[PATCH 1 of 2] bdiff: early pruning of common prefix before doing expensive computations

[Augie Fackler]

On Thu, Nov 17, 2016 at 08:29:46PM +0100, Mads Kiilerich wrote:
> On 11/17/2016 07:53 PM, Gregory Szorc wrote:
> >On Thu, Nov 17, 2016 at 9:16 AM, Mads Kiilerich <mads at kiilerich.com
> ><mailto:mads at kiilerich.com>> wrote:
> >
> >    # HG changeset patch
> >    # User Mads Kiilerich <madski at unity3d.com <mailto:madski at unity3d.com>>
> >    # Date 1479321935 -3600
> >    #      Wed Nov 16 19:45:35 2016 +0100
> >    # Node ID 7f39bccc1c96bffc83f3c6e774da57ecd38982a7
> >    # Parent  fe6a3576b863955a6c40ca46bd1d6c8e5384dedf
> >    bdiff: early pruning of common prefix before doing expensive
> >    computations

[...]

> >    diff --git a/mercurial/bdiff_module.c b/mercurial/bdiff_module.c
> >    --- a/mercurial/bdiff_module.c
> >    +++ b/mercurial/bdiff_module.c
> >    @@ -61,12 +61,12 @@ nomem:
> >
> >     static PyObject *bdiff(PyObject *self, PyObject *args)
> >
> >
> >Implementing this in the Python module means that CFFI/PyPy won't be able
> >to realize the perf wins :(
> >
> >How do you feel about implementing this in bdiff.c?
>
> I guess other logic also should move from bdiff_module to bdiff.c? This was
> just the easy way to hook in before the two sides got split into lines.

If you're willing, I'd be a big fan of this change happening in such a
way that pypy gets the wins too. What say you?