changeset 46046:f105c49e89cd

upgrade: split actual upgrade code away from the main module The main module is getting big and hard to follow. So we are splitting all the logic to actually run an upgrade in a sub module. It nicely highlight that there are very few actual call point to the code we just moved. Differential Revision: https://phab.mercurial-scm.org/D9476
author Pierre-Yves David <pierre-yves.david@octobus.net>
date Tue, 01 Dec 2020 09:13:08 +0100
parents 7905899c4f8f
children 4b89cf08d8dc
files hgext/lfs/wrapper.py mercurial/upgrade.py mercurial/upgrade_utils/__init__.py mercurial/upgrade_utils/engine.py setup.py tests/testlib/ext-sidedata.py
diffstat 5 files changed, 518 insertions(+), 494 deletions(-) [+]
line wrap: on
line diff
--- a/hgext/lfs/wrapper.py	Sat Dec 05 23:11:49 2020 +0100
+++ b/hgext/lfs/wrapper.py	Tue Dec 01 09:13:08 2020 +0100
@@ -34,6 +34,8 @@
     wireprotov1server,
 )
 
+from mercurial.upgrade_utils import engine as upgrade_engine
+
 from mercurial.interfaces import repository
 
 from mercurial.utils import (
@@ -520,7 +522,7 @@
     remoteblob.writebatch(pointers, repo.svfs.lfslocalblobstore)
 
 
-@eh.wrapfunction(upgrade, b'_finishdatamigration')
+@eh.wrapfunction(upgrade_engine, b'_finishdatamigration')
 def upgradefinishdatamigration(orig, ui, srcrepo, dstrepo, requirements):
     orig(ui, srcrepo, dstrepo, requirements)
 
--- a/mercurial/upgrade.py	Sat Dec 05 23:11:49 2020 +0100
+++ b/mercurial/upgrade.py	Tue Dec 01 09:13:08 2020 +0100
@@ -7,24 +7,18 @@
 
 from __future__ import absolute_import
 
-import stat
-
 from .i18n import _
-from .pycompat import getattr
 from . import (
-    changelog,
     error,
-    filelog,
     hg,
     localrepo,
-    manifest,
-    metadata,
     pycompat,
     requirements,
-    revlog,
-    scmutil,
     util,
-    vfs as vfsmod,
+)
+
+from .upgrade_utils import (
+    engine as upgrade_engine,
 )
 
