hgext/narrow/narrowbundle2.py

narrow: add narrow and ellipses as server capabilities

Right now we don't have a way to differentiate between whether a server can
serve ellipsis or not. The way we check whether a server is narrow enabled is by
checking bundle2 capability which does not scale outside of bundle2 world.

The goal is to use have wireprotocol commands just like remotefilelog for
widening the narrow clone, atleast in non-ellipses cases. Having a server
capability will help there as we can't rely on bundle2 capability there.

Also having a server capability is neat than having a bundle2 capability.

There are lot of things we can optimize locally on the client side by knowing
before hand that whether the server supports ellipses or not.

This will also help us in making sure that a client ellipses repo does not
communicate with a server repo without ellipses.

Differential Revision: https://phab.mercurial-scm.org/D4521

# narrowbundle2.py - bundle2 extensions for narrow repository support
#
# Copyright 2017 Google, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import errno
import struct

from mercurial.i18n import _
from mercurial.node import (
    bin,
    nullid,
)
from mercurial import (
    bundle2,
    changegroup,
    error,
    exchange,
    extensions,
    narrowspec,
    repair,
    repository,
    util,
    wireprototypes,
)
from mercurial.utils import (
    stringutil,
)

NARROWCAP = 'narrow'
ELLIPSESCAP = 'ellipses'
_NARROWACL_SECTION = 'narrowhgacl'
_CHANGESPECPART = NARROWCAP + ':changespec'
_SPECPART = NARROWCAP + ':spec'
_SPECPART_INCLUDE = 'include'
_SPECPART_EXCLUDE = 'exclude'
_KILLNODESIGNAL = 'KILL'
_DONESIGNAL = 'DONE'
_ELIDEDCSHEADER = '>20s20s20sl' # cset id, p1, p2, len(text)
_ELIDEDMFHEADER = '>20s20s20s20sl' # manifest id, p1, p2, link id, len(text)
_CSHEADERSIZE = struct.calcsize(_ELIDEDCSHEADER)
_MFHEADERSIZE = struct.calcsize(_ELIDEDMFHEADER)

# When advertising capabilities, always include narrow clone support.
def getrepocaps_narrow(orig, repo, **kwargs):
    caps = orig(repo, **kwargs)
    caps[NARROWCAP] = ['v0']
    return caps

def getbundlechangegrouppart_widen(bundler, repo, source, bundlecaps=None,
                                   b2caps=None, heads=None, common=None,
                                   **kwargs):
    """Handling changegroup changegroup generation on the server when user
    is widening their narrowspec"""

    cgversions = b2caps.get('changegroup')
    if cgversions:  # 3.1 and 3.2 ship with an empty value
        cgversions = [v for v in cgversions
                      if v in changegroup.supportedoutgoingversions(repo)]
        if not cgversions:
            raise ValueError(_('no common changegroup version'))
        version = max(cgversions)
    else:
        raise ValueError(_("server does not advertise changegroup version,"
                           " can't negotiate support for ellipsis nodes"))

    include = sorted(filter(bool, kwargs.get(r'includepats', [])))
    exclude = sorted(filter(bool, kwargs.get(r'excludepats', [])))
    newmatch = narrowspec.match(repo.root, include=include, exclude=exclude)
    oldinclude = sorted(filter(bool, kwargs.get(r'oldincludepats', [])))
    oldexclude = sorted(filter(bool, kwargs.get(r'oldexcludepats', [])))
    common = set(common or [nullid])

    if (oldinclude != include or oldexclude != exclude):
        common = repo.revs("::%ln", common)
        commonnodes = set()
        cl = repo.changelog
        for c in common:
            commonnodes.add(cl.node(c))
        if commonnodes:
            # XXX: we should only send the filelogs (and treemanifest). user
            # already has the changelog and manifest
            packer = changegroup.getbundler(version, repo,
                                            filematcher=newmatch,
                                            fullnodes=commonnodes)
            cgdata = packer.generate(set([nullid]), list(commonnodes), False,
                    source)

            part = bundler.newpart('changegroup', data=cgdata)
            part.addparam('version', version)
            if 'treemanifest' in repo.requirements:
                part.addparam('treemanifest', '1')

