# HG changeset patch
# User Simon Sapin <simon.sapin@octobus.net>
# Date 2021-05-19 16:35:43
# Node ID a43d256c041a59b9dc5859d79e3f28aebabd9180
# Parent  e985a36c2aa383f98f9a303013efe6ad0bd24ff0

dirstate-v2: Add `hg debugupgraderepo` command support

This command changes changes the file formats used inside an existing
repository to what they would be in a new repository with the current config.

For example:

    hg debugupgraderepo --config format.exp-dirstate-v2=1 --run
    hg debugupgraderepo --config format.exp-dirstate-v2=0 --run

If a repository has a dirstate in v1 format, the first command would upgrade it
to dirstate-v2. Conversely, if a repository has a dirstate in v2 format, the
second command would downgrade it to v1. (Both may also run some unrelated
upgrades.)

Since `format.exp-dirstate-v2` is currently disabled by default, not specifying
it in `--config` or any configuration file would result in the second command.

Differential Revision: https://phab.mercurial-scm.org/D10769

diff --git a/mercurial/dirstate.py b/mercurial/dirstate.py
--- a/mercurial/dirstate.py
+++ b/mercurial/dirstate.py
@@ -1775,6 +1775,12 @@ if rustmod is not None:
             # for consistent view between _pl() and _read() invocations
             self._pendingmode = None
 
+            self._use_dirstate_tree = self._ui.configbool(
+                b"experimental",
+                b"dirstate-tree.in-memory",
+                False,
+            )
+
         def addfile(self, *args, **kwargs):
             return self._rustmap.addfile(*args, **kwargs)
 
@@ -1903,13 +1909,8 @@ if rustmod is not None:
                     raise
                 st = b''
 
-            use_dirstate_tree = self._ui.configbool(
-                b"experimental",
-                b"dirstate-tree.in-memory",
-                False,
-            )
             self._rustmap, parents = rustmod.DirstateMap.new(
-                use_dirstate_tree, self._use_dirstate_v2, st
+                self._use_dirstate_tree, self._use_dirstate_v2, st
             )
 
             if parents and not self._dirtyparents:
diff --git a/mercurial/upgrade_utils/actions.py b/mercurial/upgrade_utils/actions.py
--- a/mercurial/upgrade_utils/actions.py
+++ b/mercurial/upgrade_utils/actions.py
@@ -80,7 +80,7 @@ class improvement(object):
     # operation in which this improvement was removed
     postdowngrademessage = None
 
-    # By default for now, we assume every improvement touches all the things
+    # By default we assume that every improvement touches requirements and all revlogs
 
     # Whether this improvement touches filelogs
     touches_filelogs = True
@@ -94,6 +94,9 @@ class improvement(object):
     # Whether this improvement changes repository requirements
     touches_requirements = True
 
+    # Whether this improvement touches the dirstate
+    touches_dirstate = False
+
 
 allformatvariant = []  # type: List[Type['formatvariant']]
 
@@ -167,6 +170,27 @@ class fncache(requirementformatvariant):
 
 
 @registerformatvariant
+class dirstatev2(requirementformatvariant):
+    name = b'dirstate-v2'
+    _requirement = requirements.DIRSTATE_V2_REQUIREMENT
+
+    default = False
+
+    description = _(
+        b'version 1 of the dirstate file format requires '
+        b'reading and parsing it all at once.'
+    )
+
+    upgrademessage = _(b'"hg status" will be faster')
+
+    touches_filelogs = False
+    touches_manifests = False
+    touches_changelog = False
+    touches_requirements = True
+    touches_dirstate = True
+
+
+@registerformatvariant
 class dotencode(requirementformatvariant):
     name = b'dotencode'
 
@@ -644,7 +668,6 @@ class UpgradeOperation(object):
         self.current_requirements = current_requirements
         # list of upgrade actions the operation will perform
         self.upgrade_actions = upgrade_actions
-        self._upgrade_actions_names = set([a.name for a in upgrade_actions])
         self.removed_actions = removed_actions
         self.revlogs_to_process = revlogs_to_process
         # requirements which will be added by the operation
@@ -667,41 +690,42 @@ class UpgradeOperation(object):
         ]
 
