repo-upgrade: write new requirement before upgrading the dirstate

This will prevent a small race condition where another hg process still
believes the repo is dirstate-v1 during the upgrade process.

This is good to have, but it is not a proper fix for the underlying problem.
There is code that assumes a requirement means a usage, e.g. having the
`generaldelta` requirement would imply *all* revlogs to use general delta,
but it's not true, it simply means that the repository advertises to the
client it needs to understand `generaldelta` in order to read the repo.

In the case of the dirstate, having the requirement *technically* should always
be the same as using dirstate-v2, since there is only one dirstate and
requirements should be as minimal as possible. However, we should not assume
this and make the code more robust in a future patch (series).

mercurial/upgrade_utils/engine.py

@@ -1,683 +1,689 b''
 # upgrade.py - functions for in place upgrade of Mercurial repository
 #
 # Copyright (c) 2016-present, Gregory Szorc
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 
 import stat
 
 from ..i18n import _
 from ..pycompat import getattr
 from .. import (
     changelog,
     error,
     filelog,
     manifest,
     metadata,
     pycompat,
     requirements,
     scmutil,
     store,
     util,
     vfs as vfsmod,
 )
 from ..revlogutils import (
     constants as revlogconst,
     flagutil,
     nodemap,
     sidedata as sidedatamod,
 )
 from . import actions as upgrade_actions
 
 
 def get_sidedata_helpers(srcrepo, dstrepo):
     use_w = srcrepo.ui.configbool(b'experimental', b'worker.repository-upgrade')
     sequential = pycompat.iswindows or not use_w
     if not sequential:
         srcrepo.register_sidedata_computer(
             revlogconst.KIND_CHANGELOG,
             sidedatamod.SD_FILES,
             (sidedatamod.SD_FILES,),
             metadata._get_worker_sidedata_adder(srcrepo, dstrepo),
             flagutil.REVIDX_HASCOPIESINFO,
             replace=True,
         )
     return sidedatamod.get_sidedata_helpers(srcrepo, dstrepo._wanted_sidedata)
 
 
 def _revlogfrompath(repo, rl_type, path):
     """Obtain a revlog from a repo path.
 
     An instance of the appropriate class is returned.
     """
     if rl_type & store.FILEFLAGS_CHANGELOG:
         return changelog.changelog(repo.svfs)
     elif rl_type & store.FILEFLAGS_MANIFESTLOG:
         mandir = b''
         if b'/' in path:
             mandir = path.rsplit(b'/', 1)[0]
         return manifest.manifestrevlog(
             repo.nodeconstants, repo.svfs, tree=mandir
         )
     else:
         # drop the extension and the `data/` prefix
         path_part = path.rsplit(b'.', 1)[0].split(b'/', 1)
         if len(path_part) < 2:
             msg = _(b'cannot recognize revlog from filename: %s')
             msg %= path
             raise error.Abort(msg)
         path = path_part[1]
         return filelog.filelog(repo.svfs, path)
 
 
 def _copyrevlog(tr, destrepo, oldrl, rl_type, unencodedname):
     """copy all relevant files for `oldrl` into `destrepo` store
 
     Files are copied "as is" without any transformation. The copy is performed
     without extra checks. Callers are responsible for making sure the copied
     content is compatible with format of the destination repository.
     """
     oldrl = getattr(oldrl, '_revlog', oldrl)
     newrl = _revlogfrompath(destrepo, rl_type, unencodedname)
     newrl = getattr(newrl, '_revlog', newrl)
 
     oldvfs = oldrl.opener
     newvfs = newrl.opener
     oldindex = oldvfs.join(oldrl._indexfile)
     newindex = newvfs.join(newrl._indexfile)
     olddata = oldvfs.join(oldrl._datafile)
     newdata = newvfs.join(newrl._datafile)
 
     with newvfs(newrl._indexfile, b'w'):
         pass  # create all the directories
 
     util.copyfile(oldindex, newindex)
     copydata = oldrl.opener.exists(oldrl._datafile)
     if copydata:
         util.copyfile(olddata, newdata)
 
     if rl_type & store.FILEFLAGS_FILELOG:
         destrepo.svfs.fncache.add(unencodedname)
         if copydata:
             destrepo.svfs.fncache.add(unencodedname[:-2] + b'.d')
 