 from .utils import compression
@@ -692,480 +686,6 @@
     return newactions
 
 
-def _revlogfrompath(repo, path):
-    """Obtain a revlog from a repo path.
-
-    An instance of the appropriate class is returned.
-    """
-    if path == b'00changelog.i':
-        return changelog.changelog(repo.svfs)
-    elif path.endswith(b'00manifest.i'):
-        mandir = path[: -len(b'00manifest.i')]
-        return manifest.manifestrevlog(repo.svfs, tree=mandir)
-    else:
-        # reverse of "/".join(("data", path + ".i"))
-        return filelog.filelog(repo.svfs, path[5:-2])
-
-
-def _copyrevlog(tr, destrepo, oldrl, 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, 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 not (
-        unencodedname.endswith(b'00changelog.i')
-        or unencodedname.endswith(b'00manifest.i')
-    ):
-        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 getsidedatacompanion(srcrepo, dstrepo):
-    sidedatacompanion = None
-    removedreqs = srcrepo.requirements - dstrepo.requirements
-    addedreqs = dstrepo.requirements - srcrepo.requirements
-    if requirements.SIDEDATA_REQUIREMENT in removedreqs:
-
-        def sidedatacompanion(rl, rev):
-            rl = getattr(rl, '_revlog', rl)
-            if rl.flags(rev) & revlog.REVIDX_SIDEDATA:
-                return True, (), {}, 0, 0
-            return False, (), {}, 0, 0
-
-    elif requirements.COPIESSDC_REQUIREMENT in addedreqs:
-        sidedatacompanion = metadata.getsidedataadder(srcrepo, dstrepo)
-    elif requirements.COPIESSDC_REQUIREMENT in removedreqs:
-        sidedatacompanion = metadata.getsidedataremover(srcrepo, dstrepo)
-    return sidedatacompanion
-
-
-def matchrevlog(revlogfilter, entry):
-    """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 entry.endswith(b'00changelog.i'):
-        return UPGRADE_CHANGELOG in revlogfilter
-    elif entry.endswith(b'00manifest.i'):
-        return UPGRADE_MANIFEST in revlogfilter
-    return UPGRADE_FILELOGS in revlogfilter
-
-
-def _clonerevlogs(
-    ui,
-    srcrepo,
-    dstrepo,
-    tr,
-    deltareuse,
-    forcedeltabothparents,
-    revlogs=UPGRADE_ALL_REVLOGS,
-):
-    """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())
-
-    # Perform a pass to collect metadata. This validates we can open all
-    # source files and allows a unified progress bar to be displayed.
-    for unencoded, encoded, size in alldatafiles:
-        if unencoded.endswith(b'.d'):
-            continue
-
-        rl = _revlogfrompath(srcrepo, 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 isinstance(rl, changelog.changelog):
-            crevcount += len(rl)
-            csrcsize += datasize
-            crawsize += rawsize
-        elif isinstance(rl, manifest.manifestrevlog):
-            mcount += 1
-            mrevcount += len(rl)
-            msrcsize += datasize
-            mrawsize += rawsize
-        elif isinstance(rl, filelog.filelog):
-            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()
-
-    sidedatacompanion = getsidedatacompanion(srcrepo, dstrepo)
-
-    # Do the actual copying.
-    # FUTURE this operation can be farmed off to worker processes.
-    seen = set()
-    for unencoded, encoded, size in alldatafiles:
-        if unencoded.endswith(b'.d'):
-            continue
-
-        oldrl = _revlogfrompath(srcrepo, unencoded)
-
-        if isinstance(oldrl, changelog.changelog) and b'c' not in seen:
-            ui.status(
-                _(
-                    b'finished migrating %d manifest revisions across %d '
-                    b'manifests; change in size: %s\n'
-                )
-                % (mrevcount, mcount, util.bytecount(mdstsize - msrcsize))
-            )
-
-            ui.status(
-                _(
-                    b'migrating changelog containing %d revisions '
-                    b'(%s in store; %s tracked data)\n'
-                )
-                % (
-                    crevcount,
-                    util.bytecount(csrcsize),
-                    util.bytecount(crawsize),
-                )
-            )
-            seen.add(b'c')
-            progress = srcrepo.ui.makeprogress(
-                _(b'changelog revisions'), total=crevcount
-            )
-        elif isinstance(oldrl, manifest.manifestrevlog) and b'm' not in seen:
-            ui.status(
-                _(
-                    b'finished migrating %d filelog revisions across %d '
-                    b'filelogs; change in size: %s\n'
-                )
-                % (frevcount, fcount, util.bytecount(fdstsize - fsrcsize))
-            )
-
-            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),
-                )
-            )
-            seen.add(b'm')
-            if progress:
-                progress.complete()
-            progress = srcrepo.ui.makeprogress(
-                _(b'manifest revisions'), total=mrevcount
-            )
-        elif b'f' not in seen:
