annotate hgext/obsolete.py @ 121:7280eede21ea

obsolete: improve locking when writing obsolete data

# obsolete.py - introduce the obsolete concept in mercurial.
#
# Copyright 2011 Pierre-Yves David <[e-mail]>
#                Logilab SA        <[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.
"""Introduce the Obsolete concept to mercurial

General concept
===============

This extension introduces the *obsolete* concept. It adds a new *obsolete*
relation between two changesets. A relation ``<changeset B> obsolete <changeset
A>`` is set to denote that ``<changeset B>`` is new version of ``<changeset
A>``.

The *obsolete* relation act as a **perpendicular history** to the standard
changeset history. Standard changeset history versions files. The *obsolete*
relation versions changesets.

:obsolete:     a changeset that have been replace by another one.
:unstable:     a non-obsolet changeset based on another one.
:suspended:    an obsolete changeset with unstable descendant.

Another name for unstable could be out of sync.



Usage and Feature
=================


Display and Exchange
....................

obsolete changesets are hidden. (except if they have non obsolete changeset)

obsolete changesets are currently not exchange. This will probably change later
but it was the simpler solution for now.

New commands
............

a ``debugobsolete`` command has been added.

It add an obsolete relation between too relation.

Context object
..............

Context gain a ``obsolete`` method that return True if a changeset is obsolete
False otherwise.

revset
......

Add an ``obsolete()`` entry.

repo extension
..............

To Do
-----

* refuse to obsolete published changesets

* handle split

* handle conflict

* handle unstable // out of sync

"""
import os
try:
    from cStringIO import StringIO
except ImportError:
    from StringIO import StringIO

from mercurial.i18n import _

import base64

from mercurial import util
from mercurial import context
from mercurial import revset
from mercurial import scmutil
from mercurial import extensions
from mercurial import pushkey
from mercurial import discovery
from mercurial import error
from mercurial import commands
from mercurial import changelog
from mercurial import phases
from mercurial.node import hex, bin, short, nullid
from mercurial.lock import release

### Patch changectx
#############################

def obsolete(ctx):
    """is the changeset obsolete by other"""
    if ctx.node()is None:
        return False
    return bool(ctx._repo.obsoletedby(ctx.node())) and ctx.phase()

context.changectx.obsolete = obsolete


### revset
#############################


def revsetobsolete(repo, subset, x):
    """filter obsolet entry"""
    args = revset.getargs(x, 0, 0, 'publicheads takes no arguments')
    # XXX slow stop using context
    return [r for r in subset if r in repo._obsoleteset and repo._phaserev[r] > 0]

### Other Extension compat
############################

def concludenode(orig, repo, rev, *args, **kwargs):
    """wrapper for rebase 's concludenode that set obsolete relation"""
    newrev = orig(repo, rev, *args, **kwargs)
    oldnode = repo[rev].node()
    newnode = repo[newrev].node()
    repo.addobsolete(newnode, oldnode)
    return newrev

def cmdrebase(orig, repo, ui, *args, **kwargs):
    oldkeep = kwargs.pop('keep', False)
    if oldkeep:
        ui.warn('WARNING --keep option ignored by experimental obsolete extension')
    kwargs['keep'] = True
    return orig(repo, ui, *args, **kwargs)


### Filter obsolet changeset
############################

def filterobsoleteout(orig, repo, remote, *args,**kwargs):
    """wrapper for findcommonoutgoing that remove obsolete changeset

    This behaviour is temporary"""
    common, heads = orig(repo, remote, *args, **kwargs)

    # filter obsolete
    heads = set(map(repo.changelog.rev, heads))
    obsoletes = set()
    for obj in repo._obsobjrels:
        try:
            obsoletes.add(repo.changelog.rev(obj))
        except error.LookupError:
            pass # we don't have this node locally

    outgoing = set(repo.changelog.ancestors(*heads))
    outgoing.update(heads)

    selected = outgoing - obsoletes
    heads = sorted(map(repo.changelog.node, selected))

    return common, heads

def extsetup(ui):

    revset.symbols["obsolete"] = revsetobsolete

    extensions.wrapfunction(discovery, 'findcommonoutgoing', filterobsoleteout)

    try:
        rebase = extensions.find('rebase')
        if rebase:
            extensions.wrapfunction(rebase, 'concludenode', concludenode)
            extensions.wrapcommand(rebase.cmdtable, "rebase", cmdrebase)
    except KeyError:
        pass # rebase not found

