status
======================

This feature is still in development.  If you see this help, you have enable an
extension that turned this feature on.

Obsolescence markers will be exchanged between repositories that explicitly
assert support for the obsolescence feature (this can currently only be done
via an extension).""".strip()


import sys, os
import random
from StringIO import StringIO
import struct
import re
import collections
import socket
import errno
sha1re = re.compile(r'\b[0-9a-f]{6,40}\b')

import mercurial
from mercurial import util

try:
    from mercurial import obsolete
    if not obsolete._enabled:
        obsolete._enabled = True
    from mercurial import wireproto
    gboptslist = getattr(wireproto, 'gboptslist', None)
    gboptsmap = getattr(wireproto, 'gboptsmap', None)
except (ImportError, AttributeError):
    gboptslist = gboptsmap = None

# Flags for enabling optional parts of evolve
commandopt = 'allnewcommands'

from mercurial import bookmarks
from mercurial import cmdutil
from mercurial import commands
from mercurial import context
from mercurial import copies
from mercurial import error
from mercurial import exchange
from mercurial import extensions
from mercurial import help
from mercurial import httppeer
from mercurial import hg
from mercurial import lock as lockmod
from mercurial import merge
from mercurial import node
from mercurial import phases
from mercurial import patch
from mercurial import revset
from mercurial import scmutil
from mercurial import templatekw
from mercurial.i18n import _
from mercurial.commands import walkopts, commitopts, commitopts2, mergetoolopts
from mercurial.node import nullid
from mercurial import wireproto
from mercurial import localrepo
from mercurial.hgweb import hgweb_mod

cmdtable = {}
command = cmdutil.command(cmdtable)

_pack = struct.pack

if gboptsmap is not None:
    memfilectx = context.memfilectx
elif gboptslist is not None:
    oldmemfilectx = context.memfilectx
    def memfilectx(repo, *args, **kwargs):
        return oldmemfilectx(*args, **kwargs)
else:
    raise ImportError('evolve needs version %s or above' % min(testedwith.split()))

aliases, entry = cmdutil.findcmd('commit', commands.table)
hasinteractivemode = any(['interactive' in e for e in entry[1]])
if hasinteractivemode:
    interactiveopt = [['i', 'interactive', None, _('use interactive mode')]]
else:
    interactiveopt = []
# This extension contains the following code
#
# - Extension Helper code
# - Obsolescence cache
# - ...
# - Older format compat


#####################################################################
### Extension helper                                              ###
#####################################################################

class exthelper(object):
    """Helper for modular extension setup

    A single helper should be instanciated for each extension. Helper
    methods are then used as decorator for various purpose.

    All decorators return the original function and may be chained.
    """

    def __init__(self):
        self._uicallables = []
        self._extcallables = []
        self._repocallables = []
        self._revsetsymbols = []
        self._templatekws = []
        self._commandwrappers = []
        self._extcommandwrappers = []
        self._functionwrappers = []
        self._duckpunchers = []

    def final_uisetup(self, ui):
        """Method to be used as the extension uisetup

        The following operations belong here:

        - Changes to ui.__class__ . The ui object that will be used to run the
          command has not yet been created. Changes made here will affect ui
          objects created after this, and in particular the ui that will be
          passed to runcommand
        - Command wraps (extensions.wrapcommand)
        - Changes that need to be visible to other extensions: because
          initialization occurs in phases (all extensions run uisetup, then all
          run extsetup), a change made here will be visible to other extensions
          during extsetup
        - Monkeypatch or wrap function (extensions.wrapfunction) of dispatch
          module members
        - Setup of pre-* and post-* hooks
        - pushkey setup
        """
        for cont, funcname, func in self._duckpunchers:
            setattr(cont, funcname, func)
        for command, wrapper, opts in self._commandwrappers:
            entry = extensions.wrapcommand(commands.table, command, wrapper)
            if opts:
                for short, long, val, msg in opts:
                    entry[1].append((short, long, val, msg))
        for cont, funcname, wrapper in self._functionwrappers:
            extensions.wrapfunction(cont, funcname, wrapper)
        for c in self._uicallables:
            c(ui)

    def final_extsetup(self, ui):
        """Method to be used as a the extension extsetup

        The following operations belong here:

        - Changes depending on the status of other extensions. (if
          extensions.find('mq'))
        - Add a global option to all commands
        - Register revset functions
        """
        knownexts = {}
        for name, symbol in self._revsetsymbols:
            revset.symbols[name] = symbol
        for name, kw in self._templatekws:
            templatekw.keywords[name] = kw
        for ext, command, wrapper, opts in self._extcommandwrappers:
            if ext not in knownexts:
                try:
                    e = extensions.find(ext)
                except KeyError:
                    # Extension isn't enabled, so don't bother trying to wrap
                    # it.
                    continue
                knownexts[ext] = e.cmdtable
            entry = extensions.wrapcommand(knownexts[ext], command, wrapper)
            if opts:
                for short, long, val, msg in opts:
                    entry[1].append((short, long, val, msg))

        for c in self._extcallables:
            c(ui)

    def final_reposetup(self, ui, repo):
        """Method to be used as a the extension reposetup

        The following operations belong here:

        - All hooks but pre-* and post-*
        - Modify configuration variables
        - Changes to repo.__class__, repo.dirstate.__class__
        """
        for c in self._repocallables:
            c(ui, repo)

    def uisetup(self, call):
        """Decorated function will be executed during uisetup

        example::

            @eh.uisetup
            def setupbabar(ui):
                print 'this is uisetup!'
        """
        self._uicallables.append(call)
        return call

    def extsetup(self, call):
        """Decorated function will be executed during extsetup

        example::

            @eh.extsetup
            def setupcelestine(ui):
                print 'this is extsetup!'
        """
        self._extcallables.append(call)
        return call

    def reposetup(self, call):
        """Decorated function will be executed during reposetup

        example::

            @eh.reposetup
            def setupzephir(ui, repo):
                print 'this is reposetup!'
        """
        self._repocallables.append(call)
        return call

    def revset(self, symbolname):
        """Decorated function is a revset symbol

        The name of the symbol must be given as the decorator argument.
        The symbol is added during `extsetup`.

        example::

            @eh.revset('hidden')
            def revsetbabar(repo, subset, x):
                args = revset.getargs(x, 0, 0, 'babar accept no argument')
                return [r for r in subset if 'babar' in repo[r].description()]
        """
        def dec(symbol):
            self._revsetsymbols.append((symbolname, symbol))
            return symbol
        return dec


    def templatekw(self, keywordname):
        """Decorated function is a template keyword

        The name of the keyword must be given as the decorator argument.
        The symbol is added during `extsetup`.

        example::

            @eh.templatekw('babar')
            def kwbabar(ctx):
                return 'babar'
        """
        def dec(keyword):
            self._templatekws.append((keywordname, keyword))
            return keyword
        return dec

    def wrapcommand(self, command, extension=None, opts=[]):
        """Decorated function is a command wrapper

        The name of the command must be given as the decorator argument.
        The wrapping is installed during `uisetup`.

        If the second option `extension` argument is provided, the wrapping
        will be applied in the extension commandtable. This argument must be a
        string that will be searched using `extension.find` if not found and
        Abort error is raised. If the wrapping applies to an extension, it is
        installed during `extsetup`

        example::

            @eh.wrapcommand('summary')
            def wrapsummary(orig, ui, repo, *args, **kwargs):
                ui.note('Barry!')
                return orig(ui, repo, *args, **kwargs)

        The `opts` argument allows specifying additional arguments for the
        command.

        """
        def dec(wrapper):
            if extension is None:
                self._commandwrappers.append((command, wrapper, opts))
            else:
                self._extcommandwrappers.append((extension, command, wrapper,
                    opts))
            return wrapper
        return dec

    def wrapfunction(self, container, funcname):
        """Decorated function is a function wrapper

        This function takes two arguments, the container and the name of the
        function to wrap. The wrapping is performed during `uisetup`.
        (there is no extension support)

        example::

            @eh.function(discovery, 'checkheads')
            def wrapfunction(orig, *args, **kwargs):
                ui.note('His head smashed in and his heart cut out')
                return orig(*args, **kwargs)
        """
        def dec(wrapper):
            self._functionwrappers.append((container, funcname, wrapper))
            return wrapper
        return dec

    def addattr(self, container, funcname):
        """Decorated function is to be added to the container

        This function takes two arguments, the container and the name of the
        function to wrap. The wrapping is performed during `uisetup`.

        example::

            @eh.function(context.changectx, 'babar')
            def babar(ctx):
                return 'babar' in ctx.description
        """
        def dec(func):
            self._duckpunchers.append((container, funcname, func))
            return func
        return dec

eh = exthelper()
uisetup = eh.final_uisetup
extsetup = eh.final_extsetup
reposetup = eh.final_reposetup

#####################################################################
### Option configuration                                          ###
#####################################################################

@eh.reposetup # must be the first of its kin.
def _configureoptions(ui, repo):
    # If no capabilities are specified, enable everything.
    # This is so existing evolve users don't need to change their config.
    evolveopts = ui.configlist('experimental', 'evolution')
    if not evolveopts:
        evolveopts = ['all']
        ui.setconfig('experimental', 'evolution', evolveopts)

@eh.uisetup
def _configurecmdoptions(ui):
    # Unregister evolve commands if the command capability is not specified.
    #
    # This must be in the same function as the option configuration above to
    # guarantee it happens after the above configuration, but before the
    # extsetup functions.
    evolvecommands = ui.configlist('experimental', 'evolutioncommands')
    evolveopts = ui.configlist('experimental', 'evolution')
    if evolveopts and (commandopt not in evolveopts and
                       'all' not in evolveopts):
        # We build whitelist containing the commands we want to enable
        whitelist = set()
        for cmd in evolvecommands:
            matchingevolvecommands = [e for e in cmdtable.keys() if cmd in e]
            if not matchingevolvecommands:
                raise error.Abort(_('unknown command: %s') % cmd)
            elif len(matchingevolvecommands) > 1:
                raise error.Abort(_('ambiguous command specification: "%s" matches %r')
                                  % (cmd, matchingevolvecommands))
            else:
                whitelist.add(matchingevolvecommands[0])
        for disabledcmd in set(cmdtable) - whitelist:
            del cmdtable[disabledcmd]

#####################################################################
### experimental behavior                                         ###
#####################################################################

commitopts3 = [
    ('D', 'current-date', None,
     _('record the current date as commit date')),
    ('U', 'current-user', None,
     _('record the current user as committer')),
]

def _resolveoptions(ui, opts):
    """modify commit options dict to handle related options

    For now, all it does is figure out the commit date: respect -D unless
    -d was supplied.
    """
    # N.B. this is extremely similar to setupheaderopts() in mq.py
    if not opts.get('date') and opts.get('current_date'):
        opts['date'] = '%d %d' % util.makedate()
    if not opts.get('user') and opts.get('current_user'):
        opts['user'] = ui.username()

getrevs = obsolete.getrevs

#####################################################################
### Additional Utilities                                          ###
#####################################################################

# This section contains a lot of small utility function and method

# - Function to create markers
# - useful alias pstatus and pdiff (should probably go in evolve)
# - "troubles" method on changectx
# - function to travel throught the obsolescence graph
# - function to find useful changeset to stabilize


### Useful alias

@eh.uisetup
def _installalias(ui):
    if ui.config('alias', 'pstatus', None) is None:
        ui.setconfig('alias', 'pstatus', 'status --rev .^')
    if ui.config('alias', 'pdiff', None) is None:
        ui.setconfig('alias', 'pdiff', 'diff --rev .^')
    if ui.config('alias', 'olog', None) is None:
        ui.setconfig('alias', 'olog', "log -r 'precursors(.)' --hidden")
    if ui.config('alias', 'odiff', None) is None:
        ui.setconfig('alias', 'odiff',
            "diff --hidden --rev 'limit(precursors(.),1)' --rev .")
    if ui.config('alias', 'grab', None) is None:
        if os.name == 'nt':
            ui.setconfig('alias', 'grab',
                "! " + util.hgexecutable() + " rebase --dest . --rev $@ && "
                 + util.hgexecutable() + " up tip")
        else:
            ui.setconfig('alias', 'grab',
                "! $HG rebase --dest . --rev $@ && $HG up tip")


### Troubled revset symbol

@eh.revset('troubled')
def revsettroubled(repo, subset, x):
    """``troubled()``
    Changesets with troubles.
    """
    revset.getargs(x, 0, 0, 'troubled takes no arguments')
    troubled = set()
    troubled.update(getrevs(repo, 'unstable'))
    troubled.update(getrevs(repo, 'bumped'))
    troubled.update(getrevs(repo, 'divergent'))
    troubled = revset.baseset(troubled)
    troubled.sort() # set is non-ordered, enforce order
    return subset & troubled

### Obsolescence graph

# XXX SOME MAJOR CLEAN UP TO DO HERE XXX

def _precursors(repo, s):
    """Precursor of a changeset"""
    cs = set()
    nm = repo.changelog.nodemap
    markerbysubj = repo.obsstore.precursors
    node = repo.changelog.node
    for r in s:
        for p in markerbysubj.get(node(r), ()):
            pr = nm.get(p[0])
            if pr is not None:
                cs.add(pr)
    cs -= repo.changelog.filteredrevs # nodemap has no filtering
    return cs

def _allprecursors(repo, s):  # XXX we need a better naming
    """transitive precursors of a subset"""
    node = repo.changelog.node
    toproceed = [node(r) for r in s]
    seen = set()
    allsubjects = repo.obsstore.precursors
    while toproceed:
        nc = toproceed.pop()
        for mark in allsubjects.get(nc, ()):
            np = mark[0]
            if np not in seen:
                seen.add(np)
                toproceed.append(np)
    nm = repo.changelog.nodemap
    cs = set()
    for p in seen:
        pr = nm.get(p)
        if pr is not None:
            cs.add(pr)
    cs -= repo.changelog.filteredrevs # nodemap has no filtering
    return cs

def _successors(repo, s):
    """Successors of a changeset"""
    cs = set()
    node = repo.changelog.node
    nm = repo.changelog.nodemap
    markerbyobj = repo.obsstore.successors
    for r in s:
        for p in markerbyobj.get(node(r), ()):
            for sub in p[1]:
                sr = nm.get(sub)
                if sr is not None:
                    cs.add(sr)
    cs -= repo.changelog.filteredrevs # nodemap has no filtering
    return cs

def _allsuccessors(repo, s, haltonflags=0):  # XXX we need a better naming
    """transitive successors of a subset

    haltonflags allows to provide flags which prevent the evaluation of a
    marker.  """
    node = repo.changelog.node
    toproceed = [node(r) for r in s]
    seen = set()
    allobjects = repo.obsstore.successors
    while toproceed:
        nc = toproceed.pop()
        for mark in allobjects.get(nc, ()):
            if mark[2] & haltonflags:
                continue
            for sub in mark[1]:
                if sub == nullid:
                    continue # should not be here!
                if sub not in seen:
                    seen.add(sub)
                    toproceed.append(sub)
    nm = repo.changelog.nodemap
    cs = set()
    for s in seen:
        sr = nm.get(s)
        if sr is not None:
            cs.add(sr)
    cs -= repo.changelog.filteredrevs # nodemap has no filtering
    return cs




