sapling/pushrebase.py

# pushrebase.py - server-side rebasing of pushed commits
#
# Copyright 2014 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

import errno, os, tempfile, sys, operator, resource, collections, time

try:
    import json
except ImportError:
    import simplejson as json

from mercurial import bundle2, cmdutil, hg, scmutil, exchange, commands
from mercurial import util, error, discovery, changegroup, context, revset
from mercurial import obsolete, pushkey, phases, extensions
from mercurial import bookmarks, lock as lockmod
from mercurial.extensions import wrapcommand, wrapfunction
from mercurial.hg import repository
from mercurial.node import nullid, hex, bin
from mercurial.i18n import _

testedwith = '3.4'

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

rebaseparttype = 'b2x:rebase'
commonheadsparttype = 'b2x:commonheads'

experimental = 'experimental'
configonto = 'server-rebase-onto'
pushrebasemarker = '__pushrebase_processed__'
donotrebasemarker = '__pushrebase_donotrebase__'

def uisetup(ui):
    # remotenames circumvents the default push implementation entirely, so make
    # sure we load after it so that we wrap it.
    order = extensions._order
    order.remove('pushrebase')
    order.append('pushrebase')
    extensions._order = order

def extsetup(ui):
    entry = wrapcommand(commands.table, 'push', _push)
    try:
        # Don't add the 'to' arg if it already exists
        extensions.find('remotenames')
    except KeyError:
        entry[1].append(('', 'to', '', _('server revision to rebase onto')))

    partorder = exchange.b2partsgenorder
    partorder.insert(partorder.index('changeset'),
                     partorder.pop(partorder.index(rebaseparttype)))

    partorder.insert(0, partorder.pop(partorder.index(commonheadsparttype)))

    wrapfunction(discovery, 'checkheads', _checkheads)
    # we want to disable the heads check because in pushrebase repos, we
    # expect the heads to change during the push and we should not abort.

    # The check heads functions are used to verify that the heads haven't
    # changed since the client did the initial discovery. Pushrebase is meant
    # to allow concurrent pushes, so the heads may have very well changed.
    # So let's not do this check.
    wrapfunction(exchange, 'check_heads', _exchangecheckheads)
    wrapfunction(exchange, '_pushb2ctxcheckheads', _skipcheckheads)

    origpushkeyhandler = bundle2.parthandlermapping['pushkey']
    newpushkeyhandler = lambda *args, **kwargs: \
        bundle2pushkey(origpushkeyhandler, *args, **kwargs)
    newpushkeyhandler.params = origpushkeyhandler.params
    bundle2.parthandlermapping['pushkey'] = newpushkeyhandler
    bundle2.parthandlermapping['b2x:pushkey'] = newpushkeyhandler

    wrapfunction(exchange, 'unbundle', unbundle)

    wrapfunction(hg, '_peerorrepo', _peerorrepo)

def reposetup(ui, repo):
    if repo.ui.configbool('pushrebase', 'blocknonpushrebase'):
        repo.ui.setconfig('hooks', 'prechangegroup.blocknonpushrebase',
                          blocknonpushrebase)

def blocknonpushrebase(ui, repo, **kwargs):
    if not repo.ui.configbool('pushrebase', pushrebasemarker):
        raise error.Abort("this repository requires that you push using "
                         "'hg push --to'")

def _peerorrepo(orig, ui, path, create=False):
    # Force hooks to use a bundle repo
    bundlepath = os.environ.get("HG_HOOK_BUNDLEPATH")
    if bundlepath:
        return orig(ui, bundlepath, create=create)
    return orig(ui, path, create)

def unbundle(orig, repo, cg, heads, source, url):
    # Preload the manifests that the client says we'll need. This happens
    # outside the lock, thus cutting down on our lock time and increasing commit
    # throughput.
    if util.safehasattr(cg, 'params'):
        preloadmfs = cg.params.get('preloadmanifests')
        if preloadmfs:
            for mfnode in preloadmfs.split(','):
                repo.manifest.read(bin(mfnode))