-            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),
-                )
-            )
-            seen.add(b'f')
-            if progress:
-                progress.complete()
-            progress = srcrepo.ui.makeprogress(
-                _(b'file revisions'), total=frevcount
-            )
-
-        if matchrevlog(revlogs, unencoded):
-            ui.note(
-                _(b'cloning %d revisions from %s\n') % (len(oldrl), unencoded)
-            )
-            newrl = _revlogfrompath(dstrepo, unencoded)
-            oldrl.clone(
-                tr,
-                newrl,
-                addrevisioncb=oncopiedrevision,
-                deltareuse=deltareuse,
-                forcedeltabothparents=forcedeltabothparents,
-                sidedatacompanion=sidedatacompanion,
-            )
-        else:
-            msg = _(b'blindly copying %s containing %i revisions\n')
-            ui.note(msg % (unencoded, len(oldrl)))
-            _copyrevlog(tr, dstrepo, oldrl, unencoded)
-
-            newrl = _revlogfrompath(dstrepo, unencoded)
-
-        info = newrl.storageinfo(storedsize=True)
-        datasize = info[b'storedsize'] or 0
-
-        dstsize += datasize
-
-        if isinstance(newrl, changelog.changelog):
-            cdstsize += datasize
-        elif isinstance(newrl, manifest.manifestrevlog):
-            mdstsize += datasize
-        else:
-            fdstsize += datasize
-
-    progress.complete()
-
-    ui.status(
-        _(
-            b'finished migrating %d changelog revisions; change in size: '
-            b'%s\n'
-        )
-        % (crevcount, util.bytecount(cdstsize - csrcsize))
-    )
-
-    ui.status(
-        _(
-            b'finished migrating %d total revisions; total change in store '
-            b'size: %s\n'
-        )
-        % (revcount, util.bytecount(dstsize - srcsize))
-    )
-
-
-def _filterstorefile(srcrepo, dstrepo, requirements, path, mode, st):
-    """Determine whether to copy a store file during upgrade.
-
-    This function is called when migrating store files from ``srcrepo`` to
-    ``dstrepo`` as part of upgrading a repository.
-
-    Args:
-      srcrepo: repo we are copying from
-      dstrepo: repo we are copying to
-      requirements: set of requirements for ``dstrepo``
-      path: store file being examined
-      mode: the ``ST_MODE`` file type of ``path``
-      st: ``stat`` data structure for ``path``
-
-    Function should return ``True`` if the file is to be copied.
-    """
-    # Skip revlogs.
-    if path.endswith((b'.i', b'.d', b'.n', b'.nd')):
-        return False
-    # Skip transaction related files.
-    if path.startswith(b'undo'):
-        return False
-    # Only copy regular files.
-    if mode != stat.S_IFREG:
-        return False
-    # Skip other skipped files.
-    if path in (b'lock', b'fncache'):
-        return False
-
-    return True
-
-
-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 _upgraderepo(
-    ui, srcrepo, dstrepo, requirements, actions, revlogs=UPGRADE_ALL_REVLOGS
-):
-    """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()
-
-    ui.status(
-        _(
-            b'(it is safe to interrupt this process any time before '
-            b'data migration completes)\n'
-        )
-    )
-
-    if b're-delta-all' in actions:
-        deltareuse = revlog.revlog.DELTAREUSENEVER
-    elif b're-delta-parent' in actions:
-        deltareuse = revlog.revlog.DELTAREUSESAMEREVS
-    elif b're-delta-multibase' in actions:
-        deltareuse = revlog.revlog.DELTAREUSESAMEREVS
-    elif b're-delta-fulladd' in actions:
-        deltareuse = revlog.revlog.DELTAREUSEFULLADD
-    else:
-        deltareuse = revlog.revlog.DELTAREUSEALWAYS
-
-    with dstrepo.transaction(b'upgrade') as tr:
-        _clonerevlogs(
-            ui,
-            srcrepo,
-            dstrepo,
-            tr,
-            deltareuse,
-            b're-delta-multibase' in actions,
-            revlogs=revlogs,
-        )
-
-    # Now copy other files in the store directory.
-    # The sorted() makes execution deterministic.
-    for p, kind, st in sorted(srcrepo.store.vfs.readdir(b'', stat=True)):
-        if not _filterstorefile(srcrepo, dstrepo, requirements, p, kind, st):
-            continue
-
-        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 migrated to temporary repository\n'))
-
-    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'))
-    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()
-    util.rename(srcrepo.spath, backupvfs.join(b'store'))
-    util.rename(dstrepo.spath, srcrepo.spath)
-    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, requirements)
-
-    # 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.
-    backupvfs.unlink(b'store/lock')
-
-    return backuppath
-
-
 def upgraderepo(
     ui,
     repo,
@@ -1182,11 +702,11 @@
     optimize = {legacy_opts_map.get(o, o) for o in optimize}
     repo = repo.unfiltered()
 