#####################################################################
### Extending revset and template                                 ###
#####################################################################

# this section add several useful revset symbol not yet in core.
# they are subject to changes


### XXX I'm not sure this revset is useful
@eh.revset('suspended')
def revsetsuspended(repo, subset, x):
    """``suspended()``
    Obsolete changesets with non-obsolete descendants.
    """
    revset.getargs(x, 0, 0, 'suspended takes no arguments')
    suspended = revset.baseset(getrevs(repo, 'suspended'))
    suspended.sort()
    return subset & suspended


@eh.revset('precursors')
def revsetprecursors(repo, subset, x):
    """``precursors(set)``
    Immediate precursors of changesets in set.
    """
    s = revset.getset(repo, revset.fullreposet(repo), x)
    s = revset.baseset(_precursors(repo, s))
    s.sort()
    return subset & s


@eh.revset('allprecursors')
def revsetallprecursors(repo, subset, x):
    """``allprecursors(set)``
    Transitive precursors of changesets in set.
    """
    s = revset.getset(repo, revset.fullreposet(repo), x)
    s = revset.baseset(_allprecursors(repo, s))
    s.sort()
    return subset & s


@eh.revset('successors')
def revsetsuccessors(repo, subset, x):
    """``successors(set)``
    Immediate successors of changesets in set.
    """
    s = revset.getset(repo, revset.fullreposet(repo), x)
    s = revset.baseset(_successors(repo, s))
    s.sort()
    return subset & s

@eh.revset('allsuccessors')
def revsetallsuccessors(repo, subset, x):
    """``allsuccessors(set)``
    Transitive successors of changesets in set.
    """
    s = revset.getset(repo, revset.fullreposet(repo), x)
    s = revset.baseset(_allsuccessors(repo, s))
    s.sort()
    return subset & s

### template keywords
# XXX it does not handle troubles well :-/

@eh.templatekw('obsolete')
def obsoletekw(repo, ctx, templ, **args):
    """:obsolete: String. The obsolescence level of the node, could be
    ``stable``, ``unstable``, ``suspended`` or ``extinct``.
    """
    if ctx.obsolete():
        if ctx.extinct():
            return 'extinct'
        else:
            return 'suspended'
    elif ctx.unstable():
        return 'unstable'
    return 'stable'

@eh.templatekw('troubles')
def showtroubles(repo, ctx, **args):
    """:troubles: List of strings. Evolution troubles affecting the changeset
    (zero or more of "unstable", "divergent" or "bumped")."""
    return templatekw.showlist('trouble', ctx.troubles(), plural='troubles',
                               **args)

#####################################################################
### Various trouble warning                                       ###
#####################################################################

# This section take care of issue warning to the user when troubles appear

@eh.wrapcommand("update")
@eh.wrapcommand("parents")
@eh.wrapcommand("pull")
def wrapmayobsoletewc(origfn, ui, repo, *args, **opts):
    """Warn that the working directory parent is an obsolete changeset"""
    def warnobsolete():
        if repo['.'].obsolete():
            ui.warn(_('working directory parent is obsolete!\n'))
            if (not ui.quiet) and obsolete.isenabled(repo, commandopt):
                ui.warn(_('(use "hg evolve" to update to its successor)\n'))
    wlock = None
    try:
        wlock = repo.wlock()
        repo._afterlock(warnobsolete)
        res = origfn(ui, repo, *args, **opts)
    finally:
        lockmod.release(wlock)
    return res

# XXX this could wrap transaction code
# XXX (but this is a bit a layer violation)
@eh.wrapcommand("commit")
@eh.wrapcommand("import")
@eh.wrapcommand("push")
@eh.wrapcommand("pull")
@eh.wrapcommand("graft")
@eh.wrapcommand("phase")
@eh.wrapcommand("unbundle")
def warnobserrors(orig, ui, repo, *args, **kwargs):
    """display warning is the command resulted in more instable changeset"""
    # part of the troubled stuff may be filtered (stash ?)
    # This needs a better implementation but will probably wait for core.
    filtered = repo.changelog.filteredrevs
    priorunstables = len(set(getrevs(repo, 'unstable')) - filtered)
    priorbumpeds = len(set(getrevs(repo, 'bumped')) - filtered)
    priordivergents = len(set(getrevs(repo, 'divergent')) - filtered)
    ret = orig(ui, repo, *args, **kwargs)
    # workaround phase stupidity
    #phases._filterunknown(ui, repo.changelog, repo._phasecache.phaseroots)
    filtered = repo.changelog.filteredrevs
    newunstables = \
        len(set(getrevs(repo, 'unstable')) - filtered) - priorunstables
    newbumpeds = \
        len(set(getrevs(repo, 'bumped')) - filtered) - priorbumpeds
    newdivergents = \
        len(set(getrevs(repo, 'divergent')) - filtered) - priordivergents
    if newunstables > 0:
        ui.warn(_('%i new unstable changesets\n') % newunstables)
    if newbumpeds > 0:
        ui.warn(_('%i new bumped changesets\n') % newbumpeds)
    if newdivergents > 0:
        ui.warn(_('%i new divergent changesets\n') % newdivergents)
    return ret

@eh.wrapfunction(mercurial.exchange, 'push')
def push(orig, repo, *args, **opts):
    """Add a hint for "hg evolve" when troubles make push fails
    """
    try:
        return orig(repo, *args, **opts)
    except util.Abort, ex:
        hint = _("use 'hg evolve' to get a stable history "
                 "or --force to ignore warnings")
        if (len(ex.args) >= 1
            and ex.args[0].startswith('push includes ')
            and ex.hint is None):
            ex.hint = hint
        raise

def summaryhook(ui, repo):
    def write(fmt, count):
        s = fmt % count
        if count:
            ui.write(s)
        else:
            ui.note(s)

    nbunstable = len(getrevs(repo, 'unstable'))
    nbbumped = len(getrevs(repo, 'bumped'))
    nbdivergent = len(getrevs(repo, 'divergent'))
    write('unstable: %i changesets\n', nbunstable)
    write('bumped: %i changesets\n', nbbumped)
    write('divergent: %i changesets\n', nbdivergent)

@eh.extsetup
def obssummarysetup(ui):
    cmdutil.summaryhooks.add('evolve', summaryhook)


#####################################################################
### Core Other extension compat                                   ###
#####################################################################


@eh.extsetup
def _rebasewrapping(ui):
    # warning about more obsolete
    try:
        rebase = extensions.find('rebase')
        if rebase:
            extensions.wrapcommand(rebase.cmdtable, 'rebase', warnobserrors)
    except KeyError:
        pass  # rebase not found
    try:
        histedit = extensions.find('histedit')
        if histedit:
            extensions.wrapcommand(histedit.cmdtable, 'histedit', warnobserrors)
    except KeyError:
        pass  # rebase not found

#####################################################################
### Old Evolve extension content                                  ###
#####################################################################

# XXX need clean up and proper sorting in other section

### util function
#############################

### changeset rewriting logic
#############################

def rewrite(repo, old, updates, head, newbases, commitopts):
    """Return (nodeid, created) where nodeid is the identifier of the
    changeset generated by the rewrite process, and created is True if
    nodeid was actually created. If created is False, nodeid
    references a changeset existing before the rewrite call.
    """
    if len(old.parents()) > 1: #XXX remove this unecessary limitation.
        raise error.Abort(_('cannot amend merge changesets'))
    base = old.p1()
    updatebookmarks = _bookmarksupdater(repo, old.node())

    # commit a new version of the old changeset, including the update
    # collect all files which might be affected
    files = set(old.files())
    for u in updates:
        files.update(u.files())

    # Recompute copies (avoid recording a -> b -> a)
    copied = copies.pathcopies(base, head)


    # prune files which were reverted by the updates
    def samefile(f):
        if f in head.manifest():
            a = head.filectx(f)
            if f in base.manifest():
                b = base.filectx(f)
                return (a.data() == b.data()
                        and a.flags() == b.flags())
            else:
                return False
        else:
            return f not in base.manifest()
    files = [f for f in files if not samefile(f)]
    # commit version of these files as defined by head
    headmf = head.manifest()
    def filectxfn(repo, ctx, path):
        if path in headmf:
            fctx = head[path]
            flags = fctx.flags()
            mctx = memfilectx(repo, fctx.path(), fctx.data(),
                              islink='l' in flags,
                              isexec='x' in flags,
                              copied=copied.get(path))
            return mctx
        return None

    message = cmdutil.logmessage(repo.ui, commitopts)
    if not message:
        message = old.description()

    user = commitopts.get('user') or old.user()
    date = commitopts.get('date') or None # old.date()
    extra = dict(commitopts.get('extra', {}))
    extra['branch'] = head.branch()

    new = context.memctx(repo,
                         parents=newbases,
                         text=message,
                         files=files,
                         filectxfn=filectxfn,
                         user=user,
                         date=date,
                         extra=extra)

    if commitopts.get('edit'):
        new._text = cmdutil.commitforceeditor(repo, new, [])
    revcount = len(repo)
    newid = repo.commitctx(new)
    new = repo[newid]
    created = len(repo) != revcount
    updatebookmarks(newid)

    return newid, created

class MergeFailure(util.Abort):
    pass

def relocate(repo, orig, dest, keepbranch=False):
    """rewrite <rev> on dest"""
    if orig.rev() == dest.rev():
        raise util.Abort(_('tried to relocate a node on top of itself'),
                         hint=_("This shouldn't happen. If you still "
                                "need to move changesets, please do so "
                                "manually with nothing to rebase - working "
                                "directory parent is also destination"))

    if not orig.p2().rev() == node.nullrev:
        raise util.Abort(
            'no support for evolving merge changesets yet',
            hint="Redo the merge and use `hg prune <old> --succ <new>` to obsolete the old one")
    destbookmarks = repo.nodebookmarks(dest.node())
    nodesrc = orig.node()
    destphase = repo[nodesrc].phase()
    commitmsg = orig.description()

    cache = {}
    sha1s = re.findall(sha1re, commitmsg)
    unfi = repo.unfiltered()
    for sha1 in sha1s:
        ctx = None
        try:
            ctx = unfi[sha1]
        except error.RepoLookupError:
            continue

        if not ctx.obsolete():
            continue

        successors = obsolete.successorssets(repo, ctx.node(), cache)

        # We can't make any assumptions about how to update the hash if the
        # cset in question was split or diverged.
        if len(successors) == 1 and len(successors[0]) == 1:
            newsha1 = node.hex(successors[0][0])
            commitmsg = commitmsg.replace(sha1, newsha1[:len(sha1)])
        else:
            repo.ui.note(_('The stale commit message reference to %s could '
                           'not be updated\n') % sha1)

    tr = repo.transaction('relocate')
    try:
        try:
            if repo['.'].rev() != dest.rev():
                merge.update(repo, dest, False, True, False)
            if bmactive(repo):
                repo.ui.status(_("(leaving bookmark %s)\n") % bmactive(repo))
            bmdeactivate(repo)
            if keepbranch:
                repo.dirstate.setbranch(orig.branch())
            r = merge.graft(repo, orig, orig.p1(), ['local', 'graft'])
            if r[-1]:  #some conflict
                raise util.Abort(
                        'unresolved merge conflicts (see hg help resolve)')
            if commitmsg is None:
                commitmsg = orig.description()
            extra = {'rebase_source': orig.hex()}

            backup = repo.ui.backupconfig('phases', 'new-commit')
            try:
                targetphase = max(orig.phase(), phases.draft)
                repo.ui.setconfig('phases', 'new-commit', targetphase, 'rebase')
                # Commit might fail if unresolved files exist
                nodenew = repo.commit(text=commitmsg, user=orig.user(),
                                      date=orig.date(), extra=extra)
            finally:
                repo.ui.restoreconfig(backup)
        except util.Abort, exc:
            repo.dirstate.beginparentchange()
            repo.setparents(repo['.'].node(), nullid)
            repo.dirstate.write()
            # fix up dirstate for copies and renames
            copies.duplicatecopies(repo, dest.rev(), orig.p1().rev())
            repo.dirstate.endparentchange()
            class LocalMergeFailure(MergeFailure, exc.__class__):
                pass
            exc.__class__ = LocalMergeFailure
            raise
        oldbookmarks = repo.nodebookmarks(nodesrc)
        if nodenew is not None:
            phases.retractboundary(repo, tr, destphase, [nodenew])
            obsolete.createmarkers(repo, [(repo[nodesrc], (repo[nodenew],))])
            for book in oldbookmarks:
                repo._bookmarks[book] = nodenew
        else:
            obsolete.createmarkers(repo, [(repo[nodesrc], ())])
            # Behave like rebase, move bookmarks to dest
            for book in oldbookmarks:
                repo._bookmarks[book] = dest.node()
        for book in destbookmarks: # restore bookmark that rebase move
            repo._bookmarks[book] = dest.node()
        if oldbookmarks or destbookmarks:
            repo._bookmarks.write()
        tr.close()
    finally:
        tr.release()
    return nodenew

def _bookmarksupdater(repo, oldid):
    """Return a callable update(newid) updating the current bookmark
    and bookmarks bound to oldid to newid.
    """
    def updatebookmarks(newid):
        dirty = False
        oldbookmarks = repo.nodebookmarks(oldid)
        if oldbookmarks:
            for b in oldbookmarks:
                repo._bookmarks[b] = newid
            dirty = True
        if dirty:
            repo._bookmarks.write()
    return updatebookmarks

### bookmarks api compatibility layer ###
def bmdeactivate(repo):
    try:
        return bookmarks.deactivate(repo)
    except AttributeError:
        return bookmarks.unsetcurrent(repo)
def bmactivate(repo, book):
    try:
        return bookmarks.activate(repo, book)
    except AttributeError:
        return bookmarks.setcurrent(repo, book)

def bmactive(repo):
    try:
        return repo._activebookmark
    except AttributeError:
        return repo._bookmarkcurrent

### new command
#############################
metadataopts = [
    ('d', 'date', '',
     _('record the specified date in metadata'), _('DATE')),
    ('u', 'user', '',
     _('record the specified user in metadata'), _('USER')),
]

@eh.uisetup
def _installimportobsolete(ui):
    entry = cmdutil.findcmd('import', commands.table)[1]
    entry[1].append(('', 'obsolete', False,
                    _('mark the old node as obsoleted by '
                      'the created commit')))

@eh.wrapfunction(mercurial.cmdutil, 'tryimportone')
def tryimportone(orig, ui, repo, hunk, parents, opts, *args, **kwargs):
    extracted = patch.extract(ui, hunk)
    expected = extracted[5]
    if expected is not None:
        expected = node.bin(expected)
    oldextract = patch.extract
    try:
        patch.extract = lambda ui, hunk: extracted
        ret = orig(ui, repo, hunk, parents, opts, *args, **kwargs)
    finally:
        patch.extract = oldextract
    created = ret[1]
    if (opts['obsolete'] and None not in (created, expected)
        and created != expected):
            tr = repo.transaction('import-obs')
            try:
                metadata = {'user': ui.username()}
                repo.obsstore.create(tr, expected, (created,),
                                     metadata=metadata)
                tr.close()
            finally:
                tr.release()
    return ret


def _deprecatealias(oldalias, newalias):
    '''Deprecates an alias for a command in favour of another

    Creates a new entry in the command table for the old alias. It creates a
    wrapper that has its synopsis set to show that is has been deprecated.
    The documentation will be replace with a pointer to the new alias.
    If a user invokes the command a deprecation warning will be printed and
    the command of the *new* alias will be invoked.

