[PATCH 1 of 3] rebase: use one dirstateguard for entire rebase

[Yuya Nishihara]

On Mon, 20 Mar 2017 20:14:20 +0900, FUJIWARA Katsunori wrote:
> (Cc-ed to yuya, for confirmation)
> 
> At Sun, 19 Mar 2017 12:00:56 -0700,
> Durham Goode wrote:
> > 
> > # HG changeset patch
> > # User Durham Goode <durham at fb.com>
> > # Date 1489949655 25200
> > #      Sun Mar 19 11:54:15 2017 -0700
> > # Node ID c2f68e8cd96f92c2fa240fe04e541c14c1bad3d8
> > # Parent  75e4bae56068bec4f965773a2d5f4d272a8dc5b0
> > 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.
> > 
> > diff --git a/hgext/rebase.py b/hgext/rebase.py
> > --- a/hgext/rebase.py
> > +++ b/hgext/rebase.py
> > @@ -475,12 +475,24 @@ 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:
> 
> This hunk just moves dirstateguard creation from concludenode() to
> caller side.
> 
> Therefore, creation of dirstateguard at each concludenode() while
> rebasing is not "one dirstateguard for entire rebase" but still
> "dirstateguard per rebased-revision".
> 
> In addition to it, dirstateguard in this hunk should be redundant,
> because we already know that another dirstategurad is certainly
> created in outer scope (but in same transaction) as below hunk.

This is actually _two_ dirstateguards for entire rebase. One for
_performrebase and the other for _finishrebase. I haven't investigated if
we can move _finishrebase into the transaction.