dirstate: remove the dedicated backup logic

When alone, the dirstate can now take care of its commit/rollback pattern
itself.

When in a transaction, the transaction deal with commit/rollback pattern quite
fine.

Why did you have a dedicated backup logic?

hgext/git/dirstate.py

@@ -327,14 +327,6 b' class gitdirstate:'
             r[path] = s
         return r
 
-    def savebackup(self, tr, backupname):
-        # TODO: figure out a strategy for saving index backups.
-        pass
-
-    def restorebackup(self, tr, backupname):
-        # TODO: figure out a strategy for saving index backups.
-        pass
-
     def set_tracked(self, f, reset_copy=False):
         # TODO: support copies and reset_copy=True
         uf = pycompat.fsdecode(f)
@@ -397,10 +389,6 b' class gitdirstate:'
         # TODO: should this be added to the dirstate interface?
         self._plchangecallbacks[category] = callback
 
-    def clearbackup(self, tr, backupname):
-        # TODO
-        pass
-
     def setbranch(self, branch):
         raise error.Abort(
             b'git repos do not support branches. try using bookmarks'

mercurial/dirstate.py

@@ -31,7 +31,6 b' from . import ('
 )
 
 from .dirstateutils import (
-    docket as docketmod,
     timestamp,
 )
 
@@ -1631,123 +1630,6 b' class dirstate:'
         else:
             return (self._filename,)
 
-    def data_backup_filename(self, backupname):
-        if not self._use_dirstate_v2:
-            return None
-        return backupname + b'.v2-data'
-
-    def _new_backup_data_filename(self, backupname):
-        """return a filename to backup a data-file or None"""
-        if not self._use_dirstate_v2:
-            return None
-        if self._map.docket.uuid is None:
-            # not created yet, nothing to backup
-            return None
-        data_filename = self._map.docket.data_filename()
-        return data_filename, self.data_backup_filename(backupname)
-
-    def backup_data_file(self, backupname):
-        if not self._use_dirstate_v2:
-            return None
-        docket = docketmod.DirstateDocket.parse(
-            self._opener.read(backupname),
-            self._nodeconstants,
-        )
-        return self.data_backup_filename(backupname), docket.data_filename()
-
-    def savebackup(self, tr, backupname):
-        '''Save current dirstate into backup file'''
-        filename = self._actualfilename(tr)
-        assert backupname != filename
-
-        # use '_writedirstate' instead of 'write' to write changes certainly,
-        # because the latter omits writing out if transaction is running.
-        # output file will be used to create backup of dirstate at this point.
-        if self._dirty:
-            self._writedirstate(
-                tr,
-                self._opener(filename, b"w", atomictemp=True, checkambig=True),
-            )
-
-        if tr:
-            # ensure that subsequent tr.writepending returns True for
-            # changes written out above, even if dirstate is never
-            # changed after this
-            tr.addfilegenerator(
-                b'dirstate-1-main',
-                (self._filename,),
-                lambda f: self._writedirstate(tr, f),
-                location=b'plain',
-                post_finalize=True,
-            )
-
-        self._opener.tryunlink(backupname)
-        if self._opener.exists(filename):
-            # hardlink backup is okay because _writedirstate is always called
-            # with an "atomictemp=True" file.
-            util.copyfile(
-                self._opener.join(filename),
-                self._opener.join(backupname),
-                hardlink=True,
-            )
-            data_pair = self._new_backup_data_filename(backupname)
-            if data_pair is not None:
-                data_filename, bck_data_filename = data_pair
-                util.copyfile(
-                    self._opener.join(data_filename),
-                    self._opener.join(bck_data_filename),
-                    hardlink=True,
-                )
-                if tr is not None:
-                    # ensure that pending file written above is unlinked at
-                    # failure, even if tr.writepending isn't invoked until the
-                    # end of this transaction
-                    tr.registertmp(bck_data_filename, location=b'plain')
-
-    def restorebackup(self, tr, backupname):
-        '''Restore dirstate by backup file'''
-        # this "invalidate()" prevents "wlock.release()" from writing
-        # changes of dirstate out after restoring from backup file
-        self.invalidate()
-        o = self._opener
-        if not o.exists(backupname):
-            # there was no file backup, delete existing files
-            filename = self._actualfilename(tr)
-            data_file = None
-            if self._use_dirstate_v2 and self._map.docket.uuid is not None:
-                data_file = self._map.docket.data_filename()
-            if o.exists(filename):
-                o.unlink(filename)
-            if data_file is not None and o.exists(data_file):
-                o.unlink(data_file)
-            return
-        filename = self._actualfilename(tr)
-        data_pair = self.backup_data_file(backupname)
-        if o.exists(filename) and util.samefile(
-            o.join(backupname), o.join(filename)
-        ):
-            o.unlink(backupname)
-        else:
-            o.rename(backupname, filename, checkambig=True)
-
-        if data_pair is not None:
-            data_backup, target = data_pair
-            if o.exists(target) and util.samefile(
-                o.join(data_backup), o.join(target)
-            ):
-                o.unlink(data_backup)
-            else:
-                o.rename(data_backup, target, checkambig=True)
-
-    def clearbackup(self, tr, backupname):
-        '''Clear backup file'''
-        o = self._opener
-        if o.exists(backupname):
-            data_backup = self.backup_data_file(backupname)
-            o.unlink(backupname)
-            if data_backup is not None:
-                o.unlink(data_backup[0])
-
     def verify(self, m1, m2, p1, narrow_matcher=None):
         """
         check the dirstate contents against the parent manifest and yield errors

mercurial/interfaces/dirstate.py

@@ -220,15 +220,6 b' class idirstate(interfaceutil.Interface)'
         return files in the dirstate (in whatever state) filtered by match
         """
 
-    def savebackup(tr, backupname):
-        '''Save current dirstate into backup file'''
-
-    def restorebackup(tr, backupname):
-        '''Restore dirstate by backup file'''
-
-    def clearbackup(tr, backupname):
-        '''Clear backup file'''
-
     def verify(m1, m2, p1, narrow_matcher=None):
         """
         check the dirstate contents against the parent manifest and yield errors