    This function is loosely based on the extensions.wrapcommand function.
    '''
    try:
        aliases, entry = cmdutil.findcmd(newalias, cmdtable)
    except error.UnknownCommand:
        # Commands may be disabled
        return
    for alias, e in cmdtable.iteritems():
        if e is entry:
            break

    synopsis = '(DEPRECATED)'
    if len(entry) > 2:
        fn, opts, _syn = entry
    else:
        fn, opts, = entry
    deprecationwarning = _('%s have been deprecated in favor of %s\n' % (
        oldalias, newalias))
    def newfn(*args, **kwargs):
        ui = args[0]
        ui.warn(deprecationwarning)
        util.checksignature(fn)(*args, **kwargs)
    newfn.__doc__  = deprecationwarning
    cmdwrapper = command(oldalias, opts, synopsis)
    cmdwrapper(newfn)

@eh.extsetup
def deprecatealiases(ui):
    _deprecatealias('gup', 'next')
    _deprecatealias('gdown', 'previous')

@command('debugrecordpruneparents', [], '')
def cmddebugrecordpruneparents(ui, repo):
    """add parents data to prune markers when possible

    This commands search the repo for prune markers without parent information.
    If the pruned node is locally known, a new markers with parent data is
    created."""
    pgop = 'reading markers'

    # lock from the beginning to prevent race
    wlock = lock = tr = None
    try:
        wlock = repo.wlock()
        lock = repo.lock()
        tr = repo.transaction('recordpruneparents')
        unfi = repo.unfiltered()
        nm = unfi.changelog.nodemap
        store = repo.obsstore
        pgtotal = len(store._all)
        for idx, mark in enumerate(list(store._all)):
            if not mark[1]:
                rev = nm.get(mark[0])
                if rev is not None:
                    ctx = unfi[rev]
                    parents = tuple(p.node() for p in ctx.parents())
                    before = len(store._all)
                    store.create(tr, mark[0], mark[1], mark[2], marks[3],
                                 parents=parents)
                    if len(store._all) - before:
                        ui.write('created new markers for %i\n' % rev)
            ui.progress(pgop, idx, total=pgtotal)
        tr.close()
        ui.progress(pgop, None)
    finally:
        lockmod.release(tr, lock, wlock)

@command('debugobsstorestat', [], '')
def cmddebugobsstorestat(ui, repo):
    def _updateclustermap(nodes, mark, clustersmap):
        c = (set(nodes), set([mark]))
        toproceed = set(nodes)
        while toproceed:
            n = toproceed.pop()
            other = clustersmap.get(n)
            if (other is not None
                and other is not c):
                other[0].update(c[0])
                other[1].update(c[1])
                for on in c[0]:
                    if on in toproceed:
                        continue
                    clustersmap[on] = other
                c = other
            clustersmap[n] = c

    """print statistic about obsolescence markers in the repo"""
    store = repo.obsstore
    unfi = repo.unfiltered()
    nm = unfi.changelog.nodemap
    ui.write('markers total:              %9i\n' % len(store._all))
    sucscount = [0, 0 , 0, 0]
    known = 0
    parentsdata = 0
    metakeys = {}
    # node -> cluster mapping
    #   a cluster is a (set(nodes), set(markers)) tuple
    clustersmap = {}
    # same data using parent information
    pclustersmap= {}
    for mark in store:
        if mark[0] in nm:
            known += 1
        nbsucs = len(mark[1])
        sucscount[min(nbsucs, 3)] += 1
        meta = mark[3]
        for key, value in meta:
            metakeys.setdefault(key, 0)
            metakeys[key] += 1
        meta = dict(meta)
        parents = [meta.get('p1'), meta.get('p2')]
        parents = [node.bin(p) for p in parents if p is not None]
        if parents:
            parentsdata += 1
        # cluster handling
        nodes = set(mark[1])
        nodes.add(mark[0])
        _updateclustermap(nodes, mark, clustersmap) 
        # same with parent data
        nodes.update(parents)
        _updateclustermap(nodes, mark, pclustersmap) 

    # freezing the result
    for c in clustersmap.values():
        fc = (frozenset(c[0]), frozenset(c[1]))
        for n in fc[0]:
            clustersmap[n] = fc
    # same with parent data
    for c in pclustersmap.values():
        fc = (frozenset(c[0]), frozenset(c[1]))
        for n in fc[0]:
            pclustersmap[n] = fc
    ui.write('    for known precursors:   %9i\n' % known)
    ui.write('    with parents data:      %9i\n' % parentsdata)
    # successors data
    ui.write('markers with no successors: %9i\n' % sucscount[0])
    ui.write('              1 successors: %9i\n' % sucscount[1])
    ui.write('              2 successors: %9i\n' % sucscount[2])
    ui.write('    more than 2 successors: %9i\n' % sucscount[3])
    # meta data info
    ui.write('    available  keys:\n')
    for key in sorted(metakeys):
        ui.write('    %15s:        %9i\n' % (key, metakeys[key]))

    allclusters = list(set(clustersmap.values()))
    allclusters.sort(key=lambda x: len(x[1]))
    ui.write('disconnected clusters:      %9i\n' % len(allclusters))

    ui.write('        any known node:     %9i\n'
             % len([c for c in allclusters
                    if [n for n in c[0] if nm.get(n) is not None]]))
    if allclusters:
        nbcluster = len(allclusters)
        ui.write('        smallest length:    %9i\n' % len(allclusters[0][1]))
        ui.write('        longer length:      %9i\n' % len(allclusters[-1][1]))
        median = len(allclusters[nbcluster//2][1])
        ui.write('        median length:      %9i\n' % median)
        mean = sum(len(x[1]) for x in allclusters) // nbcluster
        ui.write('        mean length:        %9i\n' % mean)
    allpclusters = list(set(pclustersmap.values()))
    allpclusters.sort(key=lambda x: len(x[1]))
    ui.write('    using parents data:     %9i\n' % len(allpclusters))
    ui.write('        any known node:     %9i\n'
             % len([c for c in allclusters
                    if [n for n in c[0] if nm.get(n) is not None]]))
    if allpclusters:
        nbcluster = len(allpclusters)
        ui.write('        smallest length:    %9i\n' % len(allpclusters[0][1]))
        ui.write('        longer length:      %9i\n' % len(allpclusters[-1][1]))
        median = len(allpclusters[nbcluster//2][1])
        ui.write('        median length:      %9i\n' % median)
        mean = sum(len(x[1]) for x in allpclusters) // nbcluster
        ui.write('        mean length:        %9i\n' % mean)

def _solveone(ui, repo, ctx, dryrun, confirm, progresscb, category):
    """Resolve the troubles affecting one revision"""
    wlock = lock = tr = None
    try:
        wlock = repo.wlock()
        lock = repo.lock()
        tr = repo.transaction("evolve")
        if 'unstable' == category:
            result = _solveunstable(ui, repo, ctx, dryrun, confirm, progresscb)
        elif 'bumped' == category:
            result = _solvebumped(ui, repo, ctx, dryrun, confirm, progresscb)
        elif 'divergent' == category:
            result = _solvedivergent(ui, repo, ctx, dryrun, confirm,
                                   progresscb)
        else:
            assert False, "unknown trouble category: %s" % (category)
        tr.close()
        return result
    finally:
        lockmod.release(tr, lock, wlock)

def _handlenotrouble(ui, repo, allopt, revopt, anyopt, targetcat):
    """Used by the evolve function to display an error message when
    no troubles can be resolved"""
    troublecategories = ['bumped', 'divergent', 'unstable']
    unselectedcategories = [c for c in troublecategories if c != targetcat]
    msg = None
    hint = None

    troubled = {
            "unstable": repo.revs("unstable()"),
            "divergent": repo.revs("divergent()"),
            "bumped": repo.revs("bumped()"),
            "all": repo.revs("troubled()"),
    }


    hintmap = {
            'bumped': _("do you want to use --bumped"),
            'bumped+divergent': _("do you want to use --bumped or --divergent"),
            'bumped+unstable': _("do you want to use --bumped or --unstable"),
            'divergent': _("do you want to use --divergent"),
            'divergent+unstable': _("do you want to use --divergent"
                                    " or --unstable"),
            'unstable': _("do you want to use --unstable"),
            'any+bumped': _("do you want to use --any (or --rev) and --bumped"),
            'any+bumped+divergent': _("do you want to use --any (or --rev) and"
                                      " --bumped or --divergent"),
            'any+bumped+unstable': _("do you want to use --any (or --rev) and"
                                     "--bumped or --unstable"),
            'any+divergent': _("do you want to use --any (or --rev) and"
                               " --divergent"),
            'any+divergent+unstable': _("do you want to use --any (or --rev)"
                                        " and --divergent or --unstable"),
            'any+unstable': _("do you want to use --any (or --rev)"
                              "and --unstable"),
    }

    if revopt:
        revs = scmutil.revrange(repo, revopt)
        if not revs:
            msg = _("set of specified revisions is empty")
        else:
            msg = _("no %s changesets in specified revisions") % targetcat
            othertroubles = []
            for cat in unselectedcategories:
                if revs & troubled[cat]:
                    othertroubles.append(cat)
            if othertroubles:
                hint = hintmap['+'.join(othertroubles)]

    elif anyopt:
        msg = _("no %s changesets to evolve") % targetcat
        othertroubles = []
        for cat in unselectedcategories:
            if troubled[cat]:
                othertroubles.append(cat)
        if othertroubles:
            hint = hintmap['+'.join(othertroubles)]

    else:
        # evolve without any option = relative to the current wdir
        if targetcat == 'unstable':
            msg = _("nothing to evolve on current working copy parent")
        else:
            msg = _("current working copy parent is not %s") % targetcat

        p1 = repo['.'].rev()
        othertroubles = []
        for cat in unselectedcategories:
            if p1 in troubled[cat]:
                othertroubles.append(cat)
        if othertroubles:
            hint = hintmap['+'.join(othertroubles)]
        else:
            l = len(troubled[targetcat])
            if l:
                hint = (_("%d other %s in the repository, do you want --any or --rev")
                        % (l, targetcat))
            else:
                othertroubles = []
                for cat in unselectedcategories:
                    if troubled[cat]:
                        othertroubles.append(cat)
                if othertroubles:
                    hint = hintmap['any+'+('+'.join(othertroubles))]
                else:
                    msg = _("no troubled changesets")

    assert msg is not None
    ui.write_err(msg+"\n")
    if hint:
        ui.write_err("("+hint+")\n")
        return 2
    else:
        return 1

def _cleanup(ui, repo, startnode, showprogress):
    if showprogress:
        ui.progress('evolve', None)
    if repo['.'] != startnode:
        ui.status(_('working directory is now at %s\n') % repo['.'])

class MultipleSuccessorsError(RuntimeError):
    """Exception raised by _singlesuccessor when multiple sucessors sets exists

    The object contains the list of successorssets in its 'successorssets'
    attribute to call to easily recover.
    """

    def __init__(self, successorssets):
        self.successorssets = successorssets

def _singlesuccessor(repo, p):
    """returns p (as rev) if not obsolete or its unique latest successors

    fail if there are no such successor"""

    if not p.obsolete():
        return p.rev()
    obs = repo[p]
    ui = repo.ui
    newer = obsolete.successorssets(repo, obs.node())
    # search of a parent which is not killed
    while not newer:
        ui.debug("stabilize target %s is plain dead,"
                 " trying to stabilize on its parent\n" %
                 obs)
        obs = obs.parents()[0]
        newer = obsolete.successorssets(repo, obs.node())
    if len(newer) > 1 or len(newer[0]) > 1:
        raise MultipleSuccessorsError(newer)

    return repo[newer[0][0]].rev()

def builddependencies(repo, revs):
    """returns dependency graphs giving an order to solve instability of revs
    (see _orderrevs for more information on usage)"""

    # For each troubled revision we keep track of what instability if any should
    # be resolved in order to resolve it. Example:
    # dependencies = {3: [6], 6:[]}
    # Means that: 6 has no dependency, 3 depends on 6 to be solved
    dependencies = {}
    # rdependencies is the inverted dict of dependencies
    rdependencies = collections.defaultdict(set)

    for r in revs:
        dependencies[r] = set()
        for p in repo[r].parents():
            try:
                succ = _singlesuccessor(repo, p)
            except MultipleSuccessorsError, exc:
                dependencies[r] = exc.successorssets
                continue
            if succ in revs:
                dependencies[r].add(succ)
                rdependencies[succ].add(r)
    return dependencies, rdependencies

def _selectrevs(repo, allopt, revopt, anyopt, targetcat):
    """select troubles in repo matching according to given options"""
    revs = set()
    if allopt or revopt:
        revs = repo.revs(targetcat+'()')
        if revopt:
            revs = scmutil.revrange(repo, revopt) & revs
        elif not anyopt and targetcat == 'unstable':
            revs = set(_aspiringdescendant(repo, repo.revs('(.::) - obsolete()::')))
    elif anyopt:
        revs = repo.revs('first(%s())' % (targetcat))
    elif targetcat == 'unstable':
        revs = set(_aspiringchildren(repo, repo.revs('(.::) - obsolete()::')))
        if 1 < len(revs):
            msg = "multiple evolve candidates"
            hint = (_("select one of %s with --rev")
                    % ', '.join([str(repo[r]) for r in sorted(revs)]))
            raise error.Abort(msg, hint=hint)
    elif targetcat in repo['.'].troubles():
        revs = set([repo['.'].rev()])
    return revs


def _orderrevs(repo, revs):
    """Compute an ordering to solve instability for the given revs

    - Takes revs a list of instable revisions

    - Returns the same revisions ordered to solve their instability from the
    bottom to the top of the stack that the stabilization process will produce
    eventually.