         # delta reuse mode of this upgrade operation
+        upgrade_actions_names = self.upgrade_actions_names
         self.delta_reuse_mode = revlog.revlog.DELTAREUSEALWAYS
-        if b're-delta-all' in self._upgrade_actions_names:
+        if b're-delta-all' in upgrade_actions_names:
             self.delta_reuse_mode = revlog.revlog.DELTAREUSENEVER
-        elif b're-delta-parent' in self._upgrade_actions_names:
+        elif b're-delta-parent' in upgrade_actions_names:
             self.delta_reuse_mode = revlog.revlog.DELTAREUSESAMEREVS
-        elif b're-delta-multibase' in self._upgrade_actions_names:
+        elif b're-delta-multibase' in upgrade_actions_names:
             self.delta_reuse_mode = revlog.revlog.DELTAREUSESAMEREVS
-        elif b're-delta-fulladd' in self._upgrade_actions_names:
+        elif b're-delta-fulladd' in upgrade_actions_names:
             self.delta_reuse_mode = revlog.revlog.DELTAREUSEFULLADD
 
         # should this operation force re-delta of both parents
         self.force_re_delta_both_parents = (
-            b're-delta-multibase' in self._upgrade_actions_names
+            b're-delta-multibase' in upgrade_actions_names
         )
 
         # should this operation create a backup of the store
         self.backup_store = backup_store
 
-        # whether the operation touches different revlogs at all or not
-        self.touches_filelogs = self._touches_filelogs()
-        self.touches_manifests = self._touches_manifests()
-        self.touches_changelog = self._touches_changelog()
-        # whether the operation touches requirements file or not
-        self.touches_requirements = self._touches_requirements()
-        self.touches_store = (
-            self.touches_filelogs
-            or self.touches_manifests
-            or self.touches_changelog
-        )
+    @property
+    def upgrade_actions_names(self):
+        return set([a.name for a in self.upgrade_actions])
+
+    @property
+    def requirements_only(self):
         # does the operation only touches repository requirement
-        self.requirements_only = (
-            self.touches_requirements and not self.touches_store
+        return (
+            self.touches_requirements
+            and not self.touches_filelogs
+            and not self.touches_manifests
+            and not self.touches_changelog
+            and not self.touches_dirstate
         )
 
-    def _touches_filelogs(self):
+    @property
+    def touches_filelogs(self):
         for a in self.upgrade_actions:
             # in optimisations, we re-process the revlogs again
             if a.type == OPTIMISATION:
@@ -713,7 +737,8 @@ class UpgradeOperation(object):
                 return True
         return False
 
-    def _touches_manifests(self):
+    @property
+    def touches_manifests(self):
         for a in self.upgrade_actions:
             # in optimisations, we re-process the revlogs again
             if a.type == OPTIMISATION:
@@ -725,7 +750,8 @@ class UpgradeOperation(object):
                 return True
         return False
 
-    def _touches_changelog(self):
+    @property
+    def touches_changelog(self):
         for a in self.upgrade_actions:
             # in optimisations, we re-process the revlogs again
             if a.type == OPTIMISATION:
@@ -737,7 +763,8 @@ class UpgradeOperation(object):
                 return True
         return False
 
-    def _touches_requirements(self):
+    @property
+    def touches_requirements(self):
         for a in self.upgrade_actions:
             # optimisations are used to re-process revlogs and does not result
             # in a requirement being added or removed
@@ -749,6 +776,18 @@ class UpgradeOperation(object):
             if a.touches_requirements:
                 return True
 
+    @property
+    def touches_dirstate(self):
+        for a in self.upgrade_actions:
+            # revlog optimisations do not affect the dirstate
+            if a.type == OPTIMISATION:
+                pass
+            elif a.touches_dirstate:
+                return True
+        for a in self.removed_actions:
+            if a.touches_dirstate:
+                return True
+
         return False
 