# Serve a changegroup for a client with a narrow clone.
def getbundlechangegrouppart_narrow(bundler, repo, source,
                                    bundlecaps=None, b2caps=None, heads=None,
                                    common=None, **kwargs):
    assert repo.ui.configbool('experimental', 'narrowservebrokenellipses')

    cgversions = b2caps.get('changegroup')
    if cgversions:  # 3.1 and 3.2 ship with an empty value
        cgversions = [v for v in cgversions
                      if v in changegroup.supportedoutgoingversions(repo)]
        if not cgversions:
            raise ValueError(_('no common changegroup version'))
        version = max(cgversions)
    else:
        raise ValueError(_("server does not advertise changegroup version,"
                           " can't negotiate support for ellipsis nodes"))

    include = sorted(filter(bool, kwargs.get(r'includepats', [])))
    exclude = sorted(filter(bool, kwargs.get(r'excludepats', [])))
    newmatch = narrowspec.match(repo.root, include=include, exclude=exclude)

    depth = kwargs.get(r'depth', None)
    if depth is not None:
        depth = int(depth)
        if depth < 1:
            raise error.Abort(_('depth must be positive, got %d') % depth)

    heads = set(heads or repo.heads())
    common = set(common or [nullid])
    oldinclude = sorted(filter(bool, kwargs.get(r'oldincludepats', [])))
    oldexclude = sorted(filter(bool, kwargs.get(r'oldexcludepats', [])))
    known = {bin(n) for n in kwargs.get(r'known', [])}
    if known and (oldinclude != include or oldexclude != exclude):
        # Steps:
        # 1. Send kill for "$known & ::common"
        #
        # 2. Send changegroup for ::common
        #
        # 3. Proceed.
        #
        # In the future, we can send kills for only the specific
        # nodes we know should go away or change shape, and then
        # send a data stream that tells the client something like this:
        #
        # a) apply this changegroup
        # b) apply nodes XXX, YYY, ZZZ that you already have
        # c) goto a
        #
        # until they've built up the full new state.
        # Convert to revnums and intersect with "common". The client should
        # have made it a subset of "common" already, but let's be safe.
        known = set(repo.revs("%ln & ::%ln", known, common))
        # TODO: we could send only roots() of this set, and the
        # list of nodes in common, and the client could work out
        # what to strip, instead of us explicitly sending every
        # single node.
        deadrevs = known
        def genkills():
            for r in deadrevs:
                yield _KILLNODESIGNAL
                yield repo.changelog.node(r)
            yield _DONESIGNAL
        bundler.newpart(_CHANGESPECPART, data=genkills())
        newvisit, newfull, newellipsis = exchange._computeellipsis(
            repo, set(), common, known, newmatch)
        if newvisit:
            packer = changegroup.getbundler(version, repo,
                                            filematcher=newmatch,
                                            ellipses=True,
                                            shallow=depth is not None,
                                            ellipsisroots=newellipsis,
                                            fullnodes=newfull)
            cgdata = packer.generate(common, newvisit, False, source)

            part = bundler.newpart('changegroup', data=cgdata)
            part.addparam('version', version)
            if 'treemanifest' in repo.requirements:
                part.addparam('treemanifest', '1')

    visitnodes, relevant_nodes, ellipsisroots = exchange._computeellipsis(
        repo, common, heads, set(), newmatch, depth=depth)

    repo.ui.debug('Found %d relevant revs\n' % len(relevant_nodes))
    if visitnodes:
        packer = changegroup.getbundler(version, repo,
                                        filematcher=newmatch,
                                        ellipses=True,
                                        shallow=depth is not None,
                                        ellipsisroots=ellipsisroots,
                                        fullnodes=relevant_nodes)
        cgdata = packer.generate(common, visitnodes, False, source)

        part = bundler.newpart('changegroup', data=cgdata)
        part.addparam('version', version)
        if 'treemanifest' in repo.requirements:
            part.addparam('treemanifest', '1')

@bundle2.parthandler(_SPECPART, (_SPECPART_INCLUDE, _SPECPART_EXCLUDE))
def _handlechangespec_2(op, inpart):
    includepats = set(inpart.params.get(_SPECPART_INCLUDE, '').splitlines())
    excludepats = set(inpart.params.get(_SPECPART_EXCLUDE, '').splitlines())
    if not repository.NARROW_REQUIREMENT in op.repo.requirements:
        op.repo.requirements.add(repository.NARROW_REQUIREMENT)
        op.repo._writerequirements()
    op.repo.setnarrowpats(includepats, excludepats)

@bundle2.parthandler(_CHANGESPECPART)
def _handlechangespec(op, inpart):
    repo = op.repo
    cl = repo.changelog

    # changesets which need to be stripped entirely. either they're no longer
    # needed in the new narrow spec, or the server is sending a replacement
    # in the changegroup part.
    clkills = set()