 
 UPGRADE_CHANGELOG = b"changelog"
 UPGRADE_MANIFEST = b"manifest"
 UPGRADE_FILELOGS = b"all-filelogs"
 
 UPGRADE_ALL_REVLOGS = frozenset(
     [UPGRADE_CHANGELOG, UPGRADE_MANIFEST, UPGRADE_FILELOGS]
 )
 
 
 def matchrevlog(revlogfilter, rl_type):
     """check if a revlog is selected for cloning.
 
     In other words, are there any updates which need to be done on revlog
     or it can be blindly copied.
 
     The store entry is checked against the passed filter"""
     if rl_type & store.FILEFLAGS_CHANGELOG:
         return UPGRADE_CHANGELOG in revlogfilter
     elif rl_type & store.FILEFLAGS_MANIFESTLOG:
         return UPGRADE_MANIFEST in revlogfilter
     assert rl_type & store.FILEFLAGS_FILELOG
     return UPGRADE_FILELOGS in revlogfilter
 
 
 def _perform_clone(
     ui,
     dstrepo,
     tr,
     old_revlog,
     rl_type,
     unencoded,
     upgrade_op,
     sidedata_helpers,
     oncopiedrevision,
 ):
     """returns the new revlog object created"""
     newrl = None
     if matchrevlog(upgrade_op.revlogs_to_process, rl_type):
         ui.note(
             _(b'cloning %d revisions from %s\n') % (len(old_revlog), unencoded)
         )
         newrl = _revlogfrompath(dstrepo, rl_type, unencoded)
         old_revlog.clone(
             tr,
             newrl,
             addrevisioncb=oncopiedrevision,
             deltareuse=upgrade_op.delta_reuse_mode,
             forcedeltabothparents=upgrade_op.force_re_delta_both_parents,
             sidedata_helpers=sidedata_helpers,
         )
     else:
         msg = _(b'blindly copying %s containing %i revisions\n')
         ui.note(msg % (unencoded, len(old_revlog)))
         _copyrevlog(tr, dstrepo, old_revlog, rl_type, unencoded)
 
         newrl = _revlogfrompath(dstrepo, rl_type, unencoded)
     return newrl
 
 
 def _clonerevlogs(
     ui,
     srcrepo,
     dstrepo,
     tr,
     upgrade_op,
 ):
     """Copy revlogs between 2 repos."""
     revcount = 0
     srcsize = 0
     srcrawsize = 0
     dstsize = 0
     fcount = 0
     frevcount = 0
     fsrcsize = 0
     frawsize = 0
     fdstsize = 0
     mcount = 0
     mrevcount = 0
     msrcsize = 0
     mrawsize = 0
     mdstsize = 0
     crevcount = 0
     csrcsize = 0
     crawsize = 0
     cdstsize = 0
 
     alldatafiles = list(srcrepo.store.walk())
     # mapping of data files which needs to be cloned
     # key is unencoded filename
     # value is revlog_object_from_srcrepo
     manifests = {}
     changelogs = {}
     filelogs = {}
 
     # Perform a pass to collect metadata. This validates we can open all
     # source files and allows a unified progress bar to be displayed.
     for rl_type, unencoded, size in alldatafiles:
         if not rl_type & store.FILEFLAGS_REVLOG_MAIN:
             continue
 