-    revlogs = set(UPGRADE_ALL_REVLOGS)
+    revlogs = set(upgrade_engine.UPGRADE_ALL_REVLOGS)
     specentries = (
-        (UPGRADE_CHANGELOG, changelog),
-        (UPGRADE_MANIFEST, manifest),
-        (UPGRADE_FILELOGS, filelogs),
+        (upgrade_engine.UPGRADE_CHANGELOG, changelog),
+        (upgrade_engine.UPGRADE_MANIFEST, manifest),
+        (upgrade_engine.UPGRADE_FILELOGS, filelogs),
     )
     specified = [(y, x) for (y, x) in specentries if x is not None]
     if specified:
@@ -1287,7 +807,7 @@
     removedreqs = repo.requirements - newreqs
     addedreqs = newreqs - repo.requirements
 
-    if revlogs != UPGRADE_ALL_REVLOGS:
+    if revlogs != upgrade_engine.UPGRADE_ALL_REVLOGS:
         incompatible = RECLONES_REQUIREMENTS & (removedreqs | addedreqs)
         if incompatible:
             msg = _(
@@ -1295,7 +815,7 @@
                 b'change: %s\n'
             )
             ui.warn(msg % b', '.join(sorted(incompatible)))
-            revlogs = UPGRADE_ALL_REVLOGS
+            revlogs = upgrade_engine.UPGRADE_ALL_REVLOGS
 
     def write_labeled(l, label):
         first = True
@@ -1447,7 +967,7 @@
             dstrepo = hg.repository(repoui, path=tmppath, create=True)
 