     def _write_labeled(self, l, label):
@@ -908,6 +947,7 @@ def supportremovedrequirements(repo):
         requirements.REVLOGV2_REQUIREMENT,
         requirements.CHANGELOGV2_REQUIREMENT,
         requirements.REVLOGV1_REQUIREMENT,
+        requirements.DIRSTATE_V2_REQUIREMENT,
     }
     for name in compression.compengines:
         engine = compression.compengines[name]
@@ -970,6 +1010,7 @@ def allowednewrequirements(repo):
         requirements.REVLOGV1_REQUIREMENT,
         requirements.REVLOGV2_REQUIREMENT,
         requirements.CHANGELOGV2_REQUIREMENT,
+        requirements.DIRSTATE_V2_REQUIREMENT,
     }
     for name in compression.compengines:
         engine = compression.compengines[name]
diff --git a/mercurial/upgrade_utils/engine.py b/mercurial/upgrade_utils/engine.py
--- a/mercurial/upgrade_utils/engine.py
+++ b/mercurial/upgrade_utils/engine.py
@@ -30,6 +30,7 @@ from ..revlogutils import (
     nodemap,
     sidedata as sidedatamod,
 )
+from . import actions as upgrade_actions
 
 
 def get_sidedata_helpers(srcrepo, dstrepo):
@@ -458,6 +459,19 @@ def upgrade(ui, srcrepo, dstrepo, upgrad
         )
     )
 