         # the store.walk function will wrongly pickup transaction backup and
         # get confused. As a quick fix for 5.9 release, we ignore those.
         # (this is not a module constants because it seems better to keep the
         # hack together)
         skip_undo = (
             b'undo.backup.00changelog.i',
             b'undo.backup.00manifest.i',
         )
         if unencoded in skip_undo:
             continue
 
         rl = _revlogfrompath(srcrepo, rl_type, unencoded)
 
         info = rl.storageinfo(
             exclusivefiles=True,
             revisionscount=True,
             trackedsize=True,
             storedsize=True,
         )
 
         revcount += info[b'revisionscount'] or 0
         datasize = info[b'storedsize'] or 0
         rawsize = info[b'trackedsize'] or 0
 
         srcsize += datasize
         srcrawsize += rawsize
 
         # This is for the separate progress bars.
         if rl_type & store.FILEFLAGS_CHANGELOG:
             changelogs[unencoded] = rl_type
             crevcount += len(rl)
             csrcsize += datasize
             crawsize += rawsize
         elif rl_type & store.FILEFLAGS_MANIFESTLOG:
             manifests[unencoded] = rl_type
             mcount += 1
             mrevcount += len(rl)
             msrcsize += datasize
             mrawsize += rawsize
         elif rl_type & store.FILEFLAGS_FILELOG:
             filelogs[unencoded] = rl_type
             fcount += 1
             frevcount += len(rl)
             fsrcsize += datasize
             frawsize += rawsize
         else:
             error.ProgrammingError(b'unknown revlog type')
 
     if not revcount:
         return
 
     ui.status(
         _(
             b'migrating %d total revisions (%d in filelogs, %d in manifests, '
             b'%d in changelog)\n'
         )
         % (revcount, frevcount, mrevcount, crevcount)
     )
     ui.status(
         _(b'migrating %s in store; %s tracked data\n')
         % ((util.bytecount(srcsize), util.bytecount(srcrawsize)))
     )
 
     # Used to keep track of progress.
     progress = None
 
     def oncopiedrevision(rl, rev, node):
         progress.increment()
 
     sidedata_helpers = get_sidedata_helpers(srcrepo, dstrepo)
 
     # Migrating filelogs
     ui.status(
         _(
             b'migrating %d filelogs containing %d revisions '
             b'(%s in store; %s tracked data)\n'
         )
         % (
             fcount,
             frevcount,
             util.bytecount(fsrcsize),
             util.bytecount(frawsize),
         )
     )
     progress = srcrepo.ui.makeprogress(_(b'file revisions'), total=frevcount)
     for unencoded, rl_type in sorted(filelogs.items()):
         oldrl = _revlogfrompath(srcrepo, rl_type, unencoded)
 
         newrl = _perform_clone(
             ui,
             dstrepo,
             tr,
             oldrl,
             rl_type,
             unencoded,
             upgrade_op,
             sidedata_helpers,
             oncopiedrevision,
         )
         info = newrl.storageinfo(storedsize=True)
         fdstsize += info[b'storedsize'] or 0
     ui.status(
         _(
             b'finished migrating %d filelog revisions across %d '
             b'filelogs; change in size: %s\n'
         )
         % (frevcount, fcount, util.bytecount(fdstsize - fsrcsize))
     )
 
     # Migrating manifests
     ui.status(
         _(
             b'migrating %d manifests containing %d revisions '
             b'(%s in store; %s tracked data)\n'
         )
         % (
             mcount,
             mrevcount,
             util.bytecount(msrcsize),
             util.bytecount(mrawsize),
         )
     )
     if progress:
         progress.complete()
     progress = srcrepo.ui.makeprogress(
         _(b'manifest revisions'), total=mrevcount
     )
     for unencoded, rl_type in sorted(manifests.items()):
         oldrl = _revlogfrompath(srcrepo, rl_type, unencoded)
         newrl = _perform_clone(
             ui,
             dstrepo,
             tr,
             oldrl,
             rl_type,
             unencoded,
             upgrade_op,
             sidedata_helpers,
             oncopiedrevision,
         )
         info = newrl.storageinfo(storedsize=True)
         mdstsize += info[b'storedsize'] or 0
     ui.status(
         _(
             b'finished migrating %d manifest revisions across %d '
             b'manifests; change in size: %s\n'
         )
         % (mrevcount, mcount, util.bytecount(mdstsize - msrcsize))
     )
 
