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Re: [Monotone-devel] Re: Bug in monotone lca
From: |
Nathaniel Smith |
Subject: |
Re: [Monotone-devel] Re: Bug in monotone lca |
Date: |
Fri, 20 May 2005 02:19:07 -0700 |
User-agent: |
Mutt/1.5.9i |
On Fri, May 20, 2005 at 09:48:06AM +0200, Wim Oudshoorn wrote:
> Nathaniel Smith <address@hidden> writes:
> > It doesn't make much of a difference for anything
> > that monotone uses its LCA algorithm for, though; in fact, "nearest
> > common ancestor" is probably better. (We just use LCA when we want a
> > nearby common ancestor, that we can use to generate a path from one
> > node to another, for instance.)
> >
> > This is why, though, if someone wanted to make
> > unique-lca-or-else-lca+dom into the merge ancestor selection
> > algorithm as a temporary stopgap measure, they would have to actually
> > do some work, since for merging you really do need to use the "minimal
> > common ancestor" variant.
>
> Yes indeed. But a looked at the code a little and although
> the lca code I more or less undestand, I can't figure
> out what lcad is doing.
>
> Is there some precise specification of what it is supposed to do?
It is supposed to find the unique node A such that:
- A is a common ancestor
- A is comparable to all ancestors of one side
- no descendents of A have the above two properties
This is always unique, and so long as the graph is single rooted,
always defined.
> P.S.: As a stopgap measure, I still think my proposal of a week
> ago is better :-)
Indeed, it looked quite interesting and plausible; I've been meaning
to respond, but it takes some effort to wrap my head back around what
sort of properties are needed and figure out whether I really believe
your suggestion handles all the bad cases...
> However that also requires real implementation
> work :-(.
Perhaps less than you might think; some things are already written.
(For instance, there's already a function that finds the heads of an
arbitrary revision set, which I seem to recall being one of the
primitives you want...)
> I might want to try to refresh my C++ knowledge,
> however monotone takes over 2hrs to compile on my fast computer :-(.
> I dread how long it will take to compile on my server
> which is really slow.
'./configure CFLAGS="-O0 -ggdb3" CXXFLAGS="-O0 -ggdb3"' makes a huge
difference :-). (Actually just the -O0 part, but when you're
developing, it's sorta handy to always have debugging info there
without having to recompile for it.)
(ccache is also very, very helpful.)
-- Nathaniel
--
"On arrival in my ward I was immediately served with lunch. `This is
what you ordered yesterday.' I pointed out that I had just arrived,
only to be told: `This is what your bed ordered.'"
-- Letter to the Editor, The Times, September 2000
- [Monotone-devel] Bug in monotone lca, Wim Oudshoorn, 2005/05/19
- Re: [Monotone-devel] Bug in monotone lca, Timothy Brownawell, 2005/05/19
- Re: [Monotone-devel] Bug in monotone lca, Wim Oudshoorn, 2005/05/19
- Re: [Monotone-devel] Bug in monotone lca, Nathaniel Smith, 2005/05/19
- [Monotone-devel] Re: Bug in monotone lca, Wim Oudshoorn, 2005/05/20
- Re: [Monotone-devel] Re: Bug in monotone lca,
Nathaniel Smith <=
- [Monotone-devel] Re: Bug in monotone lca, Wim Oudshoorn, 2005/05/20
- Re: [Monotone-devel] Re: Bug in monotone lca, Nathaniel Smith, 2005/05/20
- [Monotone-devel] Re: Bug in monotone lca, Wim Oudshoorn, 2005/05/20
- Re: [Monotone-devel] Re: Bug in monotone lca, Nathaniel Smith, 2005/05/20
- Re: [Monotone-devel] Re: Bug in monotone lca, Florian Weimer, 2005/05/20
- [Monotone-devel] Re: Bug in monotone lca, Wim Oudshoorn, 2005/05/20
- Re: [Monotone-devel] Re: Bug in monotone lca, Nathaniel Smith, 2005/05/20