             with dstrepo.wlock(), dstrepo.lock():
-                backuppath = _upgraderepo(
+                backuppath = upgrade_engine.upgrade(
                     ui, repo, dstrepo, newreqs, upgradeactions, revlogs=revlogs
                 )
             if not (backup or backuppath is None):
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mercurial/upgrade_utils/engine.py	Tue Dec 01 09:13:08 2020 +0100
@@ -0,0 +1,500 @@
+# 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.
+
+from __future__ import absolute_import
+
+import stat
+
+from ..i18n import _
+from ..pycompat import getattr
+from .. import (
+    changelog,
+    error,
+    filelog,
+    manifest,
+    metadata,
+    pycompat,
+    requirements,
+    revlog,
+    scmutil,
+    util,
+    vfs as vfsmod,
+)
+
+
+def _revlogfrompath(repo, path):
+    """Obtain a revlog from a repo path.
+
+    An instance of the appropriate class is returned.
+    """
+    if path == b'00changelog.i':
+        return changelog.changelog(repo.svfs)
+    elif path.endswith(b'00manifest.i'):
+        mandir = path[: -len(b'00manifest.i')]
+        return manifest.manifestrevlog(repo.svfs, tree=mandir)
+    else:
+        # reverse of "/".join(("data", path + ".i"))
+        return filelog.filelog(repo.svfs, path[5:-2])
+
+
+def _copyrevlog(tr, destrepo, oldrl, 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, 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 not (
+        unencodedname.endswith(b'00changelog.i')
+        or unencodedname.endswith(b'00manifest.i')
+    ):
+        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 getsidedatacompanion(srcrepo, dstrepo):
+    sidedatacompanion = None
+    removedreqs = srcrepo.requirements - dstrepo.requirements
+    addedreqs = dstrepo.requirements - srcrepo.requirements
+    if requirements.SIDEDATA_REQUIREMENT in removedreqs:
+
+        def sidedatacompanion(rl, rev):
+            rl = getattr(rl, '_revlog', rl)
+            if rl.flags(rev) & revlog.REVIDX_SIDEDATA:
+                return True, (), {}, 0, 0
+            return False, (), {}, 0, 0
+
+    elif requirements.COPIESSDC_REQUIREMENT in addedreqs:
+        sidedatacompanion = metadata.getsidedataadder(srcrepo, dstrepo)
+    elif requirements.COPIESSDC_REQUIREMENT in removedreqs:
+        sidedatacompanion = metadata.getsidedataremover(srcrepo, dstrepo)
+    return sidedatacompanion
+
+
+def matchrevlog(revlogfilter, entry):
+    """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 entry.endswith(b'00changelog.i'):
+        return UPGRADE_CHANGELOG in revlogfilter
+    elif entry.endswith(b'00manifest.i'):
+        return UPGRADE_MANIFEST in revlogfilter
+    return UPGRADE_FILELOGS in revlogfilter
+
+
+def _clonerevlogs(
+    ui,
+    srcrepo,
+    dstrepo,
+    tr,
+    deltareuse,
+    forcedeltabothparents,
+    revlogs=UPGRADE_ALL_REVLOGS,
+):
+    """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())
+
+    # Perform a pass to collect metadata. This validates we can open all
+    # source files and allows a unified progress bar to be displayed.
+    for unencoded, encoded, size in alldatafiles:
+        if unencoded.endswith(b'.d'):
+            continue
+
+        rl = _revlogfrompath(srcrepo, 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 isinstance(rl, changelog.changelog):
+            crevcount += len(rl)
+            csrcsize += datasize
+            crawsize += rawsize
+        elif isinstance(rl, manifest.manifestrevlog):
+            mcount += 1
+            mrevcount += len(rl)
+            msrcsize += datasize
+            mrawsize += rawsize
+        elif isinstance(rl, filelog.filelog):
+            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()
+
+    sidedatacompanion = getsidedatacompanion(srcrepo, dstrepo)
+
+    # Do the actual copying.
+    # FUTURE this operation can be farmed off to worker processes.
+    seen = set()
+    for unencoded, encoded, size in alldatafiles:
+        if unencoded.endswith(b'.d'):
+            continue
+
+        oldrl = _revlogfrompath(srcrepo, unencoded)
+
+        if isinstance(oldrl, changelog.changelog) and b'c' not in seen:
+            ui.status(
+                _(
+                    b'finished migrating %d manifest revisions across %d '
+                    b'manifests; change in size: %s\n'
+                )
+                % (mrevcount, mcount, util.bytecount(mdstsize - msrcsize))
+            )
+
+            ui.status(
+                _(
+                    b'migrating changelog containing %d revisions '
+                    b'(%s in store; %s tracked data)\n'
+                )
+                % (
+                    crevcount,
+                    util.bytecount(csrcsize),
+                    util.bytecount(crawsize),
+                )
+            )
+            seen.add(b'c')
+            progress = srcrepo.ui.makeprogress(
+                _(b'changelog revisions'), total=crevcount
+            )
+        elif isinstance(oldrl, manifest.manifestrevlog) and b'm' not in seen:
+            ui.status(
+                _(
+                    b'finished migrating %d filelog revisions across %d '
+                    b'filelogs; change in size: %s\n'
+                )
+                % (frevcount, fcount, util.bytecount(fdstsize - fsrcsize))
+            )
+
+            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),
+                )
+            )
+            seen.add(b'm')
+            if progress:
+                progress.complete()
+            progress = srcrepo.ui.makeprogress(
+                _(b'manifest revisions'), total=mrevcount
+            )
+        elif b'f' not in seen:
+            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),
