[PATCH 3 of 3] localrepo: use dirstate backup instead of handling dirstate file manually

[Mateusz Kwapich]

# HG changeset patch
# User Mateusz Kwapich <mitrandir at fb.com>
# Date 1462494839 25200
#      Thu May 05 17:33:59 2016 -0700
# Node ID fce6ff5bc4dbf5529a271c1c8dc4b0e461e26251
# Parent  960056f578173d3da54cd0a3c1e05e06b39e64fe
localrepo: use dirstate backup instead of handling dirstate file manually

This is one step towards having dirstate manage its own storage. It will
be useful for the implementation of sql dirstate [1].

[1] https://www.mercurial-scm.org/wiki/SQLDirstatePlan

diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -1013,9 +1013,6 @@ class localrepository(object):
                 _("abandoned transaction found"),
                 hint=_("run 'hg recover' to clean up transaction"))
 
-        # make journal.dirstate contain in-memory changes at this point
-        self.dirstate.write(None)
-
         idbase = "%.40f#%f" % (random.random(), time.time())
         txnid = 'TXN:' + util.sha1(idbase).hexdigest()
         self.hook('pretxnopen', throw=True, txnname=desc, txnid=txnid)
@@ -1049,7 +1046,7 @@ class localrepository(object):
 
                 # discard all changes (including ones already written
                 # out) in this transaction
-                repo.vfs.rename('journal.dirstate', 'dirstate')
+                repo.dirstate.restorebackup(None, prefix='journal.')
 
                 repo.invalidate(clearfilecache=True)
 
@@ -1104,8 +1101,7 @@ class localrepository(object):
         return [(vfs, undoname(x)) for vfs, x in self._journalfiles()]
 
     def _writejournal(self, desc):
-        self.vfs.write("journal.dirstate",
-                          self.vfs.tryread("dirstate"))
+        self.dirstate.savebackup(None, prefix='journal.')
         self.vfs.write("journal.branch",
                           encoding.fromlocal(self.dirstate.branch()))
         self.vfs.write("journal.desc",
@@ -1191,7 +1187,7 @@ class localrepository(object):
             # prevent dirstateguard from overwriting already restored one
             dsguard.close()
 
-            self.vfs.rename('undo.dirstate', 'dirstate')
+            self.dirstate.restorebackup(None, prefix='undo.')
             try:
                 branch = self.vfs.read('undo.branch')
                 self.dirstate.setbranch(encoding.tolocal(branch))
@@ -1200,7 +1196,6 @@ class localrepository(object):
                           'current branch is still \'%s\'\n')
                         % self.dirstate.branch())
 
-            self.dirstate.invalidate()
             parents = tuple([p.rev() for p in self[None].parents()])
             if len(parents) > 1:
                 ui.status(_('working directory now based on '
diff --git a/tests/test-inherit-mode.t b/tests/test-inherit-mode.t
--- a/tests/test-inherit-mode.t
+++ b/tests/test-inherit-mode.t
@@ -117,6 +117,7 @@ group can still write everything
   00660 ../push/.hg/cache/branch2-base
   00660 ../push/.hg/cache/rbc-names-v1
   00660 ../push/.hg/cache/rbc-revs-v1
+  00660 ../push/.hg/dirstate
   00660 ../push/.hg/requires
   00770 ../push/.hg/store/
   00660 ../push/.hg/store/00changelog.i