    # A changespec part contains all the updates to ellipsis nodes
    # that will happen as a result of widening or narrowing a
    # repo. All the changes that this block encounters are ellipsis
    # nodes or flags to kill an existing ellipsis.
    chunksignal = changegroup.readexactly(inpart, 4)
    while chunksignal != _DONESIGNAL:
        if chunksignal == _KILLNODESIGNAL:
            # a node used to be an ellipsis but isn't anymore
            ck = changegroup.readexactly(inpart, 20)
            if cl.hasnode(ck):
                clkills.add(ck)
        else:
            raise error.Abort(
                _('unexpected changespec node chunk type: %s') % chunksignal)
        chunksignal = changegroup.readexactly(inpart, 4)

    if clkills:
        # preserve bookmarks that repair.strip() would otherwise strip
        bmstore = repo._bookmarks
        class dummybmstore(dict):
            def applychanges(self, repo, tr, changes):
                pass
            def recordchange(self, tr): # legacy version
                pass
        repo._bookmarks = dummybmstore()
        chgrpfile = repair.strip(op.ui, repo, list(clkills), backup=True,
                                 topic='widen')
        repo._bookmarks = bmstore
        if chgrpfile:
            op._widen_uninterr = repo.ui.uninterruptable()
            op._widen_uninterr.__enter__()
            # presence of _widen_bundle attribute activates widen handler later
            op._widen_bundle = chgrpfile
    # Set the new narrowspec if we're widening. The setnewnarrowpats() method
    # will currently always be there when using the core+narrowhg server, but
    # other servers may include a changespec part even when not widening (e.g.
    # because we're deepening a shallow repo).
    if util.safehasattr(repo, 'setnewnarrowpats'):
        repo.setnewnarrowpats()

def handlechangegroup_widen(op, inpart):
    """Changegroup exchange handler which restores temporarily-stripped nodes"""
    # We saved a bundle with stripped node data we must now restore.
    # This approach is based on mercurial/repair.py@6ee26a53c111.
    repo = op.repo
    ui = op.ui

    chgrpfile = op._widen_bundle
    del op._widen_bundle
    vfs = repo.vfs

    ui.note(_("adding branch\n"))
    f = vfs.open(chgrpfile, "rb")
    try:
        gen = exchange.readbundle(ui, f, chgrpfile, vfs)
        if not ui.verbose:
            # silence internal shuffling chatter
            ui.pushbuffer()
        if isinstance(gen, bundle2.unbundle20):
            with repo.transaction('strip') as tr:
                bundle2.processbundle(repo, gen, lambda: tr)
        else:
            gen.apply(repo, 'strip', 'bundle:' + vfs.join(chgrpfile), True)
        if not ui.verbose:
            ui.popbuffer()
    finally:
        f.close()

    # remove undo files
    for undovfs, undofile in repo.undofiles():
        try:
            undovfs.unlink(undofile)
        except OSError as e:
            if e.errno != errno.ENOENT:
                ui.warn(_('error removing %s: %s\n') %
                        (undovfs.join(undofile), stringutil.forcebytestr(e)))

    # Remove partial backup only if there were no exceptions
    op._widen_uninterr.__exit__(None, None, None)
    vfs.unlink(chgrpfile)

def setup():
    """Enable narrow repo support in bundle2-related extension points."""
    extensions.wrapfunction(bundle2, 'getrepocaps', getrepocaps_narrow)

    getbundleargs = wireprototypes.GETBUNDLE_ARGUMENTS

    getbundleargs['narrow'] = 'boolean'
    getbundleargs['widen'] = 'boolean'
    getbundleargs['depth'] = 'plain'
    getbundleargs['oldincludepats'] = 'csv'
    getbundleargs['oldexcludepats'] = 'csv'
    getbundleargs['includepats'] = 'csv'
    getbundleargs['excludepats'] = 'csv'
    getbundleargs['known'] = 'csv'

    # Extend changegroup serving to handle requests from narrow clients.
    origcgfn = exchange.getbundle2partsmapping['changegroup']
    def wrappedcgfn(*args, **kwargs):
        repo = args[1]
        if repo.ui.has_section(_NARROWACL_SECTION):
            kwargs = exchange.applynarrowacl(repo, kwargs)

        if (kwargs.get(r'narrow', False) and
            repo.ui.configbool('experimental', 'narrowservebrokenellipses')):
            getbundlechangegrouppart_narrow(*args, **kwargs)
        elif kwargs.get(r'widen', False) and kwargs.get(r'narrow', False):
            getbundlechangegrouppart_widen(*args, **kwargs)
        else:
            origcgfn(*args, **kwargs)
    exchange.getbundle2partsmapping['changegroup'] = wrappedcgfn

    # Extend changegroup receiver so client can fixup after widen requests.
    origcghandler = bundle2.parthandlermapping['changegroup']
    def wrappedcghandler(op, inpart):
        origcghandler(op, inpart)
        if util.safehasattr(op, '_widen_bundle'):
            handlechangegroup_widen(op, inpart)
    wrappedcghandler.params = origcghandler.params
    bundle2.parthandlermapping['changegroup'] = wrappedcghandler