+                )
+            )
+            seen.add(b'f')
+            if progress:
+                progress.complete()
+            progress = srcrepo.ui.makeprogress(
+                _(b'file revisions'), total=frevcount
+            )
+
+        if matchrevlog(revlogs, unencoded):
+            ui.note(
+                _(b'cloning %d revisions from %s\n') % (len(oldrl), unencoded)
+            )
+            newrl = _revlogfrompath(dstrepo, unencoded)
+            oldrl.clone(
+                tr,
+                newrl,
+                addrevisioncb=oncopiedrevision,
+                deltareuse=deltareuse,
+                forcedeltabothparents=forcedeltabothparents,
+                sidedatacompanion=sidedatacompanion,
+            )
+        else:
+            msg = _(b'blindly copying %s containing %i revisions\n')
+            ui.note(msg % (unencoded, len(oldrl)))
+            _copyrevlog(tr, dstrepo, oldrl, unencoded)
+
+            newrl = _revlogfrompath(dstrepo, unencoded)
+
+        info = newrl.storageinfo(storedsize=True)
+        datasize = info[b'storedsize'] or 0
+
+        dstsize += datasize
+
+        if isinstance(newrl, changelog.changelog):
+            cdstsize += datasize
+        elif isinstance(newrl, manifest.manifestrevlog):
+            mdstsize += datasize
+        else:
+            fdstsize += datasize
+
+    progress.complete()
+
+    ui.status(
+        _(
+            b'finished migrating %d changelog revisions; change in size: '
+            b'%s\n'
+        )
+        % (crevcount, util.bytecount(cdstsize - csrcsize))
+    )
+
+    ui.status(
+        _(
+            b'finished migrating %d total revisions; total change in store '
+            b'size: %s\n'
+        )
+        % (revcount, util.bytecount(dstsize - srcsize))
+    )
+
+
+def _filterstorefile(srcrepo, dstrepo, requirements, path, mode, st):
+    """Determine whether to copy a store file during upgrade.
+
+    This function is called when migrating store files from ``srcrepo`` to
+    ``dstrepo`` as part of upgrading a repository.
+
+    Args:
+      srcrepo: repo we are copying from
+      dstrepo: repo we are copying to
+      requirements: set of requirements for ``dstrepo``
+      path: store file being examined
+      mode: the ``ST_MODE`` file type of ``path``
+      st: ``stat`` data structure for ``path``
+
+    Function should return ``True`` if the file is to be copied.
+    """
+    # Skip revlogs.
+    if path.endswith((b'.i', b'.d', b'.n', b'.nd')):
+        return False
+    # Skip transaction related files.
+    if path.startswith(b'undo'):
+        return False
+    # Only copy regular files.
+    if mode != stat.S_IFREG:
+        return False
+    # Skip other skipped files.
+    if path in (b'lock', b'fncache'):
+        return False
+
+    return True
+
+
+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, requirements, actions, revlogs=UPGRADE_ALL_REVLOGS
+):
+    """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()
+
+    ui.status(
+        _(
+            b'(it is safe to interrupt this process any time before '
+            b'data migration completes)\n'
+        )
+    )
+
+    if b're-delta-all' in actions:
+        deltareuse = revlog.revlog.DELTAREUSENEVER
+    elif b're-delta-parent' in actions:
+        deltareuse = revlog.revlog.DELTAREUSESAMEREVS
+    elif b're-delta-multibase' in actions:
+        deltareuse = revlog.revlog.DELTAREUSESAMEREVS
+    elif b're-delta-fulladd' in actions:
+        deltareuse = revlog.revlog.DELTAREUSEFULLADD
+    else:
+        deltareuse = revlog.revlog.DELTAREUSEALWAYS
+
+    with dstrepo.transaction(b'upgrade') as tr:
+        _clonerevlogs(
+            ui,
+            srcrepo,
+            dstrepo,
+            tr,
+            deltareuse,
+            b're-delta-multibase' in actions,
+            revlogs=revlogs,
+        )
+
+    # Now copy other files in the store directory.
+    # The sorted() makes execution deterministic.
+    for p, kind, st in sorted(srcrepo.store.vfs.readdir(b'', stat=True)):
+        if not _filterstorefile(srcrepo, dstrepo, requirements, p, kind, st):
+            continue
+
+        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 migrated to temporary repository\n'))
+
+    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'))
+    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()
+    util.rename(srcrepo.spath, backupvfs.join(b'store'))
+    util.rename(dstrepo.spath, srcrepo.spath)
+    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, requirements)
+
+    # 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.
+    backupvfs.unlink(b'store/lock')
+
+    return backuppath
--- a/setup.py	Sat Dec 05 23:11:49 2020 +0100
+++ b/setup.py	Tue Dec 01 09:13:08 2020 +0100
@@ -1287,6 +1287,7 @@
     'mercurial.thirdparty.attr',
     'mercurial.thirdparty.zope',
     'mercurial.thirdparty.zope.interface',
+    'mercurial.upgrade_utils',
     'mercurial.utils',
     'mercurial.revlogutils',
     'mercurial.testing',
--- a/tests/testlib/ext-sidedata.py	Sat Dec 05 23:11:49 2020 +0100
+++ b/tests/testlib/ext-sidedata.py	Tue Dec 01 09:13:08 2020 +0100
@@ -15,9 +15,10 @@
     node,
     requirements,
     revlog,
-    upgrade,
 )
 
+from mercurial.upgrade_utils import engine as upgrade_engine
+
 from mercurial.revlogutils import sidedata
 
 
@@ -79,5 +80,5 @@
     extensions.wrapfunction(revlog.revlog, 'addrevision', wrapaddrevision)
     extensions.wrapfunction(revlog.revlog, 'revision', wraprevision)
     extensions.wrapfunction(
-        upgrade, 'getsidedatacompanion', wrapgetsidedatacompanion
+        upgrade_engine, 'getsidedatacompanion', wrapgetsidedatacompanion
     )