# Pushkey mechanism for mutable
#########################################

def pushobsolete(repo, key, old, raw):
    """push obsolete relation through pushkey"""
    assert key == "relations"
    w = repo.wlock()
    try:
        tmp = StringIO()
        tmp.write(raw)
        tmp.seek(0)
        relations = _obsdeserialise(tmp)
        for sub, objs in relations.iteritems():
            for obj in objs:
                try:
                    repo.addobsolete(sub, obj)
                except error.RepoLookupError:
                    pass
        return 0
    finally:
        w.release()

def listobsolete(repo):
    """dump all obsolete relation in

    XXX this have be improved"""
    tmp = StringIO()
    _obsserialise(repo._obssubrels, tmp)
    return {'relations': base64.b64encode(tmp.getvalue())}

pushkey.register('obsolete', pushobsolete, listobsolete)

### New commands
#############################


def cmddebugobsolete(ui, repo, subject, object):
    """Add an obsolete relation between a too node

    The subject is expected to be a newer version of the object"""
    sub = repo[subject]
    obj = repo[object]
    repo.addobsolete(sub.node(), obj.node())
    return 0

cmdtable = {'debugobsolete': (cmddebugobsolete, [], '<subject> <object>')}

### Altering existing command
#############################

def wrapmayobsoletewc(origfn, ui, repo, *args, **opts):
    res = origfn(ui, repo, *args, **opts)
    if repo['.'].obsolete():
        ui.warn(_('Working directory parent is obsolete\n'))
    return res

def uisetup(ui):
    extensions.wrapcommand(commands.table, "update", wrapmayobsoletewc)
    extensions.wrapcommand(commands.table, "pull", wrapmayobsoletewc)

### serialisation
#############################

def _obsserialise(obssubrels, flike):
    """serialise an obsolete relation mapping in a plain text one

    this is for subject -> [objects] mapping

    format is::

        <subject-full-hex> <object-full-hex>\n"""
    for sub, objs in obssubrels.iteritems():
        for obj in objs:
            if sub is None:
                sub = nullid
            flike.write('%s %s\n' % (hex(sub), hex(obj)))

def _obsdeserialise(flike):
    """read a file like object serialised with _obsserialise

    this desierialize into a {subject -> objects} mapping"""
    rels = {}
    for line in flike:
        subhex, objhex = line.split()
        subnode = bin(subhex)
        if subnode == nullid:
            subnode = None
        rels.setdefault( subnode, set()).add(bin(objhex))
    return rels

### diagnostique tools
#############################

def unstables(repo):
    """Return all unstable changeset"""
    return scmutil.revrange(repo, ['obsolete():: and (not obsolete())'])

def newerversion(repo, obs):
    """Return the newer version of an obsolete changeset"""
    toproceed = set([obs])
    # XXX know optimization available
    newer = set()
    while toproceed:
        current = toproceed.pop()
        if current in repo._obsobjrels:
            toproceed.update(repo._obsobjrels[current])
        elif current is not None: # None is kill
            newer.add(current)
    return sorted(newer)


### repo subclassing
#############################

def reposetup(ui, repo):

    if not repo.local():
        return

    opull = repo.pull
    opush = repo.push
    orollback = repo.rollback
    o_writejournal = repo._writejournal
    ocancopy = repo.cancopy

    class obsoletingrepo(repo.__class__):

        ### Public method
        def obsoletedby(self, node):
            """return the set of node that make <node> obsolete (obj)"""
            return self._obsobjrels.get(node, set())

        def obsolete(self, node):
            """return the set of node that <node> make obsolete (sub)"""
            return self._obssubrels.get(node, set())

        @util.propertycache
        def _obsoleteset(self):
            obs = set()
            for obj in self._obsobjrels:
                try:
                    obs.add(self.changelog.rev(obj))
                except error.LookupError:
                    pass
            return obs

        def addobsolete(self, sub, obj):
            """Add a relation marking that node <sub> is a new version of <obj>"""
            if sub == nullid:
                sub = None
            self._obssubrels.setdefault(sub, set()).add(obj)
            self._obsobjrels.setdefault(obj, set()).add(sub)
            try:
                if self[obj].phase() == 0:
                    if sub is None:
                        self.ui.warn(
                            _("trying to kill immutable changeset %(obj)s\n")
                            % {'obj': short(obj)})
                    if sub is not None:
                        self.ui.warn(
                            _("%(sub)s try to obsolete immutable changeset %(obj)s\n")
                            % {'sub': short(sub), 'obj': short(obj)})
                self.changelog.hiddenrevs.add(repo[obj].rev())
            except (error.RepoLookupError, error.LookupError):
                pass #unknow revision (but keep propagating the data
            self._writeobsrels()
            if '_obsobjrels' in vars(self):
                del self._obsobjrels
            if '_obssubrels' in vars(self):
                del self._obssubrels
            if '_obsoleteset' in vars(self):
                del self._obsoleteset