    return orig(repo, cg, heads, source, url)

def validaterevset(repo, revset):
    "Abort if this is a rebasable revset, return None otherwise"
    if not repo.revs(revset):
        raise error.Abort(_('nothing to rebase'))

    if repo.revs('%r and public()', revset):
        raise error.Abort(_('cannot rebase public changesets'))

    if repo.revs('%r and obsolete()', revset):
        raise error.Abort(_('cannot rebase obsolete changesets'))

    heads = repo.revs('heads(%r)', revset)
    if len(heads) > 1:
        raise error.Abort(_('cannot rebase divergent changesets'))

    repo.ui.note(_('validated revset for rebase\n'))

def getrebasepart(repo, peer, outgoing, onto, newhead):
    if not outgoing.missing:
        raise error.Abort(_('no commits to rebase'))

    if rebaseparttype not in bundle2.bundle2caps(peer):
        raise error.Abort(_('no server support for %r') % rebaseparttype)

    validaterevset(repo, revset.formatspec('%ln', outgoing.missing))

    cg = changegroup.getlocalchangegroupraw(repo, 'push', outgoing)

    # .upper() marks this as a mandatory part: server will abort if there's no
    #  handler
    return bundle2.bundlepart(
        rebaseparttype.upper(),
        mandatoryparams={
            'onto': onto,
            'newhead': repr(newhead),
        }.items(),
        data = cg)

def _checkheads(orig, pushop):
    repo = pushop.repo
    onto = repo.ui.config(experimental, configonto)
    if onto: # This is a rebasing push
        # If remotenames is enabled, we don't want to abort if the user uses
        # --to, even if the server doesn't support pushrebase.
        if checkremotenames():
            return

        # The rest of the checks are performed during bundle2 part processing;
        # we need to bypass the regular push checks because it will look like
        # we're pushing a new head, which isn't normally allowed
        if not repo.ui.configbool('experimental', 'bundle2-exp', False):
            raise error.Abort(_('bundle2 needs to be enabled on client'))
        if not remote.capable('bundle2-exp'):
            raise error.Abort(_('bundle2 needs to be enabled on server'))
        return
    else:
        return orig(pushop)

def _exchangecheckheads(orig, repo, *args, **kwargs):
    onto = repo.ui.config(experimental, configonto)
    if not onto:
        # Only do this work if it's not a rebasing push
        return orig(repo, *args, **kwargs)

def _skipcheckheads(orig, pushop, bundler):
    if not pushop.ui.config(experimental, configonto): # no check if we rebase
        return orig(pushop, bundler)

def _push(orig, ui, repo, *args, **opts):
    oldonto = ui.backupconfig(experimental, configonto)
    oldremotenames = ui.backupconfig('remotenames', 'allownonfastforward')
    oldphasemove = None

    try:
        onto = opts.get('to')
        if not onto and not opts.get('rev') and not opts.get('dest'):
            try:
                # If it's a tracking bookmark, remotenames will push there,
                # so let's set that up as our --to.
                remotenames = extensions.find('remotenames')
                active = remotenames.bmactive(repo)
                tracking = remotenames._readtracking(repo)
                if active and active in tracking:
                    track = tracking[active]
                    path, book = remotenames.splitremotename(track)
                    onto = book
            except KeyError:
                # No remotenames? No big deal.
                pass

        ui.setconfig(experimental, configonto, onto, '--to')
        if ui.config(experimental, configonto):
            ui.setconfig(experimental, 'bundle2.pushback', True)
            oldphasemove = wrapfunction(exchange, '_localphasemove', _phasemove)
        ui.setconfig('remotenames', 'allownonfastforward', True)
        result = orig(ui, repo, *args, **opts)
    finally:
        ui.restoreconfig(oldonto)
        ui.restoreconfig(oldremotenames)
        if oldphasemove:
            exchange._localphasemove = oldphasemove

    return result

def _phasemove(orig, pushop, nodes, phase=phases.public):
    """prevent commits from being marked public