     # Migrating changelog
     ui.status(
         _(
             b'migrating changelog containing %d revisions '
             b'(%s in store; %s tracked data)\n'
         )
         % (
             crevcount,
             util.bytecount(csrcsize),
             util.bytecount(crawsize),
         )
     )
     if progress:
         progress.complete()
     progress = srcrepo.ui.makeprogress(
         _(b'changelog revisions'), total=crevcount
     )
     for unencoded, rl_type in sorted(changelogs.items()):
         oldrl = _revlogfrompath(srcrepo, rl_type, unencoded)
         newrl = _perform_clone(
             ui,
             dstrepo,
             tr,
             oldrl,
             rl_type,
             unencoded,
             upgrade_op,
             sidedata_helpers,
             oncopiedrevision,
         )
         info = newrl.storageinfo(storedsize=True)
         cdstsize += info[b'storedsize'] or 0
     progress.complete()
     ui.status(
         _(
             b'finished migrating %d changelog revisions; change in size: '
             b'%s\n'
         )
         % (crevcount, util.bytecount(cdstsize - csrcsize))
     )
 
     dstsize = fdstsize + mdstsize + cdstsize
     ui.status(
         _(
             b'finished migrating %d total revisions; total change in store '
             b'size: %s\n'
         )
         % (revcount, util.bytecount(dstsize - srcsize))
     )
 
 
 def _files_to_copy_post_revlog_clone(srcrepo):
     """yields files which should be copied to destination after revlogs
     are cloned"""
     for path, kind, st in sorted(srcrepo.store.vfs.readdir(b'', stat=True)):
         # don't copy revlogs as they are already cloned
         if store.revlog_type(path) is not None:
             continue
         # Skip transaction related files.
         if path.startswith(b'undo'):
             continue
         # Only copy regular files.
         if kind != stat.S_IFREG:
             continue
         # Skip other skipped files.
         if path in (b'lock', b'fncache'):
             continue
         # TODO: should we skip cache too?
 
         yield path
 
 
 def _replacestores(currentrepo, upgradedrepo, backupvfs, upgrade_op):
     """Replace the stores after current repository is upgraded
 
     Creates a backup of current repository store at backup path
     Replaces upgraded store files in current repo from upgraded one
 
     Arguments:
       currentrepo: repo object of current repository
       upgradedrepo: repo object of the upgraded data
       backupvfs: vfs object for the backup path
       upgrade_op: upgrade operation object
                   to be used to decide what all is upgraded
     """
     # TODO: don't blindly rename everything in store
     # There can be upgrades where store is not touched at all
     if upgrade_op.backup_store:
         util.rename(currentrepo.spath, backupvfs.join(b'store'))
     else:
         currentrepo.vfs.rmtree(b'store', forcibly=True)
     util.rename(upgradedrepo.spath, currentrepo.spath)
 
 
 def finishdatamigration(ui, srcrepo, dstrepo, requirements):
     """Hook point for extensions to perform additional actions during upgrade.
 
     This function is called after revlogs and store files have been copied but
     before the new store is swapped into the original location.
     """
 
 
 def upgrade(ui, srcrepo, dstrepo, upgrade_op):
     """Do the low-level work of upgrading a repository.
 
     The upgrade is effectively performed as a copy between a source
     repository and a temporary destination repository.
 
     The source repository is unmodified for as long as possible so the
     upgrade can abort at any time without causing loss of service for
     readers and without corrupting the source repository.
     """
     assert srcrepo.currentwlock()
     assert dstrepo.currentwlock()
     backuppath = None
     backupvfs = None
 
     ui.status(
         _(
             b'(it is safe to interrupt this process any time before '
             b'data migration completes)\n'
         )
     )
 
     if upgrade_actions.dirstatev2 in upgrade_op.upgrade_actions:
         ui.status(_(b'upgrading to dirstate-v2 from v1\n'))
         upgrade_dirstate(ui, srcrepo, upgrade_op, b'v1', b'v2')
         upgrade_op.upgrade_actions.remove(upgrade_actions.dirstatev2)
 
     if upgrade_actions.dirstatev2 in upgrade_op.removed_actions:
         ui.status(_(b'downgrading from dirstate-v2 to v1\n'))
         upgrade_dirstate(ui, srcrepo, upgrade_op, b'v2', b'v1')
         upgrade_op.removed_actions.remove(upgrade_actions.dirstatev2)
 