+    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 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)
@@ -466,7 +480,7 @@ def upgrade(ui, srcrepo, dstrepo, upgrad
     # through the whole cloning process
     elif (
         len(upgrade_op.upgrade_actions) == 1
-        and b'persistent-nodemap' in upgrade_op._upgrade_actions_names
+        and b'persistent-nodemap' in upgrade_op.upgrade_actions_names
         and not upgrade_op.removed_actions
     ):
         ui.status(
@@ -591,3 +605,28 @@ def upgrade(ui, srcrepo, dstrepo, upgrad
             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')
+        )
+        util.copyfile(
+            srcrepo.vfs.join(b'dirstate'), backupvfs.join(b'dirstate')
+        )
+
+    assert srcrepo.dirstate._use_dirstate_v2 == (old == b'v2')
+    srcrepo.dirstate._map._use_dirstate_tree = True
+    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._dirty = True
+    srcrepo.dirstate.write(None)
+
+    scmutil.writereporequirements(srcrepo, upgrade_op.new_requirements)
diff --git a/tests/test-copies-chain-merge.t b/tests/test-copies-chain-merge.t
--- a/tests/test-copies-chain-merge.t
+++ b/tests/test-copies-chain-merge.t
@@ -1652,6 +1652,7 @@ We upgrade a repository that is not usin
   $ hg debugformat -v
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -1691,6 +1692,7 @@ We upgrade a repository that is not usin
   $ hg debugformat -v
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
diff --git a/tests/test-copies-in-changeset.t b/tests/test-copies-in-changeset.t
--- a/tests/test-copies-in-changeset.t
+++ b/tests/test-copies-in-changeset.t
@@ -35,6 +35,7 @@ Check that copies are recorded correctly
   $ hg debugformat -v
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -52,6 +53,7 @@ Check that copies are recorded correctly
   $ hg debugformat -v
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -426,6 +428,7 @@ downgrading
   $ hg debugformat -v
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -456,6 +459,7 @@ downgrading
   $ hg debugformat -v
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -483,6 +487,7 @@ upgrading
   $ hg debugformat -v
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
diff --git a/tests/test-persistent-nodemap.t b/tests/test-persistent-nodemap.t
--- a/tests/test-persistent-nodemap.t
+++ b/tests/test-persistent-nodemap.t
@@ -57,6 +57,7 @@ As a result, -1 passed from Rust for the
   $ hg debugformat
   format-variant     repo
   fncache:            yes
+  dirstate-v2:         no
   dotencode:          yes
   generaldelta:       yes
   share-safe:          no
@@ -577,6 +578,7 @@ downgrading
   $ hg debugformat -v
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -626,6 +628,7 @@ upgrading
   $ hg debugformat -v
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
diff --git a/tests/test-sidedata.t b/tests/test-sidedata.t
--- a/tests/test-sidedata.t
+++ b/tests/test-sidedata.t
@@ -52,6 +52,7 @@ Check that we can upgrade to sidedata
   $ hg debugformat -v -R up-no-side-data
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -68,6 +69,7 @@ Check that we can upgrade to sidedata
   $ hg debugformat -v -R up-no-side-data --config experimental.revlogv2=enable-unstable-format-and-corrupt-my-data
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -90,6 +92,7 @@ Check that we can downgrade from sidedat
   $ hg debugformat -v -R up-side-data
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -106,6 +109,7 @@ Check that we can downgrade from sidedat
   $ hg debugformat -v -R up-side-data --config experimental.revlogv2=no
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
diff --git a/tests/test-upgrade-repo.t b/tests/test-upgrade-repo.t
--- a/tests/test-upgrade-repo.t
+++ b/tests/test-upgrade-repo.t
@@ -57,6 +57,7 @@ An upgrade of a repository created with 
   $ hg debugformat
   format-variant     repo
   fncache:            yes
+  dirstate-v2:         no
   dotencode:          yes
   generaldelta:       yes
   share-safe:          no
@@ -72,6 +73,7 @@ An upgrade of a repository created with 
   $ hg debugformat --verbose
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -88,6 +90,7 @@ An upgrade of a repository created with 
   $ hg debugformat --verbose --config format.usefncache=no
   format-variant     repo config default
   fncache:            yes     no     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes     no     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -104,6 +107,7 @@ An upgrade of a repository created with 
   $ hg debugformat --verbose --config format.usefncache=no --color=debug
   format-variant     repo config default
   [formatvariant.name.mismatchconfig|fncache:           ][formatvariant.repo.mismatchconfig| yes][formatvariant.config.special|     no][formatvariant.default|     yes]
+  [formatvariant.name.uptodate|dirstate-v2:       ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
   [formatvariant.name.mismatchconfig|dotencode:         ][formatvariant.repo.mismatchconfig| yes][formatvariant.config.special|     no][formatvariant.default|     yes]
   [formatvariant.name.uptodate|generaldelta:      ][formatvariant.repo.uptodate| yes][formatvariant.config.default|    yes][formatvariant.default|     yes]
   [formatvariant.name.uptodate|share-safe:        ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
@@ -126,6 +130,12 @@ An upgrade of a repository created with 
     "repo": true
    },
    {
+    "config": false,
+    "default": false,
+    "name": "dirstate-v2",
+    "repo": false
+   },
+   {
     "config": true,
     "default": true,
     "name": "dotencode",
@@ -327,6 +337,7 @@ Various sub-optimal detections work
   $ hg debugformat
   format-variant     repo
   fncache:             no
+  dirstate-v2:         no
   dotencode:           no
   generaldelta:        no
   share-safe:          no
@@ -341,6 +352,7 @@ Various sub-optimal detections work
   $ hg debugformat --verbose
   format-variant     repo config default
   fncache:             no    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:           no    yes     yes
   generaldelta:        no    yes     yes
   share-safe:          no     no      no
@@ -357,6 +369,7 @@ Various sub-optimal detections work
   $ hg debugformat --verbose --config format.usegeneraldelta=no
   format-variant     repo config default
   fncache:             no    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:           no    yes     yes
   generaldelta:        no     no     yes
   share-safe:          no     no      no
@@ -373,6 +386,7 @@ Various sub-optimal detections work
   $ hg debugformat --verbose --config format.usegeneraldelta=no --color=debug
   format-variant     repo config default
   [formatvariant.name.mismatchconfig|fncache:           ][formatvariant.repo.mismatchconfig|  no][formatvariant.config.default|    yes][formatvariant.default|     yes]
+  [formatvariant.name.uptodate|dirstate-v2:       ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
   [formatvariant.name.mismatchconfig|dotencode:         ][formatvariant.repo.mismatchconfig|  no][formatvariant.config.default|    yes][formatvariant.default|     yes]
   [formatvariant.name.mismatchdefault|generaldelta:      ][formatvariant.repo.mismatchdefault|  no][formatvariant.config.special|     no][formatvariant.default|     yes]
   [formatvariant.name.uptodate|share-safe:        ][formatvariant.repo.uptodate|  no][formatvariant.config.default|     no][formatvariant.default|      no]
@@ -1355,6 +1369,7 @@ upgrade
   $ hg debugformat -v
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -1396,6 +1411,7 @@ downgrade
   $ hg debugformat -v
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -1440,6 +1456,7 @@ upgrade from hgrc
   $ hg debugformat -v
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -1490,6 +1507,7 @@ upgrade
   $ hg debugformat -v
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -1537,6 +1555,7 @@ downgrade
   $ hg debugformat -v
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -1585,6 +1604,7 @@ upgrade from hgrc
   $ hg debugformat -v
   format-variant     repo config default
   fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
   dotencode:          yes    yes     yes
   generaldelta:       yes    yes     yes
   share-safe:          no     no      no
@@ -1613,3 +1633,105 @@ Demonstrate that nothing to perform upgr
 