    This ensure the minimal number of stabilization as we can stabilize each
    revision on its final, stabilized, destination.
    """
    # Step 1: Build the dependency graph
    dependencies, rdependencies = builddependencies(repo, revs)
    # Step 2: Build the ordering
    # Remove the revisions with no dependency(A) and add them to the ordering.
    # Removing these revisions leads to new revisions with no dependency (the
    # one depending on A) that we can remove from the dependency graph and add
    # to the ordering. We progress in a similar fashion until the ordering is
    # built
    solvablerevs = collections.deque([r for r in sorted(dependencies.keys())
                                      if not dependencies[r]])
    ordering = []
    while solvablerevs:
        rev = solvablerevs.popleft()
        for dependent in rdependencies[rev]:
            dependencies[dependent].remove(rev)
            if not dependencies[dependent]:
                solvablerevs.append(dependent)
        del dependencies[rev]
        ordering.append(rev)

    ordering.extend(sorted(dependencies))
    return ordering

@command('^evolve|stabilize|solve',
    [('n', 'dry-run', False,
        'do not perform actions, just print what would be done'),
     ('', 'confirm', False,
        'ask for confirmation before performing the action'),
    ('A', 'any', False, 'also consider troubled changesets unrelated to current working directory'),
    ('r', 'rev', [], 'solves troubles of these revisions'),
    ('', 'bumped', False, 'solves only bumped changesets'),
    ('', 'divergent', False, 'solves only divergent changesets'),
    ('', 'unstable', False, 'solves only unstable changesets (default)'),
    ('a', 'all', False, 'evolve all troubled changesets related to the current '
                         'working directory and its descendants'),
    ('c', 'continue', False, 'continue an interrupted evolution'),
    ] + mergetoolopts,
    _('[OPTIONS]...'))
def evolve(ui, repo, **opts):
    """solve troubles in your repository

    - rebase unstable changesets to make them stable again,
    - create proper diffs from bumped changesets,
    - fuse divergent changesets back together,
    - update to a successor if the working directory parent is
      obsolete

    If no argument are passed and the current working copy parent is obsolete,
    :hg:`evolve` will update the working copy to the successors of this working
    copy parent. If the working copy parent is not obsolete (and still no
    argument passed) each invocation of :hg:`evolve` will evolve a single
    unstable changeset, It will only select a changeset to be evolved if it
    will result in a new children for the current working copy parent or its
    descendants. The working copy will be updated on the result
    (this last behavior will most likely to change in the future).
    You can evolve all the unstable changesets that will be evolved on the
    parent of the working copy and all its descendants recursively by using
    :hg:`evolve` --all.

    You can decide to evolve other categories of trouble using the --divergent
    and --bumped flags. If no other option are specified, this will try to
    solve the specified troubles for the working copy parent.

    You can also evolve changesets affected by troubles of the selected
    category using the --rev options. You can pick the next one anywhere in the
    repo using --any.

    You can evolve all the changesets affected by troubles of the selected
    category using --all --any.

    The working directory is updated to the newly created revision.
    """

    # Options
    contopt = opts['continue']
    anyopt = opts['any']
    allopt = opts['all']
    startnode = repo['.']
    dryrunopt = opts['dry_run']
    confirmopt = opts['confirm']
    revopt = opts['rev']
    troublecategories = ['bumped', 'divergent', 'unstable']
    specifiedcategories = [t for t in troublecategories if opts[t]]
    targetcat = 'unstable'
    if 1 < len(specifiedcategories):
        msg = _('cannot specify more than one trouble category to solve (yet)')
        raise util.Abort(msg)
    elif len(specifiedcategories) == 1:
        targetcat = specifiedcategories[0]
    elif repo['.'].obsolete():
        displayer = cmdutil.show_changeset(ui, repo, {'template': shorttemplate})
        # no args and parent is obsolete, update to successors
        try:
            ctx = repo[_singlesuccessor(repo, repo['.'])]
        except MultipleSuccessorsError, exc:
            repo.ui.write_err('parent is obsolete with multiple successors:\n')
            for ln in exc.successorssets:
                for n in ln:
                    displayer.show(repo[n])
            return 2


        ui.status(_('update:'))
        if not ui.quiet:
            displayer.show(ctx)

        if dryrunopt:
            return 0
        res = hg.update(repo, ctx.rev())
        if ctx != startnode:
            ui.status(_('working directory is now at %s\n') % ctx)
        return res

    ui.setconfig('ui', 'forcemerge', opts.get('tool', ''), 'evolve')
    troubled = set(repo.revs('troubled()'))

    # Progress handling
    seen = 1
    count = allopt and len(troubled) or 1
    showprogress = allopt

    def progresscb():
        if revopt or allopt:
            ui.progress('evolve', seen, unit='changesets', total=count)

    # Continuation handling
    if contopt:
        if anyopt:
            raise util.Abort('cannot specify both "--any" and "--continue"')
        if allopt:
            raise util.Abort('cannot specify both "--all" and "--continue"')
        graftcmd = commands.table['graft'][0]
        return graftcmd(ui, repo, old_obsolete=True, **{'continue': True})
    cmdutil.bailifchanged(repo)


    if revopt and allopt:
        raise util.Abort('cannot specify both "--rev" and "--all"')
    if revopt and anyopt:
        raise util.Abort('cannot specify both "--rev" and "--any"')

    revs = _selectrevs(repo, allopt, revopt, anyopt, targetcat)

    if not revs:
        return _handlenotrouble(ui, repo, allopt, revopt, anyopt, targetcat)

    # For the progress bar to show
    count = len(revs)
    # Order the revisions
    if targetcat == 'unstable':
        revs = _orderrevs(repo, revs)
    for rev in revs:
        progresscb()
        _solveone(ui, repo, repo[rev], dryrunopt, confirmopt,
                progresscb, targetcat)
        seen += 1
    progresscb()
    _cleanup(ui, repo, startnode, showprogress)

def _possibledestination(repo, rev):
    """return all changesets that may be a new parent for REV"""
    tonode = repo.changelog.node
    parents = repo.changelog.parentrevs
    torev = repo.changelog.rev
    dest = set()
    tovisit = list(parents(rev))
    while tovisit:
        r = tovisit.pop()
        succsets = obsolete.successorssets(repo, tonode(r))
        if not succsets:
            tovisit.extend(parents(r))
        else:
            # We should probably pick only one destination from split
            # (case where '1 < len(ss)'), This could be the currently tipmost
            # but logic is less clear when result of the split are now on
            # multiple branches.
            for ss in succsets:
                for n in ss:
                    dest.add(torev(n))
    return dest

def _aspiringchildren(repo, revs):
    """Return a list of changectx which can be stabilized on top of pctx or
    one of its descendants. Empty list if none can be found."""
    target = set(revs)
    result = []
    for r in repo.revs('unstable() - %ld', revs):
        dest = _possibledestination(repo, r)
        if target & dest:
            result.append(r)
    return result

def _aspiringdescendant(repo, revs):
    """Return a list of changectx which can be stabilized on top of pctx or
    one of its descendants recursively. Empty list if none can be found."""
    target = set(revs)
    result = set(target)
    paths = collections.defaultdict(set)
    for r in repo.revs('unstable() - %ld', revs):
        for d in _possibledestination(repo, r):
            paths[d].add(r)

    result = set(target)
    tovisit = list(revs)
    while tovisit:
        base = tovisit.pop()
        for unstable in paths[base]:
            if unstable not in result:
                tovisit.append(unstable)
                result.add(unstable)
    return sorted(result - target)

def _solveunstable(ui, repo, orig, dryrun=False, confirm=False,
                   progresscb=None):
    """Stabilize a unstable changeset"""
    obs = orig.parents()[0]
    if not obs.obsolete() and len(orig.parents()) == 2:
        obs = orig.parents()[1] # second parent is obsolete ?

    if not obs.obsolete():
        ui.warn("cannot solve instability of %s, skipping\n" % orig)
        return False
    newer = obsolete.successorssets(repo, obs.node())
    # search of a parent which is not killed
    while not newer or newer == [()]:
        ui.debug("stabilize target %s is plain dead,"
                 " trying to stabilize on its parent\n" %
                 obs)
        obs = obs.parents()[0]
        newer = obsolete.successorssets(repo, obs.node())
    if len(newer) > 1:
        msg = _("skipping %s: divergent rewriting. can't choose destination\n" % obs)
        ui.write_err(msg)
        return 2
    targets = newer[0]
    assert targets
    if len(targets) > 1:
        msg = _("does not handle split parents yet\n")
        ui.write_err(msg)
        return 2
    target = targets[0]
    displayer = cmdutil.show_changeset(ui, repo, {'template': shorttemplate})
    target = repo[target]
    if not ui.quiet or confirm:
        repo.ui.write(_('move:'))
        displayer.show(orig)
        repo.ui.write(_('atop:'))
        displayer.show(target)
    if confirm and ui.prompt('perform evolve? [Ny]', 'n') != 'y':
            raise util.Abort(_('evolve aborted by user'))
    if progresscb: progresscb()
    todo = 'hg rebase -r %s -d %s\n' % (orig, target)
    if dryrun:
        repo.ui.write(todo)
    else:
        repo.ui.note(todo)
        if progresscb: progresscb()
        keepbranch = orig.p1().branch() != orig.branch()
        try:
            relocate(repo, orig, target, keepbranch)
        except MergeFailure:
            repo.opener.write('graftstate', orig.hex() + '\n')
            repo.ui.write_err(_('evolve failed!\n'))
            repo.ui.write_err(
                _('fix conflict and run "hg evolve --continue"'
                  ' or use "hg update -C" to abort\n'))
            raise

def _solvebumped(ui, repo, bumped, dryrun=False, confirm=False,
                 progresscb=None):
    """Stabilize a bumped changeset"""
    repo = repo.unfiltered()
    bumped = repo[bumped.rev()]
    # For now we deny bumped merge
    if len(bumped.parents()) > 1:
        msg = _('skipping %s : we do not handle merge yet\n' % bumped)
        ui.write_err(msg)
        return 2
    prec = repo.set('last(allprecursors(%d) and public())', bumped).next()
    # For now we deny target merge
    if len(prec.parents()) > 1:
        msg = _('skipping: %s: public version is a merge, this not handled yet\n' % prec)
        ui.write_err(msg)
        return 2

    displayer = cmdutil.show_changeset(ui, repo, {'template': shorttemplate})
    if not ui.quiet or confirm:
        repo.ui.write(_('recreate:'))
        displayer.show(bumped)
        repo.ui.write(_('atop:'))
        displayer.show(prec)
    if confirm and ui.prompt('perform evolve? [Ny]', 'n') != 'y':
        raise util.Abort(_('evolve aborted by user'))
    if dryrun:
        todo = 'hg rebase --rev %s --dest %s;\n' % (bumped, prec.p1())
        repo.ui.write(todo)
        repo.ui.write('hg update %s;\n' % prec)
        repo.ui.write('hg revert --all --rev %s;\n' % bumped)
        repo.ui.write('hg commit --msg "bumped update to %s"')
        return 0
    if progresscb: progresscb()
    newid = tmpctx = None
    tmpctx = bumped
    bmupdate = _bookmarksupdater(repo, bumped.node())
    # Basic check for common parent. Far too complicated and fragile
    tr = repo.transaction('bumped-stabilize')
    try:
        if not list(repo.set('parents(%d) and parents(%d)', bumped, prec)):
            # Need to rebase the changeset at the right place
            repo.ui.status(
                _('rebasing to destination parent: %s\n') % prec.p1())
            try:
                tmpid = relocate(repo, bumped, prec.p1())
                if tmpid is not None:
                    tmpctx = repo[tmpid]
                    obsolete.createmarkers(repo, [(bumped, (tmpctx,))])
            except MergeFailure:
                repo.opener.write('graftstate', bumped.hex() + '\n')
                repo.ui.write_err(_('evolution failed!\n'))
                repo.ui.write_err(
                    _('fix conflict and run "hg evolve --continue"\n'))
                raise
        # Create the new commit context
        repo.ui.status(_('computing new diff\n'))
        files = set()
        copied = copies.pathcopies(prec, bumped)
        precmanifest = prec.manifest()
        # 3.3.2 needs a list.
        # future 3.4 don't detect the size change during iteration
        # this is fishy
        for key, val in list(bumped.manifest().iteritems()):
            precvalue = precmanifest.get(key, None)
            if precvalue is not None:
                del precmanifest[key]
            if precvalue != val:
                files.add(key)
        files.update(precmanifest)  # add missing files
        # commit it
        if files: # something to commit!
            def filectxfn(repo, ctx, path):
                if path in bumped:
                    fctx = bumped[path]
                    flags = fctx.flags()
                    mctx = memfilectx(repo, fctx.path(), fctx.data(),
                                      islink='l' in flags,
                                      isexec='x' in flags,
                                      copied=copied.get(path))
                    return mctx
                return None
            text = 'bumped update to %s:\n\n' % prec
            text += bumped.description()

            new = context.memctx(repo,
                                 parents=[prec.node(), node.nullid],
                                 text=text,
                                 files=files,
                                 filectxfn=filectxfn,
                                 user=bumped.user(),
                                 date=bumped.date(),
                                 extra=bumped.extra())