     if upgrade_actions.dirstatetrackedkey in upgrade_op.upgrade_actions:
         ui.status(_(b'create dirstate-tracked-hint file\n'))
         upgrade_tracked_hint(ui, srcrepo, upgrade_op, add=True)
         upgrade_op.upgrade_actions.remove(upgrade_actions.dirstatetrackedkey)
     elif upgrade_actions.dirstatetrackedkey in upgrade_op.removed_actions:
         ui.status(_(b'remove dirstate-tracked-hint file\n'))
         upgrade_tracked_hint(ui, srcrepo, upgrade_op, add=False)
         upgrade_op.removed_actions.remove(upgrade_actions.dirstatetrackedkey)
 
     if not (upgrade_op.upgrade_actions or upgrade_op.removed_actions):
         return
 
     if upgrade_op.requirements_only:
         ui.status(_(b'upgrading repository requirements\n'))
         scmutil.writereporequirements(srcrepo, upgrade_op.new_requirements)
     # if there is only one action and that is persistent nodemap upgrade
     # directly write the nodemap file and update requirements instead of going
     # through the whole cloning process
     elif (
         len(upgrade_op.upgrade_actions) == 1
         and b'persistent-nodemap' in upgrade_op.upgrade_actions_names
         and not upgrade_op.removed_actions
     ):
         ui.status(
             _(b'upgrading repository to use persistent nodemap feature\n')
         )
         with srcrepo.transaction(b'upgrade') as tr:
             unfi = srcrepo.unfiltered()
             cl = unfi.changelog
             nodemap.persist_nodemap(tr, cl, force=True)
             # we want to directly operate on the underlying revlog to force
             # create a nodemap file. This is fine since this is upgrade code
             # and it heavily relies on repository being revlog based
             # hence accessing private attributes can be justified
             nodemap.persist_nodemap(
                 tr, unfi.manifestlog._rootstore._revlog, force=True
             )
         scmutil.writereporequirements(srcrepo, upgrade_op.new_requirements)
     elif (
         len(upgrade_op.removed_actions) == 1
         and [
             x
             for x in upgrade_op.removed_actions
             if x.name == b'persistent-nodemap'
         ]
         and not upgrade_op.upgrade_actions
     ):
         ui.status(
             _(b'downgrading repository to not use persistent nodemap feature\n')
         )
         with srcrepo.transaction(b'upgrade') as tr:
             unfi = srcrepo.unfiltered()
             cl = unfi.changelog
             nodemap.delete_nodemap(tr, srcrepo, cl)
             # check comment 20 lines above for accessing private attributes
             nodemap.delete_nodemap(
                 tr, srcrepo, unfi.manifestlog._rootstore._revlog
             )
         scmutil.writereporequirements(srcrepo, upgrade_op.new_requirements)
     else:
         with dstrepo.transaction(b'upgrade') as tr:
             _clonerevlogs(
                 ui,
                 srcrepo,
                 dstrepo,
                 tr,
                 upgrade_op,
             )
 
         # Now copy other files in the store directory.
         for p in _files_to_copy_post_revlog_clone(srcrepo):
             srcrepo.ui.status(_(b'copying %s\n') % p)
             src = srcrepo.store.rawvfs.join(p)
             dst = dstrepo.store.rawvfs.join(p)
             util.copyfile(src, dst, copystat=True)
 
         finishdatamigration(ui, srcrepo, dstrepo, requirements)
 
         ui.status(_(b'data fully upgraded in a temporary repository\n'))
 
         if upgrade_op.backup_store:
             backuppath = pycompat.mkdtemp(
                 prefix=b'upgradebackup.', dir=srcrepo.path
             )
             backupvfs = vfsmod.vfs(backuppath)
 
             # Make a backup of requires file first, as it is the first to be modified.
             util.copyfile(
                 srcrepo.vfs.join(b'requires'), backupvfs.join(b'requires')
             )
 