    Since these are going to be mutated on the server, they aren't really being
    published, their successors are.  If we mark these as public now, hg evolve
    will refuse to fix them for us later."""

    if phase != phases.public:
        orig(pushop, nodes, phase)

@exchange.b2partsgenerator(commonheadsparttype)
def commonheadspartgen(pushop, bundler):
    if rebaseparttype not in bundle2.bundle2caps(pushop.remote):
        # Server doesn't support pushrebase, so just fallback to normal push.
        return

    bundler.newpart(commonheadsparttype,
                    data=''.join(pushop.outgoing.commonheads))

@bundle2.parthandler(commonheadsparttype)
def commonheadshandler(op, inpart):
    nodeid = inpart.read(20)
    while len(nodeid) == 20:
        op.records.add(commonheadsparttype, nodeid)
        nodeid = inpart.read(20)
    assert not nodeid # data should split evenly into blocks of 20 bytes

def checkremotenames():
    try:
        extensions.find('remotenames')
        return True
    except KeyError:
        return False

@exchange.b2partsgenerator(rebaseparttype)
def partgen(pushop, bundler):
    onto = pushop.ui.config(experimental, configonto)
    if 'changesets' in pushop.stepsdone or not onto:
        return

    if (rebaseparttype not in bundle2.bundle2caps(pushop.remote) and
        checkremotenames()):
        # Server doesn't support pushrebase, but --to is valid in remotenames as
        # well, so just let it through.
        return

    pushop.stepsdone.add('changesets')
    if not pushop.outgoing.missing:
        # It's important that this text match the text found in upstream
        # Mercurial, since some tools rely on this string to know if a push
        # succeeded despite not pushing commits.
        pushop.ui.status(_('no changes found\n'))
        pushop.cgresult = 0
        return

    # Force push means no rebasing, so let's just take the existing parent.
    if pushop.force:
        onto = donotrebasemarker

    rebasepart = getrebasepart(pushop.repo,
                               pushop.remote,
                               pushop.outgoing,
                               onto,
                               pushop.newbranch)

    bundler.addpart(rebasepart)

    # Tell the server which manifests to load before taking the lock.
    # This helps shorten the duration of the lock, which increases our potential
    # commit rate.
    missing = pushop.outgoing.missing
    roots = pushop.repo.set('parents(%ln) - %ln', missing, missing)
    preloadnodes = [hex(r.manifestnode()) for r in roots]
    bundler.addparam("preloadmanifests", ','.join(preloadnodes))

    def handlereply(op):
        # server either succeeds or aborts; no code to read
        pushop.cgresult = 1

    return handlereply

bundle2.capabilities[rebaseparttype] = ()

def _makebundlefile(part):
    """constructs a temporary bundle file

    part.data should be an uncompressed v1 changegroup"""

    fp = None
    fd, bundlefile = tempfile.mkstemp()
    try: # guards bundlefile
        try: # guards fp
            fp = os.fdopen(fd, 'wb')
            magic = 'HG10UN'
            fp.write(magic)
            data = part.read(resource.getpagesize() - len(magic))
            while data:
                fp.write(data)
                data = part.read(resource.getpagesize())
        finally:
            fp.close()
    except Exception:
        try:
            os.unlink(bundlefile)
        except Exception:
            # we would rather see the original exception
            pass
        raise

    return bundlefile

def _getrevs(bundle, onto):
    'extracts and validates the revs to be imported'
    validaterevset(bundle, 'bundle()')
    revs = [bundle[r] for r in bundle.revs('sort(bundle())')]
    onto = bundle[onto.hex()]
    # Fast forward update, no rebase needed
    if list(bundle.set('bundle() & %d::', onto.rev())):
        return revs, onto