            newid = repo.commitctx(new)
        if newid is None:
            obsolete.createmarkers(repo, [(tmpctx, ())])
            newid = prec.node()
        else:
            phases.retractboundary(repo, tr, bumped.phase(), [newid])
            obsolete.createmarkers(repo, [(tmpctx, (repo[newid],))],
                                   flag=obsolete.bumpedfix)
        bmupdate(newid)
        tr.close()
        repo.ui.status(_('committed as %s\n') % node.short(newid))
    finally:
        tr.release()
    # reroute the working copy parent to the new changeset
    repo.dirstate.beginparentchange()
    repo.dirstate.setparents(newid, node.nullid)
    repo.dirstate.endparentchange()

def _solvedivergent(ui, repo, divergent, dryrun=False, confirm=False,
                    progresscb=None):
    repo = repo.unfiltered()
    divergent = repo[divergent.rev()]
    base, others = divergentdata(divergent)
    if len(others) > 1:
        othersstr = "[%s]" % (','.join([str(i) for i in others]))
        msg = _("skipping %d:divergent with a changeset that got splitted into multiple ones:\n"
                 "|[%s]\n"
                 "| This is not handled by automatic evolution yet\n"
                 "| You have to fallback to manual handling with commands "
                 "such as:\n"
                 "| - hg touch -D\n"
                 "| - hg prune\n"
                 "| \n"
                 "| You should contact your local evolution Guru for help.\n"
                 % (divergent, othersstr))
        ui.write_err(msg)
        return 2
    other = others[0]
    if divergent.phase() <= phases.public:
        msg = _("skipping %s: we can't resolve divergence from the public side\n") % divergent
        ui.write_err(msg)
        hint = _("(%s is public, try from %s)\n" % (divergent, other))
        ui.write_err(hint)
        return 2
    if len(other.parents()) > 1:
        msg = _("skipping %s: divergent changeset can't be a merge (yet)\n" % divergent)
        ui.write_err(msg)
        hint = _("You have to fallback to solving this by hand...\n"
                 "| This probably means redoing the merge and using \n"
                 "| `hg prune` to kill older version.\n")
        ui.write_err(hint)
        return 2
    if other.p1() not in divergent.parents():
        msg = _("skipping %s: have a different parent than %s (not handled yet)\n") % (divergent, other)
        hint = _("| %(d)s, %(o)s are not based on the same changeset.\n"
                 "| With the current state of its implementation, \n"
                 "| evolve does not work in that case.\n"
                 "| rebase one of them next to the other and run \n"
                 "| this command again.\n"
                 "| - either: hg rebase --dest 'p1(%(d)s)' -r %(o)s\n"
                 "| - or:     hg rebase --dest 'p1(%(o)s)' -r %(d)s\n"
                 % {'d': divergent, 'o': other})
        ui.write_err(msg)
        ui.write_err(hint)
        return 2

    displayer = cmdutil.show_changeset(ui, repo, {'template': shorttemplate})
    if not ui.quiet or confirm:
        ui.write(_('merge:'))
        displayer.show(divergent)
        ui.write(_('with: '))
        displayer.show(other)
        ui.write(_('base: '))
        displayer.show(base)
    if confirm and ui.prompt('perform evolve? [Ny]', 'n') != 'y':
        raise util.Abort(_('evolve aborted by user'))
    if dryrun:
        ui.write('hg update -c %s &&\n' % divergent)
        ui.write('hg merge %s &&\n' % other)
        ui.write('hg commit -m "auto merge resolving conflict between '
                 '%s and %s"&&\n' % (divergent, other))
        ui.write('hg up -C %s &&\n' % base)
        ui.write('hg revert --all --rev tip &&\n')
        ui.write('hg commit -m "`hg log -r %s --template={desc}`";\n'
                 % divergent)
        return
    if divergent not in repo[None].parents():
        repo.ui.status(_('updating to "local" conflict\n'))
        hg.update(repo, divergent.rev())
    repo.ui.note(_('merging divergent changeset\n'))
    if progresscb: progresscb()
    stats = merge.update(repo,
                         other.node(),
                         branchmerge=True,
                         force=False,
                         partial=None,
                         ancestor=base.node(),
                         mergeancestor=True)
    hg._showstats(repo, stats)
    if stats[3]:
        repo.ui.status(_("use 'hg resolve' to retry unresolved file merges "
                         "or 'hg update -C .' to abandon\n"))
    if stats[3] > 0:
        raise util.Abort('merge conflict between several amendments '
            '(this is not automated yet)',
            hint="""/!\ You can try:
/!\ * manual merge + resolve => new cset X
/!\ * hg up to the parent of the amended changeset (which are named W and Z)
/!\ * hg revert --all -r X
/!\ * hg ci -m "same message as the amended changeset" => new cset Y
/!\ * hg kill -n Y W Z
""")
    if progresscb: progresscb()
    tr = repo.transaction('stabilize-divergent')
    try:
        repo.dirstate.beginparentchange()
        repo.dirstate.setparents(divergent.node(), node.nullid)
        repo.dirstate.endparentchange()
        oldlen = len(repo)
        amend(ui, repo, message='', logfile='')
        if oldlen == len(repo):
            new = divergent
            # no changes
        else:
            new = repo['.']
        obsolete.createmarkers(repo, [(other, (new,))])
        phases.retractboundary(repo, tr, other.phase(), [new.node()])
        tr.close()
    finally:
        tr.release()

def divergentdata(ctx):
    """return base, other part of a conflict

    This only return the first one.

    XXX this woobly function won't survive XXX
    """
    repo = ctx._repo.unfiltered()
    for base in repo.set('reverse(allprecursors(%d))', ctx):
        newer = obsolete.successorssets(ctx._repo, base.node())
        # drop filter and solution including the original ctx
        newer = [n for n in newer if n and ctx.node() not in n]
        if newer:
            return base, tuple(ctx._repo[o] for o in newer[0])
    raise util.Abort("base of divergent changeset %s not found" % ctx,
                     hint='this case is not yet handled')



shorttemplate = '[{rev}] {desc|firstline}\n'

@command('^previous',
         [('B', 'move-bookmark', False,
             _('Move active bookmark after update')),
          ('', 'merge', False, _('bring uncommited change along'))],
         '[-B]')
def cmdprevious(ui, repo, **opts):
    """update to parent and display summary lines"""
    wkctx = repo[None]
    wparents = wkctx.parents()
    if len(wparents) != 1:
        raise util.Abort('merge in progress')
    if not opts['merge']:
        try:
            cmdutil.bailifchanged(repo)
        except error.Abort, exc:
            exc.hint = _('do you want --merge?')
            raise

    parents = wparents[0].parents()
    displayer = cmdutil.show_changeset(ui, repo, {'template': shorttemplate})
    if len(parents) == 1:
        p = parents[0]
        bm = bmactive(repo)
        shouldmove = opts.get('move_bookmark') and bm is not None
        ret = hg.update(repo, p.rev())
        if not ret:
            if shouldmove:
                repo._bookmarks[bm] = p.node()
                repo._bookmarks.write()
            else:
                bmdeactivate(repo)
        displayer.show(p)
        return 0
    else:
        for p in parents:
            displayer.show(p)
        ui.warn(_('multiple parents, explicitly update to one\n'))
        return 1

@command('^next',
         [('B', 'move-bookmark', False,
             _('Move active bookmark after update')),
          ('', 'merge', False, _('bring uncommited change along')),
          ('', 'evolve', False, _('evolve the next changeset if necessary'))],
         '[-B]')
def cmdnext(ui, repo, **opts):
    """update to next child

    You can use the --evolve flag to get unstable children evolved on demand.

    The summary line of the destination is displayed for clarity"""
    wkctx = repo[None]
    wparents = wkctx.parents()
    if len(wparents) != 1:
        raise util.Abort('merge in progress')
    if not opts['merge']:
        try:
            cmdutil.bailifchanged(repo)
        except error.Abort, exc:
            exc.hint = _('do you want --merge?')
            raise

    children = [ctx for ctx in wparents[0].children() if not ctx.obsolete()]
    displayer = cmdutil.show_changeset(ui, repo, {'template': shorttemplate})
    if len(children) == 1:
        c = children[0]
        bm = bmactive(repo)
        shouldmove = opts.get('move_bookmark') and bm is not None
        ret = hg.update(repo, c.rev())
        if not ret:
            if shouldmove:
                repo._bookmarks[bm] = c.node()
                repo._bookmarks.write()
            else:
                bmdeactivate(repo)
        displayer.show(c)
        result = 0
    elif children:
        ui.warn("ambigious next changeset:\n")
        for c in children:
            displayer.show(c)
        ui.warn(_('explicitly update to one of them\n'))
        result = 1
    else:
        aspchildren = _aspiringchildren(repo, [repo['.'].rev()])
        if not opts['evolve']:
            ui.warn(_('no children\n'))
            if aspchildren:
                msg = _('(%i unstable changesets to be evolved here, '
                        'do you want --evolve?)\n')
                ui.warn(msg % len(aspchildren))
            result = 1
        elif 1 < len(aspchildren):
            ui.warn("ambigious next (unstable) changeset:\n")
            for c in aspchildren:
                displayer.show(repo[c])
            ui.warn(_('(run "hg evolve --rev REV" on one of them)\n'))
            return 1
        else:
            cmdutil.bailifchanged(repo)
            result = _solveone(ui, repo, repo[aspchildren[0]], False,
                               False, lambda:None, category='unstable')
            if not result:
                ui.status(_('working directory now at %s\n') % repo['.'])
            return result
        return 1
    return result

def _reachablefrombookmark(repo, revs, mark):
    """filter revisions and bookmarks reachable from the given bookmark
    yoinked from mq.py
    """
    marks = repo._bookmarks
    if mark not in marks:
        raise util.Abort(_("bookmark '%s' not found") % mark)

    # If the requested bookmark is not the only one pointing to a
    # a revision we have to only delete the bookmark and not strip
    # anything. revsets cannot detect that case.
    uniquebm = True
    for m, n in marks.iteritems():
        if m != mark and n == repo[mark].node():
            uniquebm = False
            break
    if uniquebm:
        rsrevs = repo.revs("ancestors(bookmark(%s)) - "
                           "ancestors(head() and not bookmark(%s)) - "
                           "ancestors(bookmark() and not bookmark(%s)) - "
                           "obsolete()",
                           mark, mark, mark)
        revs = set(revs)
        revs.update(set(rsrevs))
        revs = sorted(revs)
    return marks, revs

def _deletebookmark(ui, marks, mark):
    del marks[mark]
    marks.write()
    ui.write(_("bookmark '%s' deleted\n") % mark)



def _getmetadata(**opts):
    metadata = {}
    date = opts.get('date')
    user = opts.get('user')
    if date:
        metadata['date'] = '%i %i' % util.parsedate(date)
    if user:
        metadata['user'] = user
    return metadata


@command('^prune|obsolete|kill',
    [('n', 'new', [], _("successor changeset (DEPRECATED)")),
     ('s', 'succ', [], _("successor changeset")),
     ('r', 'rev', [], _("revisions to prune")),
     ('k', 'keep', None, _("does not modify working copy during prune")),
     ('', 'biject', False, _("do a 1-1 map between rev and successor ranges")),
     ('B', 'bookmark', '', _("remove revs only reachable from given"
                             " bookmark"))] + metadataopts,
    _('[OPTION] [-r] REV...'))
    # -U  --noupdate option to prevent wc update and or bookmarks update ?
def cmdprune(ui, repo, *revs, **opts):
    """hide changesets by marking them obsolete

    Obsolete changesets becomes invisible to all commands.

    Unpruned descendants of pruned changesets becomes "unstable". Use the
    :hg:`evolve` to handle such situation.

    When the working directory parent is pruned, the repository is updated to a
    non-obsolete parent.

    You can use the ``--succ`` option to inform mercurial that a newer version
    of the pruned changeset exists.

    You can use the ``--biject`` option to specify a 1-1 (bijection) between
    revisions to prune and successor changesets. This option may be removed in
    a future release (with the functionality absorbed automatically).

    """
    revs = scmutil.revrange(repo, list(revs) + opts.get('rev'))
    succs = opts['new'] + opts['succ']
    bookmark = opts.get('bookmark')
    metadata = _getmetadata(**opts)
    biject = opts.get('biject')

    if bookmark:
        marks,revs = _reachablefrombookmark(repo, revs, bookmark)
        if not revs:
            # no revisions to prune - delete bookmark immediately
            _deletebookmark(ui, marks, bookmark)

    if not revs:
        raise util.Abort(_('nothing to prune'))

    wlock = lock = tr = None
    try:
        wlock = repo.wlock()
        lock = repo.lock()
        tr = repo.transaction('prune')
        # defines pruned changesets
        precs = []
        revs.sort()
        for p in revs:
            cp = repo[p]
            if not cp.mutable():
                # note: createmarkers() would have raised something anyway
                raise util.Abort('cannot prune immutable changeset: %s' % cp,
                                 hint='see "hg help phases" for details')
            precs.append(cp)
        if not precs:
            raise util.Abort('nothing to prune')

        if not obsolete.isenabled(repo, obsolete.allowunstableopt):
            if repo.revs("(%ld::) - %ld", revs, revs):
                raise util.Abort(_("cannot prune in the middle of a stack"))

        # defines successors changesets
        sucs = scmutil.revrange(repo, succs)
        sucs.sort()
        sucs = tuple(repo[n] for n in sucs)
        if not biject and len(sucs) > 1 and len(precs) > 1:
            msg = "Can't use multiple successors for multiple precursors"
            raise util.Abort(msg)

        if biject and len(sucs) != len(precs):
            msg = "Can't use %d successors for %d precursors" \
                % (len(sucs), len(precs))
            raise util.Abort(msg)

        relations = [(p, sucs) for p in precs]
        if biject:
            relations = [(p, (s,)) for p, s in zip(precs, sucs)]

        wdp = repo['.']

        if len(sucs) == 1 and len(precs) == 1 and wdp in precs:
            # '.' killed, so update to the successor
            newnode = sucs[0]
        else:
            # update to an unkilled parent
            newnode = wdp

            while newnode in precs or newnode.obsolete():
                newnode = newnode.parents()[0]


        if newnode.node() != wdp.node():
            if opts.get('keep', False):
                # This is largely the same as the implementation in
                # strip.stripcmd(). We might want to refactor this somewhere
                # common at some point.