   $ hg debugupgraderepo --run
   nothing to do
+
+#if rust
+
+Upgrade to dirstate-v2
+
+  $ hg debugformat -v --config format.exp-dirstate-v2=1
+  format-variant     repo config default
+  fncache:            yes    yes     yes
+  dirstate-v2:         no    yes      no
+  dotencode:          yes    yes     yes
+  generaldelta:       yes    yes     yes
+  share-safe:          no     no      no
+  sparserevlog:       yes    yes     yes
+  persistent-nodemap: yes    yes      no
+  copies-sdc:          no     no      no
+  revlog-v2:          yes    yes      no
+  changelog-v2:        no     no      no
+  plain-cl-delta:     yes    yes     yes
+  compression:        zstd   zstd    zstd
+  compression-level:  default default default
+  $ hg debugupgraderepo --config format.exp-dirstate-v2=1 --run
+  upgrade will perform the following actions:
+  
+  requirements
+     preserved: dotencode, exp-revlogv2.2, fncache, generaldelta, persistent-nodemap, revlog-compression-zstd, sparserevlog, store
+     added: exp-dirstate-v2
+  
+  dirstate-v2
+     "hg status" will be faster
+  
+  processed revlogs:
+    - all-filelogs
+    - changelog
+    - manifest
+  
+  beginning upgrade...
+  repository locked and read-only
+  creating temporary repository to stage upgraded data: $TESTTMP/sparserevlogrepo/.hg/upgrade.* (glob)
+  (it is safe to interrupt this process any time before data migration completes)
+  upgrading to dirstate-v2 from v1
+  replaced files will be backed up at $TESTTMP/sparserevlogrepo/.hg/upgradebackup.* (glob)
+  removing temporary repository $TESTTMP/sparserevlogrepo/.hg/upgrade.* (glob)
+  $ ls .hg/upgradebackup.*/dirstate
+  .hg/upgradebackup.*/dirstate (glob)
+  $ hg debugformat -v
+  format-variant     repo config default
+  fncache:            yes    yes     yes
+  dirstate-v2:        yes     no      no
+  dotencode:          yes    yes     yes
+  generaldelta:       yes    yes     yes
+  share-safe:          no     no      no
+  sparserevlog:       yes    yes     yes
+  persistent-nodemap: yes    yes      no
+  copies-sdc:          no     no      no
+  revlog-v2:          yes    yes      no
+  changelog-v2:        no     no      no
+  plain-cl-delta:     yes    yes     yes
+  compression:        zstd   zstd    zstd
+  compression-level:  default default default
+  $ hg status
+  $ dd status=none bs=12 count=1 if=.hg/dirstate
+  dirstate-v2
+
+Downgrade from dirstate-v2
+
+  $ hg debugupgraderepo --run
+  upgrade will perform the following actions:
+  
+  requirements
+     preserved: dotencode, exp-revlogv2.2, fncache, generaldelta, persistent-nodemap, revlog-compression-zstd, sparserevlog, store
+     removed: exp-dirstate-v2
+  
+  processed revlogs:
+    - all-filelogs
+    - changelog
+    - manifest
+  
+  beginning upgrade...
+  repository locked and read-only
+  creating temporary repository to stage upgraded data: $TESTTMP/sparserevlogrepo/.hg/upgrade.* (glob)
+  (it is safe to interrupt this process any time before data migration completes)
+  downgrading from dirstate-v2 to v1
+  replaced files will be backed up at $TESTTMP/sparserevlogrepo/.hg/upgradebackup.* (glob)
+  removing temporary repository $TESTTMP/sparserevlogrepo/.hg/upgrade.* (glob)
+  $ hg debugformat -v
+  format-variant     repo config default
+  fncache:            yes    yes     yes
+  dirstate-v2:         no     no      no
+  dotencode:          yes    yes     yes
+  generaldelta:       yes    yes     yes
+  share-safe:          no     no      no
+  sparserevlog:       yes    yes     yes
+  persistent-nodemap: yes    yes      no
+  copies-sdc:          no     no      no
+  revlog-v2:          yes    yes      no
+  changelog-v2:        no     no      no
+  plain-cl-delta:     yes    yes     yes
+  compression:        zstd   zstd    zstd
+  compression-level:  default default default
+  $ hg status
+
+#endif