         # We install an arbitrary requirement that clients must not support
         # as a mechanism to lock out new clients during the data swap. This is
         # better than allowing a client to continue while the repository is in
         # an inconsistent state.
         ui.status(
             _(
                 b'marking source repository as being upgraded; clients will be '
                 b'unable to read from repository\n'
             )
         )
         scmutil.writereporequirements(
             srcrepo, srcrepo.requirements | {b'upgradeinprogress'}
         )
 
         ui.status(_(b'starting in-place swap of repository data\n'))
         if upgrade_op.backup_store:
             ui.status(
                 _(b'replaced files will be backed up at %s\n') % backuppath
             )
 
         # Now swap in the new store directory. Doing it as a rename should make
         # the operation nearly instantaneous and atomic (at least in well-behaved
         # environments).
         ui.status(_(b'replacing store...\n'))
         tstart = util.timer()
         _replacestores(srcrepo, dstrepo, backupvfs, upgrade_op)
         elapsed = util.timer() - tstart
         ui.status(
             _(
                 b'store replacement complete; repository was inconsistent for '
                 b'%0.1fs\n'
             )
             % elapsed
         )
 
         # We first write the requirements file. Any new requirements will lock
         # out legacy clients.
         ui.status(
             _(
                 b'finalizing requirements file and making repository readable '
                 b'again\n'
             )
         )
         scmutil.writereporequirements(srcrepo, upgrade_op.new_requirements)
 
         if upgrade_op.backup_store:
             # The lock file from the old store won't be removed because nothing has a
             # reference to its new location. So clean it up manually. Alternatively, we
             # could update srcrepo.svfs and other variables to point to the new
             # location. This is simpler.
             assert backupvfs is not None  # help pytype
             backupvfs.unlink(b'store/lock')
 
     return backuppath
 
 
 def upgrade_dirstate(ui, srcrepo, upgrade_op, old, new):
     if upgrade_op.backup_store:
         backuppath = pycompat.mkdtemp(
             prefix=b'upgradebackup.', dir=srcrepo.path
         )
         ui.status(_(b'replaced files will be backed up at %s\n') % backuppath)
         backupvfs = vfsmod.vfs(backuppath)
         util.copyfile(
             srcrepo.vfs.join(b'requires'), backupvfs.join(b'requires')
         )
         try:
             util.copyfile(
                 srcrepo.vfs.join(b'dirstate'), backupvfs.join(b'dirstate')
             )
         except FileNotFoundError:
             # The dirstate does not exist on an empty repo or a repo with no
             # revision checked out
             pass
 
     assert srcrepo.dirstate._use_dirstate_v2 == (old == b'v2')
+    use_v2 = new == b'v2'
+    if use_v2:
+        # Write the requirements *before* upgrading
+        scmutil.writereporequirements(srcrepo, upgrade_op.new_requirements)
+
     srcrepo.dirstate._map.preload()
-    srcrepo.dirstate._use_dirstate_v2 = new == b'v2'
-    srcrepo.dirstate._map._use_dirstate_v2 = srcrepo.dirstate._use_dirstate_v2
+    srcrepo.dirstate._use_dirstate_v2 = use_v2
+    srcrepo.dirstate._map._use_dirstate_v2 = use_v2
     srcrepo.dirstate._dirty = True
     try:
         srcrepo.vfs.unlink(b'dirstate')
     except FileNotFoundError:
         # The dirstate does not exist on an empty repo or a repo with no
         # revision checked out
         pass
 
     srcrepo.dirstate.write(None)
-
-    scmutil.writereporequirements(srcrepo, upgrade_op.new_requirements)
+    if not use_v2:
+        # Remove the v2 requirement *after* downgrading
+        scmutil.writereporequirements(srcrepo, upgrade_op.new_requirements)
 
 
 def upgrade_tracked_hint(ui, srcrepo, upgrade_op, add):
     if add:
         srcrepo.dirstate._use_tracked_hint = True
         srcrepo.dirstate._dirty = True
         srcrepo.dirstate._dirty_tracked_set = True
         srcrepo.dirstate.write(None)
     if not add:
         srcrepo.dirstate.delete_tracked_hint()
 
     scmutil.writereporequirements(srcrepo, upgrade_op.new_requirements)