[PATCH 1 of 4] histedit: add a method to cleanup nodes safely

[Yuya Nishihara]

On Fri, 17 Mar 2017 08:37:14 -0700, Jun Wu wrote:
> Excerpts from Yuya Nishihara's message of 2017-03-17 22:32:45 +0900:
> > On Mon, 13 Mar 2017 22:36:16 -0700, Jun Wu wrote:
> > > # HG changeset patch
> > > # User Jun Wu <quark at fb.com>
> > > # Date 1489464645 25200
> > > #      Mon Mar 13 21:10:45 2017 -0700
> > > # Node ID b4cf155f7a41ebf314407000f6948716ae0a64e2
> > > # Parent  3d3109339b57341b333c1112beb41dd281fa944a
> > > # Available At https://bitbucket.org/quark-zju/hg-draft 
> > > #              hg pull https://bitbucket.org/quark-zju/hg-draft  -r b4cf155f7a41
> > > histedit: add a method to cleanup nodes safely
> > 
> > The series looks good to me, but one nit.
> > 
> > > diff --git a/hgext/histedit.py b/hgext/histedit.py
> > > --- a/hgext/histedit.py
> > > +++ b/hgext/histedit.py
> > > @@ -1582,4 +1582,29 @@ def cleanupnode(ui, repo, name, nodes):
> > >              repair.strip(ui, repo, c)
> > >  
> > > +def safecleanupnode(ui, repo, name, nodes):
> > > +    """strip or obsolete nodes
> > > +
> > > +    nodes could be either a set or dict which maps to replacements.
> > > +    nodes could be unknown (outside the repo).
> > > +    """
> > > +    supportsmarkers = obsolete.isenabled(repo, obsolete.createmarkersopt)
> > > +    if supportsmarkers:
> > > +        if util.safehasattr(nodes, 'get'):
> > > +            # nodes is a dict-like mapping
> > > +            # use unfiltered repo for successors in case they are hidden
> > > +            urepo = repo.unfiltered()
> > > +            marker = lambda x: (repo[x], (urepo[n] for n in nodes.get(x, ())))
> >                                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > 
> > This isn't a tuple but a generator. Is that by intention?
> 
> Yes. Since obsolete.createmarkers only requires an "iterable", I think a
> generator may make the space complexity from O(N) to O(1). Another reason is
> the code fits in one line.

Well, it works as 'sucs' is consumed only once, but the doc doesn't say
'sucs' can be an iterable. And it seems to me that each item of 'relations'
is designed as immutable.

  "<relations> must be an iterable of (<old>, (<new>, ...)[,{metadata}]) tuple."