        ### obsolete storage
        @util.propertycache
        def _obsobjrels(self):
            """{<old-node> -> set(<new-node>)}

            also compute hidden revision"""
            #reverse sub -> objs mapping
            objrels = {}
            for sub, objs in self._obssubrels.iteritems():
                for obj in objs:
                    objrels.setdefault(obj, set()).add(sub)
            return objrels

        @util.propertycache
        def _obssubrels(self):
            """{<new-node> -> set(<old-node>)}"""
            return self._readobsrels()




        ### Disk IO
        def _readobsrels(self):
            """Write obsolete relation on disk"""
            # XXX handle lock
            try:
                f = self.opener('obsolete-relations')
                try:
                    return _obsdeserialise(f)
                finally:
                    f.close()
            except IOError:
                return {}

        def _writeobsrels(self):
            """Write obsolete relation on disk"""
            # XXX handle lock
            lock = self.wlock()
            try:
                f = self.opener('obsolete-relations', 'w', atomictemp=True)
                try:
                    _obsserialise(self._obssubrels, f)
                    try:
                        f.rename()
                    except AttributeError: # old version
                        f.close()
                finally:
                    f.close()
            finally:
                lock.release()

        ### local clone support

        def cancopy(self):
            """wrapper on cancopy that deny copy if there is obsolete relation"""
            return ocancopy() and not bool(self._obsobjrels)  # you can't copy if there is obsolete

        ### pull // push support

        def pull(self, remote, *args, **kwargs):
            """wrapper around push that push obsolete relation"""
            result = opull(remote, *args, **kwargs)
            if 'obsolete' in remote.listkeys('namespaces'):
                tmp = StringIO()
                rels = remote.listkeys('obsolete')['relations']
                tmp.write(base64.b64decode(rels))
                tmp.seek(0)
                obsrels = _obsdeserialise(tmp)
                for sub, objs in obsrels.iteritems():
                    for obj in objs:
                        self.addobsolete(sub, obj)
            return result

        def push(self, remote, *args, **opts):
            """wrapper around pull that pull obsolete relation"""
            result = opush(remote, *args, **opts)
            if 'obsolete' in remote.listkeys('namespaces'):
                tmp = StringIO()
                _obsserialise(self._obssubrels, tmp)
                remote.pushkey('obsolete', 'relations', '', tmp.getvalue())

            return result



        ### rollback support

        def _writejournal(self, desc):
            """wrapped version of _writejournal that save obsolete data"""
            entries = list(o_writejournal(desc))
            filename = 'obsolete-relations'
            filepath = self.join(filename)
            if  os.path.exists(filepath):
                journalname = 'journal.' + filename
                journalpath = self.join(journalname)
                util.copyfile(filepath, journalpath)
                entries.append(journalpath)
            return tuple(entries)

        def rollback(self, dryrun=False, **kwargs):
            """wrapped version of rollback that restore obsolete data"""
            wlock = lock = None
            try:
                wlock = self.wlock()
                lock = self.lock()
                ret = orollback(dryrun, **kwargs)
                if not (ret or dryrun): #rollback did not failed
                    src = self.join('undo.obsolete-relations')
                    dst = self.join('obsolete-relations')
                    if os.path.exists(src):
                        util.rename(src, dst)
                    elif os.path.exists(dst): #unlink in any case
                        os.unlink(dst)
                    # invalidate cache
                    self.__dict__.pop('_obssubrels', None)
                    self.__dict__.pop('_obsobjrels', None)
                return ret
            finally:
                release(lock, wlock)

        @scmutil.filecache('00changelog.i', True)
        def changelog(self):
            changelog = getattr(super(obsoletingrepo, self), 'changelog')
            assert not changelog.__dict__.pop('hiddenrevs', ())
            def _sethidden(changelog, value):
                print 'COIN COIN', value
                assert not value


            class hchangelog(changelog.__class__):
                @util.propertycache
                def hiddenrevs(changelog):
                    shown = ['not obsolete()', '.', 'bookmark()', 'tagged()',
                             'public()']
                    basicquery = 'obsolete() - (::(%s))' % (' or '.join(shown))
                    # !!! self is repo not changelog
                    result = set(scmutil.revrange(self, [basicquery]))
                    return result
            changelog.__class__ = hchangelog
            return changelog




    repo.__class__ = obsoletingrepo
    obsoletes = [c.node() for c in repo.set('obsolete() - public()')]
    lock = repo.lock()
    if repo.ui.configbool('obsolete', 'secret-unstable', True):
        try:
            phases.retractboundary(repo, 2, obsoletes)
        finally:
            lock.release()