    if revs:
        # We want to rebase the highest bundle root that is an ancestor of
        # `onto`.
        oldonto = list(bundle.set('max(parents(bundle()) - bundle() & ::%d)',
                                  onto.rev()))
        if not oldonto:
            # If there's no shared history, only allow the rebase if the
            # incoming changes are completely distinct.
            sharedparents = list(bundle.set('parents(bundle()) - bundle()'))
            if not sharedparents:
                return revs, bundle[nullid]
            raise error.Abort(_('pushed commits do not branch from an ancestor '
                               'of the desired destination %s') % onto.hex())
        oldonto = oldonto[0]

        # Computes a list of all files that are in the changegroup, and diffs it
        # against all the files that changed between the old onto (ex: our old
        # bookmark location) and the new onto (ex: the server's actual bookmark
        # location). Since oldonto->onto is the distance of the rebase, this
        # should catch any conflicting changes.
        files = set()
        for rev in revs:
            files |= set(rev.files())
        filematcher = scmutil.matchfiles(bundle, files)
        commonmanifest = oldonto.manifest().matches(filematcher)
        ontomanifest = onto.manifest().matches(filematcher)
        conflicts = ontomanifest.diff(commonmanifest).keys()
        if conflicts:
            raise error.Abort(_('conflicting changes in:\n%s') %
                             ''.join('    %s\n' % f for f in sorted(conflicts)))

    return revs, oldonto

def _graft(repo, rev, mapping):
    '''duplicate changeset "rev" with parents from "mapping"'''
    oldp1 = rev.p1().node()
    oldp2 = rev.p2().node()
    newp1 = mapping.get(oldp1, oldp1)
    newp2 = mapping.get(oldp2, oldp2)
    m = rev.manifest()
    def getfilectx(repo, memctx, path):
        if path in m:
            fctx = rev[path]
            flags = fctx.flags()
            copied = fctx.renamed()
            if copied:
                copied = copied[0]
            return context.memfilectx(repo, fctx.path(), fctx.data(),
                              islink='l' in flags,
                              isexec='x' in flags,
                              copied=copied)
        else:
            return None


    # If the incoming commit has no parents, but requested a rebase,
    # allow it only for the first commit. The null/null commit will always
    # be the first commit since we only allow a nullid->nonnullid mapping if the
    # incoming commits are a completely distinct history (see `sharedparents` in
    # getrevs()), so there's no risk of commits with a single null parent
    # accidentally getting translated first.
    if oldp1 == nullid and oldp2 == nullid:
        if newp1 != nullid:
            newp2 = nullid
            del mapping[nullid]

    if oldp1 != nullid and oldp2 != nullid:
        # If it's a merge commit, Mercurial's rev.files() only returns the files
        # that are different from both p1 and p2, so it would not capture all of
        # the incoming changes from p2 (for instance, new files in p2). The fix
        # is to manually diff the rev manifest and it's p1 to get the list of
        # files that have changed. We only need to diff against p1, and not p2,
        # because Mercurial constructs new commits by applying our specified
        # files on top of a copy of the p1 manifest, so we only need the diff
        # against p1.
        bundlerepo = rev._repo
        files = rev.manifest().diff(bundlerepo[oldp1].manifest()).keys()
    else:
        files = rev.files()


    date = rev.date()
    if repo.ui.configbool('pushrebase', 'rewritedates'):
        date = (time.time(), date[1])
    return context.memctx(repo,
                          [newp1, newp2],
                          rev.description(),
                          files,
                          getfilectx,
                          rev.user(),
                          date,
                          rev.extra(),
                         ).commit()

def _buildobsolete(replacements, oldrepo, newrepo):
    'adds obsolete markers in replacements if enabled in newrepo'
    if obsolete.isenabled(newrepo, obsolete.createmarkersopt):
        markers = [(oldrepo[oldrev], (newrepo[newrev],))
                   for oldrev, newrev in replacements.items()
                   if newrev != oldrev]

