narrow: keep bookmarks temporarily stripped for as long as commits are

The narrow extension also has support for shallowness and for
inserting older commits on pull. It works by temporarily stripping
newer commits, adding the older commits, then re-applying the stripped
bundle. The regular Mercurial server uses that when you widen,
although it shouldn't be necessary there. Our Google-internal server
does it when the user requests an older commit.

Our Google-internal tests fail since 7caf632e30c3 (filecache:
unimplement __set__() and __delete__() (API), 2018-10-20). I haven't
quite understood the problem, but it's related to the way we
temporarily hide bookmarks while the commits they point to are
stripped. When a transaction is started, Mercurial tries to read
various things from the repo for the transaction summary. That leads
to computation of hidden commits, which leads to an attempt to find
commits pinned by bookmarks. This is the reason we temporarily hide
the bookmarks. I think the aforementioned commit makes the restored
bookmarks visible earlier than before (which seems like an
improvement), so we can no longer incorrectly rely on the
repo._bookmarks field being cached too long (IIUC).

This patch makes it so we restore the temporarily hidden bookmarks
only after the temporary bundle has been re-applied. It also adapts
the code to update the repo.__bookmarks field using the pattern
described in the aforementioned commit instead of writing directly to
the fiels.

I have spent many hours trying to understand what was going on here,
but I still don't know if this can also happen without our custom
server. So this patch unfortunately does not add any tests; I have
only been able to test the fix using our Google-internal tests.

Differential Revision: https://phab.mercurial-scm.org/D5398

hgext/narrow/narrowbundle2.py

@@ -1,274 +1,279 b''
 # 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,
+    localrepo,
     narrowspec,
     repair,
     repository,
     util,
     wireprototypes,
 )
 from mercurial.utils import (
     stringutil,
 )
 
 _NARROWACL_SECTION = 'narrowhgacl'
 _CHANGESPECPART = 'narrow:changespec'
 _SPECPART = 'narrow: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)
 
 # 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,
                                             matcher=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,
                                         matcher=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
+        op._bookmarksbackup = repo._bookmarks
         class dummybmstore(dict):
             def applychanges(self, repo, tr, changes):
                 pass
-        repo._bookmarks = dummybmstore()
+        localrepo.localrepository._bookmarks.set(repo, 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."""
     getbundleargs = wireprototypes.GETBUNDLE_ARGUMENTS
 
     getbundleargs['narrow'] = 'boolean'
     getbundleargs['depth'] = 'plain'
     getbundleargs['oldincludepats'] = 'csv'
     getbundleargs['oldexcludepats'] = '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)
+        if util.safehasattr(op, '_bookmarksbackup'):
+            localrepo.localrepository._bookmarks.set(op.repo,
+                                                     op._bookmarksbackup)
+            del op._bookmarksbackup
+
     wrappedcghandler.params = origcghandler.params
     bundle2.parthandlermapping['changegroup'] = wrappedcghandler