                # only reset the dirstate for files that would actually change
                # between the working context and uctx
                descendantrevs = repo.revs("%d::." % newnode.rev())
                changedfiles = []
                for rev in descendantrevs:
                    # blindly reset the files, regardless of what actually changed
                    changedfiles.extend(repo[rev].files())

                # reset files that only changed in the dirstate too
                dirstate = repo.dirstate
                dirchanges = [f for f in dirstate if dirstate[f] != 'n']
                changedfiles.extend(dirchanges)
                repo.dirstate.rebuild(newnode.node(), newnode.manifest(), changedfiles)
                repo.dirstate.write()
            else:
                bookactive = bmactive(repo)
                # Active bookmark that we don't want to delete (with -B option)
                # we deactivate and move it before the update and reactivate it
                # after
                movebookmark = bookactive and not bookmark
                if movebookmark:
                    bmdeactivate(repo)
                    repo._bookmarks[bookactive] = newnode.node()
                    repo._bookmarks.write()
                commands.update(ui, repo, newnode.rev())
                ui.status(_('working directory now at %s\n') % newnode)
                if movebookmark:
                    bmactivate(repo, bookactive)

        # update bookmarks
        if bookmark:
            _deletebookmark(ui, marks, bookmark)

        # create markers
        obsolete.createmarkers(repo, relations, metadata=metadata)
        
        # informs that changeset have been pruned
        ui.status(_('%i changesets pruned\n') % len(precs))

        for ctx in repo.unfiltered().set('bookmark() and %ld', precs):
            # used to be:
            #
            #   ldest = list(repo.set('max((::%d) - obsolete())', ctx))
            #   if ldest:
            #      c = ldest[0]
            #
            # but then revset took a lazy arrow in the knee and became much
            # slower. The new forms makes as much sense and a much faster.
            for dest in ctx.ancestors():
                if not dest.obsolete():
                    updatebookmarks = _bookmarksupdater(repo, ctx.node())
                    updatebookmarks(dest.node())
                    break

        tr.close()
    finally:
        lockmod.release(tr, lock, wlock)

@command('amend|refresh',
    [('A', 'addremove', None,
     _('mark new/missing files as added/removed before committing')),
    ('e', 'edit', False, _('invoke editor on commit messages')),
    ('', 'close-branch', None,
     _('mark a branch as closed, hiding it from the branch list')),
    ('s', 'secret', None, _('use the secret phase for committing')),
    ] + walkopts + commitopts + commitopts2 + commitopts3 + interactiveopt,
    _('[OPTION]... [FILE]...'))
def amend(ui, repo, *pats, **opts):
    """combine a changeset with updates and replace it with a new one

    Commits a new changeset incorporating both the changes to the given files
    and all the changes from the current parent changeset into the repository.

    See :hg:`commit` for details about committing changes.

    If you don't specify -m, the parent's message will be reused.

    Behind the scenes, Mercurial first commits the update as a regular child
    of the current parent. Then it creates a new commit on the parent's parents
    with the updated contents. Then it changes the working copy parent to this
    new combined changeset. Finally, the old changeset and its update are hidden
    from :hg:`log` (unless you use --hidden with log).

    Returns 0 on success, 1 if nothing changed.
    """
    opts = opts.copy()
    edit = opts.pop('edit', False)
    log = opts.get('logfile')
    opts['amend'] = True
    if not (edit or opts['message'] or log):
        opts['message'] = repo['.'].description()
    _resolveoptions(ui, opts)
    _alias, commitcmd = cmdutil.findcmd('commit', commands.table)
    return commitcmd[0](ui, repo, *pats, **opts)


def _touchedbetween(repo, source, dest, match=None):
    touched = set()
    for files in repo.status(source, dest, match=match)[:3]:
        touched.update(files)
    return touched

def _commitfiltered(repo, ctx, match, target=None):
    """Recommit ctx with changed files not in match. Return the new
    node identifier, or None if nothing changed.
    """
    base = ctx.p1()
    if target is None:
        target = base
    # ctx
    initialfiles = _touchedbetween(repo, base, ctx)
    if base == target:
        affected = set(f for f in initialfiles if match(f))
        newcontent = set()
    else:
        affected = _touchedbetween(repo, target, ctx, match=match)
        newcontent = _touchedbetween(repo, target, base, match=match)
    # The commit touchs all existing files
    # + all file that needs a new content
    # - the file affected bny uncommit with the same content than base.
    files = (initialfiles - affected) | newcontent
    if not newcontent and files == initialfiles:
        return None

    # Filter copies
    copied = copies.pathcopies(target, ctx)
    copied = dict((src, dst) for src, dst in copied.iteritems()
                  if dst in files)
    def filectxfn(repo, memctx, path, contentctx=ctx, redirect=newcontent):
        if path in redirect:
            return filectxfn(repo, memctx, path, contentctx=target, redirect=())
        if path not in contentctx:
            return None
        fctx = contentctx[path]
        flags = fctx.flags()
        mctx = memfilectx(repo, fctx.path(), fctx.data(),
                          islink='l' in flags,
                          isexec='x' in flags,
                          copied=copied.get(path))
        return mctx

    new = context.memctx(repo,
                         parents=[base.node(), node.nullid],
                         text=ctx.description(),
                         files=files,
                         filectxfn=filectxfn,
                         user=ctx.user(),
                         date=ctx.date(),
                         extra=ctx.extra())
    # commitctx always create a new revision, no need to check
    newid = repo.commitctx(new)
    return newid

def _uncommitdirstate(repo, oldctx, match):
    """Fix the dirstate after switching the working directory from
    oldctx to a copy of oldctx not containing changed files matched by
    match.
    """
    ctx = repo['.']
    ds = repo.dirstate
    copies = dict(ds.copies())
    m, a, r = repo.status(oldctx.p1(), oldctx, match=match)[:3]
    for f in m:
        if ds[f] == 'r':
            # modified + removed -> removed
            continue
        ds.normallookup(f)

    for f in a:
        if ds[f] == 'r':
            # added + removed -> unknown
            ds.drop(f)
        elif ds[f] != 'a':
            ds.add(f)

    for f in r:
        if ds[f] == 'a':
            # removed + added -> normal
            ds.normallookup(f)
        elif ds[f] != 'r':
            ds.remove(f)

    # Merge old parent and old working dir copies
    oldcopies = {}
    for f in (m + a):
        src = oldctx[f].renamed()
        if src:
            oldcopies[f] = src[0]
    oldcopies.update(copies)
    copies = dict((dst, oldcopies.get(src, src))
                  for dst, src in oldcopies.iteritems())
    # Adjust the dirstate copies
    for dst, src in copies.iteritems():
        if (src not in ctx or dst in ctx or ds[dst] != 'a'):
            src = None
        ds.copy(src, dst)

@command('^uncommit',
    [('a', 'all', None, _('uncommit all changes when no arguments given')),
     ('r', 'rev', '', _('revert commit content to REV instead')),
     ] + commands.walkopts,
    _('[OPTION]... [NAME]'))
def uncommit(ui, repo, *pats, **opts):
    """move changes from parent revision to working directory

    Changes to selected files in the checked out revision appear again as
    uncommitted changed in the working directory. A new revision
    without the selected changes is created, becomes the checked out
    revision, and obsoletes the previous one.

    The --include option specifies patterns to uncommit.
    The --exclude option specifies patterns to keep in the commit.

    The --rev argument let you change the commit file to a content of another
    revision. It still does not change the content of your file in the working
    directory.

    Return 0 if changed files are uncommitted.
    """

    wlock = lock = tr = None
    try:
        wlock = repo.wlock()
        lock = repo.lock()
        wctx = repo[None]
        if len(wctx.parents()) <= 0:
            raise util.Abort(_("cannot uncommit null changeset"))
        if len(wctx.parents()) > 1:
            raise util.Abort(_("cannot uncommit while merging"))
        old = repo['.']
        if old.phase() == phases.public:
            raise util.Abort(_("cannot rewrite immutable changeset"))
        if len(old.parents()) > 1:
            raise util.Abort(_("cannot uncommit merge changeset"))
        oldphase = old.phase()
        updatebookmarks = _bookmarksupdater(repo, old.node())


        rev = None
        if opts.get('rev'):
            rev = scmutil.revsingle(repo, opts.get('rev'))
            ctx = repo[None]
            if ctx.p1() == rev or ctx.p2() == rev:
                raise util.Abort(_("cannot uncommit to parent changeset"))

        onahead = old.rev() in repo.changelog.headrevs()
        disallowunstable = not obsolete.isenabled(repo, obsolete.allowunstableopt)
        if disallowunstable and not onahead:
            raise util.Abort(_("cannot uncommit in the middle of a stack"))

        # Recommit the filtered changeset
        tr = repo.transaction('uncommit')
        newid = None
        includeorexclude = opts.get('include') or opts.get('exclude')
        if (pats or includeorexclude or opts.get('all')):
            match = scmutil.match(old, pats, opts)
            newid = _commitfiltered(repo, old, match, target=rev)
        if newid is None:
            raise util.Abort(_('nothing to uncommit'),
                             hint=_("use --all to uncommit all files"))
        # Move local changes on filtered changeset
        obsolete.createmarkers(repo, [(old, (repo[newid],))])
        phases.retractboundary(repo, tr, oldphase, [newid])
        repo.dirstate.beginparentchange()
        repo.dirstate.setparents(newid, node.nullid)
        _uncommitdirstate(repo, old, match)
        repo.dirstate.endparentchange()
        updatebookmarks(newid)
        if not repo[newid].files():
            ui.warn(_("new changeset is empty\n"))
            ui.status(_('(use "hg prune ." to remove it)\n'))
        tr.close()
    finally:
        lockmod.release(tr, lock, wlock)

@eh.wrapcommand('commit')
def commitwrapper(orig, ui, repo, *arg, **kwargs):
    if kwargs.get('amend', False):
        wlock = lock = None
    else:
        wlock = repo.wlock()
        lock = repo.lock()
    try:
        obsoleted = kwargs.get('obsolete', [])
        if obsoleted:
            obsoleted = repo.set('%lr', obsoleted)
        result = orig(ui, repo, *arg, **kwargs)
        if not result: # commit successed
            new = repo['-1']
            oldbookmarks = []
            markers = []
            for old in obsoleted:
                oldbookmarks.extend(repo.nodebookmarks(old.node()))
                markers.append((old, (new,)))
            if markers:
                obsolete.createmarkers(repo, markers)
            for book in oldbookmarks:
                repo._bookmarks[book] = new.node()
            if oldbookmarks:
                repo._bookmarks.write()
        return result
    finally:
        lockmod.release(lock, wlock)

@eh.wrapcommand('strip', extension='strip', opts=[
    ('', 'bundle', None, _("delete the commit entirely and move it to a "
        "backup bundle")),
    ])
def stripwrapper(orig, ui, repo, *revs, **kwargs):
    if (not ui.configbool('experimental', 'prunestrip') or
        kwargs.get('bundle', False)):
        return orig(ui, repo, *revs, **kwargs)

    if kwargs.get('force'):
        ui.warn(_("warning: --force has no effect during strip with evolve "
                  "enabled\n"))
    if kwargs.get('no_backup', False):
        ui.warn(_("warning: --no-backup has no effect during strips with "
                  "evolve enabled\n"))

    revs = list(revs) + kwargs.pop('rev', [])
    revs = set(scmutil.revrange(repo, revs))
    revs = repo.revs("(%ld)::", revs)
    kwargs['rev'] = []
    kwargs['new'] = []
    kwargs['succ'] = []
    kwargs['biject'] = False
    return cmdprune(ui, repo, *revs, **kwargs)

@command('^touch',
    [('r', 'rev', [], 'revision to update'),
     ('D', 'duplicate', False,
      'do not mark the new revision as successor of the old one')],
    # allow to choose the seed ?
    _('[-r] revs'))
def touch(ui, repo, *revs, **opts):
    """create successors that are identical to their predecessors except for the changeset ID

    This is used to "resurrect" changesets
    """
    duplicate = opts['duplicate']
    revs = list(revs)
    revs.extend(opts['rev'])
    if not revs:
        revs = ['.']
    revs = scmutil.revrange(repo, revs)
    if not revs:
        ui.write_err('no revision to touch\n')
        return 1
    if not duplicate and repo.revs('public() and %ld', revs):
        raise util.Abort("can't touch public revision")
    wlock = lock = tr = None
    try:
        wlock = repo.wlock()
        lock = repo.lock()
        tr = repo.transaction('touch')
        revs.sort() # ensure parent are run first
        newmapping = {}
        for r in revs:
            ctx = repo[r]
            extra = ctx.extra().copy()
            extra['__touch-noise__'] = random.randint(0, 0xffffffff)
            # search for touched parent
            p1 = ctx.p1().node()
            p2 = ctx.p2().node()
            p1 = newmapping.get(p1, p1)
            p2 = newmapping.get(p2, p2)
            new, unusedvariable = rewrite(repo, ctx, [], ctx,
                                          [p1, p2],
                                          commitopts={'extra': extra})
            # store touched version to help potential children
            newmapping[ctx.node()] = new
            if not duplicate:
                obsolete.createmarkers(repo, [(ctx, (repo[new],))])
            phases.retractboundary(repo, tr, ctx.phase(), [new])
            if ctx in repo[None].parents():
                repo.dirstate.beginparentchange()
                repo.dirstate.setparents(new, node.nullid)
                repo.dirstate.endparentchange()
        tr.close()
    finally:
        lockmod.release(tr, lock, wlock)

@command('^fold|squash',
    [('r', 'rev', [], _("revision to fold")),
     ('', 'exact', None, _("only fold specified revisions"))
    ] + commitopts + commitopts2,
    _('hg fold [OPTION]... [-r] REV'))
def fold(ui, repo, *revs, **opts):
    """fold multiple revisions into a single one

    Folds a set of revisions with the parent of the working directory.
    All revisions linearly between the given revisions and the parent
    of the working directory will also be folded.

    Use --exact for folding only the specified revisions while ignoring the
    parent of the working directory. In this case, the given revisions must
    form a linear unbroken chain.

