view hgext/narrow/narrowbundle2.py @ 38829:9b64b73d702b

exchange: move disabling of rev-branch-cache bundle part out of narrow

I'm attempting to refactor changegroup code in order to better
support alternate storage backends. The narrow extension is
performing a lot of monkeypatching to this code and it is making
it difficult to reason about how everything works. I'm reasonably
certain I would be unable to abstract storage without requiring
extensive rework of narrow. I believe it is less effort to move
narrow code into core so it can be accounted for when changegroup
code is refactored. So I'll be doing that.

The first part of this is integrating the disabling of the
cache:rev-branch-cache bundle2 part into core. This doesn't seem
like it is related to changegroup, but narrow's modifications to
changegroup are invasive and also require taking its code for
bundle generation and exchange into core in order for the changegroup
code to work.

Differential Revision: https://phab.mercurial-scm.org/D4007

# 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 collections
import errno
import struct

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

NARROWCAP = 'narrow'
_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 _computeellipsis(repo, common, heads, known, match, depth=None):
    """Compute the shape of a narrowed DAG.

    Args:
      repo: The repository we're transferring.
      common: The roots of the DAG range we're transferring.
              May be just [nullid], which means all ancestors of heads.
      heads: The heads of the DAG range we're transferring.
      match: The narrowmatcher that allows us to identify relevant changes.
      depth: If not None, only consider nodes to be full nodes if they are at
             most depth changesets away from one of heads.

    Returns:
      A tuple of (visitnodes, relevant_nodes, ellipsisroots) where:

        visitnodes: The list of nodes (either full or ellipsis) which
                    need to be sent to the client.
        relevant_nodes: The set of changelog nodes which change a file inside
                 the narrowspec. The client needs these as non-ellipsis nodes.
        ellipsisroots: A dict of {rev: parents} that is used in
                       narrowchangegroup to produce ellipsis nodes with the
                       correct parents.
    """
    cl = repo.changelog
    mfl = repo.manifestlog

    cldag = dagutil.revlogdag(cl)
    # dagutil does not like nullid/nullrev
    commonrevs = cldag.internalizeall(common - set([nullid])) | set([nullrev])
    headsrevs = cldag.internalizeall(heads)
    if depth:
        revdepth = {h: 0 for h in headsrevs}

    ellipsisheads = collections.defaultdict(set)
    ellipsisroots = collections.defaultdict(set)

    def addroot(head, curchange):
        """Add a root to an ellipsis head, splitting heads with 3 roots."""
        ellipsisroots[head].add(curchange)
        # Recursively split ellipsis heads with 3 roots by finding the
        # roots' youngest common descendant which is an elided merge commit.
        # That descendant takes 2 of the 3 roots as its own, and becomes a
        # root of the head.
        while len(ellipsisroots[head]) > 2:
            child, roots = splithead(head)
            splitroots(head, child, roots)
            head = child  # Recurse in case we just added a 3rd root

    def splitroots(head, child, roots):
        ellipsisroots[head].difference_update(roots)
        ellipsisroots[head].add(child)
        ellipsisroots[child].update(roots)
        ellipsisroots[child].discard(child)

    def splithead(head):
        r1, r2, r3 = sorted(ellipsisroots[head])
        for nr1, nr2 in ((r2, r3), (r1, r3), (r1, r2)):
            mid = repo.revs('sort(merge() & %d::%d & %d::%d, -rev)',
                            nr1, head, nr2, head)
            for j in mid:
                if j == nr2:
                    return nr2, (nr1, nr2)
                if j not in ellipsisroots or len(ellipsisroots[j]) < 2:
                    return j, (nr1, nr2)
        raise error.Abort('Failed to split up ellipsis node! head: %d, '
                          'roots: %d %d %d' % (head, r1, r2, r3))

    missing = list(cl.findmissingrevs(common=commonrevs, heads=headsrevs))
    visit = reversed(missing)
    relevant_nodes = set()
    visitnodes = [cl.node(m) for m in missing]
    required = set(headsrevs) | known
    for rev in visit:
        clrev = cl.changelogrevision(rev)
        ps = cldag.parents(rev)
        if depth is not None:
            curdepth = revdepth[rev]
            for p in ps:
                revdepth[p] = min(curdepth + 1, revdepth.get(p, depth + 1))
        needed = False
        shallow_enough = depth is None or revdepth[rev] <= depth
        if shallow_enough:
            curmf = mfl[clrev.manifest].read()
            if ps:
                # We choose to not trust the changed files list in
                # changesets because it's not always correct. TODO: could
                # we trust it for the non-merge case?
                p1mf = mfl[cl.changelogrevision(ps[0]).manifest].read()
                needed = bool(curmf.diff(p1mf, match))
                if not needed and len(ps) > 1:
                    # For merge changes, the list of changed files is not
                    # helpful, since we need to emit the merge if a file
                    # in the narrow spec has changed on either side of the
                    # merge. As a result, we do a manifest diff to check.
                    p2mf = mfl[cl.changelogrevision(ps[1]).manifest].read()
                    needed = bool(curmf.diff(p2mf, match))
            else:
                # For a root node, we need to include the node if any
                # files in the node match the narrowspec.
                needed = any(curmf.walk(match))

        if needed:
            for head in ellipsisheads[rev]:
                addroot(head, rev)
            for p in ps:
                required.add(p)
            relevant_nodes.add(cl.node(rev))
        else:
            if not ps:
                ps = [nullrev]
            if rev in required:
                for head in ellipsisheads[rev]:
                    addroot(head, rev)
                for p in ps:
                    ellipsisheads[p].add(rev)
            else:
                for p in ps:
                    ellipsisheads[p] |= ellipsisheads[rev]

