rebase: use one dirstateguard for entire rebase

Recently we switched rebases to run the entire rebase inside a single
transaction, which dramatically improved the speed of rebases in repos with
large working copies. Let's also move the dirstate into a single dirstateguard
to get the same benefits. This let's us avoid serializing the dirstate after
each commit.

In a large repo, rebasing 27 commits is sped up by about 20%.

I believe the test changes are because us touching the dirstate gave the
transaction something to actually rollback.

hgext/rebase.py

@@ -475,12 +475,24 b' class rebaseruntime(object):'
                 editopt = True
             editor = cmdutil.getcommiteditor(edit=editopt, editform=editform)
             revtoreuse = max(self.state)
-            newnode = concludenode(repo, revtoreuse, p1, self.external,
-                                   commitmsg=commitmsg,
-                                   extrafn=_makeextrafn(self.extrafns),
-                                   editor=editor,
-                                   keepbranches=self.keepbranchesf,
-                                   date=self.date)
+            dsguard = dirstateguard.dirstateguard(repo, 'rebase')
+            try:
+                newnode = concludenode(repo, revtoreuse, p1, self.external,
+                                       commitmsg=commitmsg,
+                                       extrafn=_makeextrafn(self.extrafns),
+                                       editor=editor,
+                                       keepbranches=self.keepbranchesf,
+                                       date=self.date)
+                dsguard.close()
+                release(dsguard)
+            except error.InterventionRequired:
+                dsguard.close()
+                release(dsguard)
+                raise
+            except Exception:
+                release(dsguard)
+                raise
+
             if newnode is None:
                 newrev = self.target
             else:
@@ -712,11 +724,19 b' def rebase(ui, repo, **opts):'
                 return retcode
 
         with repo.transaction('rebase') as tr:
+            dsguard = dirstateguard.dirstateguard(repo, 'rebase')
             try:
                 rbsrt._performrebase(tr)
+                dsguard.close()
+                release(dsguard)
             except error.InterventionRequired:
+                dsguard.close()
+                release(dsguard)
                 tr.close()
                 raise
+            except Exception:
+                release(dsguard)
+                raise
         rbsrt._finishrebase()
     finally:
         release(lock, wlock)
@@ -840,33 +860,28 b' def concludenode(repo, rev, p1, p2, comm'
     '''Commit the wd changes with parents p1 and p2. Reuse commit info from rev
     but also store useful information in extra.
     Return node of committed revision.'''
-    dsguard = dirstateguard.dirstateguard(repo, 'rebase')
-    try:
-        repo.setparents(repo[p1].node(), repo[p2].node())
-        ctx = repo[rev]
-        if commitmsg is None:
-            commitmsg = ctx.description()
-        keepbranch = keepbranches and repo[p1].branch() != ctx.branch()
-        extra = {'rebase_source': ctx.hex()}
-        if extrafn:
-            extrafn(ctx, extra)
+    repo.setparents(repo[p1].node(), repo[p2].node())
+    ctx = repo[rev]
+    if commitmsg is None:
+        commitmsg = ctx.description()
+    keepbranch = keepbranches and repo[p1].branch() != ctx.branch()
+    extra = {'rebase_source': ctx.hex()}
+    if extrafn:
+        extrafn(ctx, extra)
 
-        targetphase = max(ctx.phase(), phases.draft)
-        overrides = {('phases', 'new-commit'): targetphase}
-        with repo.ui.configoverride(overrides, 'rebase'):
-            if keepbranch:
-                repo.ui.setconfig('ui', 'allowemptycommit', True)
-            # Commit might fail if unresolved files exist
-            if date is None:
-                date = ctx.date()
-            newnode = repo.commit(text=commitmsg, user=ctx.user(),
-                                  date=date, extra=extra, editor=editor)
+    targetphase = max(ctx.phase(), phases.draft)
+    overrides = {('phases', 'new-commit'): targetphase}
+    with repo.ui.configoverride(overrides, 'rebase'):
+        if keepbranch:
+            repo.ui.setconfig('ui', 'allowemptycommit', True)
+        # Commit might fail if unresolved files exist
+        if date is None:
+            date = ctx.date()
+        newnode = repo.commit(text=commitmsg, user=ctx.user(),
+                              date=date, extra=extra, editor=editor)
 
-        repo.dirstate.setbranch(repo[newnode].branch())
-        dsguard.close()
-        return newnode
-    finally:
-        release(dsguard)
+    repo.dirstate.setbranch(repo[newnode].branch())
+    return newnode
 
 def rebasenode(repo, rev, p1, base, state, collapse, target):
     'Rebase a single revision rev on top of p1 using base as merge ancestor'

tests/test-rebase-collapse.t

@@ -572,6 +572,8 b' Interactions between collapse and keepbr'
   o  0: 'A'
   
   $ hg rebase --keepbranches --collapse -s 1 -d 3
+  transaction abort!
+  rollback completed
   abort: cannot collapse multiple named branches
   [255]
 

tests/test-rebase-scenario-global.t

@@ -270,6 +270,8 b' G onto B - merge revision with both pare'
 
   $ hg rebase -s 6 -d 1
   rebasing 6:eea13746799a "G"
+  transaction abort!
+  rollback completed
   abort: cannot use revision 6 as base, result would have 3 parents
   [255]
   $ hg rebase --abort