wireprotov2: implement command for retrieving raw store files
Implementing shallow clone of the changelog is hard. We want the 4.8
release to have a fast implementation of partial clone in wireprotov2. In
order to achieve fast, we can't use deltas for transferring changelog and
manifestlog data.
Per discussions at the 4.8 sprint, this commit implements a somwwhat hacky
and likely-to-be-changed-drastically-or-dropped command in wireprotov2 that
facilitates access to raw store files, namely the changelog and manifestlog.
Using this command, clients can perform a "stream clone" of sorts for just
the changelog and manifestlog. This will allow clients to fetch the changelog
and manifest revlogs, stream them to disk (which should be fast), then follow
up filesdata requests for files revision data for a particular changeset.
Differential Revision: https://phab.mercurial-scm.org/D5134
# 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'
_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
# 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, 'narrow_widen')
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, 'narrow_widen')
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())
narrowspec.validatepatterns(includepats)
narrowspec.validatepatterns(excludepats)
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['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)
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