    # add common changesets as roots of their reachable ellipsis heads
    for c in commonrevs:
        for head in ellipsisheads[c]:
            addroot(head, c)
    return visitnodes, relevant_nodes, ellipsisroots

def _packellipsischangegroup(repo, common, match, relevant_nodes,
                             ellipsisroots, visitnodes, depth, source, version):
    if version in ('01', '02'):
        raise error.Abort(
            'ellipsis nodes require at least cg3 on client and server, '
            'but negotiated version %s' % version)
    # We wrap cg1packer.revchunk, using a side channel to pass
    # relevant_nodes into that area. Then if linknode isn't in the
    # set, we know we have an ellipsis node and we should defer
    # sending that node's data. We override close() to detect
    # pending ellipsis nodes and flush them.
    packer = changegroup.getbundler(version, repo)
    # Let the packer have access to the narrow matcher so it can
    # omit filelogs and dirlogs as needed
    packer._narrow_matcher = lambda : match
    # Give the packer the list of nodes which should not be
    # ellipsis nodes. We store this rather than the set of nodes
    # that should be an ellipsis because for very large histories
    # we expect this to be significantly smaller.
    packer.full_nodes = relevant_nodes
    # Maps ellipsis revs to their roots at the changelog level.
    packer.precomputed_ellipsis = ellipsisroots
    # Maps CL revs to per-revlog revisions. Cleared in close() at
    # the end of each group.
    packer.clrev_to_localrev = {}
    packer.next_clrev_to_localrev = {}
    # Maps changelog nodes to changelog revs. Filled in once
    # during changelog stage and then left unmodified.
    packer.clnode_to_rev = {}
    packer.changelog_done = False
    # If true, informs the packer that it is serving shallow content and might
    # need to pack file contents not introduced by the changes being packed.
    packer.is_shallow = depth is not None

    return packer.generate(common, visitnodes, False, source)

# 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):
    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)
    if not repo.ui.configbool("experimental", "narrowservebrokenellipses"):
        outgoing = exchange._computeoutgoing(repo, heads, common)
        if not outgoing.missing:
            return
        def wrappedgetbundler(orig, *args, **kwargs):
            bundler = orig(*args, **kwargs)
            bundler._narrow_matcher = lambda : newmatch
            return bundler
        with extensions.wrappedfunction(changegroup, 'getbundler',
                                        wrappedgetbundler):
            cg = changegroup.makestream(repo, outgoing, version, source)
        part = bundler.newpart('changegroup', data=cg)
        part.addparam('version', version)
        if 'treemanifest' in repo.requirements:
            part.addparam('treemanifest', '1')

        if include or exclude:
            narrowspecpart = bundler.newpart(_SPECPART)
            if include:
                narrowspecpart.addparam(
                    _SPECPART_INCLUDE, '\n'.join(include), mandatory=True)
            if exclude:
                narrowspecpart.addparam(
                    _SPECPART_EXCLUDE, '\n'.join(exclude), mandatory=True)

        return

    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 = _computeellipsis(
            repo, set(), common, known, newmatch)
        if newvisit:
            cg = _packellipsischangegroup(
                repo, common, newmatch, newfull, newellipsis,
                newvisit, depth, source, version)
            part = bundler.newpart('changegroup', data=cg)
            part.addparam('version', version)
            if 'treemanifest' in repo.requirements:
                part.addparam('treemanifest', '1')

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

    repo.ui.debug('Found %d relevant revs\n' % len(relevant_nodes))
    if visitnodes:
        cg = _packellipsischangegroup(
            repo, common, newmatch, relevant_nodes, ellipsisroots,
            visitnodes, depth, source, version)
        part = bundler.newpart('changegroup', data=cg)
        part.addparam('version', version)
        if 'treemanifest' in repo.requirements:
            part.addparam('treemanifest', '1')

def applyacl_narrow(repo, kwargs):
    ui = repo.ui
    username = ui.shortuser(ui.environ.get('REMOTE_USER') or ui.username())
    user_includes = ui.configlist(
        _NARROWACL_SECTION, username + '.includes',
        ui.configlist(_NARROWACL_SECTION, 'default.includes'))
    user_excludes = ui.configlist(
        _NARROWACL_SECTION, username + '.excludes',
        ui.configlist(_NARROWACL_SECTION, 'default.excludes'))
    if not user_includes:
        raise error.Abort(_("{} configuration for user {} is empty")
                          .format(_NARROWACL_SECTION, username))

    user_includes = [
        'path:.' if p == '*' else 'path:' + p for p in user_includes]
    user_excludes = [
        'path:.' if p == '*' else 'path:' + p for p in user_excludes]

    req_includes = set(kwargs.get(r'includepats', []))
    req_excludes = set(kwargs.get(r'excludepats', []))

    req_includes, req_excludes, invalid_includes = narrowspec.restrictpatterns(
        req_includes, req_excludes, user_includes, user_excludes)

    if invalid_includes:
        raise error.Abort(
            _("The following includes are not accessible for {}: {}")
            .format(username, invalid_includes))

    new_args = {}
    new_args.update(kwargs)
    new_args['includepats'] = req_includes
    if req_excludes:
        new_args['excludepats'] = req_excludes
    return new_args

@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 changegroup.NARROW_REQUIREMENT in op.repo.requirements:
        op.repo.requirements.add(changegroup.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['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):
            getbundlechangegrouppart_narrow(
                *args, **applyacl_narrow(repo, kwargs))
        elif kwargs.get(r'narrow', False):
            getbundlechangegrouppart_narrow(*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