    .. container:: verbose

     Some examples:

     - Fold the current revision with its parent::

         hg fold .^

     - Fold all draft revisions with working directory parent::

         hg fold 'draft()'

       See :hg:`help phases` for more about draft revisions and
       :hg:`help revsets` for more about the `draft()` keyword

     - Fold revisions 3, 4, 5, and 6 with the working directory parent::

         hg fold 3:6

     - Only fold revisions linearly between foo and @::

         hg fold foo::@ --exact
    """
    revs = list(revs)
    revs.extend(opts['rev'])
    if not revs:
        raise util.Abort(_('no revisions specified'))

    revs = scmutil.revrange(repo, revs)

    if not opts['exact']:
        # Try to extend given revision starting from the working directory
        extrevs = repo.revs('(%ld::.) or (.::%ld)', revs, revs)
        discardedrevs = [r for r in revs if r not in extrevs]
        if discardedrevs:
            raise util.Abort(_("cannot fold non-linear revisions"),
                               hint=_("given revisions are unrelated to parent "
                                      "of working directory"))
        revs = extrevs

    if len(revs) == 1:
        ui.write_err(_('single revision specified, nothing to fold\n'))
        return 1

    roots = repo.revs('roots(%ld)', revs)
    if len(roots) > 1:
        raise util.Abort(_("cannot fold non-linear revisions "
                           "(multiple roots given)"))
    root = repo[roots.first()]
    if root.phase() <= phases.public:
        raise util.Abort(_("cannot fold public revisions"))
    heads = repo.revs('heads(%ld)', revs)
    if len(heads) > 1:
        raise util.Abort(_("cannot fold non-linear revisions "
                           "(multiple heads given)"))
    head = repo[heads.first()]
    disallowunstable = not obsolete.isenabled(repo, obsolete.allowunstableopt)
    if disallowunstable:
        if repo.revs("(%ld::) - %ld", revs, revs):
            raise util.Abort(_("cannot fold chain not ending with a head "\
                               "or with branching"))
    wlock = lock = None
    try:
        wlock = repo.wlock()
        lock = repo.lock()
        tr = repo.transaction('touch')
        try:
            commitopts = opts.copy()
            allctx = [repo[r] for r in revs]
            targetphase = max(c.phase() for c in allctx)

            if commitopts.get('message') or commitopts.get('logfile'):
                commitopts['edit'] = False
            else:
                msgs = ["HG: This is a fold of %d changesets." % len(allctx)]
                msgs += ["HG: Commit message of changeset %s.\n\n%s\n" %
                         (c.rev(), c.description()) for c in allctx]
                commitopts['message'] =  "\n".join(msgs)
                commitopts['edit'] = True

            newid, unusedvariable = rewrite(repo, root, allctx, head,
                                            [root.p1().node(), root.p2().node()],
                                            commitopts=commitopts)
            phases.retractboundary(repo, tr, targetphase, [newid])
            obsolete.createmarkers(repo, [(ctx, (repo[newid],))
                                 for ctx in allctx])
            tr.close()
        finally:
            tr.release()
        ui.status('%i changesets folded\n' % len(revs))
        if repo['.'].rev() in revs:
            hg.update(repo, newid)
    finally:
        lockmod.release(lock, wlock)



@eh.wrapcommand('graft')
def graftwrapper(orig, ui, repo, *revs, **kwargs):
    kwargs = dict(kwargs)
    revs = list(revs) + kwargs.get('rev', [])
    kwargs['rev'] = []
    obsoleted = kwargs.setdefault('obsolete', [])

    wlock = lock = None
    try:
        wlock = repo.wlock()
        lock = repo.lock()
        if kwargs.get('old_obsolete'):
            if kwargs.get('continue'):
                obsoleted.extend(repo.opener.read('graftstate').splitlines())
            else:
                obsoleted.extend(revs)
        # convert obsolete target into revs to avoid alias joke
        obsoleted[:] = [str(i) for i in repo.revs('%lr', obsoleted)]
        if obsoleted and len(revs) > 1:

            raise error.Abort(_('cannot graft multiple revisions while '
                                'obsoleting (for now).'))

        return commitwrapper(orig, ui, repo,*revs, **kwargs)
    finally:
        lockmod.release(lock, wlock)

@eh.extsetup
def oldevolveextsetup(ui):
    for cmd in ['kill', 'uncommit', 'touch', 'fold']:
        try:
            entry = extensions.wrapcommand(cmdtable, cmd,
                                           warnobserrors)
        except error.UnknownCommand:
            # Commands may be disabled
            continue

    entry = cmdutil.findcmd('commit', commands.table)[1]
    entry[1].append(('o', 'obsolete', [],
                     _("make commit obsolete this revision (DEPRECATED)")))
    entry = cmdutil.findcmd('graft', commands.table)[1]
    entry[1].append(('o', 'obsolete', [],
                     _("make graft obsoletes this revision (DEPRECATED)")))
    entry[1].append(('O', 'old-obsolete', False,
                     _("make graft obsoletes its source (DEPRECATED)")))

#####################################################################
### Obsolescence marker exchange experimenation                   ###
#####################################################################

def obsexcmsg(ui, message, important=False):
    verbose = ui.configbool('experimental', 'verbose-obsolescence-exchange',
                             False)
    if verbose:
        message = 'OBSEXC: ' + message
    if important or verbose:
        ui.status(message)

def obsexcprg(ui, *args, **kwargs):
    topic = 'obsmarkers exchange'
    if ui.configbool('experimental', 'verbose-obsolescence-exchange', False):
        topic = 'OBSEXC'
    ui.progress(topic, *args, **kwargs)

@eh.wrapfunction(exchange, '_pushdiscoveryobsmarkers')
def _pushdiscoveryobsmarkers(orig, pushop):
    if (obsolete.isenabled(pushop.repo, obsolete.exchangeopt)
        and pushop.repo.obsstore
        and 'obsolete' in pushop.remote.listkeys('namespaces')):
        repo = pushop.repo
        obsexcmsg(repo.ui, "computing relevant nodes\n")
        revs = list(repo.revs('::%ln', pushop.futureheads))
        unfi = repo.unfiltered()
        cl = unfi.changelog
        if not pushop.remote.capable('_evoext_obshash_0'):
            # do not trust core yet
            # return orig(pushop)
            nodes = [cl.node(r) for r in revs]
            if nodes:
                obsexcmsg(repo.ui, "computing markers relevant to %i nodes\n"
                                   % len(nodes))
                pushop.outobsmarkers = repo.obsstore.relevantmarkers(nodes)
            else:
                obsexcmsg(repo.ui, "markers already in sync\n")
                pushop.outobsmarkers = []
                pushop.outobsmarkers = repo.obsstore.relevantmarkers(nodes)
            return

        common = []
        obsexcmsg(repo.ui, "looking for common markers in %i nodes\n"
                           % len(revs))
        commonrevs = list(unfi.revs('::%ln', pushop.outgoing.commonheads))
        common = findcommonobsmarkers(pushop.ui, unfi, pushop.remote, commonrevs)

        revs = list(unfi.revs('%ld - (::%ln)', revs, common))
        nodes = [cl.node(r) for r in revs]
        if nodes:
            obsexcmsg(repo.ui, "computing markers relevant to %i nodes\n"
                               % len(nodes))
            pushop.outobsmarkers = repo.obsstore.relevantmarkers(nodes)
        else:
            obsexcmsg(repo.ui, "markers already in sync\n")
            pushop.outobsmarkers = []

@eh.wrapfunction(wireproto, 'capabilities')
def discocapabilities(orig, repo, proto):
    """wrapper to advertise new capability"""
    caps = orig(repo, proto)
    if obsolete.isenabled(repo, obsolete.exchangeopt):
        caps += ' _evoext_obshash_0'
    return caps

@eh.extsetup
def _installobsmarkersdiscovery(ui):
    hgweb_mod.perms['evoext_obshash'] = 'pull'
    hgweb_mod.perms['evoext_obshash1'] = 'pull'
    # wrap command content
    oldcap, args = wireproto.commands['capabilities']
    def newcap(repo, proto):
        return discocapabilities(oldcap, repo, proto)
    wireproto.commands['capabilities'] = (newcap, args)
    wireproto.commands['evoext_obshash'] = (srv_obshash, 'nodes')
    wireproto.commands['evoext_obshash1'] = (srv_obshash1, 'nodes')
    if getattr(exchange, '_pushdiscoveryobsmarkers', None) is None:
        ui.warn('evolve: your mercurial version is too old\n'
                'evolve: (running in degraded mode, push will includes all markers)\n')
    else:
        olddisco = exchange.pushdiscoverymapping['obsmarker']
        def newdisco(pushop):
            _pushdiscoveryobsmarkers(olddisco, pushop)
        exchange.pushdiscoverymapping['obsmarker'] = newdisco

### Set discovery START

from mercurial import dagutil
from mercurial import setdiscovery

def _obshash(repo, nodes, version=0):
    if version == 0:
        hashs = _obsrelsethashtreefm0(repo)
    elif version ==1:
        hashs = _obsrelsethashtreefm1(repo)
    else:
        assert False
    nm = repo.changelog.nodemap
    revs = [nm.get(n) for n in nodes]
    return [r is None and nullid or hashs[r][1] for r in revs]

def srv_obshash(repo, proto, nodes):
    return wireproto.encodelist(_obshash(repo, wireproto.decodelist(nodes)))

def srv_obshash1(repo, proto, nodes):
    return wireproto.encodelist(_obshash(repo, wireproto.decodelist(nodes), version=1))

@eh.addattr(localrepo.localpeer, 'evoext_obshash')
def local_obshash(peer, nodes):
    return _obshash(peer._repo, nodes)

@eh.addattr(localrepo.localpeer, 'evoext_obshash1')
def local_obshash1(peer, nodes):
    return _obshash(peer._repo, nodes, version=1)

@eh.addattr(wireproto.wirepeer, 'evoext_obshash')
def peer_obshash(self, nodes):
    d = self._call("evoext_obshash", nodes=wireproto.encodelist(nodes))
    try:
        return wireproto.decodelist(d)
    except ValueError:
        self._abort(error.ResponseError(_("unexpected response:"), d))

@eh.addattr(wireproto.wirepeer, 'evoext_obshash1')
def peer_obshash1(self, nodes):
    d = self._call("evoext_obshash1", nodes=wireproto.encodelist(nodes))
    try:
        return wireproto.decodelist(d)
    except ValueError:
        self._abort(error.ResponseError(_("unexpected response:"), d))

def findcommonobsmarkers(ui, local, remote, probeset,
                         initialsamplesize=100,
                         fullsamplesize=200):
    # from discovery
    roundtrips = 0
    cl = local.changelog
    dag = dagutil.revlogdag(cl)
    missing = set()
    common = set()
    undecided = set(probeset)
    _takefullsample = setdiscovery._takefullsample
    if remote.capable('_evoext_obshash_1'):
        getremotehash = remote.evoext_obshash1
        localhash = _obsrelsethashtreefm1(local)
    else:
        getremotehash = remote.evoext_obshash
        localhash = _obsrelsethashtreefm0(local)

    while undecided:

        ui.note(_("sampling from both directions\n"))
        if len(undecided) < fullsamplesize:
            sample = set(undecided)
        else:
            sample = _takefullsample(dag, undecided, size=fullsamplesize)

        roundtrips += 1
        ui.debug("query %i; still undecided: %i, sample size is: %i\n"
                 % (roundtrips, len(undecided), len(sample)))
        # indices between sample and externalized version must match
        sample = list(sample)
        remotehash = getremotehash(dag.externalizeall(sample))

        yesno = [localhash[ix][1] == remotehash[si]
                 for si, ix in enumerate(sample)]

        commoninsample = set(n for i, n in enumerate(sample) if yesno[i])
        common.update(dag.ancestorset(commoninsample, common))

        missinginsample = [n for i, n in enumerate(sample) if not yesno[i]]
        missing.update(dag.descendantset(missinginsample, missing))

        undecided.difference_update(missing)
        undecided.difference_update(common)


    result = dag.headsetofconnecteds(common)
    ui.debug("%d total queries\n" % roundtrips)

    if not result:
        return set([nullid])
    return dag.externalizeall(result)


_pushkeyescape = getattr(obsolete, '_pushkeyescape', None)

class pushobsmarkerStringIO(StringIO):
    """hacky string io for progress"""

    @util.propertycache
    def length(self):
        return len(self.getvalue())

    def read(self, size=None):
        obsexcprg(self.ui, self.tell(), unit="bytes", total=self.length)
        return StringIO.read(self, size)

    def __iter__(self):
        d = self.read(4096)
        while d:
            yield d
            d = self.read(4096)

@eh.wrapfunction(exchange, '_pushobsolete')
def _pushobsolete(orig, pushop):
    """utility function to push obsolete markers to a remote"""
    stepsdone = getattr(pushop, 'stepsdone', None)
    if stepsdone is not None:
        if 'obsmarkers' in stepsdone:
            return
        stepsdone.add('obsmarkers')
    if util.safehasattr(pushop, 'cgresult'):
        cgresult = pushop.cgresult
    else:
        cgresult = pushop.ret
    if cgresult == 0:
        return
    pushop.ui.debug('try to push obsolete markers to remote\n')
    repo = pushop.repo
    remote = pushop.remote
    if (obsolete.isenabled(repo, obsolete.exchangeopt) and repo.obsstore and
        'obsolete' in remote.listkeys('namespaces')):
        markers = pushop.outobsmarkers
        if not markers:
            obsexcmsg(repo.ui, "no marker to push\n")
        elif remote.capable('_evoext_pushobsmarkers_0'):
            obsdata = pushobsmarkerStringIO()
            for chunk in obsolete.encodemarkers(markers, True):
                obsdata.write(chunk)
            obsdata.seek(0)
            obsdata.ui = repo.ui
            obsexcmsg(repo.ui, "pushing %i obsolescence markers (%i bytes)\n"
                               % (len(markers), len(obsdata.getvalue())),
                      True)
            remote.evoext_pushobsmarkers_0(obsdata)
            obsexcprg(repo.ui, None)
        else:
            rslts = []
            remotedata = _pushkeyescape(markers).items()
            totalbytes = sum(len(d) for k,d in remotedata)
            sentbytes = 0
            obsexcmsg(repo.ui, "pushing %i obsolescence markers in %i pushkey payload (%i bytes)\n"
                                % (len(markers), len(remotedata), totalbytes),
                      True)
            for key, data in remotedata:
                obsexcprg(repo.ui, sentbytes, item=key, unit="bytes",
                          total=totalbytes)
                rslts.append(remote.pushkey('obsolete', key, '', data))
                sentbytes += len(data)
                obsexcprg(repo.ui, sentbytes, item=key, unit="bytes",
                          total=totalbytes)
            obsexcprg(repo.ui, None)
            if [r for r in rslts if not r]:
                msg = _('failed to push some obsolete markers!\n')
                repo.ui.warn(msg)
        obsexcmsg(repo.ui, "DONE\n")