        obsolete.createmarkers(newrepo, markers)

def _addpushbackchangegroup(repo, reply, outgoing):
    '''adds changegroup part to reply containing revs from outgoing.missing'''
    cgversions = set(reply.capabilities.get('changegroup'))
    if not cgversions:
        cgversions.add('01')
    version = max(cgversions & set(changegroup.supportedoutgoingversions(repo)))

    cg = changegroup.getlocalchangegroupraw(repo,
                                            'rebase:reply',
                                            outgoing,
                                            version = version)

    cgpart = reply.newpart('CHANGEGROUP', data=cg)
    if version != '01':
        cgpart.addparam('version', version)

def _addpushbackobsolete(repo, reply, newrevs):
    '''adds obsoletion markers to reply that are relevant to newrevs
    (if enabled)'''
    if (obsolete.isenabled(repo, obsolete.exchangeopt) and repo.obsstore):
        try:
            markers = repo.obsstore.relevantmarkers(newrevs)
            exchange.buildobsmarkerspart(reply, markers)
        except ValueError as exc:
            repo.ui.status(_("can't send obsolete markers: %s") % exc.message)

def _addpushbackparts(op, replacements):
    '''adds pushback to reply if supported by the client'''
    if (op.records[commonheadsparttype]
        and op.reply
        and 'pushback' in op.reply.capabilities):
        outgoing = discovery.outgoing(op.repo.changelog,
                                      op.records[commonheadsparttype],
                                      [new for old, new in replacements.items()
                                       if old != new])

        if outgoing.missing:
            plural = 's' if len(outgoing.missing) > 1 else ''
            op.repo.ui.warn(_("%s new commit%s from the server will be "
                              "downloaded\n") % (len(outgoing.missing), plural))
            _addpushbackchangegroup(op.repo, op.reply, outgoing)
            _addpushbackobsolete(op.repo, op.reply, replacements.values())

@bundle2.parthandler(rebaseparttype, ('onto', 'newhead'))
def bundle2rebase(op, part):
    '''unbundle a bundle2 containing a changegroup to rebase'''

    params = part.params

    bundlefile = None

    try: # guards bundlefile
        bundlefile = _makebundlefile(part)
        bundlepath = "bundle:%s+%s" % (op.repo.root, bundlefile)
        bundle = repository(op.repo.ui, bundlepath)

        # Allow running hooks on the new commits before we take the lock
        prelockrebaseargs = op.hookargs.copy()
        prelockrebaseargs['source'] = 'push'
        prelockrebaseargs['bundle2'] = '1'
        prelockrebaseargs['node'] = scmutil.revsingle(bundle,
                                                      'min(bundle())').hex()
        prelockrebaseargs['hook_bundlepath'] = bundlefile
        op.repo.hook("prepushrebase", throw=True, **prelockrebaseargs)

        op.repo.ui.setconfig('pushrebase', pushrebasemarker, True)
        tr = op.gettransaction()
        hookargs = dict(tr.hookargs)

        # Recreate the bundle repo, since taking the lock in gettransaction()
        # may have caused it to become out of date.
        # (but grab a copy of the cache first)
        bundle = repository(op.repo.ui, bundlepath)

        # Preload the caches with data we already have. We need to make copies
        # here so that original repo caches don't get tainted with bundle
        # specific data.
        bundle.manifest._mancache = op.repo.manifest._mancache.copy()

        try:
            # onto is None means don't do rebasing
            onto = None
            ontoarg = params.get('onto', donotrebasemarker)
            if ontoarg != donotrebasemarker:
                onto = scmutil.revsingle(op.repo, ontoarg)
        except error.RepoLookupError:
            # Probably a new bookmark. Leave onto as None to not do any rebasing
            pass

        if not params['newhead']:
            if not op.repo.revs('%r and head()', params['onto']):
                raise error.Abort(_('rebase would create a new head on server'))

        if onto is None:
            maxcommonanc = list(bundle.set('max(parents(bundle()) - bundle())'))
            if not maxcommonanc:
                onto = op.repo[nullid]
            else:
                onto = maxcommonanc[0]

        revs, oldonto = _getrevs(bundle, onto)

        op.repo.hook("prechangegroup", **hookargs)

        mapping = {}

        # Seed the mapping with oldonto->onto
        mapping[oldonto.node()] = onto.node()

        replacements = {}
        added = []

        # Notify the user of what is being pushed
        plural = 's' if len(revs) > 1 else ''
        op.repo.ui.warn(_("pushing %s commit%s:\n") % (len(revs), plural))
        maxoutput = 10
        for i in range(0, min(len(revs), maxoutput)):
            firstline = bundle[revs[i]].description().split('\n')[0][:50]
            op.repo.ui.warn(("    %s  %s\n") % (revs[i], firstline))

        if len(revs) > maxoutput + 1:
            op.repo.ui.warn(("    ...\n"))
            firstline = bundle[revs[-1]].description().split('\n')[0][:50]
            op.repo.ui.warn(("    %s  %s\n") % (revs[-1], firstline))

        for rev in revs:
            newrev = _graft(op.repo, rev, mapping)

            new = op.repo[newrev]
            oldnode = rev.node()
            newnode = new.node()
            replacements[oldnode] = newnode
            mapping[oldnode] = newnode
            added.append(newnode)

            if 'node' not in tr.hookargs:
                tr.hookargs['node'] = hex(newnode)
            hookargs['node'] = hex(newnode)

        _buildobsolete(replacements, bundle, op.repo)
    finally:
        try:
            if bundlefile:
                os.unlink(bundlefile)
        except OSError as e:
            if e.errno != errno.ENOENT:
                raise

    publishing = op.repo.ui.configbool('phases', 'publish', True)
    if publishing:
        phases.advanceboundary(op.repo, tr, phases.public, [added[-1]])

    p = lambda: tr.writepending() and op.repo.root or ""
    op.repo.hook("pretxnchangegroup", throw=True, pending=p, **hookargs)

    def runhooks():
        args = hookargs.copy()
        args['node'] = hex(added[0])
        op.repo.hook("changegroup", **args)
        for n in added:
            args = hookargs.copy()
            args['node'] = hex(n)
            op.repo.hook("incoming", **args)

    tr.addpostclose('serverrebase-cg-hooks',
                    lambda tr: op.repo._afterlock(runhooks))

    _addpushbackparts(op, replacements)

    for k in replacements.keys():
        replacements[hex(k)] = hex(replacements[k])
    op.records.add(rebaseparttype, replacements)

    return 1

def bundle2pushkey(orig, op, part):
    replacements = dict(sum([record.items()
                             for record
                             in op.records[rebaseparttype]],
                            []))

    namespace = pushkey.decode(part.params['namespace'])
    if namespace == 'phases':
        key = pushkey.decode(part.params['key'])
        part.params['key'] = pushkey.encode(replacements.get(key, key))
    if namespace == 'bookmarks':
        new = pushkey.decode(part.params['new'])
        part.params['new'] = pushkey.encode(replacements.get(new, new))
        serverbin = op.repo._bookmarks.get(part.params['key'])
        clienthex = pushkey.decode(part.params['old'])

        if serverbin and clienthex:
            cl = op.repo.changelog
            revserver = cl.rev(serverbin)
            revclient = cl.rev(bin(clienthex))
            if revclient in cl.ancestors([revserver]):
                # if the client's bookmark origin is an lagging behind the
                # server's location for that bookmark (usual for pushrebase)
                # then update the old location to match the real location
                #
                # TODO: We would prefer to only do this for pushrebase pushes
                # but that isn't straightforward so we just do it always here.
                # This forbids moving bookmarks backwards from clients.
                part.params['old'] = pushkey.encode(hex(serverbin))

    return orig(op, part)