@eh.addattr(wireproto.wirepeer, 'evoext_pushobsmarkers_0')
def client_pushobsmarkers(self, obsfile):
    """wireprotocol peer method"""
    self.requirecap('_evoext_pushobsmarkers_0',
                    _('push obsolete markers faster'))
    ret, output = self._callpush('evoext_pushobsmarkers_0', obsfile)
    for l in output.splitlines(True):
        self.ui.status(_('remote: '), l)
    return ret

@eh.addattr(httppeer.httppeer, 'evoext_pushobsmarkers_0')
def httpclient_pushobsmarkers(self, obsfile):
    """httpprotocol peer method
    (Cannot simply use _callpush as http is doing some special handling)"""
    self.requirecap('_evoext_pushobsmarkers_0',
                    _('push obsolete markers faster'))
    try:
        r = self._call('evoext_pushobsmarkers_0', data=obsfile)
        vals = r.split('\n', 1)
        if len(vals) < 2:
            raise error.ResponseError(_("unexpected response:"), r)

        for l in vals[1].splitlines(True):
            if l.strip():
                self.ui.status(_('remote: '), l)
        return vals[0]
    except socket.error, err:
        if err.args[0] in (errno.ECONNRESET, errno.EPIPE):
            raise util.Abort(_('push failed: %s') % err.args[1])
        raise util.Abort(err.args[1])

@eh.wrapfunction(localrepo.localrepository, '_restrictcapabilities')
def local_pushobsmarker_capabilities(orig, repo, caps):
    caps = orig(repo, caps)
    caps.add('_evoext_pushobsmarkers_0')
    return caps

def _pushobsmarkers(repo, data):
    tr = lock = None
    try:
        lock = repo.lock()
        tr = repo.transaction('pushkey: obsolete markers')
        new = repo.obsstore.mergemarkers(tr, data)
        if new is not None:
            obsexcmsg(repo.ui, "%i obsolescence markers added\n" % new, True)
        tr.close()
    finally:
        lockmod.release(tr, lock)
    repo.hook('evolve_pushobsmarkers')

@eh.addattr(localrepo.localpeer, 'evoext_pushobsmarkers_0')
def local_pushobsmarkers(peer, obsfile):
    data = obsfile.read()
    _pushobsmarkers(peer._repo, data)

def srv_pushobsmarkers(repo, proto):
    """wireprotocol command"""
    fp = StringIO()
    proto.redirect()
    proto.getfile(fp)
    data = fp.getvalue()
    fp.close()
    _pushobsmarkers(repo, data)
    return wireproto.pushres(0)

def _buildpullobsmarkersboundaries(pullop):
    """small funtion returning the argument for pull markers call
    may to contains 'heads' and 'common'. skip the key for None.

    Its a separed functio to play around with strategy for that."""
    repo = pullop.repo
    remote = pullop.remote
    unfi = repo.unfiltered()
    revs = unfi.revs('::(%ln - null)', pullop.common)
    common = [nullid]
    if remote.capable('_evoext_obshash_0'):
        obsexcmsg(repo.ui, "looking for common markers in %i nodes\n"
                           % len(revs))
        common = findcommonobsmarkers(repo.ui, repo, remote, revs)
    return {'heads': pullop.pulledsubset, 'common': common}

@eh.uisetup
def addgetbundleargs(self):
    gboptsmap['evo_obscommon'] = 'nodes'

@eh.wrapfunction(exchange, '_pullbundle2extraprepare')
def _addobscommontob2pull(orig, pullop, kwargs):
    ret = orig(pullop, kwargs)
    if 'obsmarkers' in kwargs and pullop.remote.capable('_evoext_getbundle_obscommon'):
        boundaries = _buildpullobsmarkersboundaries(pullop)
        common = boundaries['common']
        if common != [nullid]:
            kwargs['evo_obscommon'] = common
    return ret

@eh.wrapfunction(exchange, '_getbundleobsmarkerpart')
def _getbundleobsmarkerpart(orig, bundler, repo, source, **kwargs):
    if 'evo_obscommon' not in kwargs:
        return orig(bundler, repo, source, **kwargs)

    heads = kwargs.get('heads')
    if kwargs.get('obsmarkers', False):
        if heads is None:
            heads = repo.heads()
        obscommon = kwargs.get('evo_obscommon', ())
        assert obscommon
        obsset = repo.unfiltered().set('::%ln - ::%ln', heads, obscommon)
        subset = [c.node() for c in obsset]
        markers = repo.obsstore.relevantmarkers(subset)
        exchange.buildobsmarkerspart(bundler, markers)

@eh.uisetup
def installgetbundlepartgen(ui):
    origfunc = exchange.getbundle2partsmapping['obsmarkers']
    def newfunc(*args, **kwargs):
        return _getbundleobsmarkerpart(origfunc, *args, **kwargs)
    exchange.getbundle2partsmapping['obsmarkers'] = newfunc

@eh.wrapfunction(exchange, '_pullobsolete')
def _pullobsolete(orig, pullop):
    if not obsolete.isenabled(pullop.repo, obsolete.exchangeopt):
        return None
    if 'obsmarkers' not in getattr(pullop, 'todosteps', ['obsmarkers']):
        return None
    if 'obsmarkers' in getattr(pullop, 'stepsdone', []):
        return None
    wirepull = pullop.remote.capable('_evoext_pullobsmarkers_0')
    if not wirepull:
        return orig(pullop)
    if 'obsolete' not in pullop.remote.listkeys('namespaces'):
        return None # remote opted out of obsolescence marker exchange
    tr = None
    ui = pullop.repo.ui
    boundaries = _buildpullobsmarkersboundaries(pullop)
    if not set(boundaries['heads']) - set(boundaries['common']):
        obsexcmsg(ui, "nothing to pull\n")
        return None

    obsexcmsg(ui, "pull obsolescence markers\n", True)
    new = 0

    if wirepull:
        obsdata = pullop.remote.evoext_pullobsmarkers_0(**boundaries)
        obsdata = obsdata.read()
        if len(obsdata) > 5:
            obsexcmsg(ui, "merging obsolescence markers (%i bytes)\n"
                           % len(obsdata))
            tr = pullop.gettransaction()
            old = len(pullop.repo.obsstore._all)
            pullop.repo.obsstore.mergemarkers(tr, obsdata)
            new = len(pullop.repo.obsstore._all) - old
            obsexcmsg(ui, "%i obsolescence markers added\n" % new, True)
        else:
            obsexcmsg(ui, "no unknown remote markers\n")
        obsexcmsg(ui, "DONE\n")
    if new:
        pullop.repo.invalidatevolatilesets()
    return tr

def _getobsmarkersstream(repo, heads=None, common=None):
    revset = ''
    args = []
    repo = repo.unfiltered()
    if heads is None:
        revset = 'all()'
    elif heads:
        revset += "(::%ln)"
        args.append(heads)
    else:
        assert False, 'pulling no heads?'
    if common:
        revset += ' - (::%ln)'
        args.append(common)
    nodes = [c.node() for c in repo.set(revset, *args)]
    markers = repo.obsstore.relevantmarkers(nodes)
    obsdata = StringIO()
    for chunk in obsolete.encodemarkers(markers, True):
        obsdata.write(chunk)
    obsdata.seek(0)
    return obsdata

@eh.addattr(wireproto.wirepeer, 'evoext_pullobsmarkers_0')
def client_pullobsmarkers(self, heads=None, common=None):
    self.requirecap('_evoext_pullobsmarkers_0', _('look up remote obsmarkers'))
    opts = {}
    if heads is not None:
        opts['heads'] = wireproto.encodelist(heads)
    if common is not None:
        opts['common'] = wireproto.encodelist(common)
    if util.safehasattr(self, '_callcompressable'):
        f = self._callcompressable("evoext_pullobsmarkers_0", **opts)
    else:
        f = self._callstream("evoext_pullobsmarkers_0", **opts)
        f = self._decompress(f)
    length = int(f.read(20))
    chunk = 4096
    current = 0
    data = StringIO()
    ui = self.ui
    obsexcprg(ui, current, unit="bytes", total=length)
    while current < length:
        readsize = min(length-current, chunk)
        data.write(f.read(readsize))
        current += readsize
        obsexcprg(ui, current, unit="bytes", total=length)
    obsexcprg(ui, None)
    data.seek(0)
    return data

@eh.addattr(localrepo.localpeer, 'evoext_pullobsmarkers_0')
def local_pullobsmarkers(self, heads=None, common=None):
    return _getobsmarkersstream(self._repo, heads=heads, common=common)

def srv_pullobsmarkers(repo, proto, others):
    opts = wireproto.options('', ['heads', 'common'], others)
    for k, v in opts.iteritems():
        if k in ('heads', 'common'):
            opts[k] = wireproto.decodelist(v)
    obsdata = _getobsmarkersstream(repo, **opts)
    finaldata = StringIO()
    obsdata = obsdata.getvalue()
    finaldata.write('%20i' % len(obsdata))
    finaldata.write(obsdata)
    finaldata.seek(0)
    return wireproto.streamres(proto.groupchunks(finaldata))

def _obsrelsethashtreefm0(repo):
    return _obsrelsethashtree(repo, obsolete._fm0encodeonemarker)

def _obsrelsethashtreefm1(repo):
    return _obsrelsethashtree(repo, obsolete._fm1encodeonemarker)

def _obsrelsethashtree(repo, encodeonemarker):
    cache = []
    unfi = repo.unfiltered()
    markercache = {}
    for i in unfi:
        ctx = unfi[i]
        entry = 0
        sha = util.sha1()
        # add data from p1
        for p in ctx.parents():
            p = p.rev()
            if p < 0:
                p = nullid
            else:
                p = cache[p][1]
            if p != nullid:
                entry += 1
                sha.update(p)
        tmarkers = repo.obsstore.relevantmarkers([ctx.node()])
        if tmarkers:
            bmarkers = []
            for m in tmarkers:
                if not m in markercache:
                    markercache[m] = encodeonemarker(m)
                bmarkers.append(markercache[m])
            bmarkers.sort()
            for m in bmarkers:
                entry += 1
                sha.update(m)
        if entry:
            cache.append((ctx.node(), sha.digest()))
        else:
            cache.append((ctx.node(), nullid))
    return cache

@command('debugobsrelsethashtree',
        [('', 'v0', None, 'hash on marker format "0"'),
         ('', 'v1', None, 'hash on marker format "1" (default)')
         ,] , _(''))
def debugobsrelsethashtree(ui, repo, v0=False, v1=False):
    """display Obsolete markers, Relevant Set, Hash Tree
    changeset-node obsrelsethashtree-node

    It computed form the "orsht" of its parent and markers
    relevant to the changeset itself."""
    if v0 and v1:
        raise util.Abort('cannot only specify one format')
    elif v0:
        treefunc = _obsrelsethashtreefm0
    else:
        treefunc = _obsrelsethashtreefm1

    for chg, obs in treefunc(repo):
        ui.status('%s %s\n' % (node.hex(chg), node.hex(obs)))

_bestformat = max(obsolete.formats.keys())


@eh.wrapfunction(obsolete, '_checkinvalidmarkers')
def _checkinvalidmarkers(orig, markers):
    """search for marker with invalid data and raise error if needed

    Exist as a separated function to allow the evolve extension for a more
    subtle handling.
    """
    if 'debugobsconvert' in sys.argv:
        return
    for mark in markers:
        if node.nullid in mark[1]:
            raise util.Abort(_('bad obsolescence marker detected: '
                               'invalid successors nullid'),
                             hint=_('You should run `hg debugobsconvert`'))

@command(
    'debugobsconvert',
    [('', 'new-format', _bestformat, _('Destination format for markers.'))],
    '')
def debugobsconvert(ui, repo, new_format):
    if new_format == repo.obsstore._version:
        msg = _('New format is the same as the old format, not upgrading!')
        raise util.Abort(msg)
    f = repo.sopener('obsstore', 'wb', atomictemp=True)
    origmarkers = repo.obsstore._all
    known = set()
    markers = []
    for m in origmarkers:
        # filter out invalid markers
        if nullid in m[1]:
            m = list(m)
            m[1] = tuple(s for s in m[1] if s != nullid)
            m = tuple(m)
        if m in known:
            continue
        known.add(m)
        markers.append(m)
    ui.write(_('Old store is version %d, will rewrite in version %d\n') % (
        repo.obsstore._version, new_format))
    map(f.write, obsolete.encodemarkers(markers, True, new_format))
    f.close()
    ui.write(_('Done!\n'))


@eh.wrapfunction(wireproto, 'capabilities')
def capabilities(orig, repo, proto):
    """wrapper to advertise new capability"""
    caps = orig(repo, proto)
    if obsolete.isenabled(repo, obsolete.exchangeopt):
        caps += ' _evoext_pushobsmarkers_0'
        caps += ' _evoext_pullobsmarkers_0'
        caps += ' _evoext_obshash_0'
        caps += ' _evoext_obshash_1'
        caps += ' _evoext_getbundle_obscommon'
    return caps


@eh.extsetup
def _installwireprotocol(ui):
    localrepo.moderncaps.add('_evoext_pullobsmarkers_0')
    hgweb_mod.perms['evoext_pushobsmarkers_0'] = 'push'
    hgweb_mod.perms['evoext_pullobsmarkers_0'] = 'pull'
    wireproto.commands['evoext_pushobsmarkers_0'] = (srv_pushobsmarkers, '')
    wireproto.commands['evoext_pullobsmarkers_0'] = (srv_pullobsmarkers, '*')
    # wrap command content
    oldcap, args = wireproto.commands['capabilities']
    def newcap(repo, proto):
        return capabilities(oldcap, repo, proto)
    wireproto.commands['capabilities'] = (newcap, args)

def _helploader():
    return help.gettext(evolutionhelptext)

@eh.uisetup
def _setuphelp(ui):
    for entry in help.helptable:
        if entry[0] == "evolution":
            break
    else:
        help.helptable.append((["evolution"], _("Safely Rewriting History"),
                      _helploader))
        help.helptable.sort()